I was was checking out a 74 DR103 today. Nice amp but when I went to check the plate voltage (or B+) I measured a suprising 451DCV Most other Hiwatts I've measured all read around 500-5115DVC. What can be wrong with this one?? The caps are good with no hum. Could this be a bum PT from the factory just like the Marshall ones from the mid 70's??? Any comments would be appreciated. Thanks.
Joseph
74 Custom 100 with only 451DCV on the plates???
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- clusterstudios
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- clusterstudios
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Re: 74 Custom 100 with only 451DCV on the plates???
Anybody there???
- mikhailwatt
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Re: 74 Custom 100 with only 451DCV on the plates???
What was the mains voltage?
I think the spec was 460vdc plate, but you start hitting 490+ running them off modern 120-125vac on the 115v tap.
My 1980 DR504 runs about 450-460 (if I recall) with the mains knocked down to 114vac on the 115v tap.
I think the spec was 460vdc plate, but you start hitting 490+ running them off modern 120-125vac on the 115v tap.
My 1980 DR504 runs about 450-460 (if I recall) with the mains knocked down to 114vac on the 115v tap.
You can almost feel the current flowing
You can almost see the circuits blowing
You can almost see the circuits blowing
- clusterstudios
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Re: 74 Custom 100 with only 451DCV on the plates???
460DCV is common to the 50 watters but not the 100s. It's the 1st time I've seen it on a 100 watter.
Re: 74 Custom 100 with only 451DCV on the plates???
What are your mains vs. "voltage selector" voltages? The Biacrowns I've seen run silly high voltages (500+) when fed modern US mains, but the older Hylights not quite so much (unless you're feeding a 115v tap 127 volts).
--mark
--mark
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Re: 74 Custom 100 with only 451DCV on the plates???
My 83 Biacrown DR- 504 is 517v B+. Phil
Re: 74 Custom 100 with only 451DCV on the plates???
my 1972 dr103 is around 476. is there a "normal" reading that should be expected?
- clusterstudios
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Re: 74 Custom 100 with only 451DCV on the plates???
That's more like it. I'm in Toronto using 120AC.philmanatee wrote:My 83 Biacrown DR- 504 is 517v B+. Phil
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Re: 74 Custom 100 with only 451DCV on the plates???
is it possible it has a 50watt transformer in it? check the tranny codes is worth a look. a friend of mine blew his 100 tranny and replaced with a 50, god knows why? but it worked, to a fashion. just a thought......