Phoenix Gold Phorum

Looking to rebuild 1 (for sure) 2125 and 2 others that I'm assuming are 2125's (No endcaps. Or caps on the board) that I got for free.

The only thing I found that looked sketchy was a burnt chip that was replaced. With the remote wire soldered onto one of the pins?? The matching one right next to it was an SG2525A

Anything I can upgrade while I'm at it?

2 of the boards are missing the smaller transformer in between the 2 larger ones? Anyone have one laying around?


Does this parts list look right?
Caps
12X 2200uf 16v
4X 10000uf 50v
Transistors
8X IRFP044
2X SF302
2X SF302A
6X 2SA1302
6X 2SC3281
2X F15031
2X F15030
2X C3423
30 Sil Pads

I also need screws for all the transistors. Anyone know the size/pitch??

Thanks.

You'll need 12 16v 2200uf caps, pitch of transistors screws is 4-40...

Make sure you check the mosfet resistors (they may be open/bad).

trickyricky wrote:You'll need 12 16v 2200uf caps, pitch of transistors screws is 4-40...

Make sure you check the mosfet resistors (they may be open/bad).

Thanks for the tip. I will just replace them. What's the ohm/watt rating?

If the fets and their (100ohm 1/4) resistors failed then more than likely you'll have to replace the PWM ic as well (3525 ic).

This may help, I created it on my registry website and made it a hidden page, so keep the link, you'll have a hard time finding it again.


http://www.phoenixgoldregistry.com/..html

The 2sc3281/2sa1302 complimentary pairs are long, long obsolete. You can still get the MJL3281/1302 which are a good replacement, basically the OnSemi/Motorola equivalent part. The 2SC5200/2SA1943 are also still available and are normally a good choice for most of the bigger PG amps.

I don't work on a lot of of MS amps, but isn't the small "transformer" as you put it, just a common mode choke? If so, buy some cores and wind them, there are not a lot of turns on them and it sounds like you have one complete one that you can count the turns on. It shouldn't be super critical on exact number of turns, just as long as both sides are wound exactly the same and opposite. It will work fine. Measure the magnet wire on the one that you have that is intact.

There is no upgrade for the SG3525, it is a pretty robust PWM IC. They do sometimes fail when a power supply blows. Especially in amps where there is no buffer between the SG3525 and the fets. I don't know what the MS amps have, but most of the later PG amps are buffered with a complimentary pair.

Good luck,
Jason