Maintenance
7-13
7.9.5 Display checks
To troubleshoot the display board, disassemble it from the
front panel, and then reconnect the power cable and ribbon
cable with the display board on a bench.
A troubleshooting procedure is outlined in Table 7-9.
7.9.6 Using an extender card
To access circuitry on the plug-in relay cards of the Model
708A, use a Model 7070 Universal Adapter Card. The Model
7070 must be configured as an extender card by placing the
configuration jumper in the EXTEND position. See the
Model 7070 Instruction Manual for complete details on
using the card.
7.10 Handling and cleaning
Since matrix card rows are extended on the analog backplane
of the Model 708A, a contaminated backplane will degrade
card isolation specifications. If an isolation problem exists,
the backplane should be cleaned.
The following procedure describes how to clean high imped-
ance PC boards, such as the Model 708A backplane, but it
can be used to clean all PC boards. To remove the backplane,
refer to paragraph 2.2.
1. Handle the board by the edges only. Do not touch any
board surfaces. When servicing, wear clean, white cot-
ton gloves.
2. If making solder repairs on the board, use a flux that is
rosin RMA based. Remove the flux from these areas
when the repair is complete. Use methanol and clean
cotton swabs to remove the flux. Take care not to spread
the flux to other areas of the board.
3. Once the flux has been removed, swab only the repaired
area with methanol, and then blow-dry the board with
dry nitrogen gas.
4. After cleaning, the board should be placed in a 50°C low
humidity environment for several hours.
Table 7-9
Display board checks
Step Item/component
Signal
Comments
The following display board signals are referenced to digital common. When troubleshooting the LED array, check for
these signals when the LED is lit (e.g., crosspoint A1).
1
2
3
4
U204 pin 12
U205 pin 17
Front panel buttons:
U207 pins 1, 5, 6
U137 pins 3-5, 11-14
Source driver
Sink driver
Button columns
Button rows
Card row A - Logic high for 9ms.
Card column 1 - Logic low.
Logic high with a low going 1ms pulse.
Logic high with a low going 1ms pulse when button is pressed.
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
Summary of Contents for 708A
Page 135: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...
Page 136: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...
Page 137: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...
Page 138: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...
Page 139: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...
Page 145: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...
Page 146: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...
Page 147: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...
Page 148: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...
Page 149: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...
Page 150: ...Artisan Technology Group Quality Instrumentation Guaranteed 888 88 SOURCE www artisantg com ...