30 Dec
2012
30 Dec
'12
2:54 p.m.
Dan Williams said the following on 12/30/2012 5:11 PM:
Hi,
I have managed to get around to having a look at this machine. It is a
model 231.
I am getting nothing on the screen and no beeps when in diagnostic mode.
The PSU is on and the fans are running. I have checked the schematics and
the voltage is correct on all pins coming out of the supply and there is
voltage going into the screen.
The screen is not 'firing' up as I would expect. I am not an expert on CRT's
Anyone know anything about these machines or how to proceed. I have found
online service manuals for the screen and machine as well as full
schematics for both.
Thanks
Dan
Hello Dan,
One of the first things to look at is to see if the IOC (the back panel
board) is running. If you don't get any beeps when the three-position
switch is in diagnostic, that's a bad sign for that board. If you turn
up the intensity on the crt with the pot on the back panel, can you see
if there is a raster? If there is, that means that, at least, the crt
controller chip on the IOC board has been initialized.
I have found that the edge connectors on the interconnect cables are
notorious for bad connections. Clean the edges on the boards and check
the connectors for corrosion and tightness.
Dave