new Express build problems

[Randy Magee]

I hear that Mark! It just about has to be in the signal chain somewhere... all the voltages are in the ballpark... I'm sure the boards are wired correctly with the proper values... it either has to be the signal chain or a bad OT and my money is NOT on the OT...

[geetarpicker]

Heck if you have another OT around (anything in the ballpark) I'd temporarily tack that in on jumper leads and see what you get. Recently I had a reissue Marshall 20 watt head fry an output and it sounded very very weak and distorted (but it still played) though everything else voltage wise seemed ok. Perhaps your OT is suspect right off the shelf.

[M Fowler]

I have had some fried OTs myself

[fishy]

I've tried swapping the leads from the OT primaries with no joy... lifted the negative feedback with no change... I'm trying to find a 1/4" to RCA jack so I can use the sound card on my computer to generate some noise for the audio probe I made... it gets more curious all the time...

just plug the guitar in instead and use that. You should be able to follow it through the circuit.

[Randy Magee]

Things aren't looking good for the OT... I traced a clean signal through the circuit all the way through the phase inverter... what are the odds having a bad OT right off the shelf? Unfortunately, I don't have another OT that is anywhere close...

[fishy]

That is unfortunate....

If the transformer was new I would contact the supplier and see if I could work a replacement out for the dead unit.

Good luck

[RJ Guitars]

Randy,

I can send you a new OT, send me an email and we can work out the details. info at rj guitars dot net

rj

[Randy Magee]

Thanks RJ, I have contacted you by email... cheers for a straight up dude!

[fishy]

I should have known. The Tech-Caps should have given it away.
You are in very good hands with RJ.

Rest assured, your amp will sing and all the pain will have been worth it. Along the way, you will learnt something about the wonderful amp you are making and you can look back on the experience as a positive one.

[RJ Guitars]

Yeah we'll get the fix applied to this outfit and we'll all learn something in the meantime. I've had very good luck returning it to the manufacturer the one time I had a bad OT sent back to me before. That's one in several hundred so I don't think it happens too often. If this doesn't turn out to be a bad tranny then we'll still learn something and I am very confident this amp will be cooking soon.

[fishy]

I should have known when I saw the Tech-Caps.
You are in very good hands with RJ. You can search all you like but you will not find better.

Let us all know how you get on.

[Randy Magee]

I wasn't going to mention a supplier or bitch and whine... I was just going to order another OT and go about my business of making the amp work. It takes a pretty stand up guy to step forward and offer a solution. My hat is off to RJ!

[Randy Magee]

I dug around and found a 20 watt ultra linear OT... can I patch that in and just leave the screen taps unhooked to test to see if the Heyboer OT is my problem?