Old Pioneer Amp - Waveform explanation

[Nevillet]

Re: Old Pioneer Amp - Waveform explanation

According to the schematic I think the component is a 2SC2291.
I need to visualise the actual device and confirm it.
If it is the above, where would I i find one? - or a substitute?

Edit: The device is a C2259

[redwire]

Re: Old Pioneer Amp - Waveform explanation

The STV2H diodes I mentioned in post #4 are well known to fail with age and cause bias problems in vintage Japanese amplifiers.

[petehall347]

Re: Old Pioneer Amp - Waveform explanation

make up the dual packages with 2x KSC1845FTA each package .

[Nevillet]

Re: Old Pioneer Amp - Waveform explanation

Many thanks Pete and others. That's a great solution.

[redwire]

Re: Old Pioneer Amp - Waveform explanation

The transistor pair's beta need to be well matched if you're replacing the 2SC2259's and expecting low offset voltage.
At this age, I would replace the few electrolytic capacitors in the power amp. They can cause large DC offset i.e. C409, C419 if they are shorted or leaky.