pg o.s. noob ms-275 help

[malcris]

Hello all,
Just joined here cause I got an old pg ms-275 from a friend who had it in his closet for 12+ yrs. Its a grey one rev. F. Anyway, I tried to bench it and the caps smoked and leaked like a mofo all over the board. Also, it seems that one of the power fet's has a crack in it. I'm obviously going to change out the caps and I'm wondering if these are a good choice.
1. 4700uf http://search.digikey.com/scripts/DkSea ... 1957380183
2. 2200uf http://search.digikey.com/scripts/DkSea ... 1957380183

I'm kind of upset with myself for powering this up before changing the caps but I'm pretty sure I caught it before any real damage occurred.

also, the marking on the cracked fet is irfp044. I can't seem to locate this fet anywhere, I'm assuming its been replaced as the manufacture date on this amp is 12/92. Any recommendations for replacements. Should I replace all type N's (looks like 4 on board)

I'd hate to waste this amp as its in near perfect condition cosmetically and everything else looks great on it, although I'm assuming some knucklehead reversed the polarity somewhere along the way and caused this damage (strange though, no major bulge on top of caps?), probably why it sat in a closet for so long.

[Eric D]

Please post some detailed photos of the board if possible. We can help you more with what else might need work on the amp.

[malcris]

I tried, but I can't seem to upload them...I'll give it another shot...Nah, my camera's photo's are too big and when I shrink them they pixelate. Please send me an email to nitsirk1@verizon.net and I'll gladly forward what I've got. Currently, my biggest concern is the fluid from the caps leaked on the board and I'm a little hesitant to clean it but because of its age I'm wondering what these caps were filled with (glycol or weak acid) and I don't want to let it sit and eat the board. I actually removed the caps today to find the bottoms split on the sides, (weird the expansion joints on the top didn't pop, the fluid must have seperated over time)I would normaly use 99% iso to clean, but the board is gold plated and I don't want to screw it up... Honestly, the rest of the board looks pretty good, hardly any scortching at any other solder points. I've never worked with a gold plated board and any suggestions to clean it would be appreciated. I've looked at other posts here and it seem like it should be handled like any normal board. Any input on the caps and fet's would be appreciated.

[ttocs]

yea leaking caps means DO NOT HOOK UP with out a fire ext nearby. I can't remember if it is alcahol they recomend or what, what a few and they will tell ya.

[Eric D]

If the amp was hooked up backwards as you have suspected, that could account for the split caps, and split FETs.