GW Instek GDM-8245 - Display Board Checks

Trouble Shooting
41
Display Board Checks
If the display is blacked out after pressing the power
button, it indicates a problem either on the display board
or the power supply circuitry. Please refer to the Digital
control circuitry in the digital control logic section, power
supply circuitry section and use flow chart 1 and Table 2
listed below for the troubleshooting.
Flowchart 1 Display related problem trouble shooting process
Table 2
Step
Item
Expected Conditions
Comments
1
Power-on display
test
LED display should be
lit up for 2 seconds
Push down the power button
to start the test
2
J201 pin 18 to pin
16
+5VDC
Digital +5V supply on the
display board
3
U202, pin 19
4MHz clock pulse
Controller’s 4MHz clock
pulse
4
U205’s clock pulse
on pin 11
268Hz clock pulse
Referenced to pin 10
5
U604’s clock
Pulse train of about
268Hz can be
measured
On J601, pin 14 to pin 16
6
U603’s clock
Pulse train of about
268Hz can be
measured
On J601, pin 10 to pin 16
No display after pushing
down the power button
Did you hear a beep
after pushing down
the power button?
Check the power supply
outputs against the power
supply block diagram on page
33 and Table 1
Check the digital
control logic
circuitry against
Table2
No
Yes
Though power
supply outputs have
been confirmed
normal, there is still
no display.