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in article , Ray at wrote on
11/17/04 10:46 PM:
The power transformer in my 222C Amplifier is shorted, and I need the
voltages, (HV Secondary, etc) in order to locate a replacement.
The transformer is marked TR12-3-1,
The tube complement in my 222c is:
one 5ar4, two 6GH8, four 12ax7, four 7189
Any info is appreciated.
I think that the OEM transformer provides the following voltages:
720 VAC center tapped
50 VAC bias winding
5 VAC for the rectifier
6.3 VAC for the filaments
The B+ of the amplifier is 410 VDC
The DC bias voltage is 58
The amp uses a silicon bridge for the bias rectifier, so you could get by
with a 40-42 VAC winding if you switch to silicon (recommended)
Use of a SS sub for the 5AR4 (e.g. Weber Copper Cap) will obviate the need
for the 5VAC tap.
Power consumption on the original amp was 170 watts and the maximum sine
wave power for each channel was 20 watts.
These voltages are pretty common - I imagine you'd have a harder time trying
to find one that physically fit.
For example, I have a tranny in my junk box that delivers 786 VAC CT
(unloaded) and 56V bias with 6.3 volts available (at least 8A) but no 5
VAC.
Hammond's 373BX is rated as follows:
187 VA TOTAL POWER
350-0-350 SECONDARY @ 175 MA
5V @ 3A
6.3V @ 5A
50V BIAS WINDING
Problem solved?
Jon
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