Power Supply Test

[shane]

I just tested the Power Supply and get zero readings on all three test points.  What are the possible causes of this and what should my next steps be?

Pic shows plug with burnt area near bottom. 

Thanks in advance for your help.

Shane

[dhellis]

Getting 0 volts on all test points is a bid unusual. My first thought would be to make sure
that you have a good ground connection on your meter and that you are measuring DC voltages.

If that is the case (I suspect you are doing it correctly) then check the voltage from the back side
of CR1 (side without the band) and the back side of CR4, this should measure roughly 9.5 volts AC

If that voltage is not present then look at wiring or even a fuse. I you have that voltage then check
diode CR1 thru CR4.

I have repaired several of these power supplies so I would also check the bridge rectifier, I have found
more than just a few that were open.

Finally I would take a wire brush and clean all of the contacts, it is possible that the connector is not
allowing voltage to flow to the power supply

[shane]

Thanks for response.

Yes, was on DCV.  The machine was not powered on - should it be to run the test?

How much concern is the dark/burnt area on the plug?

Shane

[dhellis]

If the machine was not powered on then that solves the mystery of why you had no voltage.
You have to have power to the machine so that there is voltage for the power supply.

I would clean the connectors on the board and inspect the pins on the plug to make sure
that they are clean and making good contact. Personally, I would re-solder the connections
for the pins on the underside of the power supply board

[Trisail]

I have both of the connectors and contacts if you want to try to replace them. The connector with the wires and the connector on the board.
Turn the power on the machine and retest. Let us know what you get.

Tony

[shane]

I also have some fuses & fuse holders to replace so I will do those and re-test.

Thanks for the guidance.

Shane

[shane]

I replaced the missing fuse holders and fuses.

Testing the Power Supply I get the following readings:
  - +5 = 5 Volts
  - ZC = 7 Volts
  - +UR = 9 Volts

Can someone help me interpret these results?  Is the Power Supply okay?

Also, when I power up, the LED Display registers Code 6 in the far right column for a brief moment before changing to Code 7 in the far left column.  Anyone know what these codes mean?

Thanks for your help.

Shane