| djmiddelkoop |
My sony 777es player doesn't play SACD.
CD playback however is fine.
A SACD is not recognized, the dispay reads: TOC error *
Does anyone have an idea what is causing this ?
Do I need a new laser ?
Any help is appreciated.
Dick |
|
|
| smithie |
hi
dont want to ruin your day but let me tell you my tale....
i had the same player,it was going to be the last one i brought as i loved the build,sound,everything,paid under £1800 for it.
anyway after 14months mine developed the same problem as yours then about 2weeks after that cd reply was getting to be a problem until that gave up also.
got intouch with sony as i expected alittle more then over a yrs worth of use out of there expensive,made in japan flagship model,moreso as my old english cottage industry built cambridge cd player was still working fine after ten years use!
sonys reply was...SORRY YOUR OUT OF YOUR WARRENTY PERIOD AND THE COST AND EPAIR IS DOWN TO YOU.
needless to say i wasnt happy with that,and after many heated disscussions then threats they agreed to foot the bill for pickup and repair,the technican who got in touch with me told me the transport assembly was worn out and that it would all be replaced,total cost £500,so thank god sony was paying!
anyway when i got it back,it broke my heart to do it as i really did love this player but i sold it,just couldnt get my head around how it could be worn out so quickly and the thought of footing that bill every one to two years put me right off.
now i dont do flagship models,just buy stuff that dont cost silly money that if it breaks after a yr then it doesnt owe me anything!...sad but true.
hopefully mine might of been a one off,anywaY i wish you luck with the repair!
all the best
smithie |
|
|
| Elso Kwak |
| quote: | Originally posted by djmiddelkoop
My sony 777es player doesn't play SACD.
CD playback however is fine.
A SACD is not recognized, the dispay reads: TOC error *
Does anyone have an idea what is causing this ?
Do I need a new laser ?
Any help is appreciated.
Dick |
Hi Dick,
My friend had the same problem with the Sony SCD-1 which is essentially the same player. Sony replaced the laser under warrenty, but it was close to the end of the period.
:cool: |
|
|
| georgehifi |
My freind has had 2x Sony 9000 with the same problems, Sony had replaced the first one with a new one and now it's playing up, now they said that their not doing the high end models anymore, and offer a much cheaper model, or to have his fixed with new laser and circuit boards, but they will not say if it will fix the problem, it looks to me as Sony are getting out of the high end because of the problems they are having.
Cheers George |
|
|
| djmiddelkoop |
Thanks a lot Smithie, Elso and George for your replies.
This is what I was afraid off, the laser assy needs to be replaced and it’s costly.
:bawling:
It is indeed sad that a lot of cheaper players work fine for years and the High end break down so early.
It is even more sad when the manufacturer doesn’t give the support a High end product deserves.
We don’t get our money worth.
Sony general deals with only 5 year support of spare parts.
I asked Sony here in the Netherlands and they don’t have any on stock.
The laser assy is KHS-180A, Sony #8-820-005-02.
Dick |
|
|
| David Garretson |
I had the same problem. It is usually resolved by lubing the inside of the sled motor with spray deoxit and lubing the plastic gears in the sled assembly with moly grease, or else it is the laser. Here are the steps to follow. I resolved the SACD TOC read problem at the last step, but it is unlikely you have a bad solder joint on the Main Board unless you have been pulling it for mod work.
http://db.audioasylum.com/cgi/m.mpl...son&r=&session=
Good luck,
Dave |
|
|
| djmiddelkoop |
thanks Dave,
the link shows usefull instructions to follow.
Actually this looks more like a general way to check any suspicious transport with a laser.
I will try the lubrication anyway as it will do no harm. |
|
|
| Elso Kwak |
Molykote lub is NOT for plastics but for "steelish" material. Deoxit into a motor I dunno........????
I guess you need the white grease for plastic or in this case I would use no grease at all. Thick grease actually increases the friction with bad results.
I can tell you stories about Pioneer transports.....:rolleyes:
Very often it's a small dust or package material particle that has come between the toothes of the wheel. |
|
|
| mpmarino |
mcm
Looks like they had it at one time....maybe they will get more again?
Good luck. |
|
|
| David Garretson |
Sorry Elso, you are wrong about this one. I have studied this matter thoroughly with pro modders in the USA who extensively service SCD-1/777ES units. The common problem is that friction from dry grease in the sled gears accelerates wear in the sled motor, leading to unstable tracking and/or premature failure of the sled motor. The instability can manifest first in SACD tracking problems due to the sensitivity of the fine laser. Sometimes the sled motor can be brought back with penetrating oil and sometimes it cannot.
Regards,
Dave |
|
|
| David Garretson |
It has been awhile since I've been inside the SCD-1 transport, but my recollection is that to access the sled motor you must unsolder it from the PCB and spray deoxit or caig into holes in the motor housing on either side of the spindle. Then apply 12V in both polarities to spin up the motor in both directions and distribute the lubricant and burnish the brushes.
Also, if the CD/SACD main spindle assembly shows excessive lateral play at the collar bearings or sounds noisy during play, then the associated wobbling will first manifest as SACD read errors. The jewel end-bearing and the collar bearings should be lightly lubed from time to time to prevent premature wear.
After lubing the sled motor and gears, you will immediately notice smoother operation during loading/unloading, with no grinding of gears. Hopefully the SACD will track! Unfortunately the experience stateside is that Sony repair depots tend to replace the sled motor only after the laser and spindle motor have been replaced, when in fact the sled motor is usually the culprit.
The SCD-1/777ES has one of the best transports but it does require periodic maintenance.
Dave |
|
|
| Zero Cool |
I love my SCD-1, my only complaint is that it takes an unusually long time to load and spin up and play compared to other cd players. I dont know if this is normal or not? Once it does its thing it plays fine.
Zc |
|
|
| rabbitz |
MolyKote EM-30L is perfect for CD slide mechanisms but is only available in 1Kg lots (AFAIK).
I used Tamiya switch lubricant which worked better than anything else (including Dexron III which normally works) on a stubborn drive which now doesn't miss a beat.
I've bought some Super-Lube #21010 to try as it seems to have the right properties such as PTFE and is synthetic. |
|
|
| Elso Kwak |
| quote: | Originally posted by David Garretson
Sorry Elso, you are wrong about this one. I have studied this matter thoroughly with pro modders in the USA who extensively service SCD-1/777ES units. The common problem is that friction from dry grease in the sled gears accelerates wear in the sled motor, leading to unstable tracking and/or premature failure of the sled motor. The instability can manifest first in SACD tracking problems due to the sensitivity of the fine laser. Sometimes the sled motor can be brought back with penetrating oil and sometimes it cannot.
Regards,
Dave |
Hi David, I think the directions in the link by Zero Cool are correct!
Having repaired many CDPs I concur. The mechanism is very similar to cheap CD-players.
Will you plase be carefull with those giant car batteries in the home? These monsters can give a lot of Amperes in case of short circuit, with great fire hazard. Also an overheated battery can vent gases that are highly explosive! Beware!!!
