Quote Originally Posted by glbeas
Davies mentioned there was a workaround mod that can be done by commanding the lamp directly from the INPUT to the microprocessor, instead of from the OUTPUT, The microprocessor still controls the display, but does not control the lamp anymore, so that when it screws up, at least you do not lose the print that you are currently working on.

What this means I really can't say as I've never opened the head up to check out the board. If you find a techie willing to work on it this may be the way to go.
Email from Davies this afternoon:
No, it isn't the transformer. I fear that it may be a
part that is now obsolete The lamp voltage is controlled to 82v so as to
buffer the lamp from variations in the line [ac] voltage. However, part of
this control circuit uses an unusual type of opto isolator [more unusual
now, since they don't make it anymore] which consists of an incandescent
light source instead of an LED. I have been experimenting with repairing
this device, peeling the aluminum can open, and replacing the llight bulb
part with the closest that I can find to it, but have been only partially
If the above is the problem, then probably the best
course of action is to modify the circuit so that it puts out a voltage
close to the line voltage, and put in a 120v lamp. This, in theory, would
give you some variation in your prints due to changes in line voltage, but
in practice you would probably be ok.
Having said all of the above, it is of course possible
that the obsolete component is not the problem, could be something else. But
if you have a multimeter, and can take the end board out of the unit, then
e mail me again and I will tell you how to test it.
If you want info on this unit you need to call
Beseler, ask for parts and then ask for Steve McFadden. I believe that he
could send you a schematic, since Beseler no longer supports the 45.
While you are at it...........ask him to send me one
too, because mine is falling apart.............regards...........a

What I'm wondering now is -- if the rest of the circuit operates fine without the sensor mentioned by Davies, why not just add a separate stabilized 82v transformer just to run the lamp?

I'm gonna test that, but I don't know the integrity of the rest of this head's circuit either so if it doesn't work for me it doesn't necessarily mean it wouldn't on another head.

I have the unit apart again and am waiting for him to email the board test procedures and values.