Just replaced p/s and drivers / and outputs.
The amp comes on, however, i have about 80mv dc on the outputs.
Anyone have any ideas?
The amp comes on, however, i have about 80mv dc on the outputs.
Anyone have any ideas?
I have the same amp and quickly notice how bad the capacitors had leaked. It uses capxon or samyoung. Check them out. Not saying that will solve you're problem.
Will do...I just hooked a load up to it and noticed the bank of NPNs(TIP35c) warmed up significantly and almost instantly while the PNPs barely felt warm at all. Amp is not in the heat sink.
Clamp the transistors down and measure the DC across each of the emitter resistors. Since the terminals won't be accessible, you'll have to measure from the resistor leg to the positive speaker terminal. Post the voltage for all 8 transistors. Re-check them to confirm that the voltage is holding.
When you measure the voltage across the emitter resistors (as you did here), you need to use the full resolution of the display (0.000, not 0). It would appear that Q271 is shorted or leaking. Remove it and check it out of the circuit.
Pulled q271 and it checks out okay... I then reinstalled q271 and rechecked the emitter resistors and all show 0.000.
Nothing gets hot unless I put a load on it of course the outputs heat up but one bank will heat much much faster then the other. Also with no Audi signal if I short the speaker outputs the same bank of transistors starts to heat up.
Also I still have the dc offset of appx 80ma.
Also I still have the dc offset of appx 80ma.
This is a very poorly designed amplifier. 80mV is likely normal. Put the thing back in the heatsink and use it.
I have a 80 amp power supply coming Wednesday I will bench test it and hopefully all is well. I have had more trouble out of this amp, fortunately it's for my brother unfortunately it's probono!
With a speaker connected and 80mv of offset (assuming that it's negative 80mv), that could explain why the 36s are heating up faster.
Yea, I may continue to chase down the dc offset. I just feel like something is making this amplifier unreliable.
I guess that I should have been more clear. The reason that they're heating up is because current is flowing through them and into the speaker due to the offset. As was previously stated, it's likely not worth chasing down on this amp. The 80mv won't cause the amp to be unreliable and won't cause any damage to any speakers.
Perry, thanks for elaborating! My thanks to everyone else who provided information on this thread.
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