| gaborbela |
HI
I would like to ask for help .I have these Nakamichi OMS-5 cd player , unfortunatly does not read .It will need to replace the lasser pick-up.
If somebody has experience with these player please let me know WERE I can buy new laser pick up or were I can find help to fix it .
Unfortunatly I have the part number but is imposible to read the numbers on the laser ..
Thanks for any help.
Regards |
|
|
| anatech |
Hi gaborbela,
I used to repair them under warranty, and own an OMS-7. Nice unit.
You may not need a laser P/U. It can be checked for efficiency. It would be hard to source the NEC head these days if you do need one. The alignment is a long process, but will last years again. I have never seen a more stable RF pattern than these can produce.
-Chris |
|
|
| gaborbela |
HI
Thanks Anatech for your answer .
I belive it need the laser to be repleced , you know sometimes read .
For example if it find the disc play all the way ,depend on the condition of the disc , but if I want to go up or done it loose the signal and no longer play.
I'd like the sound of the player , so that why I would like to fix it .
Do you know from were I can order new laser . Unfortunatly not even posible to read the the part number so I dont know what part do I look for .
If I spend on to fix I want to instal new laser .
Thanks one more time .
Regards |
|
|
| anatech |
Hi gaborbela,
Okay, I'm going to warn you now.
The head is fully adjustable in free space in all axis'. The holder must be taken out and cleaned first. This is an expensive head and there are other problems that may be causing this.
There is a test to confirm the head has a weak laser (or not).
-Chris |
|
|
| gaborbela |
Thanks for the reply
Ok , I have to tell you I just purchesed these cd player not to long time a go . I used these cd player when still played (sometimes) but now no more .
The owner of the cd player when I purchased he said it was tested , cleared , adjusted ect by a service man .
So it is sure it need new laser .
I just dont know from were I can order , I wrote to Nakamichi corporation but no answer .
My point is if I spend more money on these I want to be sure it will work for a couple years more .
So that why I want new laser and not just some cleaning or so on.
I'm not sure if would be cleaned or ajust a bit it would do something because they did it already .
I find on the web a place were they fix Nakamichi CD player I will try to contact with them .
I just afraid to order a laser from somewere and they send me a non working parts how just happend with me.
I have a Nakamichi cd4 player ,it have a laser problem to but still plays . So I orderd a new laser ,I instaled and total dead .
After I put back the old one , that is working but so so.
Thanks for your help.
Regards |
|
|
| anatech |
Hi gaborbela,
I have seen very few people who can set these up properly. I was trained at Nakamichi Canada on it. Most of these that are played with are far off where they should be.
So, I have said that there are only a few guys that are capable of setting these up. They require the manual to do this.
Guess what? I have the manual. There is a chance the head is fine. If it isn't, it will be difficult to find another and it will not be cheap (unless you luck out).
Re: the CD 4. I also have the Nak Jig. I can set it up. Did those under warranty too.
-Chris |
|
|
| gaborbela |
HI
I understand your point , the cd player is 12 years old and it was used almost every day.
I know is posible some adjustment and may be plays one week or couple months .
I told if I spend money on these I want new laser to be instaed .In case if not posible or I dont find I dont want to be fix .
I just dont want spend money on and later still not working properly .
I know to fix these will cost a fortune , but it will last for a couple years .
If I dont fint parts to fix ,I will use the parts from it from it , and I use the case for a DIY preamp or gainclon.
I apresseate your help . I'm sure these need a laser , and if not posible I do not spend more money on.
After 10-12 years almost all cd player need new laser plus these was tested by a service man who is profesional .
I understand you and all my respect to you and your knolwlege about the Nak. but if you dont have posibility to instal new laser I dont vaste more money on these . I wrote to Nak service in USA for parts or service I will see what will be their answer .
Thanks anyway .
If I dont find parts I will wait until I see on the ebay another OMS-5 or 7 wich work perfect and I buy it .
May be it will be chepper that than to fix these.
Regards |
|
|
| anatech |
Hi gaborbela,
At least check the feed belt for slip. Very common. It will cause the same symptoms. Hint: if it spins like mad, the belt is slipping.
Do I know who the tech was? ;)
In testing the laser efficiency, you get an idea of the life on the head. It's a qualitative test. That is what I wanted to check.
When I bought mine used many years ago, it needed a $500 + laser head. I have serviced many where the head was fine. There is also a servo modification per Nakamichi (extensive - I did many) to allow the machine to play out of spec CD's.
You know this is a pair of 14 Bit TDA1540's don't you? It sounds too good to be true though.
-Chris |
|
|
| gaborbela |
HI
I just checked the belt , it would be great to be replased because is very slopy.
I will go tomorrow to the electronics surplus store and I will look for it.
I will see if Nakamichi will answer to my letter from USA.
Did you ever compared the sound of the OMS-5 to OMS-7 ?
Wich player has better sound , the 5 , 7 , or 7 ll .
I planing if I can fix these to purchase one wich is in a good working order .
I saw many OMS- 7mk ll on the web for sale , it start aroud $400 and up .
I will let you know what happend after I replace the belt .
Thanks |
|
|
| anatech |
Hi gaborbela,
The OMS-5 and 7 are identical in sound quality. The OMS-7II has an improved D/A section, the transport is not as good but better than most other things out there today.
Before putting the new belt on, clean the motor shaft and pulley with isopropyl alcohol first.
Where is your unit serviced? I just am curious if they know this unit (every tech is an expert on every unit ;) ).
-Chris |
|
|
| gaborbela |
HI
Thanks for the advise about the belt and how instal the new belt .
Today I went out to look around , I went to a couple of surplas stores and even went to some popular service were usualy fix cd players to .
Unfortunatly is not so simple , nobody has these tipe of flet belt .
Those who has it is much longer .
So now I need to find out were I can find belt , to test the player if work properly .
I have some similar belt but not as flat as the original , I will give a try let see if it worth to look for the original .
