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It screamed at me!


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I decided to put my V3 board in my V1 combo, so I made a few quick changes and dumped it in.

 

R1 I desoldered and dropped across the two input pins.

 

C4 I desoldered and replaced with 1uF

 

R8 I desoldered and replaced with 820R

 

R9 I desoldered and replaced with 1.2K

 

Jumpered the ground of input to the negative side of R8/C4

 

Power: T1-T2

Output: T3-T4

Filaments: T5-T6

 

Turn it on, give it about 10 seconds, it starts shrieking loud and high pitched at me. Starts high, ramps down about an octave, then stays until I turn the amp off (it ramps up and then quiets as the amp shuts down)

 

Thoughts?

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well if you really did have a rev1 combo: the board, board stand-offs and tube holes are in completely different locations then Rev2 or Rev3 units (head or combo) which are the same.

So if you didn’t have to drill new holes, cut off stand-offs that would short out the board, then you are left with only wire routing.

I remember in the “old” Epiphone amp forum that sometimes reversing T3 with T4 will get rid of squeals that come from people putting in the negative fed back mod.

3&4 are only for your OT and can get reversed without problems.

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it wasn't the ot lead switched... the ot leads go from the B+ to pin7 of the el84 output tube, so really the same point in space except the speaker is connected to the other side of the transformer.

there has to be more to it on why your unit fried.

I bet you'll find that the orange and red wires where switched or atleast 1 orange and 1 red got swapped around.

 

Now you have a big rabbit hole.. you're about the 3rd person I've heard in the past week that's fired r10.

 

Head over to sewatt.com create yourself a free account and start searching their forum.. Twang I think fried his about 2 weeks ago. Can't remember what his and the others solutions where.

 

P.S. there is no search function there, so you'll have to read through the posts.

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