Fw: Electrolytics "blow up"

[Dick Blaney]

I've been following this thread, and notice that no-one has put any
emphasis on the rectifier.  Raw AC on an electrolytic will "blow 'em
up" faster than anything I know of.  Hope it helps.
73 de
Dick, WB8MHE
wb8mhe at bright.net


-----Original Message-----
From: talen <talen at inetport.com>
To: HEATH at LISTSERV.TEMPE.GOV <HEATH at LISTSERV.TEMPE.GOV>
Date: Sunday, November 28, 1999 10:02 AM
Subject: Fw: Electrolytics "blow up"


>I see from one of the later notes that you found the problem to be
>a defective resistor which increased the voltage applied to above
>the rated levels, however, since this was ready to send, it may be
>usefull to others.
>
>---------------------------------------------------------------------
-----------------------------
>First thing to do (assuming they are the correct voltage or higher)
is
>to bring "new" electrolytics up slowly. You can do this with a variac
>on the HW-16 or connect a variable DC power supply to the
electrolytic
>and take 5-10 minutes to bring them up to rated voltage a little at a
time.
>You only have to do this the first time. Once they are damaged
internally
>and develop a current path, they eventually overheat and go.
>
>You can also get a capacitor checker to check for leakage and to
>slowly bring up electrolytics since they test at rated voltage
(switch
>selectable). Again bring them up slowly the first time. One of my cap
>checkers is a Heath IT-28.....works great.
>
>Since these checkers are current limited (good idea) you can see what
>happens. I've connected a very old "new" 450V electrolytic across the
>tester and it will indicate "high leakage" at 100V, then the eye
slowly
>opens up, then it indicates "high leakage" at 200V, then the eye
opens
>up, etc. I do this several times and finally, after fully discharging
the
>capacitor, the eye opens up quickly at 450V. You can just imagine
what
>would happen if full voltage at high current was applied immediately
as in
>your HW-16.
>
>73s  Kees K5BCQ
>
>----------
>From: Bill and Edna <Eshukis at HOME.COM>
>To: HEATH at LISTSERV.TEMPE.GOV
>Subject: Re: Electrolytics "blow up"
>Date: Sunday, November 28, 1999 12:55 AM
>
>Hmmm.. Brings back a recent memory.  I replaced two High Voltage Caps
in
>the HW-16.  They
>were about 3/4 inch diameter..rated at 40uFd and 350V.  They Blew up
in
>about 30 seconds.
>How can I tell a High Resistance from a Low Resistance Electrolytic?
>
>I'm still determined to get that Rig on the air!!
>
>Bill
>K3OBB
>
>Dave Edwards wrote:
>
>> You may be searching forever for a replacement.
>> Its just an HW16.... Get some elecrolytics, and mount them under
the
>> chassis.
>> Then you can use it with no fear of high resistance caps to blow
up.
>> ...Dave
>> -----Original Message-----
>> From: Mark V. Johnson VE3DJU <mjohnson at CA.IBM.COM>
>> To: HEATH at LISTSERV.TEMPE.GOV <HEATH at LISTSERV.TEMPE.GOV>
>> Date: Saturday, November 27, 1999 4:32 PM
>> Subject: Electrolytics
>
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