:att'n:
http://db.audioasylum.com/cgi/m.mpl...cid&r=&session=
:att'n: |
|
|
| David Garretson |
I'm sure that lithium grease is fine. Actually, I use Campagnolo race bicycle bottom bracket grease, which has an exotic blend of magical ingredients. I believe Lance Armstrong uses it in his transport.
But despite the plastic, the helical cut gears of the SCD-1 sled must be more precise than the average commercial transport that moves the laser instead of the entire CD spindle assembly for tracking.
Regards,
Dave |
|
|
| djmiddelkoop |
Thanks for all the help guys !
Today I opened the 777ES, made an extension cord for connecting the toploading assy while the thing lays aside.
When powering on, it is clearly seen that only one laser emits red light.
So, I have to browse for a laser assy after all.
Any recommended suppliers that have stock ?
Again, Thanks. |
|
|
| rabbitz |
| Further to my post 14, the Super-Lube #21010 is no good as it's too sticky. The Tamiya switch lubricant is still the best I've tried. |
|
|
| Zero Cool |
| quote: | Originally posted by djmiddelkoop
Thanks for all the help guys !
Today I opened the 777ES, made an extension cord for connecting the toploading assy while the thing lays aside.
When powering on, it is clearly seen that only one laser emits red light.
So, I have to browse for a laser assy after all.
Any recommended suppliers that have stock ?
Again, Thanks. |
Sony uses this same laser assembly in at least a half dozen models so they should be readily available. However. from reading the service manual. installation is not so easy. requiring 4 test CD's and a special alignment jig to set height that is impossible to get.
I have a friend that is an authorized Sony repair tech and he cant even get the CD's or jig!! I was hoping to be able to purchase a set and then learn how to do the set up but no luck.
Sorry thats not much help. If you find a good deal on the lasers. let me know. my understanding is that they are around $100.00
Zc |
|
|
| David Garretson |
While it is preferable to allign the laser with a scope & test disks, it is not necessary. Prior to removing the old laser, measure the distance to the nearest .5mm, between the top of the pick-up assembly at each end, to reference points on the gray spindle cover below. Replicate these heights with the replacement laser and you should be OK. The CDP will tolerate some variation in laser height and tilt is electronic-servo controlled. After it is working, vary the height a bit in both directions and tune by ear. If you have a good ear you can locate the position with the lowest jitter.
During servicing the unit can be operated without the top cover by temporarily bridging the solder pads marked "loading assy short lands" just to the left of the main board connector that receives the ribbon cable from the top cover.
Good luck.
Dave |
|
|
| fmak |
During servicing the unit can be operated without the top cover by temporarily bridging the solder pads marked "loading assy short lands" just to the left of the main board connector that receives the ribbon cable from the top cover.
Good luck.
Dave [/B][/QUOTE]------------------------------------------------------------------------------------
Dave
I am about to do my 777. I assume that one shorts the 'land' and use the remote. If not please explain.
Fred |
|
|
| fmak |
Having repaired many CDPs I concur. The mechanism is very similar to cheap CD-players.
------------------------------------------------------------------------------------
Elso
In the case of the scd777, you are talking rot. Plastic gears are not necessarilly cheap or nasty; in fact they are preferred in certain applications calling for low friction etc. If they have the technology in 1700 for plastic gears, they would have used them.:hot: |
|
|
| David Garretson |
Fred,
Put a blob of solder on each of the two pads to bridge the two crescents into two circles. Unit will function as usual but without the top connected. Remove solder with braid when done.
If installing a replacement laser, note (as documented in the service manual) that the replacement laser pickup is shipped with two such shorted lands on the laser PCB, that need to be desoldered prior to operation. Apparently they are shorted to protect against static during handling.
Elso, there is nothing that's cheap about the SCD-1/777ES transport build quality! It is just fairly complex in order to slide the platter instead of the laser. But the service manual sucks as a source for information other than schematics & parts list.
Dave |
|
|
| fmak |
| quote: | Originally posted by David Garretson
Also, if the CD/SACD main spindle assembly shows excessive lateral play at the collar bearings or sounds noisy during play, then the associated wobbling will first manifest as SACD read errors. The jewel end-bearing and the collar bearings should be lightly lubed from time to time to prevent premature wear.
After lubing the sled motor and gears, you will immediately notice smoother operation during loading/unloading, with no grinding of gears. Hopefully the SACD will track! The SCD-1/777ES has one of the best transports but it does require periodic maintenance.
Dave [/B] |
------------------------------------------------------------------------------------
Dave and others
I managed to get the scd777 working by lubricating the gears and guide. I also put a drop of light oil with a tooth pick into the sled motor bearing. Brushing a mixture of teflon and lithium grease into the cogs with a painting brush makes the job easier.
A couple of questions as I think I shall need to work on the sled motor and lube the spindle motor.
1. What is the best way of removing the sled motor? Remove the transport first and tyhen the gears or the gears and optical assembly first?
2. The plastic circlips - how do they come off; just by prising the gears from below?
I have not noticed this before. The 777 is fairly quiet when a CD is played. However, on SACD, there is some motor-boating noise when the ear is pressed against the top plate.
Has anyone noticed this, or is it a case of a failing motor/ grinding shatf/bearing?
I have a replacement sled motor; looks rather flimsy compared to other components in the SCD!
:) :) :) |
|
|
| David Garretson |
Glad you could get it working with lubrication.
To remove the sled motor, first remove the entire transport billet assembly with its PCB from the four standups and pull out the two wide ribbon cables from the main board. Leave the laser pickup untouched. Remove the circlips retaining the round gears (I believe the circlips are made of light spring steel) by twisting circlips slightly with needle nose pliers or dental pick. Be careful as they tend to fly away. Remove large round plastic gears, leaving small gear on sled motor spindle untouched. Unscrew and remove the sled motor with its housing from the transport board. Desolder & remove sled motor from housing. Spray deoxit or equivalent into motor and run in lubricant both ways by reversing polarity of 12V battery.
Yep the sled motor appears to be of the el cheapo Chinese $.10 variety, resold with proprietary housing by Sony for over $100.
I will check the noise level on my SACD platter shortly.
Dave |
|
|
| georgehifi |
I use a very fine grease for the plastic gears which works great, it's translucent blue in colour and made from natural caster beans, it said to acually preserve plastic while lubrcating, made by PBR here is the link, comes in a small tube couple of dollars.
http://www.pbr.com.au/products/repl...ancillary.shtml
Cheers George |
|
|
| fmak |
I use a very fine grease for the plastic gears which works great, it's translucent blue in colour and made from natural caster beans, it said to acually preserve plastic while lubrcating, made by PBR here is the link, comes in a small tube couple of dollars.
http://www.pbr.com.au/products/repl...ancillary.shtml
Cheers George [/QUOTE]
It's a rubber grease! Maybe too light for gears?? Would try it except it's in Australia and I am in Cyprus where you can buy surprising things but not some ordinary things.
The English sausages here are all heavilly spiced!! It is impossible to get the real thing. |
|
|
| georgehifi |
Quote
>Would try it except it's in Australia and I am in Cyprus<
PBR is a global company, look in the suppliers section all PDF files, bet there's one near you.
Yes it is a rubber and plastic grease that preserves, made for brake parts, it's consistency is perfect for plasic gears not too thick as to cause drag, not too thin as to run away.
