Ferguson 3340 radiogram

[Michael Maurice]

This was sold to someone working, but its not!

One channel is dead with the output stage at near on HT.

I've attached a diagram of the output stage, but i'm perplexed by one thing:

Transistor VT11 is listed as a BC152, but a BC152 is a PNP type. The diagram shows it as NPN, does anyone know what it should be? Can i replace it with a BC547 if its an NPN or possibly a BFX29?

I've checked around everything but keep going in circles.

I've replaced VT10, 11, 12 and 13, using AC187/188 as the output pair but it makes no difference, all the Callin capacitors have been replaced.

Does anyone have any ideas? I've ordered a whole load of parts from Cricklewood Electronics.

[paulsherwin]

The BC152 is misdescribed as PNP in a number of sources, but it's actually NPN:

https://www.web-bcs.com/transistor/tc/bc/BC152.php

It appears to be a pretty standard Si driver transistor like a BC337. A BC547 might be pushing the current rating a bit. A 2N2222 should be OK. Note the b-c-e leadout.

VT9 is a general purpose job like a BC548, 2N3904 etc., but also b-c-e. There's no DC coupling to the output stages though, so it's probably OK.

[Michael Maurice]

I had a lot of trouble getting this to work, in the end I managed to test each stage before fitting new output transistors, (The correct ones) and it worked.