On Tue, 07 Jul 2009 07:48:36 -0700, Robert Macy wrote:

Hard to believe anyone would design a circuit 'requiring' the presence
of MOV's to protect during 'normal' operation catching flyback
surges.

Yes, replace with tranzorbs.

I concur wholeheartedly here. I once worked at a place that built
several different models of HV power supplies, to do experiments
with electron beams and stuff. They had MOVs all over the place,
and the MOVs were a royal pain in the ass.

One day, one of our engineers saw the press release on TransZorbs,
and after evaluating them, the company issued EOs to replace every
single MOV with a TransZorb. (i.e., the savings over the long-term
was worth all the extra work!)

Cheers!
Rich