There isn't a speaker relay in that unit so you might hear something at power on / off. I'd check the output transistor bias setting is correct. The service manual says it should be set for 4mv between TP1(+) and TP3 - VR601 adjusts it. Do the same for TP2(+) and TP4 and VR602 adjusts it. Do it after the amp and heatsink have warmed up and with the volume set to minimum.

@@orangevalleysystems Thanks for that, I have managed to set the biases' correctly :) I have tried testing some resistors (which appear fine) which were a problem for the only account online with this model and problem. Trying to source some transistors/resistors? Scattergun I know, but it matches my knowledge level, it helped on this different model with the same problem..? kzbin.info/www/bejne/bXu7YoCBm8qri5Isi=phLRboGlj9tbNaTA Thanks for your time once more..

It looks like that receiver doesn't have a speaker protection relay fitted that normally connects the speakers to the amp a few seconds after switch on. If you connect the speakers to the B output you can then switch it on by putting the switch to the speaker A or speaker Off position then after a few seconds move it to the speaker B position. The crackle and loss of sound can often be fixed by spraying some contact cleaner into the volume control pot.

I will keep that in mind if I get another. I think that was all I could find at the time as many components in the UK are on long lead times due to supply problems.

don't forget to replace those capacitors and remove the corrosive glue.

@@mikepxg6406 hi, the zener was the issue so for 10p part the unit is up and running, sounds very nice. I have not tackled the caps yet, wanted to make sure it worked first, so the caps can wait for now. Cheers

True. it is corrosive, it will eat away the lead outs of the capacitors and zener diodes adjacent. I always replace power supply capacitors as age will lower the capacitance.

after inspecting the schematic, are they c109/c110 caps for the left and right tone controls? 0.33uf/35v| thanks

@@hokman1 Hi, the failed capacitor I had was C305, a 220uF 50v. The capacitor for that supply powers the tone controls and the turntable preamp. My notes show that the 36.5v rail with the failed capacitor measured 30v on a multimeter although it's easier to see how bad it is on an oscilloscope if you have one. I guess the level of hum and measured voltage will be dependent on how failed the capacitor is.

@@orangevalleysystems It worked, thanks very much sir! serious problem solved with a cheap part

@@orangevalleysystems Hi it's exactly true what you say I am currently repairing this amp the capacitor c305 220uf/50 volts is defective, I will replace the 2 soon I only have sound on the left channel and no sound on the right channel with background hum on both channels

@@yanng3790 I have that same problem. So far I noticed a 150 ohm resistor next to the output transistors completely burned up. And that transistor it is with also tested bad