Thanks one more time for the help .
I will let you know if I have SOME sucses with it .
Regards |
|
|
| anatech |
Hi gaborbela,
Okay, a long shot. Try Lenbrook Industries in Pickering. They are the Canadian distributors. I haven't had much luck with them so far.
I really wish Nakamichi Canada was still here. They were good people.
-Chris |
|
|
| gaborbela |
HI
Unfortunatly no answer for the belt .
I'm sure the cd player need a new belt . I just made some cleaning and I instaled back the old belt (wich is way to long) and I could play a couple track. Even I could skip to the next track , before it was inposible .
So if somebody know from were I can order a new belt for the Nak OMS-5 cd player please let me know .
I tried on the web , I looked at some surplas stores but these small size flat belt nobady has.
Just much longer for tape deck.
Regards |
|
|
| anatech |
Hi gaborbela,
Try and build up the motor shaft diameter with some heatshrink tubing. That will give a rougher surface too.
Can I say "told you so"? :D
-Chris |
|
|
| georgehifi |
This is a trick that i've used with about 50% success, depending on materials used in the belt, I've boiled them in hot water for ten minutes then tossed then in the freezer is has shrunk some of them.
Cheers George |
|
|
| gaborbela |
HI
Thanks , if I dont find something I will do that .
I just afraid on the and I remain with out belt .
Regards |
|
|
| gaborbela |
HI
I did the treatment with the hot water and after the freezer .
It got better , now I can play , I can fast foward or skip to the next track .
Not 100% but at lease work. It still take long time sometimes to find the next track or when it start up .
I think the motor is veek a bit , I bought some fine oil for the mooving parts , lets see .
Thanks for thelp for all of you .
Regards |
|
|
| anatech |
Hi gaborbela,
Do you like your CD player?
Do not oil the motor! Any oil that flows down the shaft (and it will) will destroy that belt.
So, I'll repeat my earlier advice. Find some heatshrink tubing that fits closely over the motor shaft. With the player on it's side, gently warm the heatshrink with a heat gun well back. This increases the OD of the shaft and provides a grip for the belt. That's how mine is running right now.
Take the advice of a Nakamichi tech trained on your machine.
-Chris |
|
|
| gaborbela |
Thanks
I will do that to .
I have heatsrink at home .
I just want to put some fine oil were the tray mooves just a bit .
Thanks |
|
|
| georgehifi |
JENO,good to hear it shrunk it a bit, now to go one step further boil it again 10mins this time throw into a glass of iced water, it will shink it one step further.
I didn't want to tell you the iced water way first as depending on how the belt was constructed with what materials it could of shrunk too far but your'e safe to do it now.
Cheers George |
|
|
| anatech |
Hi gaborbela,
Okay. The tray has a bunch of nylon rollers held in by a clear plastic strip with rectangular holes. The tray assembly is an incredible pain to take apart. I do not recommend you touch this assembly at all.
I know because one "child" got upset with his OMS-5 and kicked it with the tray open (under warranty). The damage caused with the parts prices and labour priced it into the "not worth repair" area. Now this was clearly customer abuse, but Eric Moos (Nak area rep) decided to cover the unit under warranty !!!!! He did make some idiot decisions, that was just one. So I had to do this for warranty rates. After taking it apart I was able to convince Nak to send me a new transport complete. It is a big job. Don't go there.
You can lubricate the slide and gear section. Remove the drive gear, clean all the existing grease (and hair + ??) out. Relubricate with white grease only, apply sparingly. Extra grease always causes problems. The lube in the rollers is also white grease. If you just apply more you will make a mess. I warned you.
-Chris ;) |
|
|
| Heiney9 |
Hi Chris,
You and I have corresponded before about Nak and Adcom equip. To add to this thread I have a question about a transport issue with a Nak OMS 3. Since you used to repair them perhaps you could give some insight. I've long given up hope that it can be repaired properly and w/o breaking the bank.
I've had this unit since new and it's been out of service for approx 3 years now. I used to be a salesman at the local high-end dealer that handeled Nak back in the day (mid 80's, early 90's). They are gone now and so is my friend the tech who used to work in the repair dept.
On to the issue. I can open the drawer place a disc in there close the drawer and hear a motor buzzing the standby light on the display will flash and within about 3-5 seconds the drawer open back up. I can do the same sequence even w/o the disc with the same results. Occasionally the disc will spin up and I can hear it speeding up and slowing down and the assocaited sound of the laser trying to track the info, but eventually it just opens the tray.
Any idea at all based on your experience if this is simply an adjustment issue or if the laser assembly is shot. This was repaired about 8 years ago and from my memory it had a new laser assembly fitted. I mainly would like to get it up and running for nostalgia, but I'd like to compare it to todays players. I always enjoyed the sound from this unit even though it only used a single dac instead of the duals of the 5 and 7. I've taken it apart just to look at it and it's built like a tank, very unlike today's units.
Sorry I just have the ability to repair anything of this complexity. I have done nothing with it other than open her and look.
Regards
Brock |
|
|
| anatech |
Hi Brock,
The drawer thing sounds like a poor contact with the drawer position switches. You should measure the little switches on the transport. Might be an easy fix. (OMS-4 had dual DAC's).
The laser head will not need adjusting. It may need a new disc motor. Do not allow anyone to just adjust the unit. Some laser heads had a problem where the lens assy would stick on the post. Head replacement was the only way to fix that. Your unit may not work with the top cover off (normal). Those were NEC transports. Harmon Kardon used the same one with fewer options.
I wish we lived closer to each other.
-Chris |
|
|
| kensell21 |
Hi All,
Ive just joined this forum site and would like to ask others for more info about the Nak cd4 as I've done a search and found this thread.
After a long time with vinyl using a michell gyro SE/techno arm A/ Ortofon MC 30 Supreme.
I wanted to compare it with my slightly dusty 12 year old Nak CD4 player with identical music.
