zenith: Alternative output stage circuit

Dear Forum members,

recently I helped a friend repair one of these receivers, with chassis 9HT40Z8. The problem was due to incorrect biassing of the output transistors, but the circuit of the audio stages bore little resemblance to the circuit diagram available here; in fact, it was much closer to the circuit for the model 3000 here - the most notable difference being the bias resistor was 27Ω rather than 36Ω. In the faulty example repaired, this resistor had increased to nearly 150Ω leading to excessive dissipation on the output stage.

Can any Zenith aficionados advise, please?

With best regards,

Mike.

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