I'm interested in this too, as I have a Beomaster 1100 that blows the 0.39 ohm resistors in one channel.

Are the BD651/BD652 usable? In that case I'm going to stock some up, as they are cheap and readily available now.

Any modern/common equivalents to the other transistors?

Good job so far.
The trimmer could easily be bad too.
They occasionally burn with the drivers and they will often have oxidized beyond hope anyways.
I suggest you replace it and try adjusting again, don't power it up again before doing that.
If that's a success, I suggest you replace the trimmer in the other channel too.

Actually, an oxidized trimmer could be the original reason the output stage has blown and
it may have fooled the previous repairer who mounted the "new" output stage.

Martin

OK, thanks, I'll try that.

However, I did measure the trimmers (in-circuit) and they seemed to be OK (range ca. 0-870 Ohms) on both channels.

-jari

First thing in nearly all vintage. Change all caps, change trimmers where posible to adjust without problems, clean the rest carefully.

Finally got time to replace the trimmers as well... but no luck!

New trimmer had no effect on the left channel, i.e. the idle voltage is still around 750mV and the trimmer has no noticeable effect on it at all. What next ?

On the brighter side, I also have a wreck of a Beomaster 5500 which had one channel burning the fuses. After the (partially) encouraging repair of the BC1400, I changed all the transistors and caps as well as the big resistors and trimmers - and that was success! Now the BM5500 works again nicely ;)

-jari

Looking more closely into the rest of the components, I got a slightly low value when measuring the resistor R141, ca.36 ohms compared to correct value (and in other channel) of 47 ohms. Could this be causing the extra idle current ??

I would replace that in any case - the resistor seems to be part of the biasing circuit and the value is way past the original tolerance of ±10%.

Those carbon composition resistors often change their resistance permanently when they overheat.

But, I would also concentrate on why the test voltage on TR19's base is so far off. It will have a direct effect to the operating point of the amp.