A MoFI vinyl and MoFI cd of Cat Stevens Izitso.
Well no brainer really and I wasn't expecting it to be.
But it did get me thinking that I must get round to replacing it for the music that I can't get on vinyl.
Could some tell me what the transport and DAC arrangement is in this machine? I will also need the clock frequency.
I like the look and feel of this machine so I am thinking about putting a new clock in it from Trichord Research.
Also would the transport of this machine be good enough to use as a dedicated transport?
Its probably had minimal use over the years. If all else fails I'm thinking about going retro and find a decent Teac Vrds transport or even a Pioneer stable platter, but that topic I might leave for another thread.
Thanks |
|
|
| waves |
Hi Chris,
Wow! I'm really impressed with the helpfulness of this thread and its participants, and I've learned alot. Especially to not give up! I stopped looking for Nakamich information a couple of years ago.
I had played my OMS-2A daily until then. It started having trouble reading discs, but the lens looked clean. Besides, when discs did play, there was more skipping that eventually became a continuous clicking. If I remember correctly, the sound was at a higher pitch than skipping caused by scratches. At any rate, I decided to observe the motor's spindle as it ran, and it seemed to have a wobble. I compared this with several other cd players, and mine seemed like it was spinning on worn bearings.
I'm assuming the motor needs to be replaced. I've read in previous posts about things I wouldn't touch, but I'm wondering if I could replace the motor. Since I couldn't find any Nakamichi motors in the parts section, I was also wondering where else to look for parts.
Thanks,
Dave |
|
|
| Salar |
Hello Dave,
maybe the motor of your OMS-2A is from Mabuchi:
http://www.mabuchi-motor.co.jp
Another supplier might be Copal
www.nidec-copal.co.jp
Mabuchi built the disc-motor of my OMS-5EII, the Copal was for the laser unit of the OMS-5EII.
They probably are discontinued, but maybe Mabuchi or Copal have contemporary models with the same specs like the old ones?
One problem will also be mounting the disc table of the OMS-2 on the new motor, because it has to be fixed in a certain height.
Maybe, making something like a "print" will help.
I do not know the english terms, i think at some kind of artifical clay which does not glue and can be modeled. This can be stuck between disc table and the motor body before disassembling them. When it has dried, it can be used as a reference for fitting the old table on the new motor.
Hope this helped a bit,
Salar |
|
|
| anatech |
Hi Dave,
Check the nylon thrust bearing at the top for wear. It will have a dent.
You must sand this out, then fine sand 'til it's smooth. I use damping fluid to lubricate the ball bearing after that.
The motor is replaced by a standard Mabuchi CD motor. Cut the shaft to the exact same length and round the end. Measure the table height carefully first and make sure it ends up at the same height. Use nail polish or thread lock on the shaft before sliding the table on.
The exact Nakamichi motor came with a brass spacer. (NLA) I think new mounting holes need to be drilled also. It can be done, I did many a long time ago. My brother has the same player - still. It works fine.
-Chris |
|
|
| Salar |
BTW, I had an OMS-5/7 for some weeks bevore buying a OMS-5II/7EII.
As far as I remember, the sound of the OMS-5II/7II was crisper with deeper bass compared to OMS5/7 |
|
|
| anatech |
Hi Salar,
The OMS-5/7 has a superiour transport, 14 bit DAC (TDA1540) and a great filter. The DAC in the type II is far superiour to the first ones. If only they kept the original transport!!!
-Chris |
|
|
| Salar |
Hi Chis, Hi Dave,
hope Niro Nakamichi will read this some day... |
|
|
| anatech |
Hi Salar,
LOL
If he is still with us (and I hope he is) he is very old. Possibly beyond caring for the older product. That would be very normal I would think.
Nakamichi's biggest problem was that they constantly swung between "lifestyle" products :dead: and some serious audio. The lack of consistency lost them customers and credibility.
Their cassette decks were the best! No question there. Now if they had ever built a full size reel to reel (the three head cassette decks treated the tape like an open reel machine), they would have been awesome indeed. Teac /Tascam would not know what to do. I think Revox and Studer were safe there. The Nakamichi electronics would have been better I think. Mechanicals and servos may have been better with Studer / Revox.
-Chris |
|
|
| Salar |
Hi Chris,
here you can find an excellent article about Nakamichi and Niro Nakamichi:
http://en.wikipedia.org/wiki/Nakamichi
BTW, I want to order a YEDS-18 Disc now. (I know, the most expensive way to go...)
But were there several issues/versions of this disc? It is sometimes stated as "YEDS-18, Type 3 and 4", which sounds like that. I asked Sony, guess what, they donīt know and told me to ask the distributor for Sony spare parts, I bet he will not know either...
I will also have to take care on the belts. About ten years ago, I used vaseline for greasing the mechanism, which crawled everywhere because of the heat. I cleaned this mess maybe 3 years ago with alcohol and now use a special grease for suspension forks (which does not crawl and does also not attac rupper or plastic), but still the mechanism becomes greasy after some months from the last remains of the vaseline... I will also try a heatshrink tubing and a second rubber belt around the gear driving the original belt.
BTW, What were the srevo mods you were talking about? Just curious, I will not open my Nak for this. I did it so many times during the last 16 years, that some screwholes start to show wear...
All the best,
Salar |
|
|
| anatech |
Hi Salar,
The major servo mod was for the OMS 5/7. Stock it will reject defective discs, after the mod it will play them unless they are really bad. The type II machines have no mods that I am aware of.
This modification is a small manual all in itself. Major work is done.
-Chris |
|
|
| Salar |
Hi Chris!
And the YEDS-18? Were there several versions if it?
All the best,
Salar |
|
|
| anatech |
Hi Salar,
I never did buy the YEDS-18. I had a ton of other test discs. Sorry I couldn't help you there.
An authorized Sony service technician should be able to sort that out for you.
