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Valvetronix VT50 Headphone Input Board Repair - need images?

musekatcher

Member
Messages
2,735
Ive googled and searched valvetronix.net, can't find an image of the input board. Anybody know where I can look? I attempted to re-soldier some cold joints, and a tiny braided jumper sprang back, and I can't determine where one end goes? If I could see an image of the soldier side of another board, I think I could figure out where it goes. Right now, speaker works fine, but headphone doesn't work, nor does it defeat the speaker.
 

musekatcher

Member
Messages
2,735
Can you read a schematic? If so here you go:

Service Manual for Vox VT50
I can't correlate the schem with what I'm seeing. For one thing, the schem has the 1/4" input, but no output for the headphone, and that's what's honked up. I'm surprised there are no images out there or on youtube. Wish I had left it alone. I don't need the headphone, but a buddy wanted to borrow, and convinced me to try and fix it :(
 

musekatcher

Member
Messages
2,735
I've got flux splattered now, making it difficult to just try bridging the strap to the leads that are within reach. I really just need an image of the soldier side.
 

Papanate

Member
Messages
19,822
I can't correlate the schem with what I'm seeing. For one thing, the schem has the 1/4" input, but no output for the headphone, and that's what's honked up. I'm surprised there are no images out there or on youtube. Wish I had left it alone. I don't need the headphone, but a buddy wanted to borrow, and convinced me to try and fix it :(
I just realized that the PDF didn't come through - so here is a Manual Link - and you can
see the actual circuit. Also contact Joe Webb Guitars via Facebook. He built a Headphone
kit for the VT series way back in 2009. He probably has your info.

And here is one side of the circuitboard:


 
Last edited:

musekatcher

Member
Messages
2,735
Thanks much - So my jumper is about 5 times larger than these in the phots, like 3/8" long, and about .040" wide - but no matter. I think I've cooked the board and circuits, or as a minimum, coated the whole board with flux and can't get fusion. I'll either look up a new board, or, figure out how to bypass it so at least the input works [again...]. So much for trying to do this with a 140W Weller soldier gun....:mad:
 

treeofpain

Gold Supporting Member
Messages
7,298
You have to be REALLY careful when working on these circuitboards. They are very easy to overheat and mess up traces.

And it is "solder", not "soldier".
 

Papanate

Member
Messages
19,822
Thanks much - So my jumper is about 5 times larger
than these in the phots, like 3/8" long, and about .040" wide - but no matter. I think I've cooked the board and
circuits, or as a minimum, coated the whole board with flux and can't get fusion. I'll either look up a new board,
or, figure out how to bypass it so at least the input works [again...]. So much for trying to do this with a 140W
Weller soldier gun....:mad:
140W???? At this point just buy another VT50. VT50 $99.
 

musekatcher

Member
Messages
2,735
140W???? At this point just buy another VT50. VT50 $99.
Yep, rush job, my gun was right there, too lazy to dig out my 30w, etc. I'm a romantic and too sentimental to let something die - I must restore it to its potential. Its a flaw... BUT, another VT50 could create a nice looking stack, if I convert this one to an extension. I really like the stock speaker-cabinet design.
 

musekatcher

Member
Messages
2,735
You have to be REALLY careful when working on these circuitboards. They are very easy to overheat and mess up traces.

And it is "solder", not "soldier".
I know, rush job. I've always misspelled and confused solder and soldier. Goes back to a very young age, dad had me working at his bench at the same time I was learning to spell! I had to stand on his stool, lol.
 

musekatcher

Member
Messages
2,735
Can you read a schematic? If so here you go:

Service Manual for Vox VT50
I just realized that the PDF didn't come through - so here is a Manual Link - and you can
see the actual circuit. Also contact Joe Webb Guitars via Facebook. He built a Headphone
kit for the VT series way back in 2009. He probably has your info.

And here is one side of the circuitboard:


Fixed - sorta. Thanks lots everyone. So, I got brave with a jumper as recommended above, and found two pins that bypassed the headphone defeat. Soldered a permanent jumper, and its functioning properly as a guitar amp - the headphone still doesn't work however. I looked around, and the the VT50 uses the same "Input Jack PCB" as the VT15/30 which is Vox number 530000001143. I found them listed for $19.95, but they stopped production, and nobody has any left. No matter, I'm back to operational and that's cool.
 






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