160 Vdc problem

[blewis999]

my VF1 is telling me the 160 Vdc is only 130 Volts.

When I measure the actual voltage it is in fact 166Vdc.

I assume P9 on the power monitor board is responsible for level shifting the 160 to something the machine can convert, but does anyone know what voltage should be there when the 160Vdc bus is at 160?

[serviceman]

wow the pmon board is old there should be a pot that is labelled a-d usually on the servo dist board machines. with a pmon not sure where it is usually you can adjust the pot you can see the feedback on the diagnostic screen it will fluctuate when you enable the servos i usually set it a little higher than it needs to be 165vdc or 170 as long as you verified that you have good dc buss. usually r42 i think 100k ohm resistor gets burned out. it is 2 watt i think usually. the charge light is dim or out but if you cannot adjust the pot to read correct voltage on your diagnostic then you probably need to change the resistor good luck

[blewis999]

Thanks for the reply. Yes its old (1990). I picked it up at an auction for next to nothing as it had some control issues. The seller told me one of his employees had tried to swap a drive card and let all the smoke out of some of the boards. I have replaced the components that are clearly cooked, looks like he must have reversed the 160 bus on the drive cards.

This is quite a task with NO docs, but I hope to make it through.

Again Thanks, I will try adjusting the pot this morning.