73 Coliseum Slave Transistor

[sunnmage]

Got a malfunctioning coliseum slave, making static..Could be filter caps, could be the green oxidized only pot inside. While looking at the Q's I noticed one of them had very rusty leads. One little touch and they snapped off. Trying to find an equivalent but it appears that part number doesn't really exist. It's a metal cap Q's titled ELM128...and then 8810 below. Found one European site with a few of them and they don't seem to be listed on the schematic. Anyone know anything about these or what an equivalent might be?

http://cdn3.fast-serve.net/cdn/markhindes/ELM128_0_0_20RUM.jpg
http://sunnforum.ampage.org/index.php?PHPSESSID=v927dcv51oibsblrknt9tfk2t4&action=dlattach;topic=5077.0;attach=989;image

I can post some pics later of mine if necessary

[loudthud]

Post a picture of the power amp board showing where the transistor came from.

[sunnmage]

Transistor is the bottom right one. There is an identical Q on the bottom left, it's the metal can package one. All the q's in this power board appear to be different than the schem..I see a mps13.. Also took a shot of the filter cap set-up..It's filtering 1.4mF..pretty gnarly. Thanks!

[loudthud]

Your amp has been repaired with non-original parts. If you are not experienced in the repair of high powered solid state amplifiers, you should take it to a competent technician in your area. Most of the transistors Sunn used are obsolete and probably difficult if not impossible to obtain. Beware of fake transistors that may have the correct numbers, but they will fail as soon as power is turned on. Suitable replacement transistors will need to be found.

Attaced below is the PCB layout and a partial parts list.

[sunnmage]

Thanks for all the info so far. That was exactly what I needed. I've repaired a few of these sunn solid state amps, so far it's been bad connections on all of them. Figured it was much safer than tube amps which I've actually built a few already. Found a new Q's with the same part number as the one that broke from mouser...You think this will work?  http://www.mouser.com/ProductDetail/STMicroelectronics/2N3440/?qs=ljbEvF4DwOOXOMDyH1Nf3g==

[loudthud]

That part should work and Mouser is a good supplier. The 2N4888 will be a lot harder to find. Also, the 2N3441 TO-66 will be hard to find anything close in that package. You can still find computer grade caps that will fit, but they are expensive. You should replace all the electrolytic caps. Use a bulb limiter when you power the amp up after repair.

[george]

  TO66 packages = unobtainable

Should be able to replace the 2N4888 with a high voltage (BVCEO) PNP in a TO-92 package.