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Capacitors for Whelen strobe power supply

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clouduster(at)austin.rr.c
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Posted: Sun Mar 25, 2007 4:12 pm Post subject: Capacitors for Whelen strobe power supply

A friend gave me his Whelen strobe power supply.  It was still cycling 

but not firing the strobes.  Whelen will not repair it because they no 

longer support this unit.  I checked the capacitors and found one of the 

two main capacitors has low resistance - partial short I believe.  I'd 

like to try to make it work again for use in my RV 7A.

The capacitors are 400UF - 300 VDC.  They were manufactured by Sprague 

and have the # D77072 on the aluminum case.  Also the numbers 7821L  

19-03  are also on the case.  Does anyone have a source I can purchase 2 

from?  I have looked on the web but don't know which capacitor design 

these are - aluminum, electroletic, etc.



Thanks much,



Dennis H.

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jmfpublic(at)comcast.net
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Posted: Sun Mar 25, 2007 10:08 pm Post subject: Capacitors for Whelen strobe power supply

Dennis,

  

 Digikey catalog lists 12 different capacitors, 9 of which are in  stock, which would work for you if they fit mechanically.  These are all  350v at 390UF units.  You can use anything rated 300 volts or better, and  the 400UF is rather approximate, as the electrolytics are rated + and -  20%.  It seems that 390 UF is now commonly used.  Prices run from the  $5 to $7 range.  I will try to send you the results of the search on the  Digikey site privately.  Below are 390UF at 350v units:

  

            �             Diameter(mm)    Length(mm)

 P11920-ND        25                          40  

 P11921-ND        30                          30

 P11790-ND        25                          45

 P11791-ND        30                          30

  

 There are others, but mainly the ratings differ for service life  at rated temperature.  The first two are 3000 hr at 85 degrees C, the  next two are 2000 hr at 105 degrees C.

  

 Search for these part numbers on the Digikey site, and they will lead you  to all the information.

  

 Jim Foerster  J400 wiring-veerry  sloooly         

    [quote][b]

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klehman(at)albedo.net
Guest

Posted: Mon Mar 26, 2007 3:52 am Post subject: Capacitors for Whelen strobe power supply

Careful guys. There is more to this.

For proper performance and decent life you need "photoflash" capacitors 

specifically designed for fast high current discharge.

They tend to be more difficult to find.

Ken



James Foerster wrote:



 	  Quote: 	
		   Dennis,

  

 Digikey catalog lists 12 different capacitors, 9 of which are in 

 stock, which would work for you if they fit mechanically.  These are 

 all 350v at 390UF units.  You can use anything rated 300 volts or 

 better, and the 400UF is rather approximate, as the electrolytics are 

 rated + and - 20%.  It seems that 390 UF is now commonly used.  Prices 

 run from the $5 to $7 range.  I will try to send you the results of 

 the search on the Digikey site privately.  Below are 390UF at 350v units:

  

                         Diameter(mm)    Length(mm)

 P11920-ND        25                        40  

 P11921-ND        30                        30

 P11790-ND        25                        45

 P11791-ND        30                        30

  

 There are others, but mainly the ratings differ for service life 

 at rated temperature.  The first two are 3000 hr at 85 degrees C, the 

 next two are 2000 hr at 105 degrees C.

  

 Search for these part numbers on the Digikey site, and they will lead 

 you to all the information.

  

 Jim Foerster  J400 wiring-veerry sloooly

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

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