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 Post subject: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Oct Tue 02, 2012 12:57 am 
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If you're looking for a scrounge source for Electrolytic Capacitors of 400v+ look inside dead LCD displays. The internal HV power supplies contain 1 HV capacitor. Sizes are usually one of the following: 40uf, 68uf, 82uf, 100uf, 120uf, or 150uf. If the display was made between 1997 and 2007 then the other electrolytic capacitors (220uf - 3300uf) are probably no good (https://en.wikipedia.org/wiki/Capacitor_plague).

There will be some blue drop HV caps as well.

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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Oct Thu 25, 2012 8:59 pm 
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Old PC power supplies will yield two 470 or 680 uF caps, but at only 200 volts working. Voltage is OK for AA5 B+ filters (not AC radios) but the capacitance is far too large to hang directly off the rectifier cathode. However, if you put a series 100 ohm 5 watt WW in there to cut the ripple current they work very well.
Cheers,
Roger

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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Oct Wed 31, 2012 5:04 pm 
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I am amazed that you see old can type lytics for sale on ebay, probably 40+ years old, and people are buying them for alot of money sometimes. They are often NOS in the box but usually untested.


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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Nov Mon 05, 2012 11:24 am 
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wazz wrote:
I am amazed that you see old can type lytics for sale on ebay, probably 40+ years old, and people are buying them for alot of money sometimes. They are often NOS in the box but usually untested.


Don't know about tested.... More likely without being reformed first, there is a strong possibility that they have depolarised (lost form). I did see possibly 2003 some NOS 1958 electrolytic caps., in a tank PSU, self destruct, dramatically (would have been as good as the cannon) when they hooked the PSU up & fired up in the tank (24V Lead acids).

Was it not F.T Barnum that said to the effect "that there was one born every day"

Marc


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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Dec Sun 16, 2012 10:31 pm 
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wazz wrote:
I am amazed that you see old can type lytics for sale on ebay, probably 40+ years old, and people are buying them for alot of money sometimes. They are often NOS in the box but usually untested.

I'll admit to using old NOS electrolytics on occasion but I carefully reform them on a Sprague TO-6A tester. Then, if they still draw more than 0.5 mA at working voltage, I toss them. I always replace old, as-found, used electros - not worth the risk even if they reform... I'm restoring for the next 50 years, so they won't last 120 years!
Cheers,
Roger

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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Dec Sun 16, 2012 11:26 pm 
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Marcc wrote:

Was it not F.T Barnum that said to the effect "that there was one born every day"

Marc

We need to bring you up to speed on your Americanisms, lol.

It was P.T. Barnum who said, "there's a sucker born every minute"... :wink:

And with E-Caps being so cheap, why gamble on re-forming, when it's even odds that it will fail anyway? If it's in a circuit with an unobtanium transformer, how you say, penny wise and... :shock:

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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Dec Mon 17, 2012 1:43 pm 
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If I HAVE to reform old HV caps, (like when I want to try to fire up some old tube electrojunk unit, and see if it MIGHT work) I start by re-polarizing the caps by first hooking up a AA, C, or D battery in a batt holder, and clip lead in, (+>+, ->-) and a voltmeter on it... I check the voltmeter to see if the cap's polarity is not confused, and leave it on for a few days to properly polarize it, and I heard that this will start to "heal" the oxide layer in the cap... Then, reform caps very slowly...

This seems to help my high success rate of first power-up... If I like unit, then I will recap...

(RISE, MONSTER, RISE, HA,HA,HA!!!!!!!!!!!!!!!!! It's the mad scientist in me!!!!!!!!)

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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Aug Sun 17, 2014 3:04 am 
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Dead laptop power supplies or any other type of external switching power supply may have a 100uf 400v ecap in them.

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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Aug Sun 17, 2014 4:37 am 
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As it was previously mentioned trying to salvage used or NOS electrolytics is a waste of time. At todays prices there is no reason to use old or used components.

Dave


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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Aug Sun 17, 2014 6:26 am 
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I keep old parts for test and klooge purposes. New ones for permanent repairs.

The purpose of a hobby is to waste time in an enjoyable manner.

RRM


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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Aug Mon 18, 2014 6:44 pm 
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If one does not immediately have a new capacitor and one has a cap that one salvaged from another piece of equipment, one could continue working on a piece of equipment while one waits on parts to arrive. One could also fix a piece of equipment in an emergency.

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 Post subject: Re: Scrounge sources for HV Electrolytic Caps 40uf - 150uf
PostPosted: Aug Tue 19, 2014 3:57 am 
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Flinx wrote:
If one does not immediately have a new capacitor and one has a cap that one salvaged from another piece of equipment, one could continue working on a piece of equipment while one waits on parts to arrive. One could also fix a piece of equipment in an emergency.


Most definitely.

They can also be good for when you are not sure what capacitor you may need for a circuit as you will more than likely have several values at different voltages that you can try.


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