Still undoing sins of the past?!?! Need help please....

[Direwolf]

So after deciding to do the R2 vol pot mod to my Mk III I discover some more "customizing" that the previous owner did. I found that C30 and C26 have been removed all together. C30 appears to be tied in to pin 6 of v3B. Could this removal attribute to the lack of highs in the lead channel? R131 has been changed to a 1.5M and R130 has been changed to a 15K. In all the great pics that you guys have so graciously posted I am seeing differemt values in these spots. I know the R130 is bypassed all together but what about R131? Do I change it or leave it? I absolutely love this amp and the tones ive been able to get are what I'm searching for with the exception of some detailed frequencies that aren't there. The more I dig into this amp the more I realize that some of that could be from previous molestation!! :evil: Any help is greatly appreciated.

 

[Boogiebabies]

C26 is in the GEQ circuit and is not used. C30 was not always used depending on what stripe you have. From the red stripe back it's a 270K resistor bypassed
with a 1000pf/.001 1KV ceramic disc capacitor. To the best of my knowledge, the cap was not used on late blue and all green stripes. It's purpose is to smooth
out the treble frequencies of the lead channel only. There is a good chance that no sin is involved here. :wink:

 

[Direwolf]

I really appreciate all your help. I will do my best to stop bothering you !!!

 

[Boogiebabies]

Not a problem. You have a 2550 or 2555 Jubilee ?

 

[Direwolf]

Its a 2550. I have a matching 4x12 cab to go with. Its not numbers matching but it is the 2550 cab with t75s in it. With my Paul I can get Appetite for Destruction all day. I used it for about 10 years. It was my first real amp actually. Pop worked at a music store and took it in on trade. I got it for my 16th birthday. After that I went on the eternal quest. Still lookin!!!! :lol:

 

[Boogiebabies]

 

[Direwolf]

:shock: I bet yours sounds twice as nice!!! My cab is in horrible shape. The head is in nice condition but it needs some attention. The gain is the same no matter where you have the gain knob. I've tried everything but a new gain knob and its still the same. I would like to find a good place to send it for a check up and what not. Thought about sending it to VooDoo amps. (?) I had it sent to a guy in Kentucky. It worked flawless for about a month. It just comes and goes with the gain.

Beautiful rig BTW!!!!!

 

[Boogiebabies]

:shock: I bet yours sounds twice as nice!!! My cab is in horrible shape. The head is in nice condition but it needs some attention. The gain is the same no matter where you have the gain knob. I've tried everything but a new gain knob and its still the same. I would like to find a good place to send it for a check up and what not. Thought about sending it to VooDoo amps. (?) I had it sent to a guy in Kentucky. It worked flawless for about a month. It just comes and goes with the gain.

Beautiful rig BTW!!!!!

That isn't the rig. Those are seldomly used. :mrgreen:

The gain in the lead channel is completely controlled by LED's. Next time you get a chance, open the amp up and look at them in lead mode.
While playing, they should blink with the input signal from the guitar. LED's can get stuck full open.

 

[Direwolf]

I'll give that a look. It's been 4 or 5 years since I cracked that thing open. Thanks again!!