Filter cap issues on a MKIII? Or Opto-Couplers!?!

[scottcrud]

I have a MKIII long chassis head, loaded. It has about half the gain on the lead channel as my other MKIII's or even my .50 Cal+. This particular head sat for a few years collecting dust before i bought it. Could the lack of gain be due to the filter caps needing to be replaced?

 

[Russ]

Try replacing the preamp tubes first. Also compare the stripe colors by the cord. The different color stripes had various affect on the amp design (or rather vice versa). These changes could also be what you are experiencing. I would still put fresh tubes in it.

 

[phyrexia]

First three preamp tubes.

 

[scottcrud]

it's a red stripe, 4/87 and it sounds just like a marshall, nothing like the other red stripe or blue stripe i had. I swap out the preamp tubes. It sounds like it's stuck in ryh 2...

 

[Russ]

If you have swapped out the tubes and are still feeling chained down with a red stripe then you might consider a cap job being that the amp sat for so long (years right?).

 

[phyrexia]

It sounds like it's stuck in ryh 2...

Are you sure it's not? Footswitches and/or push-pulls in good working order?

 

[scottcrud]

channels are working fine, the tubes have been swapped, no change, it sat for at least two years.

 

[Russ]

It could very well be cap time

 

[Shep]

i am just about to re cap my mk III.. it's a good idea for a 20 year old amp..

Russ how did you get that pic?

 

[scottcrud]

I guess I'll be calling Jeff Seal tomorrow.

 

[Russ]

Russ how did you get that pic?

What pic?

 

[scottcrud]

Well, it's been played for a year or so, but before that, it sat for a few years. The guy I bought it from had been playing it on half power, I put it on full and turned it on, and WHAMMO! Smoke and a light show. It blew a tube ( the far right) and took out some resisters ( four little brown with yellow stripes), I had those replaced and it works fine now, just half the normal gain on the lead channel. And Jeff Seal is on vacation for at least a week.
Anyone have Mike Bendinelli's ext. number?

 

[Russ]

Russ how did you get that pic?

What pic?

Your icon next to your name on the posts I think is what he's talking about. Metallica?

I got the original image online somewhere. It is actually a .gif that drips the blood continuously and somewhat randomly. The image was too big and I had to resize it. Now for some reason the thing doesn't drip anymore. I figured it looked ok even not dripping. So I used it.

 

[scottcrud]

it's been suggested to me that the opto-couplers are bad...

 

[Boogiebabies]

It could be LDR 3 or the relay is stuck open.

 

[scottcrud]

Taking it to Jeff Seal/the Speaker Surgeon in Houston.

 

[Boogiebabies]

Jeff has one of the best reps in the biz. You should be fine and not taken advantage of. I had a discussion with him about a Dagnall 100W OT and he was very kind in answering some in depth questions. A guy who has a passion for what he does it rare.