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 Post subject: Supressor Cap Replacement for Quad 33 Preamp Volume Control
PostPosted: Sep Fri 24, 2021 1:55 am 
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Joined: Sep Fri 05, 2014 11:10 pm
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I'm confused about what can and cannot be used as a replacement for the Supressor Capacitor connected to a Quad 33 preamp volume control The Quad manual says the supressor cap should be a "PMR 209M-5547-100". I removed something from my old Quad 33 that was a bit different from that: PMR 2022 0.5uF, 330 ohm (see photo). This cap did not appear to be original to the unit, but perhaps it was similar enough.

Would it be acceptable to use the yellow X2 cap pictured on the right as a substitute? The yellow one appears to be a cap only, with no internal resistor.


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 Post subject: Re: Supressor Cap Replacement for Quad 33 Preamp Volume Cont
PostPosted: Sep Fri 24, 2021 2:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Rochester NY USA
Cap may be enough, it will reduce arcing on open, but creates a small amount on switch close. Best is a cap plus series resistor - R chosen to match current that's switched (i.e. 120 Ohm for 1 A, 250 Ohm for 1/2A, etc. But not critical.)

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 Post subject: Re: Supressor Cap Replacement for Quad 33 Preamp Volume Cont
PostPosted: Sep Fri 24, 2021 7:31 am 
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Thanks! Adding a resistor in series is easy enough. Is a 1/2 watt resistor sufficient or should it be bigger?


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 Post subject: Re: Supressor Cap Replacement for Quad 33 Preamp Volume Cont
PostPosted: Sep Fri 24, 2021 2:11 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5274
Location: Rochester NY USA
I'd use 1W, since I have lots of them... 1/2W should be fine if it's carbon comp.

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