It appeared that I had solved it when I replaced the tantalum decoupling caps with higher value electrolytics. Here was my reasoning: Distortion, right? OK, I've had lots of distortion problems with these CD-4 demodulators, and a recap generally solves it. I always use Wima MKS2 polycaps as substitutes for 4.7uF and below. It just happens that all

Here's a picture of the waveform - as is evident that pure sine-wave pattern, isn't. On the right channel, it IS a perfect sine wave.

This has been a very educational experience for me, as it is the first time I've had such problems with a CD4 demodulator, so I decided to share the troubleshooting process with everyone. I have replaced all electrolytics and all trimpots, and a complete alignment with the JVC test record. This took care of most of the sound-quality issues, but

Thanks Mika, I've checked the signals on Pins 27 and 28 - a nice beep every second or so, so the control signals are there. This machine was not in great shape when the customer delivered it, no sound, CD not working, etc, lots of rust on the underside. I did a nice upgrade, all Elna and Nichicon Audio caps in the signal path, 11DQ10's and 31DQ10's

Finished the Arcam CD72 - sounds great! Finished the cap upgrade on the BC9300, now stuck on no audio AC output on the preamp PCB - see my other post. Hanging in there! Menahem

Hi all, I have a BC9300 in the bench. On PCB8, the preamp, the scope shows good AC audio input from all the opamps into the TDA7318, but there is no AC audio output on the Audio Signal Output pins 24 and 25 - just dead. All voltages check, and if I bridge pins 6&7 and 16&17 (with a 2.2uF according to the datasheet), effectively bypassing some

Hi Jim A great project, and worth it. I have restored both the S45's and S55's. Your's are the later S45-2's, with aluminium trim at the front AND the rear of the cabinet. In this thread, is my S55 project. The S45 project is also somewhere lurking in the archives.... http://forum.beoworld.org/forums/p/28504/224203.aspx Of particular

So simple and beautiful!

I have had 2 of these with the same problem. I also thought that it was the MAB chip.... then I discovered the cause by accident (as are most good solutions). The cable connectors between the PCB's are not good-quality, and the internal pincers "cut" the actual copper conductors to "grab" them. If the cables have been manipulated

Here's what I've got lined up: BeoCenter 9300 repair - replaced the CDM12 laser, and now upgrading all the signal path capacitors. BeoMaster 1600 - replacing the 4 main TO-3 output amps with MJ15003, restringing the tuner, and doing a whole bunch of rewiring. Arcam CD72 - complete rebuild. And my own BeoMaster 3400 - I've designed a modified