It's perfect for letting the teeth slide and mesh without causing any restriction.
And it's natural, not petrolium based, so it won't attack and harden the plastic, as it says, it preserves.
Cheers George |
|
|
| fmak |
| quote: | Originally posted by David Garretson
Glad you could get it working with lubrication.
I will check the noise level on my SACD platter shortly.
Dave |
Thanks for all the help. With the cover off, I can now tell that it is the spindle motor that makes the motorboat noise. Anyway you know of of lubricating from top, like dripping oil down the sleeve under the CD support? Or is it a case of strip down?
The old sled motor is actually smooth in operation.
Fred |
|
|
| David Garretson |
I believe the spindle assembly needs to be horizontal in order to drip teflon oil into the collar bearings. It's too much heartache to disassemble the spindle shaft entirely, but it's worthwhile to remove the motor housing base plate at the bottom of the spindle & clean/lube the jewel bearing and bearing cup with white lithium or moly grease. Maybe this will quiet it down. Is there much lateral play in the spindle?
Dave |
|
|
| fmak |
| quote: | Originally posted by David Garretson
Maybe this will quiet it down. Is there much lateral play in the spindle?
Dave |
No, everthing is tight.
Fred |
|
|
| djmiddelkoop |
Finally found the time to replace the laser assy (KHS-180A) for a new one.
Great dissappointment, after playing a (new) SACD still the TOC error*.
Examination showed again the second laser dead.
Well, the one that is closest to you while sitting in front, emitts red light while the second appears to be dead. This was the same before replacing the assy.
Can anyone give me a clue what to look for ?
Thanks, Dick |
|
|
| Zero Cool |
I wonder,....I have never looked at the schematic, but is there some switch circuit that turns the second laser on? maybe that switch transistor is dead? maybe the control logic isnt working correctly or something... I would start looking in that direction if it were me.
Zc |
|
|
| djmiddelkoop |
Thanks for the answer,
was thinking off something like that.....
For clarification attached the interface with the laser head.
Cannot identify where the laserpower or switchover should come from.
Any help ?
Thanks, Dick |
|
|
| Elso Kwak |
| quote: | Originally posted by djmiddelkoop
Finally found the time to replace the laser assy (KHS-180A) for a new one.
Great dissappointment, after playing a (new) SACD still the TOC error*.
Examination showed again the second laser dead.
Well, the one that is closest to you while sitting in front, emitts red light while the second appears to be dead. This was the same before replacing the assy.
Can anyone give me a clue what to look for ?
Thanks, Dick |
No static protection solder bubble present on the flex cable you have to remove after installing?
:idea: |
|
|
| djmiddelkoop |
Good Question Elso, but no.
There is a little leaflet inside the box of the laserunit reminding you of the 2 shorting bubbles.
Here is the other part of the schematic : |
|
|
| David Garretson |
Are we certain that SACD laser light is visible to the naked eye?
If not, did you first try to lubricate the transport sled & motor as previously posted? The TOC read problem typically first manifests during SACD play (before showing up in RBCD play) if there are mechanical problems in the transport such as friction or bad motor/bearings.
If you replaced the laser & lubed everything and don't have mechanical problems with the sled or spindle assys, then I'm afraid the problem is probably a bad RF or Main Board.
Dave |
|
|
| djmiddelkoop |
| quote: | | Are we certain that SACD laser light is visible to the naked eye? |
Dave,
I'm not shure either. The SACD laser is described as DVD laser, and these emit visible light.
I have lubricated the transport & motor assy before replacing the laser assy, but that didn't help. That's why I thought the laser was bad.
The next thing in line that could be the problem must indeed be the RF or Main board, but how to troubleshoot if it looks like the laser is not operating?
Any help is appreciated.
Dick. |
|
|
| Hardi |
Hello,
my SCD-1 has also the Toc Error Problem, but i have one SACD that the player will always play without any problems....
very strange behaviour.!
So i changed the Pickup...still the same...CD plays fine, SACD will not play except this one hybrid SACD (David Bowie)
My 20 other SACD still have the "Toc-Error" problem.
Any Ideas? |
|
|
| djmiddelkoop |
Hardi,
In the past time I have found out that my problem is caused by the Main Board, which is under the transport at the bottom of the case.
I also found out that the DVD laser emits unvisible light.
A new main board at Sony costs around 700 euro, which I find far to much.
In your case however, I would try to lubricate the transport as described in the other replies.
Dick |
|
|
| David Garretson |
| If unsuccessful after cleaning/lubing transport gears, spraying deoxit inside (dismantled) sled motor, moly greasing of spindle motor jewel bearing, and reseating of all cables, then resolder rails of main board connectors all around. If this doesn't do it then you probably have a bad main board or RF board. |
|
|
| Hardi |
Hello,
the transport gears and sled motor are fine. Spindle motor is also fine without noisy bearings. I changed the laser pickup and make all the alignments with test SACD´s SL/DL and scope as written in the service manual. it passes all the Tests (also the over all tests that take about 5 minutes to pass)
I upgraded the Firmware to the newest? Version 2.53.
Now i lubed all mecanical parts with teflon lubricant....No need to clean anything because it was all the time 100% clean
I checked the Laser power with a laser power meter and verified it with a Sony DVD player that uses same pickup. (DVPS-7700)
Emission is OK. Eye pattern (CD-mode) is jitter free and sharp.
CD mode is still fine....and (what i do not understand) it still plays one! of my hybrid SACD´s without problems...100% tracking, fast skip etc....
all other Hybrid or "pure" SACD will bring *Toc-Error*
seems to be a problem that is over my abilities. :xeye:
OK...SACD is nearly dead , but having a working unit would be fine. A new motherboard is too expensive. |
|
|
| djmiddelkoop |
Thanks David for your hints.
I had access to another 777 for a limited time, swapping out the transport with RF board didn't made a difference but swapping out the Main board did. Also my transport with RF board worked fine in the other machine.
Than I checked the Main board under a stereo microscope and couldn't find any bad solder joints.
Dick |
|
|
| David Garretson |
Dick,
A visual inspection even with a microscope, might not reveal small fractures caused by flexing of the connectors/headers during removal. It's worth reheating them & adding a bit of solder to the top edge of each connector rail. In my unit this step finally resolved the SACD TOC read problem after all other steps were taken.
Regards,
Dave |
|
|
| djmiddelkoop |
Thanks again Dave.
OK, I will follow your advise and do so asap.
I will post the result !
Dick |
|
|
| djmiddelkoop |
I resoldered every connector pin of the Main board but unfortunally the result is still the same : TOC error * when trying to read a SACD.
A question for Hardi : which or what kind of test SACDs did you use ?
Dick |
|
|
| Portlandmike |
| quote: | Originally posted by djmiddelkoop
I resoldered every connector pin of the Main board but unfortunally the result is still the same : TOC error * when trying to read a SACD.
A question for Hardi : which or what kind of test SACDs did you use ?
Dick |
Hi,
I'm a fellow 777 owner. I've had mine along time, bought it new. Paid $1500. Love it.
recently it had a huge offset in the left channel. One of the LM6172's in the FRND filters when bad :xeye:
Anyways. Do you have a service manual. there is a calibration method for it. I'll admit I haven't read the whole thread.
might be able to help you out.
