Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Tubes and Hybrids => Topic started by: Hawk on May 25, 2015, 04:07:16 PM

Title: Universal Transformer Hook Up Peavey Classic 30
Post by: Hawk on May 25, 2015, 04:07:16 PM
Hello Folks!

I'm trying to replace a Power Transformer for a Peavey Classic 30, 120V operation , with a Peavey Universal Transformer. The original transf. had two yellow secondary wires that attached to a connector which slid over a set of two pins on the board. There were also two red secondary wires which went to another connector and that connector slid over the other two pins on the board. Easy stuff.

But the universal transformer in the attached pic has two yellow wires with separate connectors and two reds with separate connectors. I'm guessing I need to remove the connectors and solder each of the four wires to the pins. Makes sense?

Also, the tech notes that came with Peavey transformer tell me to connect both the blue and brown to the hot side of the supply and the blue  and white to the neutral side which, again, appears easy enough.

I've never used a universal transformer replacement so I'm a little confused on this one.
 :-\
Thanks!
Title: Re: Universal Transformer Hook Up Peavey Classic 30
Post by: Enzo on May 25, 2015, 04:24:17 PM
Important!!!  You mentioned blue wire twice.  Ther is a blue and brown and a black and white wires.  You MUST connect them correctly.

yes the yellow and red wires connect to those pins.
Title: Re: Universal Transformer Hook Up Peavey Classic 30
Post by: Hawk on May 25, 2015, 05:08:27 PM
Correction: brown/black together....white/blue together.  Thanks Enzo!
Title: Re: Universal Transformer Hook Up Peavey Classic 30
Post by: Enzo on May 25, 2015, 06:23:05 PM
I always thought it was clever that they drilled little holes in the board next to those pins, the holes made a Y and an R.  I guess that way the printing could never get rubbed off.
Title: Re: Universal Transformer Hook Up Peavey Classic 30
Post by: Hawk on May 29, 2015, 10:59:34 AM
Enzo, definitely handy. The new universal transformer works but I'm concerned about the higher voltages. At junction of CR11 and CR13 I'm getting -45.6VDC.

Also the plate, screen, B++, and B+ voltages are higher. At CR8/9 junction I measure 357V. At junction R58/59 I measure 351V,and at R59/60 I measure 352 V. At  R60 on the B+ side I measure 349 volts.

I haven't put the tubes in yet as I wanted to make sure the voltages are within range.

The amp uses russian Tungsol El84 tubes and according to the data sheet, if I'm reading it correctly, these voltages are too high.... :-\

Title: Re: Universal Transformer Hook Up Peavey Classic 30
Post by: g1 on May 29, 2015, 12:28:49 PM
  The voltages will read high if the tubes are not installed.
Title: Re: Universal Transformer Hook Up Peavey Classic 30
Post by: Hawk on June 01, 2015, 11:07:03 AM
Thanks g1. Amp works great! :dbtu: