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Re: Monitor problem

Giorgio Morocutti wrote:

On Sat, 23 Feb 2008 19:25:49 +0100, Giorgio Morocutti
<giorgio.morocutti@alice.it> wrote:



On Wed, 20 Feb 2008 21:03:23 -0800 (PST), Allen Bong
<allenbsf6502@gmail.com> wrote:




Hi,

Michael was right!  I found 3 caps having some kind of electrolyte
leak at the legs of the caps at C417 1000uF 16V, C901 10uF 100V and
C206 220uF 90V.  I changed them one by one and tested the monitor
after each cap was changed.  After changing the 3rd cap, the bright
dot was gone.

I guess the cap must have become open circuit but I have no capacitor
meter to confirm.  I used caps with smaller footprints but higher
voltage rate as 90V and 100V caps were not available here.



Good news for my monitor !

I have already changed C206 and C501 ( C901 !?), now I will change
C417 1000uF-16V.




Hallo Michael and Allen

I have changed C416-100uF 25V and C417-1000uF 16V, but no result :-(


I'm sorry to hear that you aren't having any luck, Georgio.

Maybe you'll just have to live with the spot at powerdown--it probably
isn't doing any real harm, since the HV is dropping all the time.

A definitive solution would require either 1) luck, or 2) analysis of
the variation of grid and cathode bias as a function of time after
turnoff.  The latter analysis would point to either the grid or cathode
circuit as the source of the problem, and the shape might zero in on
a small set of possibilities.

-michael

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