OT: Anybody on this board an electronics wiz?

[VolvoHeretic]

After a week of dead silence on Audio Karma and DIY Audio, you guys are my only hope. I have a Stax SRA-12S electrostatic headphone driver / preamp that my tech guy says needs a dual voltage power transformer which Stax Inc says is no longer available and that I am SOL.

Anybody know how to read schematics and can figure out a workaround to this issue? The tech said he tried to bypass the high voltage crap and just wired up a low voltage 26 volt transformer, but it still wouldn’t stop blowing the main power fuse (I don't know if it blew the fuse, but it didn't work and if it isn't worth it, I don't want to spend anymore money on this thing. I am actually buying a Soundcraftsmen SP4000 preamp from him as I type).

I only use this thing as a preamp and have no use for the headphone driver if it could be disconnected.

http://dl.dropbox.com/u/9188783/Stax...e%20Manual.pdf

I have a link to the service manual.

[hemicuda]

If he tried to bypass the high voltage (power) circuit and it still blows a fuse; that tells me there's a probably a short in one of the PRIMARY windings. This is ONLY if he totally unsoldered the transformer secondary leads that go to the circuit board and tested the voltage there. If it blows a fuse by just plugging it in the wall then you know the transformer is bad. If not, there's at least one components still bad somewhere that he's overlooked or whatever. Anyways, the only real way of repairing it (IF everything else is okay) would be to probably replace one main (dual voltage) transformer with two separate transformers. Shouldn't be that hard to find replacements but getting the right physical size so both would fit might be a challenge. If you've already spent a lot of money on it then I'd say trash it and use it for parts or hang onto it and try to find transformers that will work later. By the way, did he check the obvious voltage selector switch to see if it was okay? Just a thought. Hope I helped some at least.

[VolvoHeretic]

Thanks for looking Hemi, I don't know what his conclusion was, I will contact him and find out, but I would guess that it quit blowing fusses but didn‘t work sound wise. I would be fine with an external transformer pod and would just as soon remove the hot enough to cook eggs on class A electrostatic headphone section from the preamp if possible. The $30 electronic check up ended with his conclusion that it is dead. I need a reason to continue further. I had wanted to buy a Crown IC150A preamp at half the price, but certain people talked me into this thing because it was God's gift to audio nirvana.

[RonSSS]

If the power transformer is dead, it could be replaced with 2 transformers. One HV and one LV.

(doh....Hemi already said that)

Another possibility would be to have one made. Cost about $150 or so.
I had 2 made for my tube amps.

It really doesn't seem like it would be too hard to troubleshoot that.

Just leave it to the car guys..........

Ron

[donaldpatten]

Ask your Tech to disconnect all the power transformer leads; then connect only one of the 117 volt primary windings. If it holds, and does not blow a fuse, connect the other pri and see if it holds. Then add on a secondary ...
In the old days we would rewind transformers and motors. Just measure the wire gauge , length and number of turns

[Old Guy]

Sizable project. One of the fuse blowers is shorted components in the HV section.

I did convert this to jpg it has the tranny voltages. You won't need the dual primary just the right secondaries. Maybe Hammond or Edcor? Make sure it IS the tranny first.