The Amp Garage

I was under the impression that low voltage esr testers weren't necessarily accurate for high voltage caps. That atlas tester is putting out ~12v? I have also measured plenty of old electrolytics that have blown their guts but still test OK on an LCR meter. Sometimes the amp isn't even that noisy; ...

Here’s a 1000uf 50v Rubycon that swollen and starting to leak and it still test out at only .94 ohms, unfortunately it’s only 5 years old. I have encountered caps that started spilling the dielectric and still having a low ESR. The Rubycon does look as back as one Astron caps I pulled out of my Ban...

The 10u 160V IC cap's ESR is not out of line. Check the chart that came with your Peak. Are there caps with lower ESR? Sure, and in some applications such as SMPS with high ripple current it's necessary for adequate life. Those old Mallory's appear to be good, but if that amp is going to be a playe...

TUBEDUDE wrote: ↑Wed May 15, 2024 11:14 am I have one of those cheap cap checkers (different brand) and I wonder if the measured value is similar when the cap is in circuit with high.voltage on the plates.

The caps were measured out of circuit. I tried to make it as accurate as possible.

Thanks for this test out and post, and yes that’s over a 10% different which is a lot! My math says over 1000% in ESR. A current data sheet from Mouser indicates IC is part of CDE, and the max ESR for 10uF 160V axial at 120 Hz is 33.157 ohms. IMG_0204.jpeg IMG_0205.jpeg IMG_0206.jpeg IMG_0207.jpeg ...

TUBEDUDE wrote: ↑Wed May 15, 2024 12:21 am Were they fresh off the shelf, or after some time under voltage to form the dielectric?

I bought them less than a month ago. So I’m not impressed with the performance of these caps.

Kit arrived today from Weber. Now the fun begins..... First step is shellacking the cabinet. IMG_3954.jpeg A word from someone who has screwed up this procedure. There are two ways to go. One is spraying the cab with nitrous lacquer and letting it go dark of its own accord. The second one is to use...

I got some Vishay 10uF 160v caps and the ESR figure is vastly different.
Now for the good news.
Of course you can draw your own conclusions from these pictures, but I think I have made my mind up on the matter.

You have a nice collection of carbon comp resistors there and though it looks like the boards are the real problem here was an interesting commentary on reconditioning the carbon resistors from Hi Fi Collective: Being made of organic material, they do have the tendency to absorb water from the atmo...

Perhaps you have seen what Psionic (Lyle) goes through with this issue. An alcohol lavage and meticulous removal of the residue that builds up on the wax boards can be quite effective. Then there is the under board that gets polluted. I have pulled that board out on my silver face champ and done th...

Mark, with 20-30VDC on the board, I can tell you that there is no saving this board. Its something i have tried several times....take board out, take all parts off, remove paraffin with heat gun/paper towels, acetone/brake cleaner clean off the residual mess, rebuild.... Then the same thing happene...

I admit I am curious... Are you even going to try to resurrect this beast? How do you even begin to evaluate whether an amp like this is worth saving? And to what lengths you might go to preserve the legacy value of the original? Yes, I want to save the amp, I don’t know what it will take to get it...

I never seen a Fender with these lugs before either but it is what it is. The lugs are original as the resistor attached to the lugs is the very same type as is used on the other side of the P.I. grid. There are no signs of the resistor being removed and resoldered. The solder joints are untouched a...

Purely for interest sake here is a picture of tagstrip being used to eliminate problems with a conductive board at the Fender factory.

They knew about the problem in the silver face amp days.

I have a silver face Twin on the bench and I have never seen a board like it. The board is stuffed.

When I got the amp the power transformer was stuffed, I noticed that the tone control caps are soldered on one side