CD 104 No sound

[Starry Cat]

Hello Guys,

This is my first posting on the group and I hope you can bare with my low knowledge in electronics.
However, I like the older HiFi stuff and became sad when my trusty old CD 104 one day silenced.

The thing is that everything else seem to work normal;
- The player read the records and I can not see any "jumping" in the time display or hear any strange noises from inside the player.
- All controls seem to work normal.

The player just don't give any sound.

I have searched the forum for this kind of problem on the 104 but have only found other kind of problems, like no tracking etc.

I have been thinking of maybe measure the signal strength in the output cables and see if there is *anything* there but to be true, that would probably don't give me much of an answer.

Do you have any idea of what can be wrong and if it is possible to fix it within reasonable costs?

Best Regards

Jonas Carlsson

[rfbrw]

You could check the usual suspects, the soldered links connecting the two layers of each of the two main boards but as the machine seems to be reading and playing, the problem may lie in the IC's. The next step, for which you will need the service manual or at least the datasheets for the chips and a meter and if possible an oscilloscope, would be to check for the correct power supply voltages and attempt to trace the audio signal from rf to dac.

[Starry Cat]

Thank you for giving me hints about what to look for.
I think I'll hand the unit over to a friend and ask him to see if he can find out what is wrong.

Thanks again!

Best Regards

Jonas

[Richard]

Hi Jonas

I've had a similar problem with a Philips cd 202. I traced it to the opamps and the de-emph circuit, those white things with pins and black tape around it. I replaced it from another player and got the sound back.

As rfbrw states it could be the IC's. I also experienced a faulty SAA7030 chip with symptoms exactly as you describe.

Hope this helps

Richard

[jives11]

Originally posted by Richard
Hi Jonas

I've had a similar problem with a Philips cd 202. I traced it to the opamps and the de-emph circuit, those white things with pins and black tape around it. I replaced it from another player and got the sound back.

Hope this helps

Richard

Those white things are relays. You are absolutley right, one handles deemph for both channels and and the other muting for both. If demph was stuck either way would you get silence ?

The muting relay is above the opamps on the board, close to where the output leads connect to it. This is the decoder board which you can only access from underneath.

The relay could be bypassed to see if you have signal up to that point. Looking at page 1-12 of the B&O CDX mannual (same circuit board) you could try running a temporary output from the output of caps (2573 L and 2608 R). This would be after the opamps but before the Muting relay (marked as KILL). There are some ground resistors and a filter cap after this point BUT it would help you to confirm if you get music down to this point.

If you want the CDX manual, drop me an email