Anyone ever run accross a clock upgrade for this player? |
|
|
| David Garretson |
Other problem areas for electrical contacts are the two wide ribbons between RF and Main Boards. Clean the contact surfaces & check that none of the metal traces have peeled back. For a fresh start you can trim off the edge of the ribbon & move contact to above the dimpled surfaces.
When I recently had it apart, on reassembly with bad ribbon contacts plus misc. connector & header rail discontinuities I had variously three problems with SACD: TOC Error*, TOC Reading/No Disk, and drop out of one SACD channel. After trimming the ribbons back at both ends the SACD tracked OK. Then all OK after resoldering the SACD connector rails for the third time, this time pressing down with a probe while soldering. These connections can be quite flaky even though apparently OK with solder all over them and a visual inspection. |
|
|
| David Garretson |
Portlandmike,
I've had three generations of Audiocom Superclock in the SCD-1, most recently the SC4. This is a very big improvement. It sounds best powered by a 12V battery, second best by Audiocom's dedicated power supply, and very good off the stock CDP's 12V regulator that powers the motor/servo. You can also power it with the +7V downregulator on Audio Board.
Dave |
|
|
| Portlandmike |
| quote: | Originally posted by David Garretson
Portlandmike,
I've had three generations of Audiocom Superclock in the SCD-1, most recently the SC4. This is a very big improvement. It sounds best powered by a 12V battery, second best by Audiocom's dedicated power supply, and very good off the stock CDP's 12V regulator that powers the motor/servo. You can also power it with the +7V downregulator on Audio Board.
Dave |
Dave, thanks for the info.
Dumb question now. Is this to replace the "45Mhz" clock on the audio board? So far, its the only one I could find.
Also, Op amps:
I'm pondering changing the I/V op amp from the LM6172 to a LM4562.
It also uses a rather mild mannered AD712 in the buffer output.
(in the 777 this drives a cute discrete buffer). I was thinking of totally removing the AD712 and buffer and replacing it with a LM4562. Any thoughts?
I hear good things about the OPA2132 which is used for the diff to single ended conversion. Is that worth replacing with a LM4562 also?
Thanks
Portlandmike |
|
|
| David Garretson |
Portlandmike,
I suggest you order the $18 Service Manual from Sony at 800-488-7669 to get the schematics. I've been all over the unit, first upgrading the stock analog stage and then converting to silver transformers directly attached to the STACT voltage DAC. Yes just one 45mHz clock replaces the stock oscillator chip. There are various posts to Audio Asylum regarding changing op amps, star grounding, etc.
I suggest you replace all the SOIC AD712s with OPA2132 or whatever, and perhaps a Brown Dog adapter with OPA627s in the I/V. Email me for some other ideas and I'll forward previous writings.
Dave |
|
|
| Portlandmike |
| quote: | Originally posted by David Garretson
Portlandmike,
I suggest you order the $18 Service Manual from Sony at 800-488-7669 to get the schematics. I've been all over the unit, first upgrading the stock analog stage and then converting to silver transformers directly attached to the STACT voltage DAC. Yes just one 45mHz clock replaces the stock oscillator chip. There are various posts to Audio Asylum regarding changing op amps, star grounding, etc.
I suggest you replace all the SOIC AD712s with OPA2132 or whatever, and perhaps a Brown Dog adapter with OPA627s in the I/V. Email me for some other ideas and I'll forward previous writings.
Dave |
Dave,
Cool idea with the transformer. Who needs the filters anyways!
I always thought the SACD-1 was wierd in that it took a perfectly good balanced signal and converted it to single ended then back to differential. (and that with rather low end amplifiers.)
Did you ever try driving the xformer from the I/V outputs?
Got the manual. I'll email you. Have you heard or heard the rave about the LM4562. Its less than 6 mo's old, but pretty much getting the nod as the absolute go to op amp with rare exceptions.
~10x lower THD, lower noise, better PSSR, better CMR, great specs into loads, lower cost, better... there are single and quads too. SO8 and DIPs.
Thanks
Mike |
|
|
| David Garretson |
Mike,
I tried the traffos in both locations and found they sound more natural and analog-like attached directly to the 330R resistors that follow the S-TACT. However without the added filtering of the second I/V stage, there is audible HF noise that needs to be dealt with by adding a passive LPF after the traffos. Attaching the traffos after the second I/V stage does not require this added step. But without making improvements to +/-7V power to the Current Pulse Converters the result is somewhat synthetic sounding. So each approach has its advantages & disadvantages.
Also the sound is a lot more transparent after replacing all the signal-path 330R & 10R SMD resistors with better pieces. This makes a bigger improvement than replacing the radial-lead Rikens used further down the Audio Board.
Regards,
Dave |
|
|
| djmiddelkoop |
The service manual can be downloaded here :
Sony SCD 1 / 777 service manual
Thanks again for the tips Dave, I checked the ribbon cables and they looked fine but I will double check.
What do you mean by SACD connector rails ?
Dick |
|
|
| David Garretson |
| CN705 and to a lesser degree CN706 on the Main Board is where most of my troubles occurred. By rails I mean the pins inside the header are bent 90 degrees & come out over the PCB pads where the solder joints are made. I was surprised how SACD skipping and intermittent read problems were resolved after cleaning up these joints with solder removal braid, then resoldering them while downward pressure was applied to the pin with a small screwdriver. |
|
|
| Peter Daniel |
| quote: | Originally posted by David Garretson
Are we certain that SACD laser light is visible to the naked eye?
|
It is certainly visible, pretty strong actually. |
|
|
| Peter Daniel |
I made my first "upgrade" today. I run output wires directly from I/V op amps (I replaced them with LM6172) and installed a set of XLR connectors in the rear panel. The output is connected (through BG N 10/50 coupling caps) to S&B TX102 transformers in balanced to single ended mode. Works fine.
BTW, I'm pretty much impressed with the effort Sony put into building that player. While I also have ML37, ML31.5 and CEC TL0, the Sony unit doesn't come short in build quality to any of those other transports. |
|
|
| Bratislav |
Thanks for the useful thread, guys... It was enough to have me running away FAST from a nice looking second hand Sony 777ES available locally. I don't want to buy a problem (and expensive one at that!).
I think you just saved me a nice stash of ca$h. |
|
|
| David Garretson |
Peter,
When I posted about the laser light I had not yet figured out how to defeat and remove the top cover while spinning disks. You shouldn't need the coupling caps with the traffos & it must sound better without them.
Bratislav,
Too bad-- with periodic lubrication of the transport assy this unit is reliable & the problem with connectors on the Main Board usually only manifests after repeated removal and overly rough treatment of the cabling. With the right mods the sound of the SCD-1/777ES approaches SOTA.
Dave |
|
|
| Peter Daniel |
The differential offset is approx 40mV, and since it's a circuit under test, I didn't want to risk it with transformers. I have similar offset with BiDAT and actually I found it to sound better with V-Cap in coupling (capacitor on one side only), kinda smoother.
