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Thread: 1971 Silverface Fender Twin Reverb - film capacitor types

  1. #1
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    1971 Silverface Fender Twin Reverb - film capacitor types

    I'm working on a 1971 Twin Reverb.

    6 of the film capacitors are blue blobs, which I am familiar with.

    3 of the film capacitors are light red blobs. I have a feeling these are from the factory also, but would like someone to confirm this.

    However, there are 2 film capacitors (22nF) which are a dark red with a shiny surface.
    I have a feeling that someone has installed these as replacements, but I wanted to check in case anyone has seen these in a stock Fender amp.
    Does anyone know what they are?




  2. #2
    Forum Member phantomman's Avatar
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    Re: 1971 Silverface Fender Twin Reverb - film capacitor types

    The "wrinkled" leads of those caps seem to indicate they're replacements. However, if the amp is operating correctly and sounds good, I would not swap them out.
    "When injustice becomes law then rebellion becomes duty."

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    Forum Member Michael Smith's Avatar
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    Re: 1971 Silverface Fender Twin Reverb - film capacitor types

    Looking at the schematic for the Twin Reverb from that era, (AA270) I only see one .022 cap in the circuit, it's in parallel with a 10M resistor in the vibrato circuit. I can't tell exactly from your photo, but that cap doesn't appear to be in parallel with a resistor. Maybe a picture from a different angle would help.

    As you probably already know, your cathode bypass caps also appear to be original.
    "When You're Riding Down the Highway at Night, And You're Feeling that Wild Turkey's Bite" ZZ Top

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    Re: 1971 Silverface Fender Twin Reverb - film capacitor types

    Thanks guys.

    I managed to find 1 instance of a similar vintage Fender amp which had these 2 dark red capacitors in it.
    Without further information, I will be assuming that they are factory parts and will leave them as they are.

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    Re: 1971 Silverface Fender Twin Reverb - film capacitor types

    The blue & brick red caps are original to the amp. If they aren't leaking DC, I'd leave em in. I have two of the br caps in my 67 BF Vibro Champ & they still work as intended.

  6. #6
    Forum Member phantomman's Avatar
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    Re: 1971 Silverface Fender Twin Reverb - film capacitor types

    Generally, the only caps worthy of concern are the oil-filled electrolytics found in the filter array, the bias supply, and the cathode bypass circuits.
    "When injustice becomes law then rebellion becomes duty."

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