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    PL 700 II Clair Bros Rising from the Ashes

    So here's what he had to say: I'm still winding transformers and you can contact me directly at ed_dinning@yahoo.co.uk (note _ underscore). If you can send me some pictures and the electrical spec/ schematic I can give you a quote. Cost could be in the region of £100-£200 for such a massive...
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    PL 700 II Clair Bros Rising from the Ashes

    Peter, I got a reply from the UK transformer guy. I'll put it in a PM.
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    PL 700 II Clair Bros Rising from the Ashes

    I've sent him a message. I'll let you know if and when I get a reply.
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    PL 700 II Clair Bros Rising from the Ashes

    Let me see if I can get a contact. He's on a forum for the restoration of vintage radios. I lived in the UK for a long time, still participate on the forum. He rewound an output transformer for a 1945 Ekco radio I have. Still, I think the megger is the way to go - just to see if you really...
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    Looking for phase linear 400 VU meter analogue

    I got the one I was searching for.
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    PL 700 II Clair Bros Rising from the Ashes

    I know a guy in the UK who rewinds transformers. He's not cheap, but he is fair. Shipping costs will be high. Let me know if you want to contact him.
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    WOPL update for PL400

    Appreciate that. Matches what I had gleaned. Is there a schematic for the light board?
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    WOPL update for PL400

    Everything is proceeding smoothly and then an "Ah Shit". First, I tested the power supply - both B+ & B-, without connecting either the WOPL PL400 backplane or the WOPL PL14-20 control board. It tested fine - about +/- 82 vdc. Then I connected power to both the backplane and the control board...
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    Scored this today:

    Nice! How's the condition?
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    WOPL update for PL400

    Construction continues - when I get a chance. So far, no serious issues and I've been following the instructions. Here are some notes. 1) As stated earlier, I stripped the chassis down to nothing to treat some beginning corrosion. The transformer had some. I looked at the suggestion to use...
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    And you can now connect the chassis to the line cord ground if you desire. You will, of course...

    And you can now connect the chassis to the line cord ground if you desire. You will, of course, want to check which configuration gives you the least hum pickup. But make that measurement with the inputs shorted (not open) to signal ground (not the chassis). Hope this helps.
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    Hi Peter. There is no reason to connect the signal ground (which is the center tap of the...

    Hi Peter. There is no reason to connect the signal ground (which is the center tap of the secondary) to the chassis. If you isolate the signal ground from the chassis (that screw) and make your measurement from the chassis to line cord ground, there should be 0 vac (and 0 vdc) since the...
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    PL 700 II Clair Bros Rising from the Ashes

    Sorry Peter, you're missing the point. All transformers will exhibit this behavior - it's inherent and is expected, there is nothing wrong with your transformer. If you isolate the signal ground plane (i.e. the secondary center tap from the chassis) from the earth ground of the plug, the...
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    PL 700 II Clair Bros Rising from the Ashes

    Peter, in my opinion, the chassis and signal ground should be kept separate. That is, signal ground is not connected to the chassis. The sketch below shows the idea. The signal ground which is connected to the center tap of the secondary is not connected to the chassis. The AC power earth...
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    WOPL update for PL400

    I planned to replace the power cord since its condition was looking poor. Initially I thought I'd put on a 3 prong plug with an earth and tie it to the chassis and float the amp's ground from the chassis. This would provide safety and shield the amps innards. But then the amp can't be plugged...
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    WOPL update for PL400

    Stripped the chassis down to nothing - cleaned everything. Plan is to build the WOPL PL14/20 card first. Then build up the backplane without the transformer just to make it easier to move around. Then install transformer and rebuild power supply and test it before connecting it to anything...
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    PL 700 II Clair Bros Rising from the Ashes

    I would not jump to the conclusion the hum is somehow due to the transformer. Maybe, but keep an open mind. There are other possibilities as suggested above. Is it on both channels? Can you see it on a scope (and hence measure it). Try shorting the inputs to shield - and this has to be a...
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    Schematic question

    Spent a few minutes looking at the schematic. I see what you're saying - no direct connection from the negative speaker terminals to ground. Sorry I can't be of more help.
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    PL 700 II Clair Bros Rising from the Ashes

    Beautiful! Glad to hear things have worked out. A nice new year's present.
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