4ch x 85, class ab amplifier

nonprof

Member
2011-06-08 1:33 am
Hello!

A pair of pre-driver transistors(2SA1015 and 2SC1815, TO92) that drives the pair of transistors (C907, Axxx, TO-220 package ) next to the last stage is heating up fast. All other transistors including output transistors behaves normal.

Note: Sound is not distorted or amp not in protect.

2 or 3 out of 4 channels encountered this heating problem. I replaced transistors, resistors, measured bias resistors but still NO LUCK.

Please help...

Thank you as always.
 
Last edited:

nonprof

Member
2011-06-08 1:33 am
Here is the similar schematics but some difference are it uses A1266 and C3198 pairs but the later amp uses A1015 and C1815pair and different output transistors.

An encircled parts heat fast...almost you can't touch it.
 

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