How much further

gui_tarzan · Post by **gui_tarzan** » Mon Oct 20, 2014 9:32 pm

Will these go before they burst?

YouTube · Post by **xtian** » Mon Oct 20, 2014 9:40 pm

[img:499:374]http://www.lastwordonnothing.com/wp-con ... fy-pop.png[/img]

gui_tarzan · Post by **gui_tarzan** » Mon Oct 20, 2014 9:55 pm

Phil_S · Post by **Phil_S** » Mon Oct 20, 2014 10:08 pm

Drill a relief hole in the center of the dome!

Zippy · Post by **Zippy** » Mon Oct 20, 2014 10:18 pm

gui_tarzan wrote:Will these go before they burst?

Not much.

Seriously, I'd wear safety glasses while taking those out.

Leo_Gnardo · Post by **Leo_Gnardo** » Tue Oct 21, 2014 12:15 am

Are the caps really swelling or just the plastic top taking on a dome shape? Seen it a lot in Crates and latter day Ampegs, maybe a few others. When I first encounterd these, it put me in a panic then I took a couple out, and false alarm. Caps OK, plastic discs turning into hemispheres for no obvious reason.

YouTube · Post by **xtian** » Tue Oct 21, 2014 12:18 am

Leo_Gnardo wrote:Are the caps really swelling or just the plastic top taking on a dome shape? Seen it a lot in Crates and latter day Ampegs, maybe a few others. When I first encounterd these, it put me in a panic then I took a couple out, and false alarm. Caps OK, plastic discs turning into hemispheres for no obvious reason.

Well, then, I call for AUTOPSY! AUTOPSY!!!!

Leo_Gnardo · Post by **Leo_Gnardo** » Tue Oct 21, 2014 12:42 am

xtian wrote:
Leo_Gnardo wrote:Are the caps really swelling or just the plastic top taking on a dome shape? Seen it a lot in Crates and latter day Ampegs, maybe a few others. When I first encounterd these, it put me in a panic then I took a couple out, and false alarm. Caps OK, plastic discs turning into hemispheres for no obvious reason.
Well, then, I call for AUTOPSY! AUTOPSY!!!!

Sorry no photos but some I saw had flipped their lids, nice flat aluminum surface underneath. Funny to see a couple of black plastic Pringles rattling around inside the chassis. Guitarzan, you could persuade one or more of 'em to remove themselves, a poke with a sharp probe oughta do it. If you're worried put on your full Ebola qualified haz mat suit. Or at least some safety goggles.

gui_tarzan · Post by **gui_tarzan** » Tue Oct 21, 2014 12:42 am

I'm not taking a chance with $20 worth of caps. I'm going to replace them because the amp is 20 years old and it's probably a sign of what is going to happen.

My friend that owns this said to do whatever it needs. Unfortunately someone else got inside it before I did (isn't that always the case anymore?) and really mucked up a few things. I found two broken (cut, I think) cap leads in random areas that don't make any sense, a cobbled resistor, a cap stretched across two resistors that are about two inches apart on the board... it's amazing what some people do. A mylar cap that's obviously too big for the area and the exposed lead touched and shorted on a jumper. Oh, and a smoked EL84. I think it's cracked, the getter flash is completely white. Hard to say what did that, it'll be fun figuring it out though.

Leo_Gnardo · Post by **Leo_Gnardo** » Tue Oct 21, 2014 12:53 am

gui_tarzan wrote: Unfortunately someone else got inside it before I did (isn't that always the case anymore?)

Oh my looks like Knuckle-draggin' Looie got in there.

Last week I had to pry a RI Vibroverb 2x10 board half out, found Looie or one of his friends had been back there, jumpered a couple of circuit points for what reason who knows, and used a piece of guitar string as a wire. About 2 inches of 11 ga with a matchbook as insulation and a swatch of scotch tape to hold the mess in place.

No argument with swapping out 20 y/o caps. Then nothing to worry about there for at least another 20 years.

gui_tarzan · Post by **gui_tarzan** » Tue Oct 21, 2014 1:11 am

The blue cap in pic 284 is a cathode cap for V3. Why would someone cut that?

sepulchre · Post by **sepulchre** » Tue Oct 21, 2014 4:51 am

What models is it? Crates are prime territory for modders, and some do benefit greatly from it. But whether the modder knew what they were doing is a crap shoot.

johnnyreece · Post by **johnnyreece** » Tue Oct 21, 2014 12:04 pm

That looks suspiciously like a VC50 that I gutted and build a Rocket into. Caps on the board looked strikingly similar. I was able to reuse the iron, so that's a plus.

vibratoking · Post by **vibratoking** » Tue Oct 21, 2014 4:37 pm

Although the implementation of the mods is sloppy, they may actually improve the sound of the amp depending on what you like.

The cap contacting the shorting jumper may be OK because those points could be connected on the PCB anyway. Did you check this?

Removing the cathode bypass from the circuit reduces the gain, especially at higher frequency.

http://www.valvewizard.co.uk/Common_Gain_Stage.pdf

Section 1.18

Clipping parts is common. Whether you like it or not is a different story. This guy probably watched the Gerald Weber video.

I must be a knuckle-dragger cause those mods don't bother me that much. My only concern is whether they are electrically sound.

Leo_Gnardo · Post by **Leo_Gnardo** » Tue Oct 21, 2014 5:15 pm

vibratoking wrote:I must be a knuckle-dragger cause those mods don't bother me that much. My only concern is whether they are electrically sound.

I was referring to the guy who tacked a length of guitar string onto the back of the circus board I encountered.

I'm sure when you do mods, you go about it more proper-like. FWIW I've done similar to what's in the photos on occasion, just a little neater and I'm sure you do too. Never have seen a Gerald Weber video either.

When I have time for slapstick entertainment I'll watch 3 Stooges or Soupy Sales.

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