-Chris |
|
|
| Salar |
Hi Chris,
got a YEDS-18 - you are right, mesurement does not differ from a well manufctured CD. I also replaced the pickup - KSS-123A. (the lens of the old one looked slightly greyish/dirty, but still worked)
I did not have the machine hooked to the stereo, when I made the alignment according to the service manual of the OMS-5EII. The waveforms on the scope looked o.K.
I grounded the Nak as well as the scope when measuring.
But even though the variable resistors did only need a slight readjustment, I hear a rythmic scratching (i.e the sound of a worn out burned CD) even on the YEDS-18, after I reassembled the unit and hooked it on my stereo.
This has never been before.
Foolish me, i did not have a final look on the eye pattern before reassembling the Nak.
Could it be, that a laser comes sometimes mechanicaly misaligned from the manufacturer?
Maybe Sony as OEM made several preadjustments for their customers? (Unlikely, this KSS-123A came as an original part from Sony, not nakamichi, and it replaced a KSS-123A, which also was an original part from Sony as well.)
One question:
I realign voltage when adjusting Focus, Track, E-F balance, right? (the waveform on the scope travels up and down according the turning the variable resistors).
If, as one example, the waveform should have a symmetrical plus-minus swing, whot do i take as reference when adjusting the line on the scope horizontally before measuring on each step?
Probe to ground? Or the probe to the test pin to be measured, with no signal yet?
Had a nice talk to a tech. He stated that to his experience, many faults of old laser units did not come from weak diodes but often dirty mirrors inside the unit...
He cleaned some in an ultrasonic bath.
All the best, Salar |
|
|
| anatech |
Hi Salar,
The eye pattern is the most important signal to look at. All the adjustments you make are to increase, sharpen and stabilize this one waveform. I view the factory alignment as a starting point. ;)
If you were to look at the eye pattern while playing a disc, you would see that the noise corresponds to the eye pattern becoming less well defined. You are hearing uncorrectable digital errors.
Your "0 VDC" reference for your offset adjustments is the ground on the servo board. Using a DVM will give you variable results due to the noise levels. You need to balance the 'scope on that range for zero volts before attempting the adjustment.
The Sony heads are fine. I've used them for years, they used to come from Nakamichi. Be aware that some of these heads get sticky on the pole piece. I was successful in repairing one recently.
-Chris |
|
|
| Salar |
Hmmm,
when the pole piece gets stuck, will it still move freely?
When I block the photodiodes above the tray and "mimick" an inserted cd, the lens moves up and down.
Does the pole piece gets more likely stuck in the horizontal direction?
All the best,
Salar |
|
|
| anatech |
Hi Salar,
If the pole piece gets sticky, it will generally not move easily in any direction. The motion should be quite free and springy.
It looks like your head is still fine.
-Chris |
|
|
| Salar |
Hi Chris!
Thanks for your kind and quick replies!
Just came in my mind, that once during adjustment, the servos once "ticked" when I started the cd(YEDS-18, Type4 no manufactured errors), but did not, when I stopped the CD and started it again.
As far as i remember this effect appeared randomly.
I will try another adjustment in some days.
BTW, variable resistor RV105 is for the drop out detection,
not for the APC circuit? I am asking because I do not want to mess up the laser power, when I try RV105.
All the best,
Salar |
|
|
| anatech |
Hi Salar,
RV105 is indeed the drop out detector adjustment. The laser power adjustment is on the head itself, so no worries there. On the original OMS-5/7 the laser power adjustment is right on the board.
I always fine tune the E-F Balance with a drop out disc, one with sharp dropouts. You look at the eye pattern at 0.5mS / div and look at the drop out and recovery. You can see the envelope modulated by the tracking servo waveform. You adjust slightly to optimize the recovery. This will agree with the normal method but it's a finer adjustment. You will need to filter the trigger and adjust the trigger point to get a stable pattern. Your waveform should be no higher than 2 div.
-Chris |
|
|
| Salar |
Big trouble, simple reason:
The slide ring which fixes the CD got stuck sometimes. So the CD could slightly vibrate, which caused the dropouts.
Made a new adjustment, with the ground screw/point of the Main P.C.B Board as reference.
Where needed, I adjusted the sometimes noisy ground on the scope, that it was symmetrically above and under the center horizontal line of the scope.
So everything is finished now. Sometimes, when the laser has to travel to the last track, the cd will stop, rest some seconds and than spin backwards. Maybe this is caused by the slightly bigger diameter of the pulley of the feed motor? (wrapped heatshringing rubber around it)
But a self made test CD (200hz sine together with 20050hz sine), which had audible clicks now runs perfect...
All the best, Salar |
|
|
| anatech |
Hi Salar,
Sounds like your E-F Balance might be out a little. The feed motor pulley diameter increase may cause it to go too far forward on search. Possibly it may be too sensitive in normal play too, but less likely. It normally runs off the average DC component of the tracking servo and is therefore running on need. If your tracking error signal goes negative a lot, the diameter needs to be reduced or the proper belt installed.
See if you can get a drop out disc and check the eye pattern recovery as I detailed above.
-Chris |
|
|
| Salar |
Hi Chris,
right, a plus of 0,3mm in diameter on the pulley, caused by the rubber, made the laser travel too far... removed it, cleaned the belt, now it works. I tried the eyepattern with a prepared disc (one black stipe, 1mm with) but could not interprete the signals. Turning E-F balance did not seem to change the signal of the eye pattern.
I measured the ohm value of the varable resistor of the defective OMS-7EII I bought ten years ago and aligned E-F according to it. As far as I know, nobody tried to repair the OMS-7EII when it went defective - I later found out, that a power transitor was blown. So all variable resistors should be in their original positions.
The E_F Balance is now around "eight oī clock", taking the single ground pin as a 6.
More on the less noisier side.
The unit now runs perfect, hope I wonīt have to open it the next ten years.
