Sunn Coliseum Salve Help/Ideas

[glebert]

Oh man!!! This thread may very well save me. I had my 70's coliseum bass go up in flames at a gig this past Sunday. When I compared the driver PCB 20-0026D to the avail schematics, it didn't match and had me really worried I wasn't going to be able to figure out the correct parts to put back in. TigerAmps, did you ever verify the resistor values you replaced?

Odd question, but are you with the band Goddard? I just know they had one burn up on Sunday too.

[shiner555]

Odd question, but are you with the band Goddard? I just know they had one burn up on Sunday too.

Heh.....maybe..... Were you there?

[glebert]

Heh.....maybe..... Were you there?

Old friends of mine from MTU, saw pics of the carnage on FB.

[shiner555]

Old friends of mine from MTU, saw pics of the carnage on FB.

Oh man!! Yes, ok! I know who this is! Nice to run into you on here Greg. It's Jason/Nirv. Yeah, the amp was a flame/smokeshow. I'd already be on my way to repair if the schematics I have matched the PCB's. Hopefully this thread will shed some light. I also found Conrad Sundholm online and threw him a hail mary email for possible further info.

[glebert]

Oh man!! Yes, ok! I know who this is! Nice to run into you on here Greg. It's Jason/Nirv. Yeah, the amp was a flame/smokeshow. I'd already be on my way to repair if the schematics I have matched the PCB's. Hopefully this thread will shed some light. I also found Conrad Sundholm online and threw him a hail mary email for possible further info.

Figured it was you I'll send a PM.

[TigerAmps]

I have both a coliseum slave and bass (both amps).

I did refurbish the slave (I have pictures and know the values) - the bass is still a work in progress (I just have not gotten back to it).

Can you post a picture of the board? The differences are minor mostly a cap and the 4 diodes in the middle of the board.

Check everything on the board probably will require a complete rebuild due to the age.
Also - if the main supply caps are original and you want to keep the amp, consider replacing them as well.
When I got one of the slaves, one of the main supply caps was open and it just output 60 cycle hum as a loud volume (not fun).


Any questions on component values - just ask or send a PM

The re-furbished board:

[shiner555]

Awesome!! For some reason I can't post the pix....here is a link to where they are on facebook.

https://www.facebook.com/Goddard.Mus...type=3&theater

PCB is 20-0026d

I'm looking to verify the values of the blown resistors. R217, R218, R216, R215.

It looks like R218 is the one that caused the fire. It's directly tied into Q5. It's strange as Q5 tests out just fine......I'm going to go and replace all the caps and test all of the transistors on this PCB as well. Also, I'll verify all output devices. They are only a couple of years old, so they should be good, but also could have been the cause of the problem. Then again, if Q6-8 would've went I also would've expected Q5 to go, but maybe not do to how R218 is tied into the output devices.

How did you sub's work for the small transistors on the board? Any issues?

Thanks!!