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Wang Advanced Professional Computer

M

mlasham

New Member
Joined
Jan 4, 2021
Messages
5
Location
Auckland, New Zealand
Hi
I've a Wang APC which has seen healthier days I think.
It appears to have a number of issues which I am hoping someone here may be able to help with.
First up I am after any documentation that may help, e.g. schematics, service manual etc.
I have found some of these for the PC not APC on bitsavers though they are for a system board number 8221 and mine is a 9721 which I assume is the difference between the PC and APC models.
The schematics for the 8221 look very much the same as my system board but I dont want to make assumtions.

Now the faults are:
1. Power on, system beeps, the HDD will me a noise of some sort and then power shuts down leaving just the fan running. I've had the power supply serviced and it appears to be good.
When I remove the power connector to the main system board the HDD will then spin up and stay spinning. So it looks like an issue with the system board.
I then tested the connector for the system board and found shorts between the 5v lines and GND. When I remove the system board and test the connector again (on the back plane) the short is gone.
So it appears like I have a short of some kind.
Weirdly though , if I power cycle the machine a dozen or more times sometimes it will power up enough to start the HDD and run the POST diagnostics which leads me onto the next faults.
2. No video - I just get a raster line across the monitor
3. Post code error is 01101 which looks like an IC failure according to the Tech Refence manual for the PC (not APC so could be a wrong diagnosis - hence needed the correct manual).

Any help or guidance very much appreciated.

Thanks
 

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mlasham said:
Hi
Click to expand...
Welcome to these forums.

mlasham said:
1. Power on, system beeps, the HDD will me a noise of some sort and then power shuts down leaving just the fan running. I've had the power supply serviced and it appears to be good.
When I remove the power connector to the main system board the HDD will then spin up and stay spinning. So it looks like an issue with the system board.
I then tested the connector for the system board and found shorts between the 5v lines and GND. When I remove the system board and test the connector again (on the back plane) the short is gone.
So it appears like I have a short of some kind.
Click to expand...
First, be aware that I am unfamiliar with the APC.

Reading symptom #1, there is only one cause that appeared in my head:
On many PC's the motherboard is secured to the case via metal screws that screw into metal posts.
On some of those, there is a chance that if an insulating washer is not fitted under the metal screw, that a trace on the motherboard will, or might, get shorted to the case (via the metal screw and metal post).
I wonder if you are in a similar situation, the short appearing after certain flexing of the computer case.
 
modem7 said:
Welcome to these forums.


First, be aware that I am unfamiliar with the APC.

Reading symptom #1, there is only one cause that appeared in my head:
On many PC's the motherboard is secured to the case via metal screws that screw into metal posts.
On some of those, there is a chance that if an insulating washer is not fitted under the metal screw, that a trace on the motherboard will, or might, get shorted to the case (via the metal screw and metal post).
I wonder if you are in a similar situation, the short appearing after certain flexing of the computer case.
Click to expand...
good point though in this case I dont think so as the case is removed and leaves behind a very open frame for the boards to be mounted in so in this case the system board cannot touch anything bar the socket connector and the screw to hold it in place.
 
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