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 Post subject: Eico 950B 8uf 525v cap?
PostPosted: Mar Sun 19, 2017 8:04 pm 
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Joined: May Thu 26, 2016 5:17 pm
Posts: 182
Location: Puget Sound, WA
Hello all,

I just picked up an Eico 950B cap tester at my local radio club meeting.

Looking at the parts list I'm going to need an 8uf, 525v cap.

I checked on this Mouser page and the price was $35 for a 10uf, 600v.

http://www.mouser.com/ProductDetail/Vis ... h%2fAOc%3d

Justradios has an 8uf, 600v cap for about $5.

Am I searching wrong on the Mouser site?

Why such a big price difference between Mouser and Justradios?

Does anybody know where to get the cap at a reasonable price?

Carter


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Sun 19, 2017 8:14 pm 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 8928
Location: Santa Rosa, CA
450V is the typical max voltage that most industrial distributors stock. Higher voltages are less common, so maybe priced higher.

As to the difference in price, Mouser is selling a Vishay/Sprague brand. I am not sure what Just sells; probably good stuff.

Also, axial lead caps are more rare these days and radials will always be cheaper.

Personally, I would just put two 22 uF/450 V caps in series and know that I made a safe and economical choice.

Nichicon is a good brand and you can't beat a dollar each!

http://www.mouser.com/ProductDetail/Nic ... wny6TSI%3d

Rich


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Sun 19, 2017 10:32 pm 
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Joined: May Thu 26, 2016 5:17 pm
Posts: 182
Location: Puget Sound, WA
Thanks for the advice!

It sounds like I have a plan.

Carter'


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Sun 19, 2017 11:09 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
Posts: 6723
Location: Long Island
It's not Mouser; those caps are about the same price at any distributor you check. Unless you go to DigiKey where they are half price, but not stocked and you have to take a box of 50 with a 14-week lead time! Vishay/Sprague appears to be the only recognized name brand company left still making commercial grade, axial 600-volt electrolytics. They can charge what the traffic will bear.

There is no spec sheet available for the lower priced caps so it's not possible to know what the differences are, but there have to be some. If they could charge the same price as Vishay, don't you think they would? Chances are that if you tested them side by side, you would find that the inexpensive caps have higher ESR's or leakage currents, and do not last as long. On the other hand, your Eico 950B will probably only see occasional use, so you might not need a cap that will stand up to 24/7 industrial use for 10 or 20 years. One of the $5.00 caps may be perfectly adequate for your purposes.

As Rich mentioned, you can also put two electrolytics in series if necessary. They should be new, identical caps to assure that the voltage divides equally across them. The voltage ratings are additive, so two 350 volt units will give a 700 volt rating. The capacitance divides between the capacitors when they are in series, so for two identical units the capacitance will be halved. Therefore you'd start out with two 20-uF caps in series to make 10-uF.

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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Sun 19, 2017 11:30 pm 
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Posts: 19676
Location: Haledon, NJ, usa
For a total of only 96 cents... just put two 22uf@450vdc caps in series = 11uf@ 900vdc:
http://www.ebay.com/itm/2PCS-450V-22uF- ... Swd0BV5XcZ

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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Mon 20, 2017 1:33 am 
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Joined: Mar Thu 12, 2009 2:20 am
Posts: 1346
Location: Dayton, OH
Is there any reason you have to have electrolytic? Its just a filter cap. There are quite a few film caps in the 8-10uF range > 525V, for 5-10$ from Mouser.

Eg: (Albeit the lead style is kinda fugly, but they are cheaper...)

http://www.mouser.com/search/ProductDet ... 006ID2KYSD

10uF, 800VDC, 5.33$

I would think they should work..

<shrug>

David

(And just think you'll have everyone coming out of the wood work to tell me I'm wrong, if I am. :-D )


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Mon 20, 2017 2:27 am 
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Posts: 19676
Location: Haledon, NJ, usa
dholland wrote:
Is there any reason you have to have electrolytic? Its just a filter cap. There are quite a few film caps in the 8-10uF range > 525V, for 5-10$ from Mouser.

Eg: (Albeit the lead style is kinda fugly, but they are cheaper...)

http://www.mouser.com/search/ProductDet ... 006ID2KYSD

10uF, 800VDC, 5.33$

I would think they should work..

<shrug>

David

(And just think you'll have everyone coming out of the wood work to tell me I'm wrong, if I am. :-D )

Why would you say that?
It should work fine.

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To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Mon 20, 2017 2:37 am 
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Joined: Mar Sat 28, 2009 8:27 pm
Posts: 682
Location: Georgia
Should you decide to series two electrolytics be sure to match them for several reasons. The distribution of voltage across each of the two capacitors will NOT be equal unless the caps are the same. This results in a lower total working voltage so that two 450 caps will not have a working voltage of 900.


