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.

[alancohen]

If you confirm that it is the tranny and have the voltage values, try Antek. I've gotten some very nice toroids from them at very reasonable prices.

Antek - Your reliable source of transformers, power supplies, and more.

[VolvoHeretic]

Ok, when the tech bypassed the low voltage transformer, the fuse did not blow, but he could not get any responce without the high voltage also in use. He said to dive in further would be another couple hundred $. He doesn't sound at all encouraging. Is this thing worth the effort?

He has a Soundcraftsmen SP4000 preamp for $150 which people on Audio Karma claim is a great preamp. Just a volume knob, switching box, phono preamp, and tape loop for my EQ. Maybe its just time to move on? He says I could maybe get a $100 for it as parts to someone who what's a headphone driver.

I think that I will just chock this up as dead and move on. Too bad the two old electronic guys I knew have passed away, I'm sure they could have whipped it into shape in notime.

[alancohen]

There's a nice Grounded Grid on Audiogon. Upgraded volume knob and sub outs.

Transcendent Sound Grounded Grid Preamp Upgraded volume control | Tube | American Fork, Utah 84003 | AudiogoN - The High-end Audio Community

It's not $150, but you'd be hard pressed to buy a better preamp for 4X the $$$. No phono though.

I might just get it. It's $500 for the kit, and I need another one.

[hemicuda]

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.

I agree OG... That's why I said that he just needed 2 transformers with the right secondary voltage (if that is the problem). One thing I've learned after 20 years of repairing / building electronics is to never overlook the obvious. It may be something really simple that's causing the problem. It could be one of the diodes (or bridge rectifier), a bad capacitor or either one of the transistors. I've found that a lot of electronic techs are just too lazy to really look at everything like they should. They want to find an easy solution to get it back going so they can get paid. It's a shame too. I'm not like that by any means; I'm too stubborn! It's the OPs call as to when to call it dead and just use / sell it for parts.