I thought you people must have known already about playing the unit with top cover off, but it was pretty interesting to see the laser light penetrating the disk through. I'm pretty much aware that I'm approaching that project some 5-6 years late. ;)
And I can see that this player has quite a big potential, although it's gonna be a lot of work. |
|
|
| Portlandmike |
| quote: | Originally posted by Peter Daniel
I made my first "upgrade" today. I run output wires directly from I/V op amps (I replaced them with LM6172) and installed a set of XLR connectors in the rear panel. The output is connected (through BG N 10/50 coupling caps) to S&B TX102 transformers in balanced to single ended mode. Works fine.
BTW, I'm pretty much impressed with the effort Sony put into building that player. While I also have ML37, ML31.5 and CEC TL0, the Sony unit doesn't come short in build quality to any of those other transports. |
Hi Peter,
I've still got a virgin 777 and I'm getting ready to do some mods.
First off on my list was the op amps, just because its easy.
I see you went with 6172's. Mine has 2604's, and I was pondering putting in LM4562's.
Have you tried anything else besides stock and 6172's?
Have you tried LM4562's?
I was also thinking of bumping up the gain of the I/V to 1k vs 470R. Better distortion numbers, and the LM4562 has twice the gain of the 2604 already with 20dB better THD.
More signal doesn't seem to be a bad thing and the 4562's, as well as most op amps seem to work better at about 4VRMS, distortion and noise wise.
Any comments?
Are there any thoughts on servo's vs coupling caps?
Thanks
Portlandmike |
|
|
| Peter Daniel |
I've been listening to such modified player for some time now, and while bypassing the output stage with S&B transformers provided much more resolution, space and immediacy, somehow I'm loosing the sense of music as the whole. I mean, I'm getting nice sounds, but it is not as musical as with the original Sony output stage, it seems more mechanical and less involving, although very clean. I didn't use the same interconnects for comparison, so maybe the problem is here, I will check again as soon as my new cables arrive.
I will install LM4562 as well, I just ordered some yesterday. Was also thinking about 1k feedback resistors, especially when I have some Vishay S102 in that particular value.
On Audio Asylum there is a lot of posts by jhietbrink, check them all as they guide through very interesting modification process, completely different than all usual modders do. Here are some links (pasted directly from AA post):
"Other SCD-1/777ES Mods and Information:
Analog Signal Path
Replaced RCA jacks with Vampire OFC jacks
Replaced output wire with Kimber AGSS
Revised grounding creating a star ground for audio board
http://www.audioasylum.com/forums/h...ages/41691.html
Replaced AD712s in the output buffer stage with hi-spec OPA2132s
http://www.audioasylum.com/forums/h...ages/78259.html
Replaced resistors and capacitors in I/V conversion stage
http://www.audioasylum.com/forums/h...ages/93363.html
Replaced OPA2604’s in the I/V conversion stage with LM6172’s
http://www.audioasylum.com/forums/h...ges/156269.html
Set filters to “custom”
Power Supplies
Revised capacitors on Audio Board digital power supplies and AC Board http://www.audioasylum.com/forums/h...ges/155617.html
Revised grounding, AC polarity, analog supply bypassing
http://www.audioasylum.com/forums/h...ges/107304.html
Removed choke on analog power supply
http://www.audioasylum.com/forums/h...ages/32357.html
Transport
Added capacitance to the “Digital” (Transport) Power Supplies
http://www.audioasylum.com/forums/h...ges/133431.html
Separated data and clock cables between Main (Transport) and Audio Boards
http://www.audioasylum.com/forums/h...ges/166048.html
Added a new 5V regulator to serve the RF Board
This post
Clock
Improved power supplies to oscillator and S-TACT chip and quieted ground plane
http://www.audioasylum.com/forums/h...ges/137033.html
General Description
Analog Signal Path
http://www.audioasylum.com/forums/h...ages/33130.html
"" |
|
|
| David Garretson |
Do the S&Bs have gain? I think you need at least 1:2 step-up trannies in this application. Also, if the lack of involvement you're hearing owes to slightly sluggish dynamics and shapeless bass, then this can be improved with a simple SS buffer after the trannies. Also, bypassing the I/V and attaching the trannies directly to the S-TACT is more natural & less synthetic & mechanical sounding than putting them after the I/V stage. But to do so requires additional series resistors on the primaries.
I did all of the grounding mods in jhiebrink's posts and they do make a difference. I made a star ground post at IEC earth and eliminated as many chassis ground loops as possible. For example, you can do this with the Main Board as follows: (1) remove the standup beneath the center ground tab to break chassis ground & run a wire from the ground tab to IEC earth, (2) break all other chassis grounds by putting nylon washers under the head of each PCB mounting screw. |
|
|
| Portlandmike |
Hi guys,
I've been staring at the schematics after reading about some of the 777 mods.
I look at IC107 and 207, along with Q109 and 209, on the analog board, and I can't figure out what the heck the circuit is doing. (It seems like it should be a negative regulator, but its not that, is it?
Its saying its making -4.7V going into the current pulse chip, but as I look at the circuit, it makes no sense.
I simulated it, just in case I was confused, and the output does not make -4.7V.
I traced out the ref manual board artwork, and it seems to agree with the schematic.
I'm curious now. Is this a sony cover up of some key item, or what.
Could this be setting the current in the current pulse chip CSX8042?
If so, how critical could that be, and with a AD712 doing it?
Thanks for you help and insights!
Portlandmike |
|
|
| Portlandmike |
| quote: | Originally posted by David Garretson
The STACT is a voltage DAC monolithic op amps, so the current pulse Converters puts the signal back into current mode and the "second" I/V stage back into voltage. More info here:
http://www.diyaudio.com/forums/show...10&pagenumber=1 |
Thanks David. I'm not quite ready to toss the current pulse under the bus yet.
I'm interested in what the AD712 op amp and pnp circuit is suppose to do. I don't see how this is making -4.7 and it goes to a pin called C1ref.
The op amp is running OPEN LOOP. I see no feedback to the inverting input, and the non-inverting input goes to ground.
I'm talking about IC107 and IC207 on the analog board of the SACD-1/777ES
People might be tossing the current pulse under the bus when perhaps a very critical part of the circuit is a AD712 lame duck.
Thanks
Mike |
|
|
| David Garretson |
Mike,
Prior to bypassing the I/V stage, I first put dual OPA627s on Brown Dog into the DIP socket, and later replaced the adjacent SOIC AD712 with an OPA2132. I can't remember what was originally in the DIP position. I half recall there may have been some running changes made by Sony in the parts chosen for these positions. In any case, I tested both changes sequentially, & replacing both op amps does makes a nice improvement in sound. There are other SOIC AD712s downstream in the analog section and in the balance board (SCD-1 only) that should be replaced as well.
Regards,
Dave |
|
|
| David Garretson |
Mike,
Prior to bypassing the I/V stage, I first put dual OPA627s on Brown Dog into the DIP socket, and later replaced the adjacent SOIC AD712 with an OPA2132. I can't remember what was originally in the DIP position. I half recall there may have been some running changes made by Sony in the parts chosen for these positions. In any case, I tested both changes sequentially, & replacing both op amps does makes a nice improvement in sound. There are other SOIC AD712s downstream in the analog section and in the balance board (SCD-1 only) that should be replaced as well.
