Marantz CD85 or Philips CD880 schematics or service manual

[Arjanvm]

Hi there,

My CD85 has problems in the transport. Won't track further than track 1 or 2, sometimes 5.

Sometimes doesn't recognize disc at all, and sweeps the laser unit around at madness. Not a nice sound.

I have to find out what's wrong with it.

Can anyone help me finding a service manual for this baby?

A philips CD880 is almost similar, so this service manual would help as well.

Thanks,

Arjan

[Fidelity Audio]

I cant find a service manual but check the condition of the grease on the traverse deck. It stops the laser tracking.
Clean it off

[Arjanvm]

Thanks.

I checked to see wether the pickup arm could move freely. It seems to work very well. No hickups there.

It must be something with the radial tracking circuit. Sometimes I can play a whole cd - but skipping from track to track makes it loose tracks and swing the pickup arm fiercly to the end stop.

I just cannot find a CD85 service manual. Nor Philips 880.

Any help is greatly appreciated.

Thanks.

[Elso Kwak]

I think laser has reached end of life...

[phimor]

Arjan,

it may be the laser, but in my experience there are a few other things to check first (the lasers are quite strong and long lasting):

You are right it can be in the radial servo.

I'm only familiar with CDM1, and in those there are separate op amps to control the radial function, in the case of one player a 27 nF cap was shorting the radial op amp and it gave me the same nonsense you describe.

If an early machine look in (at least) two places. The archives here, by searching, or finding a manual for a machine of the same familly eg CDM1 or CDM2. Searching under those heading should give you plenty to read.

Couple of warnings: resist the urge to adjust anything, even just to see.

Replace as many of those little blue 33uF as you can find...

Cheers

Philippe

[Fidelity Audio]

I use these, although they dont have the model(s) you require one of the other manuals may suffice,

http://www.electronicsrepair.net/scemes.html

[Michi124]

Hi Arjan,

enable your email and I'll send you the CD880 manual in PDF...

Regards, Michael

[Arjanvm]

Hi everyone,

Thanks a lot for your suggestions.

Michael, the 880 service manual would be a great help. I send you a pm with my mail address.

Now, after some research I have found the following:

Radial tracking *seems* to be OK: I can play a cd, do a fast forward or backward, the tracking servo signal is clean and looks controlled on the oscilloscope.

But, changing tracks is big trouble:
-the focus servo start sqeeling (high pitch sounds, high tones, bursts), trying to get a lock
-sometimes, after a few seconds, it gets a lock and plays
-sometimes, it ends up squeeling for ten seconds and then finally gives up.

On the oscilloscope, the servo signal for the focus coil shows short, repeating high frequency bursts.

I don't get it. It is better with some cd's, worse with others. Some cd's play fine all the way.

The problem arises with the higher track numbers: track 1 & 2 mostly play fine.

The laser seems to be OK. The RF signal and the eye pattern are clearly visible on the scope.

This is a CDM1-mkII transport, with TDA5708, TDA5709 and TCA0372 servo dual opamp. The board has two adjustment resistors: one for focus offset, and one for laser output I think. Focus offset is set correctly, the other is set to a position that gives me best results.

I replaced cap's, checked every part on the CDM1 board.
I checked the mechanics, everything moves smoothly.
The lens is clean.

Next thing I'll try is to replace some of the IC's.
TDA5708 is hard to find, but I will replace TDA5709 and TCA0372 as soon as they arrive by mail.

Anyone more suggestions?

[phimor]

Arjan,
my opinion on this:

Playing with the power setting is not useful as the diode has some sort of self limitting loop. As you have a CRO, make sure it's around 1v pp onthe eye pattern.

You say the ofset is good, but in my experience the squealin you hear tells me different. The focus ofset loop is to fine, and its feeding back. Play with that adjustment instead of the laser output, and see how you go.

I had one player that would start to emit a soft ringing noise half way through one specific CD-R, I found that backing off the ofset quietened it down. I now use that CD-R when adjusting transports.


Cheers

Philippe

[Arjanvm]

Hi,

New efforts, not much progress.

I replaced the TDA5709, TDA5708 and TCA0372.

Nothing better. Very interesting, but not helping!

Here's where I am now:

Focussing really seems to be a problem. As soon as I skip tracks, the focus servo starts hissing and squeeling, sometimes finding the lock, sometimes failing, which makes the radial arm bounce up and down (why??)
Now here is an interesting point: the problem is VERY sensitive to the laser output setting. Adjusting it a tiny bit can make a CD play, but will NOT play another. It looks like every CD has it's own precise optimal setting.

Setting the laser output to the service manual level (50mv over 18ohm collector resistor in drive circuit) does NEVER work. I need to keep it down at 30mv or else it will swing the radial arm at madness. (What is the connection between the two??)

I checked the transport three times. Even the laser angle. Checked the cd motor circuit.

By the way, the eye pattern at pin 27 of the TDA5708 looks messy. There is quite some HF interference (11 Mhz?) on it. Only after the RC filter at the decoder it looks like the picture in the books. Is it supposed to be that dirty after the 5708 amplifier?

More thoughts are greatly appreciated!

cheers,

Arjan