One easy way to know when it's time for a cap job

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talltxguy

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I recently picked up a Studio Pre for $350 from the Guitar Center used pages. Cosmetically it's in great shape. I checked the insides and discovered one of the caps had been wrapped in electric tape. The tubes were such old Mesa 12AX7s that I did not even recognize them; it wouldn't surprise me if they were stock 12AX7s from the late 80s. And a few other caps had that dry crap coming out of the ends of them. Needless to say, I did not even power her up. She's getting a cap job and will be ready for action next week. The good news is that my ADA MP-1 had the 3TM & noise mod done and is ready for pickup...it's gonna be a good day!
 
Congrats! I hope it comes back sounding great! Any chance you could take a picture of one of those tubes? I have some in my quad that look original to it, and I'm wondering if maybe they're the same kind.
 
I have a feeling my Quad Pre has some of those tubes in it. I'm also noticing some problems with the EQ fading on and off at random.

Has anyone put together a parts list for the quad or studio pre to replace all the caps?
 
I bought my studio pre this spring, plugged it in, turned it on and was very impressed. Some of the knobs are cracked or replaced and it doesn't have the rack ears, but I've never taken it apart to check the tubes or for black taped components yet, it's Labor Day and it's raining so I'm goin' rollin'. Thanks for the post, I need a kick in the butt sometimes.
 
Rob227 said:
Has anyone put together a parts list for the quad or studio pre to replace all the caps?

The caps I replaced in the Studio-Pre were:

Code:
   30uf  500VDC  x 3	$9.95	 Sprague	 @ Tube Depot
  220uf   63VDC  x 2	$ .77 	Nichicon	@ Mouser
   10uf   63VDC  x 1	$ .14 	Nichicon	@ Mouser
    1uf   50VDC  x 1	$ .33 	Nichicon	@ Mouser
 4700uf   16VDC  x 1	$1.75 	Nichicon	@ Mouser
These are 2010 prices. I ultimately ended up ordering them from Mesa since I was recapping a Simul-Sat and 50/50 and there were a few caps that they only had in stock. It just made sense to order them all from Mesa. The prices were very competative.

The Studio Pre board has traces on both sides and getting a clean solder joint can be difficult at best without pulling the board. Pulling the board means either desoldering all of the periphereal connections or, removing all the chassis components to give the wiring slack to lift the board. There's no easy solution. If you do decide to solder, be aware that the traces can be very intolerant to excessive heat. Too long on the iron can cause them to lift creating a whole new problem.

A good friend advised me that you can cut the old cap out, put one "hook" type loop in the lead on the board side and then lay the new cap down and put the new cap lead thru this hook and form an opposing hook in that lead,crimp them and solder. Then cut the excess from the cap lead. A dab of silicone under the new cap will hold it in place against future road abuse.

It's a good idea to mark the board with a Sharpie or such to note the +/- connections.
 
Cool thanks, that should take care of half of the quad.

Has anyone done the caps on the mark 3 section of the quad?
 
The ADA is fun! It's a rhythm, chunk machine. It's certainly renewed an interest in playing older Metallica and Pantera stuff.

And surprisingly, doing leads on the ADA is just as much fun as is rhythm stuff. Not sure if it's the three tubes, the noise mod, or what, but I'm getting some really nice, liquidy lead work going on it.

I don't have a power amp for the ADA at this point as I've been running it through the FX return on my Lonestar, using TWEED 10 watt mode (bedroom) and 50 watt tube rec (jamming with friends) with some pretty hot EL34s.

On lower gain settings, the ADA is certainly not as organic as the Studio Pre. I am wondering if upgrading the ADA's transformer to that MDRT tranny would help with that issue as I've heard the 12AX7s receive more voltage with that MDRT...I don't know though.

But yeah, so far I'm quite happy with it and don't see me getting rid of it.
 
Love my 3TMs as well...
I have one with standard PS and two with the MDRT which have tighter gain structure (I run JJs in all).
Not sure if those MDRT transformers are still available though.
Have you checked out the NEW ada depot?
J
 
I've been to the new ADA site. It's...growing. :) Don't think a lot of people know that it's back online.

Marshalljmp is still selling those MDRTs. I've heard nothing but good about the MDRTs. I may have to get me one.
 
Sorry to resurrect an old thread but I am thinking about changing caps on my studio pres - as well as LDR´s.

The list of caps too change- some posts over here: I can´t find the 1uF in my amp.

Anyone knows where it is?

Thanks
ReidarNikolai
 

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