Peavey Citation Transformer

[stereomonostereo]

Hey guys

I've got a Peavey Citation (320GH power section) with a power transformer problem. Once the tranny warms up, it produces a mechanical rattle. I'm guessing the lamination is shot. The transformer part number is 70518714. Peavey doesn't stock them, or a replacement. I'm getting 56v and 36v off of my secondaries, but I don't know what kind of amperage is required. Anyone have any info that would help me spec a replacement?

[J M Fahey]

VERY much doubt your transformer is bad.

M echanical rattle is just that.

[Enzo]

The transformer can rattle on its own, or it can rattle against the chassis. FInd out which. Make sure the mounting bolts/nuts are snug. Make sure the corner bolts are snug. Are the end bells snug?

I should ask: Is this tranny mounted on the wood floor or on the end of the rear power amp panel? I assume it has end bells, does it?

When it rattles, grasp it with your hands and squeeze it. Does that affect the noise?



If you do need to replace it, PV wouldn't have the 30+ year old part, but look at the schematic. There are 42v main rails, and the low voltage does what it has done in solid state Peaveys for decades - make +/-15v supplies. So find some relatively recent PV amp that also uses 42v rails. A quick look and I found the TNT115 2000 model. It has 45v rails, close enough, plus the standard low voltage. Maybe they still have that one. Power output would be the same more or less. Your amp is 160 watts, so any similarly rated PV solid state will have a similar transformer.

[stereomonostereo]

I've pulled the transformer from the chassis and removed the end bells and it continued to rattle. Nothing I've done has cut down the noise. It functions fine voltage wise, but the noise is pretty loud. Thanks for the suggestion on the replacement!

[J M Fahey]

The standard solution to rattling, and which is routinely applied at the factory, is to dunk the whole transformer, windings, iron, everything (often even with the end bells attached) inside a vat of "transformer varnish" which both protects it from humidity/rusting , insulates everything and "glues everything to everything".

Transformer varnish comes in 2 flavors: oven curing and fast air drying .

If you dare, re-dunk it , you can use any home wood varnish, even so called "marine" varnish.
Works the same, only it will take at least overnight to dry, it will be sticky for a day and first time you turn amp on and it heats up it will stink your house, so do it in a garage or backyard.

But it´s not difficult, it only takes a little patience.

And it actually takes very little, but you will need 1 liter or so anyway to submerge the transformer inside some old Tupperware pot.
The tighter fit the better because you´ll need less varnish.

Grab it by the wires (make a bundle) put the transformer inside the varnish and leave it for an hour, until all air inside bubbles out.
Then raise it away , hang it (still by the wires ) iver the pot or varnish can and let all excess drip away.

That varnish will still be usable later for its original purpose.
Let the transformer dry overnight still hanging and put some newspaper under it to catch some odd drop.

Guaranteed no more buzzing.

[Enzo]

Juan that sounds like a good idea. I would think any local motor repair shop could do that. I don't see transformer winders in many towns, but motor rewinders are all over. Actually, some of them do transformers as well.

If you have it apart, I don't know what you have done so far, but does it have the copper shielding strip around it? Sometimes they rattle, and i wedge something under them to help. But try to isolate the rattle. Is there any play in the bobbin? DO the windings have any ability to wiggle? Does grasping the windings make a difference? Are there any small gaps a shim could be wedged into?

[stereomonostereo]

When I had it apart, I checked the copper strip, checked for wiggle, etc. Even gave it a lite whack with the banjo tuner. Still rattled upon warming up. I just dunked the entire transformer in varnish for about an hour and a half and now I'm letting it dry until Monday.

[stereomonostereo]

I got around to dunking the entire transformer in some Cabot Spar Varnish. Left it in for about an hour til there was no bubbling left. Waited 24 hours and installed it back into the amplifier. Going on an hour now with absolutely no buzz. Worked like a charm. Thanks guys!