Re: PG502 power lamp off


Hi Dennis,

your objection may be justified. Only, in this case I had the strong suspicion that the 5V won't be there since the device doesn't show any sign of putting out any pulse. Right after posting my question here I was confirmed that I was right.

The +5V after the 1Ohm resistor were 0.7 V or so. I unsoldered the series regulator transistor Q650 also and measured open in every direction between b-c-e in either direction.

BTW, there was a mica isolation foil underneath the heat sink floating around and the hole for the fastening screw was empty.

Is there a screw normally in there? And is it isolated also from the backside if the PCB?
This is a plated through hole and I believe it carried GND, if I'm right. Since that kind of transistors normally have one electrode (c) connected to the heat sink I thinnk there should be a complete isolation kit in place.


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