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Old 21st September 2013, 10:50 PM   #1
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Default Need help identifying C45 for a Fender Twin Reverb RI

Hi, all.

I'm hoping someone out there has a Fender Twin Reverb Reissue open at the moment and can identify for me what used to be in the C45 location.

Background:

I'm restoring a friend's TRRI's vibrato circuit. At some point in the past he let a shop modify the circuit (I'm fuzzy on what he was told or was thinking at the time ), and they then promptly went out of business.

The modifications performed poorly, and I'm putting it back to factory for him.

I've located all the mods (at least they soldered very nicely) and reversed them, but C45 is missing and there clearly used to be a cap there. I can even see it filled here: http://www.synapticamps.com/wp-conte..._Rewire-02.jpg but I can't find a value in the service manual's part list for it, nor on the schematic (although, old eyes and tiny print do not make for perfect searching).

Does anyone know what that little sucker used to be?
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Old 22nd September 2013, 12:34 AM   #2
kevinkr is offline kevinkr  United States
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Wrong forum, this belongs in the Instruments & Amps forum. Moving thread.

Please note forum subheaders:

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Tubes / Valves All about our sweet vacuum tubes Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum
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Instruments and Amps Everything that makes music, Especially including instrument amps.
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Old 22nd September 2013, 12:36 AM   #3
kevinkr is offline kevinkr  United States
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More likely to get an answer here since the other forum is oriented at tube hifi primarily.
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Old 22nd September 2013, 01:54 AM   #4
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I only see capacitors numbered up to 39 on the parts list at this link. Is this the correct service manual for your TRRI??

http://ampwares.com/schematics/65_tw..._@20manual.pdf
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Old 22nd September 2013, 02:01 AM   #5
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I do see in the schematic a C40, tied to the trem roach, which is a .022uF @ 630v.
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Old 22nd September 2013, 04:20 PM   #6
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Quote:
Originally Posted by Sea Biscuit View Post
I only see capacitors numbered up to 39 on the parts list at this link. Is this the correct service manual for your TRRI??

http://ampwares.com/schematics/65_tw..._@20manual.pdf
Yes, it is, and yeah, there is no mention of C45 in that manual.

I'd write it off as "just a part they never stuffed," but there are clear signs of a component having been unsoldered there... something was there, now it ain't.

I retract my reference to the picture in my first post, though; upon closer examination, what I'm seeing in that picture isn't a capacitor, and the PCB shown has a slightly different layout than what I'm looking at.

Additional information: The silkscreen looks like it should be a disk cap, and it's in parallel with diode CR5. The schematic definitely does not show anything there.

I may have to just accept that life is uncertain, and not worry about it.

Last edited by MadDave12; 22nd September 2013 at 04:33 PM.
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Old 23rd September 2013, 07:03 AM   #7
Enzo is offline Enzo  United States
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To be technical, you don't have a sign the part used to be there, you have a sign that someone touched a soldering iron to those solder pads. But it probably was removed, as you suspect. Parallel to CR5 is the clue we needed. It is on the revision F and G versions, and is a 220pf 500v. I'd wager it was a disc ceramic though.


It should have no effect on your performance at all, other than the potential for a small amount of rectifier noise on the bias supply.
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Old 25th September 2013, 05:03 PM   #8
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To be technical, you don't have a sign the part used to be there, you have a sign that someone touched a soldering iron to those solder pads.
*chuckle* I thought I'd get called on that one

Thanks much - I'll leave it gone, then.
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