Thread: CRT TV SMPS
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pfm pfm is offline
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Default CRT TV SMPS

I continue to try and repair a CRT TV. The set's main SMPS is a
discrete, self oscillating design. The set powers up for a few seconds
and then shuts down; I think the Micon controller chip releases the AC
relay. The B+ open circuit voltage is 139V (ie disconnected from the
horizontal output). When a 60W bulb is substituted as a load for the
'horizontal', the voltage is zero, not a glimmer from the bulb. How
can the B+ power up the set, albeit briefly, but not light the bulb?
Is there a problem with a simple resistive load? Is it possible that
the horizontal stage is essential to the operation of the SMPS? Any
thoughts please?

BobH