Lemco silver mica voltage rating

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whopperplate
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Lemco silver mica voltage rating

Post by whopperplate » Wed Jun 08, 2016 1:21 am

I purchased these Lemco 470 p csilver mica capacitors hoping they are rated at the corrected voltage but there is no marking. Seem a little smaller than the ones in marshalls. What y'all think? Thanks
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coldengray
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Re: Lemco silver mica voltage rating

Post by coldengray » Wed Jun 08, 2016 1:55 am

Probably 350v. Post some pics and hopefully Neil will chime in. He will know.

Tazin
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Re: Lemco silver mica voltage rating

Post by Tazin » Wed Jun 08, 2016 11:17 am

I think the typical working voltages were: 350vdc, 500vdc, 750vdc, and 1000vdc. The 750v and 1000v had thicker leads. As for physical size, it varied depending on voltage rating and tolerance. A 1% and 2% tolerance cap was larger in size compared to a 5% or 10% cap.

whopperplate
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Re: Lemco silver mica voltage rating

Post by whopperplate » Wed Jun 08, 2016 2:01 pm

Thanks guys, sorry I thought I posted a pic but apparently this is a thing: "Sorry, the board attachment quota has been reached". Here's the eBay link:

http://www.ebay.com/itm/182157314364?_t ... EBIDX%3AIT

They are marked 1%. About the width of a penny and slighlty thicker.

Thank you all
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Tazin
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Re: Lemco silver mica voltage rating

Post by Tazin » Wed Jun 08, 2016 2:34 pm

They appear to be pretty far out of tolerance according to the sellers measurements. Some Lemco's have a voltage rating stamped on the back which the seller didn't post pictures of. Tough to tell from the picture which voltage these ones are, but I don't think they are 1000Vdc....Perhaps Neil might have a better insight.

whopperplate
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Re: Lemco silver mica voltage rating

Post by whopperplate » Wed Jun 08, 2016 3:00 pm

Thank you, I hope at least they are able to withstand the 1987voltages, crossing fingers. No markings on the backside.
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neikeel
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Re: Lemco silver mica voltage rating

Post by neikeel » Wed Jun 08, 2016 3:31 pm

Think they are 350v rating ones (bit smaller than the 500v ones)

They should be fine on your mixers and probably ok in a 50w tone stack, not so good in a 45/100 or early 70s Superlead.
Neil

whopperplate
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Re: Lemco silver mica voltage rating

Post by whopperplate » Wed Jun 08, 2016 4:43 pm

Thanks boss, very much appreciated.
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danman
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Re: Lemco silver mica voltage rating

Post by danman » Wed Jun 08, 2016 5:01 pm

Be sure to use a heatsink when soldering them. I have read several times lately of people having problems with noisy silver micas. It seems that they are easily damaged from overheating when soldering. I have never had an issue but using a heatsink is good insurance to prevent damage. http://www.thegearpage.net/board/index. ... t-22093134

whopperplate
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Re: Lemco silver mica voltage rating

Post by whopperplate » Wed Jun 08, 2016 7:51 pm

Thanks for the tip, got my heat sink, will do!
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Re: Lemco silver mica voltage rating

Post by RockinRocket » Thu Jun 09, 2016 1:00 am

neikeel wrote:Think they are 350v rating ones (bit smaller than the 500v ones)

They should be fine on your mixers and probably ok in a 50w tone stack, not so good in a 45/100 or early 70s Superlead.
Hmm there cant really be that much voltage on the cathode follower. 160ish on a 50w. Whats the cathode followers voltage on those amps?

whopperplate
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Re: Lemco silver mica voltage rating

Post by whopperplate » Thu Jun 09, 2016 11:44 pm

The 470p will see about 250 off of v2 in a 50 watt.
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Re: Lemco silver mica voltage rating

Post by RockinRocket » Thu Jun 09, 2016 11:54 pm

Metro build gude shows about 150 on 50watts and 170 on SLs.

whopperplate
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Re: Lemco silver mica voltage rating

Post by whopperplate » Thu Jun 09, 2016 11:59 pm

No, the 470p is off of pin 6. Plate voltage of 270 according to metro chart
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Re: Lemco silver mica voltage rating

Post by RockinRocket » Fri Jun 10, 2016 1:05 pm

No the tone stack is off the cathode Pin 8. Not the plate pin 6.. unless your not building a 1987?

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