Problem with Sunn Coliseum-300

[Destruktor]

I recently acquired a Sunn Coliseum-300 and tried it out the other day at practice. I played it through a Hartke 2x15 and a friend's 4x10. One 4 ohms and the other 8 ohms. This amp is rated at 300W @ 2 ohms.

Anyway, I was testing out the EQ and it was sounding great. I heard the occasional pop, but figured it was a cord I was using because it had that kind of sound. Well, a few minutes later there was a loud pop and the "overload" and "active" lights lit up and no sound come out. We tried to figure out what the hell went wrong and one of my buddies lightly "hit" the side and it started working again. Basically, each time it was tapped with some force, it'd switch between working and not working (with those lights on). I decided to unplug it and just use the other bass amp there. I didn't want to risk messing it up anymore than what it may be.

It doesn't seem like it'd take a lot to get fixed, but does anyone have an idea what it may be? Also any idea of where I could look to get this issue repaired?

 

[jazzblade]

The fact that hitting it causes it to work again could mean something simple like some connection is intermittent. Then again, it is probably over 25 years old. The overload and active lights coming on, I would look at the input section first I think. I'd first try tapping each of the controls and eq sections and wiggle the input jacks se if you can trace it that way.

If you feel like poking around inside. I would first check all jacks and pots, and look for any loses wires and connections BEFORE before doing the live "Chopstick" test.

(WARNING this is with the power ON, if your not comfortable with that, take it to a tech)

What I have done in the past it use a long pencil (no metal around an eraser) or chopstick to gently tap components and see if I can make it happen again to try to nail down the location of the fault. Turn the volume down first. You may find a loose connection or a bad solder joint which you can fix yourself.


Its what I would do before I decide on taking it to a tech anyway.

 

[Metal Matt]

The fact that hitting it causes it to work again could mean something simple like some connection is intermittent. Then again, it is probably over 25 years old. The overload and active lights coming on, I would look at the input section first I think. I'd first try tapping each of the controls and eq sections and wiggle the input jacks se if you can trace it that way.

If you feel like poking around inside. I would first check all jacks and pots, and look for any loses wires and connections BEFORE before doing the live "Chopstick" test.

(WARNING this is with the power ON, if your not comfortable with that, take it to a tech)

What I have done in the past it use a long pencil (no metal around an eraser) or chopstick to gently tap components and see if I can make it happen again to try to nail down the location of the fault. Turn the volume down first. You may find a loose connection or a bad solder joint which you can fix yourself.


Its what I would do before I decide on taking it to a tech anyway.

+1

A couple new years ago, my band played in my drummers basement. Had a sideways 2x15 with a 4x12 on top and a 4x10/1x18 stack next to it. Two Sunn amps on top of the 2x15/4x12 stack. Later in the night after we had played, one of our drunk friends crashed into it, my Sunn Concert Bass amp took a good 6 and a half foot fall. After hooking up a bunch of wires that had come loose from the fall, I put the amp back together. Started having the same problem as OP though and just like him was able to get it to work or not work by smacking it. Opened it up and started poking around with a piece of wood till I found an electrolytic capacitor on the pre-amp board that had a broken connection. Replaced it myself and it's been fine since.