Ampeg VL-1002 youtube Service vid and Oscope question

[jjackson7]

I have a friend with one of these amps he doesn't use anymore because of reliability issues and I stumbled across the youtube vid of lee jackson servicing one of these guys (Ampeg VL-1002 Service and Bias by Lee Jackson Part 1).  I figured i could do the service for him since he doesn't use it and it would be a good learning experience. I have two questions, though. What size/type wire should I use to replace the board jumpers? And where does he hook the oscope up at the end to check for crossover distortion during the bias check. I don't want to start a long back and forth on whether this is the correct way to check bias. I just want to see it for myself. Thanks again in advance for indulging my noob questions. Jordan.

[sluckey]

Jackson used 18AWG (see video at 7:45 minutes). Connect the scope to the speaker jack.

[jjackson7]

Doh! Thanks for pointing that out.

[escopunk]

Hi,

Ive got a VL502, this is a great amp. I modified the crap out of it. There are some great mods for these amps on line if you do a search. A few things I remember is:
1. Do the Lee Jakson mods for sure.
2. Do the foot switch delay mods, Remove the caps on the switching transformers to remove the time delay.

So here are some of the things that will cause the channel to have gain problems.
1. The LDR's, the little black boxes with 4 wires coming out of them, these fail in all kinds of weird ways, One of them is level.
2. The 100k plate resistors, R6, R10 if they start failing, it will cause that.
3. The 22uf/25v caps C3

Go to this link for other mods
http://www.amparchives.com/album/Ampeg/Schematics/Ampeg%20VL-502,%20VL-1001%20&%20VL-1002/Mods/slides/vl-1002_mod.html