Marantz CD63 & CD67 mods list

Yep, that's the one.

If you want to build something with the original crystal you could consider the CD-clock. It's a fairly simple J-FET oscillator that works quite well.

The long-term stability is less important by the way, it's o.k. if the clock doesn't give exactly 16.9344MHz (within limits of course). It's the short-term stability that matters: the signal should have low jitter.

Ray

Hey thanks Ray,

It looks simple enough, uses the original crystal and a seperate regulated power supply should be no prob's. Thanks a lot, helpfull as ever. Could it be built point to point wired ? As I don't have the equipment to make my own PCB's, unfortunately.

Also, what causes the jitter ? Is it anything to do with the even/odd order harmonics of the crystal itself or something completely different ?

Thanks:)
 
Glad to be of help! :D

Point-to-point shouldn't be a problem, I put my first prototype on a small piece of veroboard (photo is on my website). It's such a small circuit, you could even build it inside a HDAM shield can :). Use the can as ground and solder away!

The causes of jitter are multiple. If there's noise on the power supply of the oscillator, this could penetrate into the clock signal because the PSRR of the circuit is not infinitely high. There's also thermal noise in components that causes the waveform to deviate from the intended point in time (unit interval or UI). Jitter can also be caused by reflections of the clock signal in the connecting cable or wire. These reflections will 'bounce back' and influence the original signal, creating deviations in time.

Regards,

Ray
 

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Glad to be of help! :D

Point-to-point shouldn't be a problem, I put my first prototype on a small piece of veroboard (photo is on my website). It's such a small circuit, you could even build it inside a HDAM shield can :). Use the can as ground and solder away!

The causes of jitter are multiple. If there's noise on the power supply of the oscillator, this could penetrate into the clock signal because the PSRR of the circuit is not infinitely high. There's also thermal noise in components that causes the waveform to deviate from the intended point in time (unit interval or UI). Jitter can also be caused by reflections of the clock signal in the connecting cable or wire. These reflections will 'bounce back' and influence the original signal, creating deviations in time.

Regards,

Ray

Yeah, makes sense. Could the PSRR be improved ? What about thermal noise ? Does component choice become critical at this point ? Also the connecting wire ? Any solutions/ideas ?

Where there's a will, there's a way !

Cheers Ray
Gareth

P.S. I have built my own power cables similar to the ones on your site but I have used the fourth core to link to the SY shield at the other end of the cable. Using 1.5mm2 SY. I thought that it would provide greater isolation from interference as these cables were originally designed by Lapp of Germany for control purpose in factories I believe. Ideas ??? I also have my own home-made mains conditioner fed with 6mm2 SY from the mains into it, workks well I must say. Noise floor has been reduced with my system without doubt and my Plasma has been 100% better when running from it (sorry to go off a bit !)
 
The CD clock's oscillator is a single-ended design which is more sensitive to supply-noise. The circuit already has L-C decoupling of the supply lines. Separating the supply for the oscillator and the comparator will bring some gain. Improving the PSRR further basically means choosing an other circuit. The supply itself is not the lowest-noise, so that could be improved as well. But then it will stop being a simple circuit ;)

Thermal noise can be reduced by submerging the clock in liquid nitrogen :D. But by using a low-impedance design, the noise can be reduced as well. Low value resistors generate less noise than high value ones, for example. Also, the capacitors are important. Ceramics are known to be microphonic, so it's best to use NPO/COG or polystyrenes.

Good mains cables can make a world of difference. I did an A-B test once with the standard IEC cord and some decent shielded mains cords from Supra and some other brand. The difference was clearly audible (in favour of the shielded ones). Same goes for the wiring in the wall, but that's more difficult to replace. Unfortunately the pipe in my wall doesn't allow a shielded 1.5mm2 cable. Maybe i'll drill a hole through the floor some day...

Ray
 
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If you start again, you have to read the thread from the start too. :D
Already did that several times and keep reading. That is why I want to restart. new ideas came along after I "finished" my super regulated 53. I will not repeat the same mistakes and finally do the most significative mods in the first place :)

PS: I am much more experienced now and can do really neat soldering jobs.
 
Hi Pete,

I have very good experiences with BG N types, but a standard or FK also performs very well (if you can get them...). Then there's Elna Cerafine or Silmic, or Nichicon Muse, but I think the BG's sound better. The best upgrade is to get some MKP foil caps, like Auricap, Mundorf, Obbligato or ClarityCap. You should be able to get a pair of a few uF for £20. Go for low voltage and the bigger the better :)

Regards,

Ray

Thanks Ray,

I have some tiny BG N 50v 4.7uF in my caps box, maybe I should have used them from the start and I wouldn't have had to cut holes in the brace. I was thinking bigger is better:)

Regards

Pete
 
That's a coincidence - I just this minute received a package of 7x 6.3v 470uF NX for digital duties. I'll be replacing the smaller value BG STD types that I have installed currently. I wouldn't be surprised if OSCONs are better than NX in reality, but I don't mind rolling with the placebo effect of the Black Gates, if that plays a role at all :)

Having said that, I used 10uF AC as DC blocking caps on my pre-amp input for a long time, but they were not a patch on the 3.3uF Mundorf Silver/Oils that I have in there now. I think N would probably sound better than AC.

In general I've found that the larger, higher voltage rated Black Gates sound significantly better than the smaller ones of the same value. It's particularly noticeable in changing the 470uFs I have in the CD15/16 position for some reason. All this swapping in and out takes its toll though - I had the legs snap off a 100v/100uF FK the other day, which was sad enough, but then I was messing about in my amp on the weekend and one of the terminal screws in my precious 10,000uF FK smoothers fatigued and snapped right off! The horror!
 