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Mon 20, 2017 3:05 am 
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Joined: May Tue 30, 2006 4:46 pm
Posts: 8928
Location: Santa Rosa, CA
1. Modern electrolytics (brand name) are usually pretty close.

2. Since the goal was to replace a 525V cap, even with mismatch, you will be safe. You don't need a 900V cap.

Rich


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Mon 20, 2017 5:46 am 
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User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 19676
Location: Haledon, NJ, usa
When you connect two electrolytic caps of the same value in series it may be desirable to use balancing resistors across each of the two caps.
In your case a 1 meg ohm resistor across each cap in series will balance the voltage drop.:
R= 10/C
where
C= Capacitance in uF.
R= Resistance in mega-ohms.

Ref:
https://www.illinoiscapacitor.com/pdf/P ... istors.pdf
-------------------
"SERIES
Capacitors may be connected in series for increased voltage
withstanding.
Voltage Sharing
During charging the voltage on each capacitor connected in
series is proportional to the inverse of the actual capacitance,
but upon reaching final voltage, the voltage on each capacitor
is proportional to the inverse of the capacitor’s leakage current.
Of course in a series string there is only one leakage current and
the capacitors with a propensity for higher leakage current will
get less voltage. Since leakage current increases with applied
voltage, less voltage results in higher leakage resistance, and the
voltages tend to equalize. However, voltage distribution will not
be uniform, and to assure that no capacitor is subjected to more
than its rated voltage, use higher rated voltage capacitors or a
balancing scheme such as balancing resistors, discussed next.
Assist voltage sharing stability by using capacitors from the
same manufacturing lot and mounting them to operate at the
same temperature"
Ref: http://www.cde.com/resources/catalogs/AEappGUIDE.pdf

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Mon 20, 2017 8:29 am 
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Joined: May Fri 01, 2009 3:53 am
Posts: 1281
Location: Glendale, California
Some good info here.

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Senior Analog Meter Technician at IMS. I specialize in the Simpson 260.

John, KK6WHY


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Tue 21, 2017 12:49 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 4299
Location: Connecticut. USA
I use two 22uf @450 volts in series but make sure you put a 470K ohm resistor across each one, the resistors balance the voltage so one cap don't get too much voltage.
I did that on my EICO 950 and my SPRAGUE TO-5 has resistors across two electrolytics, i had to replace the electrolytics when I restored it.

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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Tue 21, 2017 1:38 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 19676
Location: Haledon, NJ, usa
Bill Benson wrote:
I use two 22uf @450 volts in series but make sure you put a 470K ohm resistor across each one, the resistors balance the voltage so one cap don't get too much voltage.
I did that on my EICO 950 and my SPRAGUE TO-5 has resistors across two electrolytics, i had to replace the electrolytics when I restored it.

470k will probably be fine.. but the formula I posted above came from Illinois Capacitor and it indicates a 1meg for this case:
----------------
R= 10/C
where
C= Capacitance in uF.
R= Resistance in mega-ohms.
-----------------------------
Ref: https://www.illinoiscapacitor.com/pdf/P ... istors.pdf

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Tue 21, 2017 2:41 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 10103
Location: Latham NY
There is not much current available from the 950 HV winding so I would opt for the 1 meg. Actually I wouldn't even use any resistors with new 450v caps of the same batch.


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Tue 21, 2017 4:12 pm 
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Joined: Jan Mon 18, 2010 2:13 am
Posts: 14378
Location: Dayton Ohio
Antique Electronic Supply sells Solen capacitors
which is available in 8.2 uf @ 630VDC for $6.50

https://www.tubesandmore.com/products/c ... ylene-fast

These are NOT electrolytics, which is a good thing. :D

-Steve

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Consoles and floor models, the bigger, the better!


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Tue 21, 2017 8:51 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 10528
Location: Mpls, Minnesota
Pbpix wrote:
When you connect two electrolytic caps of the same value in series it may be desirable to use balancing resistors across each of the two caps.
In your case a 1 meg ohm resistor across each cap in series will balance the voltage drop.:
R= 10/C
where
C= Capacitance in uF.
R= Resistance in mega-ohms.

