E8257D/67D, E8663D PSG Signal Generators Service Guide 31
Troubleshooting
Troubleshooting Assembly–Level Problems
This board contains the circuitry to disable the power supply. The ON_OFF
control line is pulled to a TTL low to disable the power supply.
Another function of the power switch/flat panel interface board is to route
the 8 data bits from the A18 CPU to the A2 Display.
— a front panel board that contains the front–panel hardkeys, softkeys, and
RPG
— a dc to ac inverter, which turns the LCD on and off via control lines received
from the CPU
The inverter also converts the 5.2 Vdc to approximately a 160 Vrms, 40 kHz
signal to drive the LCD.
Display Controls
Contrast
There are two contrast hardkeys below the A2 Display. The left up arrow key
increases the contrast while the right down arrow key decreases the contrast.
Brightness
The A2 Display brightness can be adjusted from 50 (high brightness) to 1 (low
brightness) using the RPG, arrow keys, or the numeric keypad.
Other display features located under the Utility > Display softkey, include a
screen saver and inverse video.
Display Tests
The following two screen tests are available for the LCD:
— the Black Pixel Screen Test turns the display dark
— the White Pixel Screen Test turns the display bright
Softkey Location: Utility > Display > More (1 of 2)
To exit the test, press any front panel key.
Symptom: Dark display
1. Ensure that the front panel green power on LED is on. If not, refer to
“Power Supply Troubleshooting” on page 37.
2. Press any front panel key to disable the screen saver.
3. If the display is still bad, check P12 on the A31 Motherboard for the
following signals:
Signal State
P12−15.2 Vdc
P12−3 LIGHT_EN >3 Vdc
To Next Page
Loading...
Need help?
General
