Batboard

Hey All,
I have a R2001C that I am doing some refurbs on it and came across an issue with the HVPS A10 module.
The HV Source voltage feeding J1 Pin 3 has a LM7812 inserted between the Pin 3 of the 8 pin dip and the orange wire of the ribbon cable.
This looks like a factory mod because there are two 12 Ohm flat packs mounted on top of the LM7812 wrapped in capton tape.
I have checked what few manuals that I could find and can not find this modification.
Also, I've noticed that the monitor will not power up at all without this module.
Does anybody know about this and do you have the print of this particular power supply?
Thanks

My R2001B with an R2001C HVPS has nothing like that. I wonder if there was once a problem with the LVPS that someone "fixed" by adding that regulator in series. Pin 3 normally has the DC BUS voltage (around 14VDC) on it and the HVPS is self-regulating.

I've been told that the LVPS won't power up without the HVPS attached, so you seem to have confirmed that.

I don't think any of the other R2001 models have anything like that in the manuals. The R2001D HVPS uses +12V to run the switching transistors; there's no separate HV Source voltage like in the "B" and "C".

Bob M.

That LM7812 on your HVPS is NOT a factory mod. What are the symptoms of your problem with the analyzer?

The regulator got its smoke removed when I failed to notice one of the insulators on one of the transistors was missing and thus a direct short.
I figured it was not a factory mod but not really sure why someone would put that in circuit.
Perhaps to compensate for a problem elsewhere.