Regards,
Dave |
|
|
| Portlandmike |
I think I see it now.
Its a current source for the mirror in the CXA8042!
Interesting, and seemingly important!
And the bias for this high performance SACD is set by a 3 terminal regulator!!!
No wonder no wonder you like to bypass the whole thing!
Portlandmike |
|
|
| David Garretson |
Yes, the key to improving the stock circuit is to get rid of those 3-pin regulators (both through-hole and SMD). +5V IC304, IC308, IC309 on the Audio Board & IC 401 on the Power Board can all be removed and replaced by one high-quality +5V discrete regulator on the Audio Board near all those +5V applications.
Also, if you bypass the I/V stage to a tranformer output, you can simply remove +/-7V IC105, IC106, IC205, IC206 from the Audio Board, and also remove +/-9V IC402 & IC403 from the Power Board. |
|
|
| Bratislav |
| quote: | Originally posted by David Garretson
Bratislav,
Too bad-- with periodic lubrication of the transport assy this unit is reliable & the problem with connectors on the Main Board usually only manifests after repeated removal and overly rough treatment of the cabling. With the right mods the sound of the SCD-1/777ES approaches SOTA.
Dave |
Yup, but what about all those dead laser units and main boards ?
My own experience with Sony has been not that good - the old TV (CRT) keeps plodding away (now not really in use, replaced by plasma unit) but I had to fix their "SOTA" video recorder (also '777') several times and in the end the (hermetically enclosed) switching power supply strarted playing up and that was the last straw.
Shame as it was by far the best looking VCR with a decent audio recording capability.
Not missing it at all now, (b#tt ugly) Panasonic PVR/DVR works like a charm for an occassional recording from FM (not to forget digital radio which is supposedly around the corner for my favourite ABC Classical).
Bratislav |
|
|
| David Garretson |
Bratislav,
Yeah I hear you. I have an old XBR TV from 1980 (the golden age of Sony) that still works great. But one should be cautious mucking about with an SCD-1/777ES, as some parts have already been discountinued as per Sony policy of withdrawing support after 7-10 years from date of first production. I have purchased a spare laser and motors to keep mine rolling along. D |
|
|
| Portlandmike |
| quote: | Originally posted by David Garretson
Yes, the key to improving the stock circuit is to get rid of those 3-pin regulators (both through-hole and SMD). +5V IC304, IC308, IC309 on the Audio Board & IC 401 on the Power Board can all be removed and replaced by one high-quality +5V discrete regulator on the Audio Board near all those +5V applications.
Also, if you bypass the I/V stage to a tranformer output, you can simply remove +/-7V IC105, IC106, IC205, IC206 from the Audio Board, and also remove +/-9V IC402 & IC403 from the Power Board. |
David,
Could be, yet lots of that might be of little importance.
I think the clock needs to have clean power, but not so much the DAC. Not if its only being used as a a zero crossing generator into the current pulse generator. Its way more critical if your actually using it as you are to drive your transformers. Extra so since that's a significant load and all that....
I think the concept is interesting and I want to see what it has.
I think the current pulse chip is actually really really simple, and one could build a really good one very easy.
It just seems insane to me that the whole accuracy of the output is directly proportional to a 3 pin regulator setting the current pulses. Its another perfect case of were two cents would really make a vast improvement and two dollars a huge improvement.
They used a regulator where a reference was called for, or at least another R and C to filter the noise!
I'm not tossing Sony under the bus though. Besides a 100 dollar VCR, I've never had a sony thing to bad on me. Maybe just lucky I guess.
Best Regards,
portlandmike |
|
|
| David Garretson |
| Mike, you have a better grasp of the technology than I do. I'm just a country boy with the empirical results of my ear on this. I & several others found that improving power to the S-TACT makes a big sonic improvement, whether with the stock analog section or the traffos, both for RBCD & SACD. For further improvement to SACD, you can actually bypass the S-TACT completely (as done by Allen Wright in his VSE L5+ mod). But in this scenario you need a switch, as RBCD still needs to be decoded by the S-TACT. |
|
|
| Portlandmike |
| quote: | Originally posted by David Garretson
Mike, you have a better grasp of the technology than I do. I'm just a country boy with the empirical results of my ear on this. I & several others found that improving power to the S-TACT makes a big sonic improvement, whether with the stock analog section or the traffos, both for RBCD & SACD. For further improvement to SACD, you can actually bypass the S-TACT completely (as done by Allen Wright in his VSE L5+ mod). But in this scenario you need a switch, as RBCD still needs to be decoded by the S-TACT. |
Ears rule in my book!
I don't doubt that better supplies almost anywhere will improve things. The question I ponder is where is the biggest single improvement had, then where is the next biggest one.
My player is still stock. I want to go in and do a few things to the stock design before I start bypassing everything.
I've noted some things I'd like to do. Like better op amps, better R's and C's. I think the diff to single ended converter 10k resistors are way to large.
I think the current source that sets the reference for the current pulse is weak.
The 10ohm and 68,000pF should change too.
I think I'll increase the gain out of the I/V stage one way or another. Either increasing the reference or changing the 470R's, 10R's and 68,000pF accordingly.
I wouldn't be supprised if the anti aliasing filters wouldn't actaully be better as total passives.
The attenuation at 1Mhz is 180dB by simulation. I think it could be still 150dB and be passive.
Change the R's to metal film, RN65's is what I'd likely use.
The grounding is also a huge issue.
So I'm just getting my thoughts in order before I do this "stock" change. |
|
|
| Peter Daniel |
| quote: | Originally posted by David Garretson
Do the S&Bs have gain? I think you need at least 1:2 step-up trannies in this application. Also, if the lack of involvement you're hearing owes to slightly sluggish dynamics and shapeless bass, then this can be improved with a simple SS buffer after the trannies. |
S&B offers 6dB gain, and the output level is approx the same as with Sony stage. The bass is fine too, actually it is better defined, my only complain was that sounds were missing musical purpose, but it seems to be improving now.
I tried LM4562 today, in place of LM6172, but I'm not impressed yet.
The new chips are certainly "cleaner" with more punch, however, the highs seem to be excessively etched, and I'm missing "musical purpose" even more ;)
I'm currently back to LM6172 and I'm still waiting for better interconnects (KS1130). |
|
|
| David Garretson |
Peter,
On the Audio Board the big moves are replacing the clock and upgrading the 330R and 10R SMD resistors on both sides of the S-TACT. Much more transparency & involvement with the music.
Dave |
|
|
| Peter Daniel |
I will certainly do that. Could I use 220R instead of 330R, as I have whole bunch of Caddocks in that value.
When you said "bypass the S-TACT completely", where is the signal taken from?
I'm presently installing Vishays 1K in place of 470R Rikens. |
|
|
| David Garretson |
Peter,
You would probably be OK with 220R, but be cautious, as I overloaded & destroyed an S-TACT by experimenting down to zero R when directly attaching my transformers. No fun replacing that 64 pin chip!