(My DYI cabinet makes this very complicated)
BTW, flat belts in a lenght of 5,4mm are not available any more, at least in Germany. Somebody told me, that the big chinese suppliers (about three of them, ten years ago, malaysia was the main supplier) do not manufacture this size any more.
Have a nice week and thanks a lot,
Salar |
|
|
| anatech |
Hi Salar,
The adjusting point for E-F balance is dependant on the laser head. The method (equal waveform above and below zero on your scope) is close. The method I described is even closer.
At any rate, if your machine reads a disc quickly it must be in the ball park. Close enough then!
-Chris |
|
|
| Salar |
Hi Chris
But how do I filter the trigger? I can go to a fixed point on the scope and fine tune it, that the square caused by the dropout does not drift for some time, but thatīs it.
Do I need an external signal for the trigger?
Salar |
|
|
| anatech |
Hi Salar,
Depends on the 'scope. Mine has a filter for the trigger, you can use TV-V (or TV-H, for video horizontal). You may need to invert the trigger signal as well.
It may take some experimenting. I cussed for a while with my new 'scope many years ago! ;) Now it's not that hard.
-Chris |
|
|
| Salar |
Hi Chris,
well, touching RV104, E_F Balance with a screw, makes the laser jump on a dropout disc. I also do not see the recovery.
So i went back to aligning it according to the service manual.
But aligning the unit according to the service manual gives a more blurred eye-pattern. But he symmetry looks o.k.
To get a clearer pattern on the scope, i have to raise the amplitude first (RV101 Focus) then turning E-F makes the signal clearer.
But doing so makes the dc level of TP focus in stop way off the dc level, when the player runs. The service manual states, that the DC level of focus should not change in play and stop.
Also E-F is off the regular alignement stated in the service manual.
To make things short:
Has the eye pattern to be as sharp as possible?
All the best, Salar |
|
|
| anatech |
Hi Salar,
The service manual instructions are valid for a brand new head. The suspension sags over time. Make you eye pattern the clearest. The E-F Balance adjustment should agree with the clearest eye pattern. It do it that way to get a machine running that someone else has messed with, then I fine tune it. One your E-F Balance is set, the eye pattern ought to be clear.
Do whatever makes the CD player work the best. I'll have to pay attention with the next one I get in. When something isn't working right, other things need to be compensated for. Also, check teh turntable hieght. Sometimes they get lowered over time. That will throw off your focus bias adjustment for sure.
-Chris |
|
|
| mayham |
Hi there,
Yesterday I've bought a Nakamichi OMS-5A at a carboot sale for 1 euro. Guess that's quite a bargain, although the thing's a bit scratched. But hey.... Can't have it all.
I actually suspected the thing to be dead but when I plugged it in it actually would start reading and playing CD's.
However, it doesn't want to play all CD's and unless their absolutely clean, scratchless and what not, it'll just throw out the CD after a couple of minutes spinning the thing.
I suspect that the thing's a bit off in calibration or the laser is weak..... And now I'm looking for the service manual. Seen them on eBay but I'm a bit reluctant towards eBay (don't know why.....). Next to that, I'm living in the Netherlands so don't know how that's comming along.
Also, I'd like to build a s/p diff coaxial out on the thing since I've got a realy nice DAC which I'd love to use on this Nak. So if anybody has some clues that they like to share.... Be welcome ((-:
But first things first.... The CD pickup.... Gotto clean the thing first... See where that's going (-:.... I'll let you know of my progress! (-:
Greetings,
Andreas |
|
|
| mayham |
Hi there,
Just installed my Nak on my improved tube-amp (replaced power capacitors). First I did not notice it but it seems like it has a lot of unrepairable read-errors. Strange 'ticks' in the music. Anyone got an idea what that might mean??
By the way.... The DAC is not exactly what you need to know when you want to install spdiff on a cd-rom player. I read it's the digital processing chips that you need to know. I'm still a bit reluctant to open the thing completely (I've been known to have some bolts and nuts left at the end of opening up this kind of gear) so I wondered if anyone knows which chips are inside......
Thanks many!
Andreas |
|
|
| Salar |
Hi Mayham,
this is what the given thread is about, the SAA70XX Icīs for decoding the Data and feeding the TDAīs. So many bolts and nuts arenīt there to be left over if you open the top cover to check the ICīs...
All the best, Salar |
|
|
| rfbrw |
| Having once managed to get the CS8402A to work with the SAA7000, I have to seriously question whether it is worth the effort. Whilst all the spdif flags did what they were supposed to and there were no clicks and pops, the resulting sound was so unrelentingly bad, I had to conclude something must be wrong somewhere. Either that or the SAA7000 is not good without the SAA7030 and TDA1540. |
|
|
| anatech |
Hi Andreas,
The signal processing occurs on the small board underneath. The components are mounted towards the bottom of the servo PCB. The black metal box on the rear panel contains the audio filter section.
Hi rfbw,| quote: | | the resulting sound was so unrelentingly bad, I had to conclude something must be wrong somewhere. Either that or the SAA7000 is not good without the SAA7030 and TDA1540. |
If the mech. is not set up properly you will get increased digital errors. The modified Nak OMS-5/7 has a wonderful servo section and a very stable eye pattern, low noise too. Being this is a Philips design, there is a coil that sometimes needs to be adjusted for the VCO. Misadjustment will cause exactly what you are describing, or even sound mutes and breakups.
You could always allow the servo section to work and feed the eye pattern into another chip set. That should sound pretty good. Just rip one out of a CD player that has a cheap transport, but a good D/A.
-Chris |
|
|
| rfbrw |
| My post was not so much about the Nakamachi, more the feasability of adding SPDIF to players based on the 14 bit Philips chipset. In this case it was another 14 bit machine, the CD104 and I had two at the time one, in pristine condition, used as a reference. I also used a dac with selectable inputs so I could switch between the modified CD104 and a Sony DVD player. The SPDIF modified '104 was absolutely dire. |
|
|
| anatech |
Hi rfbw,| quote: | | My post was not so much about the Nakamachi, more the feasability of adding SPDIF to players based on the 14 bit Philips chipset. |
I understand. I was trying to point out other factors that could affect your result. I belive that there were at least two, possibly three chips that needed to remain connected.
