Sun Coliseum Problem

[veganxxx]

Hi,
I recently had my coliseum short out so I did a bunch of tests which lead me to a short somewhere in the output section where there is DC voltage being output on the speaker cable.

I found a shorted transistor and a zener diode and replaced both.  I also replaced the IC just for good measure.  I still get a semi bright light with the light bulb limiter when everything is hooked up and a dim one when the output section is taken out.  I've checked all the caps, resistors, diodes, and transistors and can't find anything shorted. 

When plugging it into the wall it smoked R47.  I haven't touched the bias pot.  Any ideas? 

[george]

I'm guessing that the transistor you replaced was a TIP-29 or 30? The output board has the +- 15V PS transistor regulators on it as well - is that what you replaced? The output transistors are easily removed and can be tested outside the amp - did you do this? I also believe there are some driver transistors that also are attached to the main output devices heatsink. Check these too. There is a dual op-amp in a socket on the power amp board (servo amp circuit) - check this as well.

I think you have some damaged op-amps in the pre-amp section.

[veganxxx]

I got it.  It was the zener and driver transistor.  I just got thrown off by the large power transistors because I didn't have the right schematic at first.  For future reference my weird early 80's version of this amp is this schematic- http://sunn.ampage.org/site/svcmans/beta/ .  The power section is the same on this model as the Beta.