1974 Marshall PT color Confirmation?

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glpg80
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1974 Marshall PT color Confirmation?

Post by glpg80 » Sat Apr 04, 2020 12:49 pm

In the process of going through and restoring my 1974 Marshall I’ve noticed the secondary B+ wiring color code is odd.

I’ve got:

B+:
Blue (hot)
Yellow (center)
Red (hot)

Bias:
White (hot)
Green (gnd)

Heaters:
Black (hot)
Solid Green (gnd/center)
Black (hot)

The heaters have 0.05 ohms between the center tap and hot.

Nothing I have found shows blue as a B+ hot wire. Is this a stock Dagnall PT?

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neikeel
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Re: 1974 Marshall PT color Confirmation?

Post by neikeel » Thu Apr 09, 2020 4:13 am

Can you post some images of your PT?
The heaters and bias taps sound correct but the HT sounds funky.

Yellow is a normal centre tap colour
The HT on both my 71s are Blue/Black
Neil

glpg80
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Re: 1974 Marshall PT color Confirmation?

Post by glpg80 » Sat Apr 11, 2020 3:56 pm

The amp is currently upside down and torn apart, no good pictures right now unfortunately.

Yeah the HT is a little suspect. When I bought the amp I didnt see any writing on the bells. The transformers look original and I was told they were original. The string wrapping was still present before the restoration began and had that rosin light coating on them so it seems original?

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