Sharp MX 3100 No power

[Doug James]

Customer said they moved the copier into another room, plugged it in and it didn't come on. I went to the machine and sure enough, it's dead as a doornail. There is nothing I can find in the service manual to troubleshoot this. The power goes into the AC PCB board then to the DC Power Board. Anyone know the most likely culprit board is...

[blackcat4866]

Most machines within the last 10 years work like this: When the switch is turned ON, the power supply provides 5vdc to the main PWB. When the main PWB boots up, it signals the power supply to turn ON the 24vdc, 12vdc, -12vdc, and any other voltages.

So start with your circuit diagram and a VOM. Put your meter on the 110vac into the power supply and flip ON the power. If you get 110vac, then find the output for the 5vdc to the main PWB. If you don't have 5vdc it's time to take a closer look at the power supply. Maybe a blown fuse?

If you do have 5vdc at the power supply, find the 5vdc input to the Main PWB. No 5vdc? Look at the wiring harness and connectors. If you have 5vdc entering the Main PWB, find the signal voltage to enable the rest of the power supply. Is the Main PWB telling the PS to turn ON? If no, it's time to take a closer look at the Main PWB.

If you are getting the ON signal for the PS, find the signal pin on the PS. If you're getting the ON signal at the PS, it's time to take another look at the PS. Maybe a blown fuse? Next find the other voltages output from the power supply. Most likely you'll have pinned it down by now.

If you get this far, and you've still got all voltages at the power supply, this is where it gets really interesting. You may have a dead short pulling down one or more voltages at the power supply. Turn OFF the main power. unplug all the loads from the power supply, but leave attached the 110vac input and the On signal from the main PWB. Power up, and see if the PS output rise back to normal levels. If yes, one at a time power OFF, plug in one load connector, then power up and check voltages. Eventually you'll find one load that pulls down the output from the power supply.

And on and on. Fun, fun, fun. =^..^=

[skookumchuck]

Great troubleshooting description!

[Toner Boy]

You might want to try and pull the wiring from the paper feed drive assembly, the clutches can short and pull down the voltage (and can damage the power supply as well). Simple enough to try...
I would suspect the DC power supply as the next suspect. Have replaced a couple for no power. But Blackcat's advice is solid.

[Motormount]

OK, so no one else asked: you checked the wall voltage, right? With the machine plugged in and power on?
I used to test my trainees with this one, because we ran in to it quite a bit: Poor wiring would show proper voltage with a meter, but drop to zero under a load.

[Doug James]

Most machines within the last 10 years work like this: When the switch is turned ON, the power supply provides 5vdc to the main PWB. When the main PWB boots up, it signals the power supply to turn ON the 24vdc, 12vdc, -12vdc, and any other voltages.

So start with your circuit diagram and a VOM. Put your meter on the 110vac into the power supply and flip ON the power. If you get 110vac, then find the output for the 5vdc to the main PWB. If you don't have 5vdc it's time to take a closer look at the power supply. Maybe a blown fuse?

If you do have 5vdc at the power supply, find the 5vdc input to the Main PWB. No 5vdc? Look at the wiring harness and connectors. If you have 5vdc entering the Main PWB, find the signal voltage to enable the rest of the power supply. Is the Main PWB telling the PS to turn ON? If no, it's time to take a closer look at the Main PWB.

If you are getting the ON signal for the PS, find the signal pin on the PS. If you're getting the ON signal at the PS, it's time to take another look at the PS. Maybe a blown fuse? Next find the other voltages output from the power supply. Most likely you'll have pinned it down by now.

If you get this far, and you've still got all voltages at the power supply, this is where it gets really interesting. You may have a dead short pulling down one or more voltages at the power supply. Turn OFF the main power. unplug all the loads from the power supply, but leave attached the 110vac input and the On signal from the main PWB. Power up, and see if the PS output rise back to normal levels. If yes, one at a time power OFF, plug in one load connector, then power up and check voltages. Eventually you'll find one load that pulls down the output from the power supply.

And on and on. Fun, fun, fun. =^..^=

So So Helpful, Thanks so much !!!!

[Doug James]

OK, so no one else asked: you checked the wall voltage, right? With the machine plugged in and power on?
I used to test my trainees with this one, because we ran in to it quite a bit: Poor wiring would show proper voltage with a meter, but drop to zero under a load.

I have had that happen. .. I actually ran an extension cord to the original wall outlet...

[sharphead]

If there is a finisher disconnect it.

[MHeon71]

There is a tech tip on Sharp to help trouble shoot dead machines. The tech tip is TT-073113_5.

[Doug James]

Trouble shot the problem to the DC Power supply. The F101 fuse was blown. Put a new fuse in it and it also blew...Then replaced the DC power supply... I then disconnected the paper feed wiring, fuser and the F9 finisher. Turned the machine on. The machine powered up and I let it sit idle with everything still disconnected... After about 10 minutes the machine lost power... At this point I am saying the power source is probably the problem... I am going to send the DC power supply to Hytec and see if they can give me any clues as to the cause... I am not an electrician but considering the fact that the problem was started when they plugged the machine into another outlet pretty much points to the AC power source as far as I can tell.... Any feedback would be extremely helpful...