Years ago I modded a CD67SE with good result. Lately however it have developed a strange defect. There is no, or only bad error correction over the digital port (connected to a DAC); I hear every speck of dust and scratch. (Its on the cd for it is audible on the same spots if replayed)
But, over the analog ports it plays fine!
It might be the DAC, but if I play a cd on my pc with the same DAC on the SPDIF port, it sounds fine.
I know, I should find another real cd-player to test the DAC, but that is not easy for me at the moment.
I found the service manual, and that gives me the impression there is error correction in the SAA7372, before the signal is converted to analog.
The player gives no error codes, and I have cleaned the lens.
Anyone any idea what can cause this?
Regards!
But, over the analog ports it plays fine!
It might be the DAC, but if I play a cd on my pc with the same DAC on the SPDIF port, it sounds fine.
I know, I should find another real cd-player to test the DAC, but that is not easy for me at the moment.
I found the service manual, and that gives me the impression there is error correction in the SAA7372, before the signal is converted to analog.
The player gives no error codes, and I have cleaned the lens.
Anyone any idea what can cause this?
Regards!
Thanks for the comments!
I managed to get another cd-player with a digital output and I'm sure now that my external DAC is okay.
Now, I see the 67 has 2 clocks (at least, are there more I missed?); one 8Mhz clock for the whole digital part en another 16.9344Mhz for the internal DAC, which seems to deliver good sound on the analog port. (I swapped it long ago for a TentLabs XO, before I got an external DAC)
So can it be this 8Mhz clock is slightly faulty? Causing the chips to generate a spiky signal on errors. Too bad for the external DAC, but good enough for the internal one to create a reasonable signal? In that case I'd solder in an other 8Mhz crystal.
I see in the manual nothing about test modes. Just that service mode is canceled when the player is turned off.
I managed to get another cd-player with a digital output and I'm sure now that my external DAC is okay.
Now, I see the 67 has 2 clocks (at least, are there more I missed?); one 8Mhz clock for the whole digital part en another 16.9344Mhz for the internal DAC, which seems to deliver good sound on the analog port. (I swapped it long ago for a TentLabs XO, before I got an external DAC)
So can it be this 8Mhz clock is slightly faulty? Causing the chips to generate a spiky signal on errors. Too bad for the external DAC, but good enough for the internal one to create a reasonable signal? In that case I'd solder in an other 8Mhz crystal.
I see in the manual nothing about test modes. Just that service mode is canceled when the player is turned off.
If the clock (and it can be either DAC or player related) is slightly out of the "pull in" range then you can get this kind of effect.
Try some typical engineer tactics to narrow it down
If you put your finger on/around/near the oscillator crystal and its components does the problem dissappear (or go worse) ? What you are doing is pulling the frequency slightly one way or the other. You need to do that to the DAC as well as the player.
Beyond that and you really need dedicated test gear to check out the frequencies and levels.
Try some typical engineer tactics to narrow it down
If you put your finger on/around/near the oscillator crystal and its components does the problem dissappear (or go worse) ? What you are doing is pulling the frequency slightly one way or the other. You need to do that to the DAC as well as the player.
Beyond that and you really need dedicated test gear to check out the frequencies and levels.
Thats a surprising result tbh. Do you mean you are slightly "slowing" the disc ??? by touching the platter clamp or just touching the general "fixed" or non rotating parts. If the later then it suggests that the RF signal from the pickup is marginal. Again, the real diagnostic is to put a scope on it to see what the quality and amplitude are like. Have you cleaned the lens ?
No, no, I'm not slowing the disc, just touching gently the black stationary plastic with houses the laser, just behind the rotating disc. I feel I'm damping its vibration by doing so.
I did indeed clean the lens, with both a lens cleaning cd set which utilizes cleaning fluid and with a can of compressed air. Cant get it any cleaner without touching it with lens paper or a cloth which I am still loath to do at the moment.
But there is no difference in SQ between before and after.
I feel I'm damping its vibration by doing so.I did indeed clean the lens, with both a lens cleaning cd set which utilizes cleaning fluid and with a can of compressed air. Cant get it any cleaner without touching it with lens paper or a cloth which I am still loath to do at the moment.
But there is no difference in SQ between before and after.
Hmmm, I doubt it would be anything so deep seated tbh. I think this uses the CDM12.1 ? pickup (or so a quick search tells me). They are cheap and easy to replace.
It is still worth cleaning the lens properly. Use a good quality cotton bud but tease the cotton out at the end ever so slightly. Moisten (not wet) the bud with fluid and gently clean the lens. Use a torch to look at the surface and make sure its really clean.
I cleaned the lens meticulously (checked with 15x magnifier) There was some dirt on it, which is gone now. For a moment I thought that did it, the player sounded better than ever (if that is possible), but no, there was the spiky noise again.
I've ordered the pickup mechanism on ebay for approx. 20 euros.
I've ordered the pickup mechanism on ebay for approx. 20 euros.
I got a new unit but it appeared to be defective (of course).
By bending the contacts I could achieve that the laser could get to the start of the cd, and by endless tweaking the trimmer I even got it to play, but never without a lot of noise.
A different kind than the noise of my old unit, and I couldn't damp it out with my finger. There were no vibrations in the unit anyhow, so that's it! I put the new disc motor in the old unit and it played ok! The motor was worn out just too much for the player to correct any longer the tiniest reading errors due to the wobbly behaviour of the spinning disk.
Alas. I cannot put the cd-bearing-platter back on the motor in a reliable way. If I put it on fully, there is friction, if I put it on less firm, the laser cant focus, or it will in time sink to its friction position I suppose.
Well, the seller is sending me a new unit. Hope that one will be sound...
By bending the contacts I could achieve that the laser could get to the start of the cd, and by endless tweaking the trimmer I even got it to play, but never without a lot of noise.
A different kind than the noise of my old unit, and I couldn't damp it out with my finger. There were no vibrations in the unit anyhow, so that's it! I put the new disc motor in the old unit and it played ok! The motor was worn out just too much for the player to correct any longer the tiniest reading errors due to the wobbly behaviour of the spinning disk.
Alas. I cannot put the cd-bearing-platter back on the motor in a reliable way. If I put it on fully, there is friction, if I put it on less firm, the laser cant focus, or it will in time sink to its friction position I suppose.
Well, the seller is sending me a new unit. Hope that one will be sound...
Bad luck with the new pickup but swapping the motor has proved the rest of the player is OK from what you say. Platters are just a push fit and secured with epoxy but they must run true. And the height must be right. If you look at a CD edge on and gentle turn the disc there should be no detectable up/down motion at the disc edge. Sadly very few non original pickups achieve that.
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