Also, that chipset was selectable between 14 and 16 bit. It's possible it wasn't jumpered correctly as well. That would make a mess out of things for sure.
-Chris |
|
|
| rfbrw |
| quote: | Originally posted by anatech
Hi rfbw,
I understand. I was trying to point out other factors that could affect your result. I belive that there were at least two, possibly three chips that needed to remain connected.
Also, that chipset was selectable between 14 and 16 bit. It's possible it wasn't jumpered correctly as well. That would make a mess out of things for sure.
-Chris |
I'd like to think I'm reasonably competent in these matters and that I have a fair grasp of the in's and out's of the SAA70x0 series devices, so when I say everything was as it should be I mean just that. But that is not to say you won't succeed where I have crashed and burned, so, by all means, on James, and don't spare the horses. |
|
|
| anatech |
Hi rfbrw,| quote: | | I'd like to think I'm reasonably competent in these matters and that I have a fair grasp of the in's and out's of the SAA70x0 series devices, so when I say everything was as it should be I mean just that. |
I know you are. Please don't think I was questioning your experience. It's just that we all sometimes miss the odd small thing and I was hoping to spark something in your memory.
I have an OMS-7 that I'd like to improve the audio path in. As a transport, it shows very high potential.
-Chris |
|
|
| rfbrw |
| quote: | Originally posted by anatech
Hi rfbrw,
I know you are. Please don't think I was questioning your experience. It's just that we all sometimes miss the odd small thing and I was hoping to spark something in your memory.
I have an OMS-7 that I'd like to improve the audio path in. As a transport, it shows very high potential.
-Chris |
One of the first things to do is convert the stopped clock system to a continuous clock one. It is necessary to count clock cycles in order to reposition WS relative to the now continuously moving data. The two missing clock cycles would have loomed rather large on the scope. Not that it actually matters as data is always 16 bits. Data and STR1 is the minimum requirement. |
|
|
| anatech |
Hi rfbrw,
I'm glad I haven't started to mess with it yet. I just learned something new, thanks. ;) It might be easier to simply feed the RF signal into another system.
-Chris |
|
|
| kwasiaesem |
Dear Anatech,
Please could you help me out.
I have a Nakamichi OM5 SE.
The sound is superb but it will not always play a disc first time and will spit it out.
Also it will sometimes not play the first or last track of a CD.
I have read all your comments but when I have taken the lid off I havnt a clue where to begin.
If you have a paypal account I am more than willing to pay you for your advice in taking the thing to bits.
Best wishes
Kwasiaesem |
|
|
| anatech |
Hi Kwasiaesem,
Please check the feed belt. It is beginning to slip. What should be done is to remove the slide rail very carefully. Retain all washers and hardware, work on a well lit, clean table. Clean the slide rail and then lubricate it using a fine oil, no additives. Make sure there is a very thin film only. There should be no visible drips when you are done, just a very thin coating of fine oil. Clean any dust out of the head area and bearing area on the head itself. Reinstall the rod and reassemble the rest.
Before placing the belt back, clean all surfaces the belt runs on. Clean the belt carefully. You may find it slips on the motor shaft. If another belt is not available, place a bit of heat shrink tubing on the motor shaft and carefully shrink it into place. Now it will work if everything else was done correctly.
At no time do you disconnect any wires from the head.
If you wish to pay someone, please make a donation to DiyAudio. That would make me a happy camper. :)
Let me know how this works out for you.
-Chris |
|
|
| kwasiaesem |
Dear Anatech,
Thank you so much for your reply,
I was about to give up hope.
I stumbled across your reply by accident. I find this forum extrodinarily difficult to navigate around and highly frustrating.
Apparantly as I am not a full member I cant email you directly.
I will make a donation.
I too feel sad Nakamichi is disappearing. It must have been a brilliant place for you to work and I envy you.
I used to work for Akai UK supporting their pro audio samplers and multitrackers ( dinasaurs now) at the end of the `80s
Ive been in and out of all the top studios in London and have heard some absolutely staggering sound - not always my personal cup of tea- but but so clear it starts to scare you.
I have a 682zx cassette deck I had serviced years ago by Nakamichi in UK down in Brighton.
I could not believe the level of service.
They rang me- would I mind if I waited two weeks before work started on my machine as the 682 "guru " is on holiday ?
Fine I thought.
Later he rings me upwith a quote which was fine.
Then he asks me if I want everything else that is replacable, replaced with higher spec bits.
I ask why
He says that the technology the day it left the factory has been superceeded
I agree.
When I go down and pick it up I am told this machine will be fine for 10 years or so.
Then he pulls out a four sheet paper list of everything else replaced from pennies to a coulpe of quid.
I could not believe the sound difference- absolutely staggering.
Everything tightened up especially the bottom end.
Very nice people indeed - and my 682zx still sounds just as good.
I will follow all your advice and let you know how I get on.
Thank you once again
Chris |
|
|
| anatech |
Hi Chris,
Yes, a proper service and calibration will do wonders for a Nakamichi cassette deck. Doing a great job is as simple as following the instructions in the manual. Most people don't. :(
Those old VCR based multitrack machines didn't like to be moved or vibrated! I looked at doing these and backed out. We serviced the Tascam DA-88 format machines. Semi-pro customers could be a handful! Give me a real reel to reel any day (Studer). The upper Tascam machines were okay, but you adjusted everything to get them aligned mechanically. With Studer and Revox, you just replaced the worn parts. Much less shimming!
SO let me know how you make out with your CD.
| quote: | | I stumbled across your reply by accident. I find this forum extrodinarily difficult to navigate around and highly frustrating. |
Make sure your mail notifications are set to "on". You will get a link to your thread. You are now a full member, so the email system will work now.
