25 Apr
2007
25 Apr
'07
5:34 p.m.
WY-30, part no: 900023-01
Intial three I checked, are non-responding and no screen. Opened up
one and found that power supply is working and correctly regulating
5V and other supplies for the CRT (heater glowing direct power from
PSU) but the deflection section not sweeping. Checked digital
section and found the 68B00 (6800) is non-functioning, not even a
reset twitter on any of signals at instant of power on. Tried
replugging the ICs, xtal is oscillating thru a IC with many outputs.
Any suggestions?
Is the processor getting a clock signal? If not, where does it come from
(trace back from the processor).
What about the processor reset pin? Is the processor being held in the
reset state?
-tony