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Author Topic: .005uf @ 1.4KV replacement cap?  (Read 5218 times)
KE5DFK
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Posts: 55




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« on: April 29, 2016, 08:47:04 AM »

I am working on a SB-201 and I found one of the .005uf 1.4kv ceramic caps blown.  HK pn is 21-72 on the manual.  What can I use to replace this cap, I can't seem to find it.  I can find .005uf @ 3kv or at 1KV.
They are using it between the screw terminal ground lug and each of the 120vac lines.

Thanks
Carlos
KE5DFK
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WB2WIK
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« Reply #1 on: April 29, 2016, 08:49:04 AM »

Use the 3kV cap.

I'd replace both of them, they're old.

The .005uF isn't critical; .01uF is just as good.   But a higher voltage rating is better.
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N3QE
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« Reply #2 on: April 29, 2016, 09:04:38 AM »

I am working on a SB-201 and I found one of the .005uf 1.4kv ceramic caps blown.  HK pn is 21-72 on the manual.  What can I use to replace this cap, I can't seem to find it.  I can find .005uf @ 3kv or at 1KV.
They are using it between the screw terminal ground lug and each of the 120vac lines.

That is a "line to chassis" capacitor. The exact capacitance is not critical, but the safety rating is. Back when the amp was new, safety rated X and Y capacitors were not available so they greatly overrated the cap for voltage, and it does not need to be exactly the 1.4kV rating. For replacement, use a "Y rated" capacitor. While you are in there, replace the other AC line capacitors with modern safety-rated caps.

http://www.justradios.com/safetytips.html
http://www.vishay.com/capacitors/rfi-safety-rated-xy/
http://www.illinoiscapacitor.com/pdf/Papers/EMI_RFI_suppression_capacitors_film.pdf
http://www.kemet.com/Lists/Filestore/EvoxRifaRFIandSMD.pdf
http://www.kemet.com/Lists/Filestore/EvoxRifaRFIandSMD.pdf


« Last Edit: April 29, 2016, 09:07:56 AM by N3QE » Logged
KE5DFK
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Posts: 55




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« Reply #3 on: April 29, 2016, 09:42:17 AM »

Thanks for the info.
Looks like I may have to order.
I have .01if 2KVDC from mouser 594-S103M69Z5UP63K7R
Can I use this to test and when I get the correct type replace them?

Again Thanks
Carlos
KE5DFK
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N3QE
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« Reply #4 on: April 29, 2016, 10:03:17 AM »

Thanks for the info.
Looks like I may have to order.
I have .01if 2KVDC from mouser 594-S103M69Z5UP63K7R
Can I use this to test and when I get the correct type replace them?

By modern standards, you really want a Y-rated capacitor in there. Until the capacitor fails shorted, it is not a critical part. If it fails shorted, it suddenly becomes a critical part!

If you have any scrap computer electronics handy, you will find suitable Y-rated film capacitors right near the AC jack in a scrap computer power supply. Sometimes they are wire-lead capacitors sometimes covered with heat shrink.
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KE5DFK
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« Reply #5 on: April 29, 2016, 10:58:54 AM »

N3QE
Is this what your talking about?
 http://www.mouser.com/ProductDetail/Vishay-BC-Components/AY2472M49Y5US63L7/?qs=sGAEpiMZZMsh%252b1woXyUXj0vdnpe12uMcV2cAMdtbJbk%3d

I did find an X type across a power supply line in, but from what I was reading in the justradios link, it says not to use the X to replace a Y line 2 ground capacitor.  If this one I linked above is the correct type I will order.  Please advice if this is the correct type.

Carlos
KE5DFK
Thanks.
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KK5DR
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« Reply #6 on: April 29, 2016, 08:22:47 PM »

Value not critical, replace it with a 3kv .01 uF cap.
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N3QE
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« Reply #7 on: May 02, 2016, 06:29:56 AM »


Wow, you seem to be working hard on a very pedestrian issue!

I thought you would just put in any old Y-rated line capacitor (probably a film one out of a PC or consumer power supply).

But what you found, that's a very nice beefy part that is Y2-rated and will do great as well.
« Last Edit: May 02, 2016, 06:32:28 AM by N3QE » Logged
AD4U
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Posts: 2543




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« Reply #8 on: May 02, 2016, 08:39:02 AM »

The SB 200 (201) will run just fine without these caps, however as others recommended they should be replaced. Their main purpose was to shunt RF to ground and keep the RF off the AC mains. Their presence (or lack there-of) has nothing to do with the amp operating.

Dick AD4U
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WA1RNE
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« Reply #9 on: May 02, 2016, 09:58:55 AM »

Quote
I have .01 if 2KVDC from mouser 594-S103M69Z5UP63K7R
Can I use this to test and when I get the correct type replace them?

 Better yet, install the 0.01 uF 2 kV types and leave them in there. The new X and Y rated parts are high reliability industrial grade capacitors that conform to UL and IEC standards. Nice to have but not mandatory, especially for what you're doing.

 The original 1.5 kV DC rated parts probably lasted 40 years, and you're talking about selling the amp - don't worry about it - the 2 kV parts are perfectly OK to use.


 ...WA1RNE
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G3RZP
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« Reply #10 on: May 02, 2016, 10:18:41 AM »

Remember that in today's litigious society, because you intend to sell the amp, were a non-class Y capacitor and something bad happened, you could get sued. If you could demonstrate that you had use a modern component rated for the job, you would be in a better position.
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WA1RNE
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« Reply #11 on: May 02, 2016, 07:11:42 PM »

Quote
Remember that in today's litigious society, because you intend to sell the amp, were a non-class Y capacitor and something bad happened, you could get sued. If you could demonstrate that you had use a modern component rated for the job, you would be in a better position.

I could understand that argument if the amplifier was originally built with high reliability parts, but it wasn't - he's replacing parts with types that have a 43% higher DC voltage rating than the originals.

Even under steady state high line conditions, these Y connected capacitors will never see more than 187 volts peak in normal service - nearly 10 times less than their DC rating.
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