I'm trying to repair the RIGHT pre-amp of the lecture head of a cassette deck. (SABA CD 360).
I have written in red on the files in attchment the values I measured on the transistors which make problem.
The values on the LEFT channel are correct because this channel works fine.
The values on the RIGHT are anormalous.
With this I'm not a specialist and can't know witch component is bad. Indeed the first transistor of the Darlington gives a tiny collector courent that makes the tension of collector of 2.38 V and not the right value of 2.02 V like the left channel.
But maybe it is the second transistor that doesn't work right because its collector is quite in short circuit with its emetter (Vcollecteur = 1.8 V instead of 5.18 V).
Or eventually the two transistor are bad (the first not giving enough courent and the second giving too much) ?
Thanks for your ideas.
Note : The original values on the plans are in RECORD mode and not in PLAYBACK mode. So several values are different. You only have to compare the red values from one channel to the red values of the other.