Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: chocopower on June 04, 2014, 12:55:25 pm

Title: 220v Power Transformer with 235v wall voltage.
Post by: chocopower on June 04, 2014, 12:55:25 pm

I´m working in a old 60´s amp with a 220v designed P.T.
Since here in Spain we have now 235-240v  and the amp use a GZ34 as rectifier, Will be a good idea use a different rectifier to drop voltages in whole amp ?


This way DC  voltage will be close to original ones.

Title: Re: 220v Power Transformer with 235v wall voltage.
Post by: eleventeen on June 04, 2014, 01:35:57 pm

A 5Y3 in place of your GZ34 should drop your B+ 20-30 volts....you may need to drop it a little more.

Title: Re: 220v Power Transformer with 235v wall voltage.
Post by: PRR on June 04, 2014, 02:26:22 pm

> use a different rectifier

Your heater voltages are still high.

It may be time to study step-down transformers for all your older gear.

Title: Re: 220v Power Transformer with 235v wall voltage.
Post by: chocopower on June 04, 2014, 04:10:59 pm

Thanks all!  i´ll check filament voltages and make a decision.

Title: Re: 220v Power Transformer with 235v wall voltage.
Post by: printer2 on June 04, 2014, 09:28:29 pm

What I did once is put a resistor on the input side of the transformer. Dropped the voltage until my heater voltage was correct.