-Chris |
|
|
| kwasiaesem |
Dear Chris,
I will be starting your recomendations on Saturday.
Week days my head is too caved in ( I work in I.T. now)
I should explain that at Akai I was a software bod - user support hotline.
I did take stuff to bits with the hardware guy who was a genius.
The nearest I got, was blowing EPROMS which held the various operating systems.
All the stuff I supported was digital direct to disc stuff.
There was some "tape gear" (digital ish) in the studio there, but was more of a museum piece than anything else.
Have made a donation.
Will let you know how I get on next week.Thanks again.
Chris |
|
|
| anatech |
Hi Chris,
The donation to the site was very nice of you. Thanks from all of us!
Once you get going on your OMS-5, you should be okay. You will see what I mean.
-Chris |
|
|
| skyline889 |
Hi guys,
I have a similar problem to one of those stated here however, my problem is with my OMS-5. Like the guy with the OMS-4, when I stick a cd in I can hear the motor spinning the CD (And see it when I took the top off) but it won't play anything and will eject the disk after a few seconds. I'm handy with DIY but I've never really touched any electronics before so when I open up my player and try look for the feed belt I can't really find it. I'm hoping it's a problem with this and not the laser (My father replaced the laser once already when it used to be his and the parts are now unavailable here in Hawai'i) but any help would be greatly appreciated. Thanks in advance!
-David |
|
|
| anatech |
Hi David,
The feed belt is underneath the transport, on the bottom.
| quote: | | My father replaced the laser once already when it used to be his and the parts are now unavailable here in Hawai'i |
I am really hoping he was trained by Nakamichi on how to set this unit up. He should have the original service manual, with out which, there is zero hope of getting it running even close to properly. Replacing the head by unscrewing the old one and installint the new one isn't even close to correct. This head is completely adjustable mechanically. Margin for error is very small. Then you do the electrical stuff. A god 'scope and real test CDs are required. Philips 5A for starters.
-Chris |
|
|
| skyline889 |
Hi Chris,
Thanks for the help! Hopefully I'll be able to find it when I open it up again. About the laser, my dad didn't actually replace it himself but he payed the Nakamichi repair center here on Oahu (When they were still here) to replace the laser. He said it cost him about $500 back in the late 80s so I'm really hoping it hasn't malfunctioned again. The cd doesn't spin excessively fast when reading though, so I'm not too hopeful that it's just a feed belt problem. :(
-David |
|
|
| anatech |
Hi David,
Two things I can say from experience.
1. It's probably the belt.
2. $500 is not enough money to replace the head. My cost was over $500 for that head and I was authorized warranty for Nakamichi. This unit takes about 5 hours to set up (and I've done many).
-Chris |
|
|
| Salar |
Hi Folks,
btw, has anyone an idea, where to find replacement belts for those being used in the Naks OMS-5EII/7EII?
The lenght is 5.4 cm, as far as I remember. I once checked all available catalogues with a technician here in Germany, looks like those lenghts are not produced anymore...
All the best,
Salar |
|
|
| anatech |
Hi Salar,
I think the best thing to do is walk in to a parts place with an old belt and simply go through them all. I had always used the exact Nakamichi replacement part so I don't know about general ones to replace them.
-Chris |
|
|
| izmarkie |
Hi,
Sorry to bring back an old thread, but I have an OMS-5A II, I'm having similar symptoms to the ones listed in the first couple posts, and I'm not so sure about whether I want to mess with a CD player on my own. I've built a bunch of speaker boxes, reconed woofers, and redone crossovers and such, but when it comes to anything with a laser, I'd rather trust a pro.
Anatech, or anyone else - can you recommend someone I could send it to in the US, preferably in the southwest? Is it even worth it, or should I just buy something else? |
|
|
| Salar |
Hi izmarkie
I can mail you the service manual, if you like. (16MB) Then you can judge if you like to do the work...
All the best, Sal |
|
|
| izmarkie |
| quote: | Originally posted by Salar
Hi izmarkie
I can mail you the service manual, if you like. (16MB) Then you can judge if you like to do the work...
All the best, Sal |
That would be great. I think gmail can handle 16 megs. alexisrael at gmail dot com.
Thanks a lot! |
|
|
| Salar |
Hi Izmarkie,
youīve got mail...
And here it comes. My Nakamichi OMS-5EII / 7EII alignement adventure!
But for those, who do not want to read the entire post, one question:
Got my Nak into ball park, but it will only play scratched CDīs perfectly about ONE HOUR OR MORE after being powered up. Any Ideas on that? Some old transistor in the servo circuit? I could have the Nak being powerded up the whole day, but hey, seriously, these are not the times for wasting energy any more...
Now the alignment story:
I have a two test CDīs for this purpose, a perfectly manufactured YEDS-18 test CD from Sony - but in fact, any other well manufactured CD will do the same.
For scratches, I use Digital Recordings "CD-Check".
It has black lines printed on the disc surface, ranging from 0.3mm up to 1,5 mm for testing the error correction, divided into four check levels.
The third CD is an old one from Keith Jarrett. It has a small spot on the aluminium layer, (no scratches on the disc surface) about 0,5mm, maybe a scratch from the label side.
The Nak did not even manage to play errors of about 0.3 mm on CD - Check (which btw delivers a very clean eyepattern, it seem to be very reflective, maybe because it is gold plated). The Nak also hang on the Jarrett recording. The laser is almost brand new, I swapped it two years ago.
But my other player from Sony manages to play scratches on CD-Check of about 1mm without any clicks, as well as the Jarrett recording. Because four lines are printed on CD-Check in an angle of 90 degrees, they in fact sum up to an error/gap of 4mm!!!
A friend of mine is developing a DAC based on the PCM 1704, which i will probably built into my Nak.
Because of this and because i was so frustrated about the Naks bad performance, I decided to give other electronics a try.
