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Old 13th August 2012, 12:25 AM   #11
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now you're talking my language. I'm used to working on machines of the 2 wheeled variety. I'm used to hp, torque, and air/fuel ratio's. haha

so if i wanted to replace C3.
would this do? CDE WBR50-25 50 MFD 25 VOLTS ELECTROLYTIC CAPACITOR | eBay
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Old 13th August 2012, 12:26 AM   #12
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Also, C1?

60 MFD 50 V Tantalum Electrolytic Capaitor | eBay
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Old 13th August 2012, 12:40 AM   #13
kevinkr is offline kevinkr  United States
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Quote:
Originally Posted by JoelKnauber View Post

You'll need a 450V to 500V part here. Most of the parts you need can be purchased at Antique Electronic Supply LLC amongst many other choices. There is no exact replacement available for the quad cap in your amplifier which is an FP style, but something like this could work: Can Capacitor, Multi-section, 40/20/20/20uF 525VDC, CE Manufacturing | Antique Electronic Supply LLC it would give you a little more sag than the original when it was new, but for a guitar amplifier this is usually beneficial.

The 50uF C3 can be replaced by something like this: Capacitor - Sprague Atom, Aluminum, 50 F @ 50 V | Antique Electronic Supply LLC

They sell all sorts of coupling capacitor replacements as well.
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Old 13th August 2012, 12:47 AM   #14
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That small one is 50uf , when the amp calls for 50mfd. so that wont work.. also $35 for that other cap is steep!
my amp right now doesn't have a "quad" cap does it? just 4 separate ones?

I'm also trying to avoid sag, hence the solid state rectifier.
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Old 13th August 2012, 12:48 AM   #15
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I lied. that big thing that looks like a metal tube is the quad cap isn't it.

I'm an idiot.
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Old 13th August 2012, 01:06 AM   #16
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This one is close..

Cornell Dubilier Can Capacitor ~ 450/200/200/50V ~ 20/80/20/50 mfd ~ NOS | eBay
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Old 13th August 2012, 01:16 AM   #17
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would ^that^ one be safe to run?

..it's also cheaper.
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Old 13th August 2012, 01:47 AM   #18
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That one is likely just a few years newer than your amp is. The expected life of an electrolytic back then was about ten years. Sure, some are still in service, but as Kevin said, you're rolling the dice with some fairly expensive parts connected to them.

Your best bet, and what a lot of savvy repairmen do, is replace the cap with four new caps and hide them under the chassis to preserve the look. You can leave the can just sitting there, disconnected.
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Old 13th August 2012, 09:27 PM   #19
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That was really helpful, I didn't think of that.

also, for some reason I have been presuming that uF was nano farad and mfd was micro farad. but I realized that they are the same.. annyways.

as i was on the way out the door for work this morning i ordered 4 new caps.

60uF is now 68uF
55uF is also 68uF
both 10's are still 10uF

the 68's are good for 450v and the 10's are good for 250v. this should be all i need to replace C1 (according to my schematic)

The coupling cap (C3) will also be replaces by a 25v 50uF cap.

A set of JJ 6V6S tubes are on the way as well.

I leave for school on the 30th and have a gig on september 9th that I am really hoping this amp will be tuned up and ready to go for!
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Old 16th August 2012, 10:52 PM   #20
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soo.. got new tubes today, only to find that my OT is fried too. yup.

it buzzes sympathetically to the notes that i play on my guitar, but when i turn the amp up, it also starts to arc internally. absolutely zero buzz/hum from the speaker.

i guess that's what i get for not knowing how the 1/4 jacks i soldered in worked. i guess i put the leads on the wrong side, so when the jack was inserted, it broke the circuit, hence, i ran the amp on 0 resistance for a couple minutes.

my question is,
is what i explained sound like a bad OT?
will a simple one like THIS: work?
15 watt Push Pull 8K primary 8 ohm secondary 6V6 or EL84 output transformer | eBay

all i need is a single 8ohm output.
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