I used Caddock MK132 radials in the 330R positions & Caddock flipchips in the 10R positions. If I were doing it over again, I would use SMDs like Vishay vsm1206 (3.81x1.57mm) in place of the large MELFs on the bottom of the PCB, and smaller 0805 (2.03x1.27mm) on the top between the VC24 & the S-TACT. These SMDs have very low TCR of +/-2ppm as compared to 50ppm for the MK132s. But the Caddock radials significantly better the stock SMDs and I have also used them in signal path in the digital section.
Initially I replaced the through-hole Rikens with Vishay VSR4, but these sections of the circuit were later obsoleted by the transformers.
I don't know where Allen Wright taps the SACD bitstream in his S-TACT bypass mod. I suspect he combines the differential phases coming off the 330Rs between the VC24 & S-TACT. If you can figure this out please comment.
Dave |
|
|
| Peter Daniel |
I need to correct on my previous comments. When I was wiring the output XLRs, I didn't notice that Sony reverses output jack position with regards to audio PCB channels, so effectively I had the channels swapped for balanced output and correct for unbalanced output.;)
Now I find it much better sounding than previously. The 1K Vishays are installed in place of 470R Rikens with LM4562. This op amp seems to be better than LM6172 after all, and it produces less differential offset: 1.5mV and 12mV, so I'm not using coupling caps any longer. The only complaint I may still have is that LM4562 stresses sibilances a bit more, but I guess that can be still improved.
David,
Thanks for the tips on resistors, would those Vishays be available from Texas Components? |
|
|
| David Garretson |
| Yes, Texas Components makes them. |
|
|
| Portlandmike |
| quote: | Originally posted by Peter Daniel
I need to correct on my previous comments. When I was wiring the output XLRs, I didn't notice that Sony reverses output jack position with regards to audio PCB channels, so effectively I had the channels swapped for balanced output and correct for unbalanced output.;)
Now I find it much better sounding than previously. The 1K Vishays are installed in place of 470R Rikens with LM4562. This op amp seems to be better than LM6172 after all, and it produces less differential offset: 1.5mV and 12mV, so I'm not using coupling caps any longer. The only complaint I may still have is that LM4562 stresses sibilances a bit more, but I guess that can be still improved.
David,
Thanks for the tips on resistors, would those Vishays be available from Texas Components? |
Glad to hear you got it working.
Are you doing any extra bypassing on the I/V LM4562's?
Did you change the 4700pF cap too?
Have you thought about using the diff to single ended IC as a possible buffer? There are two, and its very close to already being a diff input to diff output drive. Just connect the other inputs out reverse order to the connected op amp and the grounded leg of the 4R diff to the output.
It potentaily a place to add pole too.
I'd guess your I/V is sitting about 8V off ground, and the positive swings might be stressed a bit. That's 8mA of there ~25mA of output current. And the signal swings into the xfrmr might be taxing it. Just a thought. Perhaps its okay though.
Also, I think you really will want to add some resistance in series with the outputs of the I/V stage before you drive the xfrmer.
Are you loading the other end of your transformer at all?
The LM4562 wants less than 100pF ideally, and I'd suspect the transformer is more than that.
Might be your sssssssssing problem....
Then again, the (noise) gain of that I/V stage is quite high though, so maybe that's not it. (unless its loaded with say 1000pF!
I did a simulation in LT spice of the current pulse to the output buffer, filters too. If your interested I can send it to you. I don't have it on this computer though, and its using idealized op amp models, since National doesn't have one yet for the LM4562.
It would not be a big stretch to add in the coupling transformer in an idealized fashon, so at least you can get a good measure of things.
One more easy change to try. The current source that sets the reference for the CSX pulse chip. I think IC107 and 207, Q109, 209?.
I think splitting the 510 ohm into, say two, or maybe three 220R's, and adding a cap to ground from the middle node. (hope that makes sense.) It will totally clean up the 7805 supply, and the current will be rock solid, especially at HF where the 7805 isn't that good, and electrolitics might not be either.
at least better than it is.
I believe that you might want to run three 220R's. I think that will decrease your gain out of the I/V slightly, which is already 2x, so it might be good. something like 510/660.
Its great dreaming about this change a bit before doing it.
David is way ahead of way I want to start. The "end" I presume.
Thanks for your links to AA. They were very good reading and get me more excited to do these mods. |
|
|
| Peter Daniel |
I didn't do any extra bypassing on LM4562 yet but I will try some.
The DC offset is indeed slightly above 8V. It is rather high and I will install 760R resistors, which I have from another project.
Didn't do anyting to 4.7n caps, I may remove them completely though.
I don't want to use any additonal buffers, that was the whole idea for using transformers. The S&B passive stage is similar to that: http://www.6moons.com/audioreviews/...st/passive.html
The differential output from I/V op amp connects directly to transformer, which acts as balanced to single ended converter and buffer with gain. I didn't use any series resistors from op amp output, but will also try. I used similar approach when modufying BiDAT and I still enjoy the results.
As it is now, it actually sounds pretty good, although a bit "hard" so adding more liquidity would be in order.
Yes, I would be interested to see simulations results. |
|
|
| Portlandmike |
| quote: | Originally posted by Peter Daniel
I didn't do any extra bypassing on LM4562 yet but I will try some.
The DC offset is indeed slightly above 8V. It is rather high and I will install 760R resistors, which I have from another project.
Didn't do anyting to 4.7n caps, I may remove them completely though.
I don't want to use any additonal buffers, that was the whole idea for using transformers. The S&B passive stage is similar to that: http://www.6moons.com/audioreviews/...st/passive.html
The differential output from I/V op amp connects directly to transformer, which acts as balanced to single ended converter and buffer with gain. I didn't use any series resistors from op amp output, but will also try. I used similar approach when modufying BiDAT and I still enjoy the results.
As it is now, it actually sounds pretty good, although a bit "hard" so adding more liquidity would be in order.
Yes, I would be interested to see simulations results. |
Daniel,
email me and I'll send the sim file.
I would not remove the 4700pF with out additional modification.
The gain of the op amp (noise gain I'm talking about) would be something like 10k/20ohms at high frequecies. I doubt it would be good. The op amp will run out of loop gain which I think would be a negative.
The 68,000pF basically shorts the to IV stages virtual grounds, except for the two 10 R's from the virtual grounds. The other two 10 ohms are in series with a current source, so its a high impedance, and has little affect except for the filter action withe 68000pF, which is important.
There are lots of options one could play with that I think in your situation would take the transformer characteristics into account.
The 4700pF limits that gain to Something around 7 at high frequencies. I was thinking you might want to put a cap in there to keep at least the time constant about the same, but the simulation, with it in AC mode, will show you what the affects are so you can decide for yourself.
I didn't look up the transformer link as I'm very busy today, but did happen to order a couple today for work (split primary 600 to 600 ohm Jensens for my Audio Precision AST-2. I did note that they have about 1nF of input capacitance! That's high enough to perhaps cause problems for an op amp like the LM4562 driving it directly, even at a gain of ~7. Thus I'd for sure try to put some resistance in series. 100ohms would almost always be enough, but you said you have good 220R's so I'd even try that. It shouldn't have any affect below 100~200kHz. Of coarse, I'm assuming 1nF of input capacitance in the windings, and your choice of R will depend on the loading.
