1971 50 Watt - Mains fuse keeps blowing
Moderator: VelvetGeorge
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Re: 1971 50 Watt - Mains fuse keeps blowing
Thanks for the test suggestion. I haven't gotten to it just yet but will as soon as I can. Thanks
- neikeel
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Re: 1971 50 Watt - Mains fuse keeps blowing
As long as bias is connected directly to half the PT HT winding that will be correct.jnew wrote: ↑Fri Mar 01, 2019 2:00 pmIn the pics from above, are you suggesting that red wires from the PT and bias tap be placed on the bottom lugs of the switch while moving the blue wires to the rectifier to the top lugs?neikeel wrote: ↑Fri Mar 01, 2019 1:36 pmWrite 1,000 lines "I must check diode polarity before soldering" and you will not do it again.jnew wrote: ↑Fri Mar 01, 2019 1:30 pmI had the diodes backards.
Amp sounds like the quintessential Marshall. It's killer. I don't know if anyone keeps track or has any interest in PT sag but I'm seeing 425V's on the plates and a big hard strum on an open E chord pulls the voltages down to about 310 or so.
Sag is pretty typical.
Waiting for OP to chime back in.
Forgot to mark the schematic above up that the bias feed should be on the other side of the standby switch to that shown above so the bias circuit sees juice when on standby.
Neil
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Re: 1971 50 Watt - Mains fuse keeps blowing
That's what I thought. Basically just want the bias "LIVE" when the power gets turned on. I wonder why the 100W amps were this way but not the 50W's.
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- neikeel
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Re: 1971 50 Watt - Mains fuse keeps blowing
They were up to 69/70 and then again ear;y 70s (73 i think)
Neil