Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Tone Junkie on September 25, 2010, 12:53:39 am
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Ok I bought one of those solid state rectifiers that plug into the 8 pin socket like what was being used for the TOS build , This is my first time using one of those now Im building this in an old music man chassis that had been an ab763 build before this one that had diodes the first reading at point (A) or at the standby switch before was about -450 with this thing its at -565 something is definitly wrong Im going to go tomorow and get a 5y3gt and try that instead but im using one of the super reverb clone trannies at 330-0-330. so the voltages should be very close to the tweed overdrive schematics numbers. Like I said first time trying one of these things. Bill
PS its gettin late time to put the soldering iron down I hope i havnt ruined any tubes with those high voltages and yes like dumb ass I stuffed it full of the good tubes first try
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Hi Tone Junkie,I've posted my voltages using a 325-0-325 Hammond transformer and it got my SS rect from tube depot. Thanks
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Thanks Timbo nice looking build you have going there my voltages are way high. Especialy since I already had it hooked up before to something else node A is coming in at 100 volts higher than yours, I will get that tube and try it tomorrow. Thanks Bill
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I use a GZ34 in both of my TOS builds. IF you are using 6L6's, you probably don't want to use 5Y3 if you have all the tubes in the amp.
With respect, Tubenit
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Can you check those voltages with another meter? The theoretical maximum you can get from a 330-0-330 PT and full wave recto is 467vdc.
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Thanks guys a gz34 it will be and yes I will get a differant meter this one is old and beat up but it has never caused me problems before , I guess my problem is if build the recifier I know exactly what it is but when i buy one that i cannot see the parts or know how to test it Im leary when odd things happen. Thanks Bill
PS I did find one problem when i got up this morning I didnt have my artificial ground no 100ohm resisters from heaters to power tube cathode. I had always used adjustible bias before in my builds and had the ht ground in the system but i had taken it off and heat shrinked it, but forgot to ground it the other way my bad. Still the voltages stayed the same.
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Stuck in a GZ34 and used a differant meter same voltages , Im going to go buy a decent one any way they dont measure ac voltage well so I cant even tell if the pt is putting out 330 per side or not. I Will get an update after I get the other meter. Bill
PS ive been using cheap harbor frieght stuff for to long.
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Please note that a low battery can give VERY elevated readings in a voltmeter.
With respect, Tubenit
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Thanks Jeff here is the laugh Ok the only time I have been able to work on this is late in the evening after Im tired, the sad part was I have made this mistake before :huh: Ok problem was not the tool but the guy behind the amp when I unhooked and covered what i thought was my heater center tap it was my ht center tap. without it grounded it shows the voltages unusually high so, there was the problem. It dawned on me after i thought about it in between soccer games i was running kids to.
The reason my meter wouldnt read the ac from the pt that i tried to check obviously it wasnt grounded so I get home sure enough that was it. so regrounded it numbers are fine now. i hate making such rookie mistakes but its good for a laugh. when i get back home tonight i will check everything else and then fire her up. Thanks Bill
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Hooray! Glad you got it resolved! :wink:
Please let us know how the amp sounds and post sound clips at some point if you can.
With respect, Tubenit