From what I know about audio transformers, which is only alittle, there are possible advantages in loading them with respect to frequency response. They are typically flatter when loaded I think. I trust you have that data, but don't be afraid to load them at least a bit, say 1k or so. It will likely be a positive.
Good Luck. Look forward to hearing your hearing results!
Portland Mike
p.s. I attatched the ltspice simulation.
Its set up in AC mode. If you go to transient mode, it just puts in a 50% duty cycle 44Mhz pulses. You can observe the waveforms as they go thru the circuit and the affect on aliasing.
AAout is I think the standard analog filter.
AAoutB is with the filters modified for other settings.
There are other possiblities and I only guessed because I don't know the logic.
I believe you are bypassing these though, so its of little concern.
You can also add a transformer. you put down inductors and define a coupling parameter. Look in help or at examples.
I didn't put much time into the op amp models. They are simple single pole models. You can, and I would recommend, that you use a two pole model and add in the open loop output resistance to get a good feel for instability into capacitive loads.
m |
|
|
| Peter Daniel |
Mike,
Thanks for all that info. Tonight I installed 760R resistors with I/V op amps and added 240R a the ouptut. The output is now at 6.5V.
I also replaced all the diodes and bridges in PS section. Will post more comments tomorrow, but it already seems to be smoother. |
|
|
| Peter Daniel |
I must gladly report that the original bridges that Sony used are actually quite good and they do not need to be replaced.
When I was modding ML37 and BiDAT I replaced stock rectifiers with custom made bridges using RGP 15B diodes with very good results. I first noticed those diodes im ML31.5 and they worked there very well, and were actually better than MSR860 I'm using in my NOS DAC.
So I made such custom bridges also for Sony, but unfortunately the results were less spectacular: somehow I got less air and dimentionality. Today, I put back the original parts and again, I started perceiving familiar signature: nice resolution in highs, improved bass, dimentionality and air, that I quite liked in that player after recent mods. So Sony bridges stay. I replaced the other 4 diodes (in analog section) with MUR860 (not parallel as originally) and I didn't notice any major improvement nor degradation.
With regards to output series resistors, I didn't like 244R Vishays S102 there. I placed 33R Rikens in that place though and I think it is better than without any resistors. |
|
|
| David Garretson |
Peter,
Prior to converting the CDP to batteries, I installed four custom low-current diode bridges made up by Reference Audio Mods in the USA and noted a major improvement in bass articulation, dynamics and pretty much all other metrics. However, I found little improvement when replacing the stock Sony high-current rectifiers powering the +/-16V supply to the Audio Board. Further improvements were obtained replacing the stock reservoir caps with 4-pole Jensen and the stock filtering caps with inexpensive Rubycon ZA and ZL.
Dave |
|
|
| Peter Daniel |
I tried few times Rubycons, but somehow I was never impressed much by them. I like to use BG N in digital circuits and if those won't be better than Silmics, I will leave the Silmics in place. I am a bit reluctant to touch capacitors yet, as Sony "house signature" is quite acceptable.
And I've listen to audiophile "approved" diodes before, but it was usually pushing the envelope too much for my taste ;)
I am not sure why Sony uses diodes in parallel in audio section. From my experience, things in parallel ususally don't work as good as single.
I will be also disconnecting from PS all the unused sections of output stage soon and this should bring some improvement as well. |
|
|
| David Garretson |
| I'm putting together a group buy for some high-end Vishay VSMP surface-mount resistors for 16 positions in the signal path on the Audio Board of the SCD-1/777ES. This buy should bring unit price of $18 down into the $6-$9 range. These are very clean resistors with ultralow TCR in the range of .02-2ppm/degree C, as compared to the stock carbon MELF resistors with TCR of 300-500ppm. Email me if interested. |
|
|
| jackh |
I am interested in the group buy,but was unable to access your email because I am still under moderation. My email is accessable.
Thanks |
|
|
| Portlandmike |
| quote: | Originally posted by David Garretson
I'm putting together a group buy for some high-end Vishay VSMP surface-mount resistors for 16 positions in the signal path on the Audio Board of the SCD-1/777ES. This buy should bring unit price of $18 down into the $6-$9 range. These are very clean resistors with ultralow TCR in the range of .02-2ppm/degree C, as compared to the stock carbon MELF resistors with TCR of 300-500ppm. Email me if interested. |
Hi David,
I'm very curious to see what the sonic improvement is with these. I'll pass on this buy though.
Near as I can tell most of those are in series with binary lines, likely to tame trassmision line affects. Maybe the ones driving the current pulse circuit would matter some.... from an engineering point, but more than half the time things that sound good don't make sense from an engineering point.
I do hope they are not any higher inductance than other choices though, as that might matter a bit more than precision.
Best Wishes, and keep us posted.
btw. How do you make you CD player work with the cover off?
Thanks
Portlandmike |
|
|
| David Garretson |
Before recently discovering the Vishay SMDs, I had already put radial-lead MK132s in the 16 positions in the signal path on both sides of the S-TACT, and also Caddock flip chips in the path between Current Pulse Converters and I/V. They all made a smart improvement in resolution & transparency that the stock Sony really needs. Putting Vishay SMDs in these positions and around the Timing Chips is an experiment to see if things improve further.
To run with the cover off, use solder to bridge the two PCB land to the left of the connector on the Main Board that accepts the ribbon cable from the cover. The lands are marked with arrows "Loading Assy Short Lands."
Dave |
|
|
| David Garretson |
To your question about the LM4562, I was thinking about its single op amp derivative for another application and received the following discouraging responses on another forum. If this op amp sounds worse than the AD712 I would stay clear of it in the Sony.
http://www.audioasylum.com/audio/tw...ges/143105.html |
|
|
| Portlandmike |
| quote: | Originally posted by David Garretson
To your question about the LM4562, I was thinking about its single op amp derivative for another application and received the following discouraging responses on another forum. If this op amp sounds worse than the AD712 I would stay clear of it in the Sony.
http://www.audioasylum.com/audio/tw...ges/143105.html |
Hi David,
That's interesting. But also there are about 10x more that rate it quite well.
w/o knowing what the circuit is, what gain its running, what cap its driver. No op amp sounds good when it is not running right.
If the guy had a unity gain Sallen and Key filter and was not paying attention to the output cap... there are so many things.
Maybe it does suck and most people reporting great results are just wanting to hear it because of its specs. I'll reserve my decision for my own test. I also do want to try the LM6172 though.
I'm still looking to try it. There is a thread on the LM4562 and there are many positive testimonials.
The AD712 can drive lots more output cap. Its slow in comparision, and has lots of gain and phase margin. |
|
|
| Portlandmike |
Peter Daniels,
I've been informed that there are some favorable improvements in the LM4562 if it is loaded from a current source to the positive rail.
In your I/V stage, the op amp will be positive output, and sourcing current.
You may want to put a stiff CRD to the positive rail, or maybe change the reference current polarity. Not sure if that will work with the current pulse though.
Just thought I'd let you know.
Adding one or two CRD's to the positive rail on the outputs would have the further benifit of unloading the I/V op amps, which couldn't hurt.
Best Regards,
Mike |
|
|
|