Ref:
https://www.illinoiscapacitor.com/pdf/P ... istors.pdf
-------------------
"SERIES
Capacitors may be connected in series for increased voltage
withstanding.
Voltage Sharing
During charging the voltage on each capacitor connected in
series is proportional to the inverse of the actual capacitance,
but upon reaching final voltage, the voltage on each capacitor
is proportional to the inverse of the capacitor’s leakage current.
Of course in a series string there is only one leakage current and
the capacitors with a propensity for higher leakage current will
get less voltage. Since leakage current increases with applied
voltage, less voltage results in higher leakage resistance, and the
voltages tend to equalize. However, voltage distribution will not
be uniform, and to assure that no capacitor is subjected to more
than its rated voltage, use higher rated voltage capacitors or a
balancing scheme such as balancing resistors, discussed next.
Assist voltage sharing stability by using capacitors from the
same manufacturing lot and mounting them to operate at the
same temperature"
Ref: http://www.cde.com/resources/catalogs/AEappGUIDE.pdf


If you look at the text above you will see that it says " use higher rated voltage capacitors or a
balancing scheme such as balancing resistors
" it gives you a choice, it does not say you have to use balancing resistors. For two electrolytics from the same batch in series balancing resistors are not required. The electrolytics are self equalizing, this has been discussed and proven by some members on ARF. Do a simple test, put two electrolytics in series and monitor the voltage on each one and apply voltage, the voltage will not rise above the rated voltage of either electrolytic. The manufacturers put two electrolytics in series and package them in a single tube to get a higher voltage electrolytic. Bottom line is for two electrolytics in series the resistors are not necessary. For three or more electrolytics in series equalizing resistors should be used.

Dave


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Wed 22, 2017 8:03 am 
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User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 19676
Location: Haledon, NJ, usa
easyrider8 wrote:
Pbpix wrote:
When you connect two electrolytic caps of the same value in series it may be desirable to use balancing resistors across each of the two caps.
In your case a 1 meg ohm resistor across each cap in series will balance the voltage drop.:
R= 10/C
where
C= Capacitance in uF.
R= Resistance in mega-ohms.

Ref:
https://www.illinoiscapacitor.com/pdf/P ... istors.pdf
-------------------
"SERIES
Capacitors may be connected in series for increased voltage
withstanding.
Voltage Sharing
During charging the voltage on each capacitor connected in
series is proportional to the inverse of the actual capacitance,
but upon reaching final voltage, the voltage on each capacitor
is proportional to the inverse of the capacitor’s leakage current.
Of course in a series string there is only one leakage current and
the capacitors with a propensity for higher leakage current will
get less voltage. Since leakage current increases with applied
voltage, less voltage results in higher leakage resistance, and the
voltages tend to equalize. However, voltage distribution will not
be uniform, and to assure that no capacitor is subjected to more
than its rated voltage, use higher rated voltage capacitors or a
balancing scheme such as balancing resistors, discussed next.
Assist voltage sharing stability by using capacitors from the
same manufacturing lot and mounting them to operate at the
same temperature"
Ref: http://www.cde.com/resources/catalogs/AEappGUIDE.pdf


If you look at the text above you will see that it says " use higher rated voltage capacitors or a
balancing scheme such as balancing resistors
" it gives you a choice, it does not say you have to use balancing resistors. For two electrolytics from the same batch in series balancing resistors are not required. The electrolytics are self equalizing, this has been discussed and proven by some members on ARF. Do a simple test, put two electrolytics in series and monitor the voltage on each one and apply voltage, the voltage will not rise above the rated voltage of either electrolytic. The manufacturers put two electrolytics in series and package them in a single tube to get a higher voltage electrolytic. Bottom line is for two electrolytics in series the resistors are not necessary. For three or more electrolytics in series equalizing resistors should be used.

Dave

I agree but if one wants to use them... there's the formula and the data.

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To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Mar Fri 31, 2017 1:40 pm 
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Joined: May Thu 26, 2016 5:17 pm
Posts: 182
Location: Puget Sound, WA
Hello all,

So I put two 450v 22uf in series along with some 1 meg ohm resistors and it's working fine.

I really don't like doing the series method unless I have to but in this case it's ok I guess.

I tested a couple of caps and the results were correct.

Thanks to all for the advice!

Carter


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Apr Sat 01, 2017 2:22 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 19676
Location: Haledon, NJ, usa
nwsalmon wrote:
Hello all,

So I put two 450v 22uf in series along with some 1 meg ohm resistors and it's working fine.

I really don't like doing the series method unless I have to but in this case it's ok I guess.

I tested a couple of caps and the results were correct.

Thanks to all for the advice!

Carter

It's just like any other standard electronic method.
Resistors in series or resistors in parallel.... either way works fine.
Capacitor in series or parallel... also works fine.

You just decided that you don't like one arrangement... but that has no bearing on the fact that it is still a sound process like any other tested and proven process of component arrangement.

_________________
To be a man, Be a non-conformist, Nothing's sacred as the integrity of your own mind.
-Emerson


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 Post subject: Re: Eico 950B 8uf 525v cap?
PostPosted: Apr Sun 02, 2017 3:30 am 
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Joined: Jul Sat 23, 2011 9:33 pm
Posts: 718
Location: Long Beach Ms. USA 39560
Before you fire it up, check the main dial potentiometer.
Mine shorted to the case internally at about mid-range.
The result was a very bright eye tube and collatteral damage.
Pat

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Pat W5THT
Unhappy tubes blush while unhappy power FETs scatter plastic


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