Since there were a lot of issues with the CD Player it took some time to solve them. First the Decoder Panel was not working. After putting all the ICs on a socket and after I exchanged all capacitors the replacement of SAA7000 and SAA7020 did the job. In the same time I have done some optimisations to the circuit. Where necessary I put capacitors for audio signals in the audio lines and also to the OpAmps. The existing MC34072 got replaced with OP752 from Analog Devices. I read somewhere that the OPA2604 would give very good results but was unable to get them. Thus I gave the AOP752 a chance and I have to say the sound – which was already very good – is now absolutely incredible. I have to admit that I also have done some optimisations to the AF Panel in the meantime with high quality audio capacitors and new OpAmps for the Pre-Amplifier (more later). The sound is very clear, instruments are more separated and overall it is more powerful (video will follow).
However, just to fix the Decoder Panel was not the only issue as I expected in this unit also the CDM2 is defect. I replaced all capacitors and the CPU with one of my spare parts but it is still not working. I checked all diodes and transistors and they seem to be fine. Since the head moves up and down it might be the TDA5709P or the L272M which I already ordered on eBay. Let’s wait until they arrive to do some further tests.
In the meantime I’ve got two Philips CD150 and it was a perfect time to get the CDM2 out of the items. Both are more or less working. One has problems to reach with tracks above 5 or 6. After replacing some capacitors (need to order more) all tracks are working fine. Of course, to replace the capacitors is absolutely necessary. Especially the light blue ones from Philips, they are all gone.
Finally the CD-Player is working and because of the changes it sound better than ever. Before I reassemble everything I will wait for the missing capacitors to replace them and to check my old CDM2 drive and hopefully get it working too.