Because I have already built a clock from Tentlabs into my Nak, I started to look for a Philips based transport clocked with 16.9344 Mhz.
Got a cheapish player CD 753 with CDM12.1 from ebay and already drew plans for building this transport into the Nak - anatech would kill me for that!!!
But you can find the CDM-12 in almost any philips based player, even in High-End machines, lasers are easy to get, so wanted to check this out.
Unpacked the Phillips, (2 kg of plastic, the Nak weights 10 kg) played CD-Check, again no problems with scratches up to 4mm .
Played the Jarrett recording, (0.5mm on the aluminium layer) and the dammn Philips hang!!!
Now it looked like the Nak was not as rusty as it seemed. Maybe, the Sonyīs and Philips optics have another focal lenght, in order to blur out scratches more easily?
I then experimented with the mechanics.
The disc motor could have been worn out. I bought a new one (Mabuchi RF-300T-11400).
But the shaft was too long. I did not want to take the risk in cutting it down, bought a bronce bearing and asked a mechanic to mill an aluminium spacer for the motor to house the bearing and shaft.
In fact, this did not seem to have any effect, but well, this construction should last forever - at least until the brushes of the motor fail...
BTW table height should be 4.5mm, measured from the top of the motor ( a brass spacer is originally fixed on it) to the bottom of the disc table.
Now the electrical alignment:
Alignment according to the service manual is only the first step. The second step is to look at the eyepattern. (Thanks anatech!)
One example:
According to the service manual, you trim focus offset by observing DC level on a certain test pin while playing a disc. You then stop playing and raise or lower the level until there is no change in play/stop mode.
But you will still get a clearer eypattern by turning the trimmer a bit more clockwise. The sweet spot is just before the eyepattern reaches the highest amplitude - and is the clearest. But according to the manual, focus is now far off, but my Nak works better now.
The same with E-F balance. When i try to align according to the service manual, I get a very noisy and bouncing signal in test mode wihich is not easy to observe.
But a workaround is to take a CD with long tracks and simply jump/skip between the tracks while observing E_F. It is now a relatively clear sinewave until the laser has reached the next/previous track and goes back to play mode. This wave should be trimmed while skipping until it crosses 0 V symmetrically.
I then took a CD with small clicks/ errors (i.e the Jarret recording) and fine tuned E-F until the cd was played without errors. In my case, this really meant turning the trimmer in fractions of a millimeter.
Now everything works perfect, I but as I stated, I get annoyed by the fact, that the Nak has to warm up for more than an hour until it performs best and I would like to find the cause for this.
Another backdraw was the additiona bearing for the disc motor . It starts to "sing" at low speeds, sounds almost like a testtone.
I later found out, that the clamper has some play. This is normal, but I fixed the clamper by placing a small brass rivet in the center hole of the clamper. The rivet sits now very tight on the motor shaft when a CD is inserted the clamper is more centered than before. I also removed the rubber cover from the clamper. With this lighter and centered clamper, the bearing runs silent now.
End of story,
all the best,
Sal |
|
|
| izmarkie |
Thanks Salar!
And... I'm definitely too intimidated to try this myself. Can anyone recommend somewhere to send it for service in the US, or should I just give up and pick up something else? |
|
|
| anatech |
Hi Salar,
And you now have a technician's touch. That is what separates the good techs from the great techs. The bad ones don't even read the manual.
Glad to hear you have it settled. It does sound like your disc table height is off a little though.
Hi izmarkie,
Look for a well regarded audio service shop or a semi-retired good technician working out of home. You need a patient, careful guy. An ex-Nakamichi tech might be a good bet. TV shops are probably not what you want, they can be destructive. Usually are on audio gear.
-Chris |
|
|
| Salar |
Hi Anatech!
I measured 4,52 mm from the disc table (bottom of the rim) to the brass spacer when I first disassembled the original disc motor and I kept that value.
Because the original Motor was worn out, this value might be wrong.
I am not sure any more: I lowered the table height once but as far as I remember, I saw no difference in focus offset.
Got the fitting motor now on ebay (new), so I will experiment with it.
But I do not have a good feeling about loosing/fastening that tiny screw several times which fixes the disc table to the shaft, looks a bit fragile to me: The disc table is made from brass, so I guess the thread for the screw will not be strong...
All the best,
Salar |
|
|
| anatech |
Hi Salar,
The set screw does not need to be very tight. Once you find the "happy spot", make a jig to hold the table and use some thread lock both on the table shaft and the set screw. Just snug it down and leave it to set overnight.
Fiddling with this no fun.
-Chris |
|
|
| Salar |
VERY strange effect-
when I touch a connector chord of my Nakamichi OMS-5AII/EII, I will hear scratches in the music and the laser will even loose track.
AND - even just holding my finger very close to the connector chord (letīs say a distance about 5-1mm) has the same effect!!!
What can this be?
The 8-pin cord (JU101) connects the photo diodes of the laser (KSS-123A) with the R-F Amp (CX20109).
Touching the second connector chord (also 8 pins) which feeds the laser and coils
has no effect.
So I replaced the connector chord, but this had no effect.
Then I tried some kind of shielding: I wrapped the connector chord with copper wire and also connected the wire to the units base, but this this only detoriates the signal.
Is this normal? Can the signals from the laser be that sensitive? This does not seem logical to me, because the cord is being moved permanently by the laser.
Any advice?
All the best, Salar |
|
|
| vonolof |
Hi folks
I've a problem with the pickup unit in NAK OMS 5E.
Maybe you can help me.
I have just cleaned pickup unit and my NAK seems to be working but still it doesn't read all the cd's. I can't set the E-F Balance (VR104) so that it could work for all kinds of cd's (the VR104 function is the only thing i've tried to set so far).
What is the mechanic element holding the tray ? it doesn't close down properly (it seems to be too loose in horizontal angle).
I haven't got any service manual for this unit.
Thanks for any helps.
Regards |
|
|
|
