From Newsgroup: sci.electronics.repair

I finally found some time to set aside to look into the distortion
issue I've been experiencing with the Uher 4000 Report Monitor AV I
bought a while ago. I've narrowed it down to one particular stage at
or around the BJT labeled T14 in the attached schematic snippet. The
1000Hz sinewave test signal's coming from the playback head at the far
left and is nice and pure right up to the base of T14, but is
noticeably distorted thereafter. No clues from the DC bias points:
they all check out as per the diagram give or take a tenth or two at
most. So I thought it might be a bit of fun (anyone remember that?) to
let the Panel here have a guess at which component(s) might have gone
rogue here. I hope to be able to complete my investigations on Sunday
afternoon if time permits and we'll find out who was right when I
report back. So: your guesses invited!


https://disk.yandex.com/i/9hIxKidwWlcfJQ
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From Newsgroup: sci.electronics.repair

I meant to also mention that since this is effectively the pre-amp for
the replay head, it's dealing with extremely weak and delicate
signals. By the time those signals hit T14, they're still too small to
be seen on a scope even at the 5mV lowest range and are buried well
and truly in the noise. So I've been unable to glean any clues by
probing T14 or probing the components around T14 either. I was only
able to spot this stage as the culprit thanks to Liz Tuddenham's high
impedance probe+ audio amp suggestion (HT, Liz).
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