[MikeD51]

Hi,
I have an 18MC with what I assume to be a PSU issue (A16B-1212-0871) presenting the following symptoms;
-On/off control is not working. The PSU turns 'on' at machine power-up and the on/off buttons on the front panel do nothing. The circuit from front panel to PSU tests good, and the main relay on the PSU test good when removed from the board.
- PIL LED is lit, alarm LED is not.
- 24v is being supplied to the CRT from the front outlet of the PSU but nothing appears on screen.
- All LED's on the CPU and other option boards are lit at machine power-up (indicating board cannot start) and, as stated, pushing the on/off buttons does not change this. (previously all LED's were off until the 'on' button was pressed)
I was hoping someone may be able to provide me with a schematic and/or testing procedure for the PSU, or even just what voltages are expected on what lines on the backplane.
Obtaining replacement boards in my part of the world is prohibitively expensive so diagnoses and (hopefully) repair myself is preferrable.
Thanks in advance
Mike

[memoryman]

I don't have schematics for that unit, but have several good ones. Where are you located? Shipping may be expensive.

[MikeD51]

Thanks for the reply. I am in New Zealand. Shipping and exchange rates are most certainly not favorable.
My main concern is ordering a part and then finding the fault is actually somewhere else, so I am hoping to at least make a more definitive diagnoses and hence the request for for technical information so I know exactly what to test.

[memoryman]

I have customers in NZ. I shipped a similar item to Malaysia for ~C$120.

[phucrobusl]

Please contact me [email protected] i have it

[MikeD51]

Email sent, thanks

[Jarwalcot]

Hi,
I have an 18MC with what I assume to be a PSU issue (A16B-1212-0871) presenting the following symptoms;
-On/off control is not working. The PSU turns 'on' at machine power-up and the on/off buttons on the front panel do nothing. The circuit from front panel to PSU tests good, and the main relay on the PSU test good when removed from the board.
- PIL LED is lit, alarm LED is not.
- 24v is being supplied to the CRT from the front outlet of the PSU but nothing appears on screen.
- All LED's on the CPU and other option boards are lit at machine power-up (indicating board cannot start) and, as stated, pushing the on/off buttons does not change this. (previously all LED's were off until the 'on' button was pressed)
I was hoping someone may be able to provide me with a schematic and/or testing procedure for the PSU, or even just what voltages are expected on what lines on the backplane.
Obtaining replacement boards in my part of the world is prohibitively expensive so diagnoses and (hopefully) repair myself is preferrable.
Thanks in advance
Mike

Check the voltage at “NCON” on the PSU. I believe you will find below the necessary 24v.

[jjjearls]

Please contact me [email protected] i have it

I am having the same problem as MikeD51. It seems like a "simple" issue of the CONTROL OFF circuit shorted to 0V. If there's some way to power the machine up without losing our data, it would really save a ton of trouble. Can I email you, phucrobusl, for the schematic for A16B-1212-0871?