Fw: GB> MOVs (was: Transformer update)

[Sandy and Kees Talen]

At 07:53 PM 05/04/2002 -0600, rayfri wrote:
><snip>
>      I had no experience or knowlege of MOV's despite 30 years as a
>ham.  The device looks just like a disc capacitor and that's what I
>thought when I first saw it so I didnt pay any more attention to it...
>only to the black, burned spot on the primary side of the transformer.
>Well, I found a small hole in the MOV, cut out the MOV, put in a new
>fuse and turned on the power supply... NO SHORT!!!   Now to connect up
>the regulator circuit to the bridge rectifier again and see what
>happens, but checks on individual components showed no obviously bad
>ones.....    Keeping my fingers crossed...
>Ray  wa7itz

I agree with what Brad said re the note above, but I would put another
MOV
back in also. Any good electronics store has them. If it shorted, it may
be
due to deterioration, but it could also be that it did it's job which is
to short
when subjected to high voltage ...a spike or otherwise, and it's job is
to
take out the fuse and break the circuit saving the downstream
electronics.
I could tell you a story about hooking a battery charger to my car
battery
while working on the electronic dash. The battery terminal came loose,
the charger was intermittantly loaded, and promptly spiked up to 27VDC.
I'm glad the MOV did its job of shorting and taking out the fuse. That
electronic dash is big bucks, the MOV was $3.

73s  Kees K5BCQ

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