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?

[loudthud]

First you need to find a schematic. Most search engines won't find anything unless you spell the name of the company that made the amp correctly. Next is the model name. There are a number of amps with Coliseum in the name, in fact a whole series of them. You need the exact name to find the correct schematic. Hint: most of them don't have an R47.

[veganxxx]

First you need to find a schematic. Most search engines won't find anything unless you spell the name of the company that made the amp correctly. Next is the model name. There are a number of amps with Coliseum in the name, in fact a whole series of them. You need the exact name to find the correct schematic. Hint: most of them don't have an R47.

Thanks,
The web had all the wrong schematics for the Sunn Coliseum Bass. That's because mine was an 80's model and not the same power board as the original. It was however the same board as a Beta model http://farm8.staticflickr.com/7229/6...8ac6d460_b.jpg so I was able to use that schematic to get all the values and placements I needed. So now the amp is fixed.