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phsyconoodler
Junior tube assistant
Posts: 17
(3/30/04 1:57 am)
output tranny wiring
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hi there,
I have an output transformer from a german amp that featured a single EL84 output tube and a single 12ax7 preamp tube with a solid state rectifier.I took it apart and tried to assemble it into a larger cahssis,but I didn't write down the wiring code for the OT.It has three very thin yellow wires with a yellow blotch on one,a red wire,and a larger guage black wire.I am at a loss as to what wire goes where.Any thoughts?
The amp was a cool sounding,dark toned ripper.But it was so crammed into the small chassis,I thought I was doing the right thing by trying to get it some breathing room.I have a schematic but no color codes.
thank you!
6G6
Junior tube assistant
Posts: 146
(3/30/04 8:46 am)
Re: output tranny wiring
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You can use your multimeter to find out which wires are on the same windings.
Some will be primary, some secondary. The primary & secondary will be seperate from each other.
The black wire may be a center tap or it may be the common wire to ground with the red and blotched yellow being different
speaker impedance taps.
That would make the two yellows the primary side.
That is not the only possible explanation, so don't start soldering right away just because I guessed at it.
It's always best to take notes before you tear things apart, but I bet you've figured that part out, on your own by now, huh?
phsyconoodler
Junior tube assistant
Posts: 18
(3/30/04 9:51 am)
Re: output tranny wiring
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Hey man!
You put me on a diagnostic pathway.I appreciate your help.you are right,in my enthusiasm,I forgot the basics.I am hoping I will get this sorted out soon.I will definitely let you know if it works out.
Thanks a bunch!
phsyconoodler
Junior tube assistant
Posts: 19
(4/2/04 11:52 am)
Re: output tranny wiring
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well......I tried my best with this OT but I think I need some more help.I can't get a sound out of this amp.I think I fried something inside.Smoke and sparks but somehow the fuse didn't blow! I think I had better go to the ax84 site and start from scratch.This OT is getting tossed in the trash can.
Thanks for trying to help me.
Tiny Daddy
I will work on all amps
Posts: 594
(4/2/04 11:59 am)
Re: output tranny wiring
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The OT may still be good, don't hurry to throw it out!
jimf
Junior tube assistant
Posts: 9
(4/2/04 3:51 pm)
oops...
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So where did the smoke come from? What bits are charred? :)
The tranny might not be bad. As for identifying which leads go where, there is a section on figuring this out in the book I'm reading.... "Valve Amplifiers" by Morgan Jones.
If you still want to try to use that tranny, I'll type the important bits into a post for you. Or you could pick up the book. It's quite good.
www.amazon.com/exec/obido...ce&s=booksJim
phsyconoodler
Junior tube assistant
Posts: 20
(4/2/04 3:57 pm)
Re: output tranny wiring
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I haven't got a clue how to wire this thing,so I don't know what other recourse I have at this point.I'll tell you the wiring colors again: there are four very thin cloth wires,with one that has a faint yellow blotch on it;one red;and one thicker black wire.I found the primary wires with my dvom,( the black and one of the cloth wires)but the other three are a mystery.
AAAAAARGGGGGGHHHH!!!!!!!
Tiny Daddy
I will work on all amps
Posts: 597
(4/2/04 4:14 pm)
Re: output tranny wiring
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Give us the resistance measurements of the windings? Are the yellow wires measuring open with respect to each other?
jimf
Junior tube assistant
Posts: 10
(4/3/04 11:24 pm)
tranny ID...
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So I was going to type a bunch in, but instead I did a search on Amazon and they have the section of the book I wanted... so I copied it into a pdf file. Do you think that constitutes fair use? Just pretend I photocopied it at the library. You really should buy the book anyway. It is quite good.
users.rcn.com/sjfinney/tu...y-ID-1.pdf
users.rcn.com/sjfinney/tu...y-ID-2.pdf
If you still can't figure it out, post the resistance from every wire to every other wire to the board. List all possible combinations just to be sure. Someone should be able to help you sort it out.
Jim
phsyconoodler
Junior tube assistant
Posts: 21
(4/4/04 12:49 pm)
Re: tranny ID...
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Cool article!
Unfortunately,i don't understand it.I am going to try to identify the wires again,and will post my results soon.I am also buried up to my neck with my new 5e3 build that is giving me some problems too.I really appreciate all the help I've recieved,but i think I need to read a book to really grasp what I'm doing.Can you recommend a good book for a complete dummy like me? I seem to know just enough to get myself in trouble.I am a mechanic by trade and it seems so much easier to me at this point.I am commited to learn,though,as this new hobby of mine is addicting.
Thanks guys!
jc
I only work on Fender's
Posts: 696
(4/4/04 2:26 pm)
Re: tranny ID...
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If you don't have an electronics background I would start with this book
Inside tube amps
It is a good beginners book. Easy to follow and does a good job showing the basics.
There is also plenty of good information available for free on the internet. Dougs site, AX84 site, Aiken amplifiers, etc. Search for tube amplifiers in google.
The best books are the London Power TUT books. They are packed with information but in my opinion not for beginners.
It will probably prove to be a frustrating place to start.
Edited by: jc at: 4/4/04 2:29 pm
phsyconoodler
Junior tube assistant
Posts: 22
(4/4/04 11:07 pm)
Re: tranny ID...
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Thank you!
I have ordered the Dan Torres book. That looks like exactly what I need! Again,thank you very much!
Your new amp nut buddy,
Phsyconoodler
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