Bad day for me as well.

Removed the ACs from the DOS board, I always have problems desoldering and replacing parts in add-on boards, I guess because of the size of the holes. Ended up trying to poke heated wires through the holes to open them up again and then put some pcb pins in so that I'd be able to change caps without removing the board in future. Again had to heat the pins and put them through.

Fitted the Ns, sound seems ok but the balance is now very towards one channel.

Checked the Ns and switched them round but the balance is the same side so I must have damaged something else on the board. Can't face trying to remove and replace any more components on the board so I think I'll wait till I have some spare time and start again with a new DOS board.

Regards

Pete
 
Ray - yes, a pricey accident, if you can even put a price to them now that they are so rare. Ugh, I feel so stupid. Fortunately they still work OK, and it should encourage me to stop needlessly fiddling with the amp. I was experimenting with bypassing the FKs with some different types of capacitor, all of which made sound quality worse anyway, and it was a nice sunny day outside so I had serious questions to ask myself afterwards.

I don't trust the leads on the Mundorfs either. They have 'future bad day' written all over them :-/

Pete - apologies if I'm teaching my grandmother to suck eggs here, but are you sure it's the DOS? Did you take the main board out at all? This happens to me all the time. I wouldn't like to say how many times I've put everything back together to find I've got no sound in one channel. Nine times out of ten, it's just a random one of the few original 12-year-old joints in power supply or output stage on the main PCB that has cracked due to repeated flexing. If I was you, I'd do a visual check first in good light and if nothing shows up, try checking trace connectivity between components with the 'diode' mode of your multimeter from the output socket backwards. I'd do that before unsoldering anything.
 
That's unfortunate Pete. It seems your soldering iron or tip isn't up to the job. I have no problems clearing the holes of the board with a 80W soldering station and a 3.2mm chisel shaped tip. It could be your tip is too small so there's not enough heat transfer. Or the power of your iron is too low. But with a good tip, 20-25W should be more than enough for a fixed iron, or 50-60W for a station.

Fill the hole with fresh solder so it's completely filled. It's much easier to clear this way than to try and pry out the last bit of old solder without flux. I use a standard desoldering gun (handpump), works fine. Braid doesn't work with plated holes.

To check the DOS, you could do a simple check between channels with a DMM. All DC levels should measure about the same for left and right. Like Ben says, it could also be the mainboard. Maybe one of the wires that run from the DAC to the DOS' inputs have come loose.

Ray
 
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I think my iron is ok but I've been trying to do it with braid, maybe I need to get a solder pump.

I checked over the main board before I decided it was the DOS board, the channel isn't dead, I'm getting sound out but the volume is lower in one channel so I don't think it can be a loose connection and I don't think there's anything left on the mainboard that could affect the channel balance.

Regards

Pete
 
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Yeah, the braid only removes the solder to about halfway, it sucks ;)

The outputs of the DAC are symmetric: there's a positive and a negative output that work together. If one of them is not connected, you only get 'half' the signal and the output of that channel will be lower. This would explain the balance problem. You can check if both outputs are connected by measuring the voltage at the inputs of the DOS (LO/RO and LON/RON): all should measure about 2.5V DC.

Ray
 
I put the NX caps in this evening, in the positions where Brent prescribes OS-CONs. Initial impressions are that the player sounds worse than it did with STD/FKs, but I guess the new caps have been sitting for around five years and will take some time to form.

My player has started skipping recently, about once every half hour or so. Does anyone have any idea why this might be happening? I think it started happening when I beefed up the power supply caps to 22k. I could try some white grease on the gears, but I somehow doubt it's mechanical.
 
Sadly not... and Christmas is a while away.

I am on my second laser assembly, and I remember now that skipping was an early symptom of the demise of the original. I was hoping I'd get more life out of the replacement as it's a newer revision of the hardware, but I've had it about 6 years, which is how long the original lasted.

It's a bit suspect that it would start skipping immediately after some mods though. It was actually worse for a while, skipping numerous times per disc, but then I changed C120 to 470uF and it seemed to improve a lot... and isn't that smoothing motor supply? I hope I'm not embarrassing myself too much here, as I'm definitely a bit out of my depth diagnosing this one.

I read that Brent actually has a 4700uF on C813 (which is what I had up until recently), in addition to a 22,000uF. I have a feeling that it might skip more on heavier music, so I was wondering if the big cap in isolation might have a side effect of causing a skip in some circumstances. I don't know how many people run such big caps on without also adding other regulators, PSUs, etc.

The other thing I changed which might've coincided with the skipping first being introduced was when I changed C111-6 from ceramic discs to silver micas... I guess I'm clutching at straws. I just can't shake the feeling that I've caused the skipping by changing component values or types somehow.

If there's no obvious known issue, and nothing I can test with just a DMM, then I suppose trying a new laser assembly would be a worthwhile test before I start undoing mods.

Thanks Ray.
 
It is possible that changing components started the skipping, by slightly altered voltages for example. But it was already at the edge most likely, and if you hadn't changed anything it probably would have started next month or so.

Six years is not too bad though, for a standard VAM unit, assuming you use the player lets say, almost every day? Have you tried cleaning the lens yet? If that doesn't help, you can raise the lasers output a bit by turning the trimmer on the laser a small notch clockwise.

Ray
 
Hi Ray, thank you so much. That makes a lot of sense to me and I've got a feeling that your insight is absolutely bang on with this as always. I really appreciate you providing an emergency support hotline for me in the middle of the night* :)

I will find the trimmer and give it a tweak.

*(It's the age old story - woke up due to nightmare about purple octopus, got up to get glass of water, stayed up to obsess about CD player).