[jhoanrojas]

I have an Okuma Howa Act-3 lathe with Fanuc 6T model B.

Last weeks it was working with displaying some alarm leds in sequence doctor (FUSE led for example, or it turned off byself). I checked the input power unit and the alarm led was ON, but no fuse was blown. So I thought that it could be an power supply failure, because int this sector the voltage has many rinse.

But now I turned On the machine but nothing is displayed on the screen and it is imposible any action with the machine. I checked all fuses, all output voltajes (+24,+15-15,+5, and 10 VDC) and they seems ok when I press the Power On button, but no alarm is displayed and all alarm leds are OFF. Then I removed the ROM pcb and no alarm or led is On.

So I think the master PCB is death.

Do you have any idea? I need a good diagnostic before looking for another pcb.

I have an mori Sl4 with Fanuc 6 T, I wonder if it's posible to change just the master board.

Thanks for your help.

Jhoan

[Scott_Tool]

It sounds like you are checking the voltages right at the fuses. Try to check them farther downstream for example where the output becomes input for the screen. You can always check your pcb by 1: visual inspection for any char/black, cracks, bad solder joints, etc (capacitors will actually explode and leave bits of insulation scattered around) 2: multimeter, start checking where your power comes in and find where it stops 3: Order a new one with a return policy, swap them out and if it still doesn't work return the one you bought.

However the original problem that caused your fuse alarm needs to be found before you replace anything unless you want to foul your new hardware the same way.

[jhoanrojas]

Input voltages to the motherboard are ok. I'm checking the POWER OFF signal (*PF) in CP35. It shows 4.0V. I think it should be 5 V.

I'll continue checking the ítems that you wrote.

Thanks

[jhoanrojas]

Hello.

I want to post the cause and the solution to this trouble.

The electronic technician checked the masterboard and he found two bad componnents checking each part witah an oscilloscope. I'm not sure if there's an datasheet. I couldn't find it. It is A-DV18 (oscillators).

We take them out from a similar motherboard, and the controller powered up. But the alarm LED "0" in the PCB was ON and the message in the CRT screen was Slave ready, Bubble Read. Checking the manual... it was the CRT PCB. After that we changed the chip controller in this small PCB.

Finally the machine is working now.

Good luck