Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ACHIEVEIT on March 15, 2012, 12:23:08 pm
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Hello guys,
i recently bought a hoffman ab763 board from theairtightgarage to replace the stock pcb of my DRRI. I also changed the OT with a classictone one but decided to keep the stock PT, as it seems adequate for the job. I live in Europe, so my primary voltage is 230V and the DRRI is the Export version. I found the DRRI service manual which explains in a rather complicated way the PT wiring. I think i decoded it, but i would like to be certain before i wire it and fry anything! :smiley:
I have attached both the service manual and my drawing. Could someone please verify that i got it right? Thanks a lot in advance!
http://ampwares.com/schematics/65_Deluxe_Reverb_RI.pdf (http://ampwares.com/schematics/65_Deluxe_Reverb_RI.pdf)
(http://farm8.staticflickr.com/7207/6838639770_6060231a14_z.jpg)
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I can't tell for sure from the service manual.
The PT primary wires are noted as going to "CP#" with different points replacing the # sign. If I were you, I'd note the wiring provided for 230v operation on the schematic, then look at the pc board itself to see which points are connected together or have no connection.
I think you're on the right track, though. The two halves of the primary would likely be in parallel for 120v wiring, in series for 240v wiring, and in series with a tap on the winding for 230v wiring.
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Start with just the transformer and a lamp-limiter. 100+ Watt 230V lamp.
If the lamp lights FULL BRIGHT, swap one primary.
If the lamp lights less than full normal brightness, you got it right.
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looks correct. :-)
CP1 - is black on 120V model. CP1 is violet on export.
CP2 - is white on 120V model. CP2 changes on export model w/ volt selection. @ 120V it's white, @ 230V it's white/black, @ 240V it's black.
CP3 - is red/black on export model.
CP5 - is black/green on export model.
we know that CP1 and CP2 are always the hot and the neutral connections.
on export model we have 8 connection points CP1thru CP8.
CP1, CP3, and CP5 primary leads wired to the PCB and they don't change.
CP3 and CP4 are shorted on the export model.
CP5 and CP6 are shorted on the export model.
CP7 is left open on export model.
CP8 is left open on export model.
for 230V:
CP1 is violet - goes to fuse - violet is always the hot on export model (at least you'll get that right, the rest is a coin-toss - j/k.).
CP6 is black/yellow and CP6 shorts to CP5 black/green,
CP7 is white goes to no connection.
CP2 is white/black goes to TH1 (neuetral).
CP8 is black goes to no connection.
CP3 is black/red shorts to CP4 which is unused.
you have 3 active winding connections:
CP1 - violet which is hot.
CP6 - black/yellow shorts to black/green
CP2 - white/black which is neutral.
i'm guessing that every primary wire in the original layout HAD to have a tie point likely to satisfy UL/VDE etc., so that they are not cut and left as taped off flying leads.
--DL
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I completely agree with you DummyLoad. These were my thoughts exactly although i couldn't express them as well in English :)
So i guess it is decoded! Thanks everyone for your input and time!
In case i am wrong though, i will notify you so that other users don't make the same mistake