OK it's finally fixed! In the end it was something trivial: a 330nf cap on the IC u741 in the power supply section. I think it has something to do with the MUTE function, but not very clear how..anyway it works and that is all that matters. Thank you to all that contributed, especially Martin and Nick. I thought I would get back to let you know

OK, I'm still waiting for the TDA 1028/9 to arrive, so I've been looking around some more. All voltages into the IC are correct, so 20 volts supply seems OK. I replaced IC1 in the power supply, but this made no change. Amp still distorts. One last thing I've just discovered, and may be related (How?). On the tuner board TR34 is too hot to

Hello Nick, Martin and Alex thank you for your words of encouragment. I still have a few things to try, like being more systematic with the power supply measurements, so far I've concentrated with the pre-amp as this seems to be where the symptoms are, but they may be only the victims of some other failure. (hard to imagine, as all the supply levels

OK, got a logic probe, and barring my unfamiliarity with using such a device, I found pin 9 reading constant 'high'. Certainly no pulse. replaced all 3 100nf decoupling caps, just in case, no change So I replaced TDA 1074, (IC3) no change. then replaced MM5450 (IC5) no change. then I substituted IC4 with the old IC3 (same TDA) still no change

Thanks Nick, I'll get a logic probe tomorow and get back. Philippe

Thank you for looking in solderon29 and Martin Martin, yes I have replaced all the caps that were in the kit, and that included a 220uf (radial) in the power supply. Is this the one you're thinking of? I have done some further testing, and looked up the chip data on the net (TDA 1074, 1028, 1029, and the scary MM5450, which may control the mute

OK, I've done a little bit more work on this. ;-) After renovating the caps in both the power amp and pre-amp sections, as well as replacing all output darlingtons, and the trim pots....no change. I tried connecting the pre-amp output to another power amp: Same result, no sound until level reaches about 4.8 on display, then any increase beyond that

Hi, my beomaster 5000 has decided to become 'uncooperative' The sound output is very (very) low, and this is regardless of source, either radio or CD(50). It sounds like the power amp section is not working...maybe. Turning sound up to full volume still only produces a whisper, only it's distorted as well (probably the pre-am is clipping