50W Project
Moderator: VelvetGeorge
Flames I wasnt challenging you I was really asking you that question about the 56ks because I dont know.
One thing Trem. The one thing Im not totally certain of is the PT. Now Im positive the reds are the secondary AC and their should be a black wire between them which is the CT that gets grounded. You know your heater supply. Thats center tapped as well. Now you can theoretically hook them up like any 50W Marshall but certain situations mismatching the current the PT is rated for is bad. I would double check your PT specs with someone here or at Ampage or Plexi Palace before you start it up.
One thing Trem. The one thing Im not totally certain of is the PT. Now Im positive the reds are the secondary AC and their should be a black wire between them which is the CT that gets grounded. You know your heater supply. Thats center tapped as well. Now you can theoretically hook them up like any 50W Marshall but certain situations mismatching the current the PT is rated for is bad. I would double check your PT specs with someone here or at Ampage or Plexi Palace before you start it up.
- Flames1950
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I know, no offense taken and hopefully none given!!Flames I wasnt challenging you I was really asking you that question about the 56ks because I dont know.
Where are you finding Laney schems at? I didn't think I saw this model at schematicheaven.com but I haven't checked a couple of oddball sites i have bookmarked somewhere. That's part of the reason I've avoided this thread 'cause it's like flying blind. The other reason is that frankly Billy Batz you're usually on the right track without much help from the rest of us anyway.
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Ok, I saw the schematic on Schemheaven for a Laney GC30V. That schematic doesn't show the voltage from the PT on the red wires/secondary. The schematic for my amp (the AOR 30), it does show the voltages for the secondary - one of the red wires is ~310V and the other red wire is ~0V. There is no center tap!
The GC30V also shows that +12V -12V thing, center tapped, as the PT in the AOR has, but the colors of the wire are different. Also, the schematic for the AOR shows the 12V wires going to another bridge rectifier(??).
Anyway, I know Billy has been suggesting I get other opinions on whether I should try to use this PT in my 50W conversion, but no one has weighed in on the subject.
If I'm wasting time trying to use this PT in my project, I'll just go ahead and order up one from George. Opinions on this would be appreciated.
The GC30V also shows that +12V -12V thing, center tapped, as the PT in the AOR has, but the colors of the wire are different. Also, the schematic for the AOR shows the 12V wires going to another bridge rectifier(??).
Anyway, I know Billy has been suggesting I get other opinions on whether I should try to use this PT in my 50W conversion, but no one has weighed in on the subject.
If I'm wasting time trying to use this PT in my project, I'll just go ahead and order up one from George. Opinions on this would be appreciated.
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- Flames1950
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Without the real specs of the tranny it's hard to guess.
In one of the posts you said the Laney schematic specified 310VDC for the B+, but was that simply what comes out of the tranny secondary or what the amp had on the power tube plates after being rectified and filtered?
If that is what the schematic shows for the tube plates I'd definitely want the 50watt tranny for EL34's. Your B+ line through the preamp would be running low as well, and I'd be worried about headroom and "openness" to the sound of the amp.
If the 310V is before being rectified the voltage will many times bump up a bit after the rectifier. Still, you may only get 340-350VDC (with some luck) which is kinda borderline for what you may want to see. Even the lowr voltage late-70's Marshalls get you into the 390VDC range.
If it was my project I'd get the new tranny. And going that route you can follow the schematics and color codes from known information; personally I still haven't found the schem or specs on that AOR30 so I'm wary of what can be re-used too.
If you're going to try the 6V6 route you could still try the existing tranny. You may find that you'll need to measure the preamp voltages, and if they're low, maybe take out a 10K B+ line resistor or something to get some headroom back in that preamp.
In one of the posts you said the Laney schematic specified 310VDC for the B+, but was that simply what comes out of the tranny secondary or what the amp had on the power tube plates after being rectified and filtered?
If that is what the schematic shows for the tube plates I'd definitely want the 50watt tranny for EL34's. Your B+ line through the preamp would be running low as well, and I'd be worried about headroom and "openness" to the sound of the amp.
If the 310V is before being rectified the voltage will many times bump up a bit after the rectifier. Still, you may only get 340-350VDC (with some luck) which is kinda borderline for what you may want to see. Even the lowr voltage late-70's Marshalls get you into the 390VDC range.
If it was my project I'd get the new tranny. And going that route you can follow the schematics and color codes from known information; personally I still haven't found the schem or specs on that AOR30 so I'm wary of what can be re-used too.
If you're going to try the 6V6 route you could still try the existing tranny. You may find that you'll need to measure the preamp voltages, and if they're low, maybe take out a 10K B+ line resistor or something to get some headroom back in that preamp.
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Thanks Flames. I think I should order the new PT. It would make things easier.
The 310 number is what shows on the schematic directly at the PT (I believe I incorrectly labeled it "DC" in my post); I didn't measure the voltages on the power tube plates prior to disassembly.
In George's site I see the only Heyboer being the only 50W PT. Is this the best way to go?
Scott
The 310 number is what shows on the schematic directly at the PT (I believe I incorrectly labeled it "DC" in my post); I didn't measure the voltages on the power tube plates prior to disassembly.
In George's site I see the only Heyboer being the only 50W PT. Is this the best way to go?
Scott
- Flames1950
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Here is a schematic for a AOR 100 if this might be any help.
http://www.braught.com/Schematics/AOR100_S2.pdf
http://www.braught.com/Schematics/AOR100_S2.pdf
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- Flames1950
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- Flames1950
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The new 50W power transformer arrived last night. Man, that thing is a monster! Its like twice the size and weight of the PT it is replacing. In fact, I'm going to have to cut the chassis again to accomodate it, and I'm going to have to move the filter cap that was over there, probably to inside the chassis mounted on one side as in that picture George posted of that JTM 45.
So its a little more planning and cutting need to take place before I can start wiring. Sometimes I think I should have just sold the Laney and ordered up the full Metro kit, it would have been easier!
So its a little more planning and cutting need to take place before I can start wiring. Sometimes I think I should have just sold the Laney and ordered up the full Metro kit, it would have been easier!