Table 5-3. Power Supply-measurements.

TM 11-5820-803-12

Voltage

Limits

Connector pin

+5V

+4.95 to +5.05V

A2A2A2A947

-6V

-4.95 to -5.05V

A2A2A2A9--4

+15V

+ 14.98 to + 15.02V

A2A2A2A9-13

- 15V

- 14.98 to -15.02V

A2A2A2A9-15

within the limits of table 5-3. The voltage adjustments

5-9.

Blower(s) Not Operating

are located within the power supply, and each access

If both blowers are not operating, check for 115V ac

hole is clearly marked to indicate the voltage controlled

between terminals E7 and E8. If voltage is not present,

by the adjustment.

refer to direct support If a single blower is not operating,

omit the voltage check and replace the inoperative

blower.

NOTE

All voltages returned to A2E2.

5-10. Cards or Connector Not Properly Seated

Remove power and remove top and bottom covers.

5-12. Thumbwheel Switch Assembly Defective

Inspect that all cards are flush with one another in the

trouble symptoms indicate that modem is not

file. Check to see that each card is properly employed in

operating at selected data or symbol rates, a continuity

its card guides Inspect all connectors to ensure that they

check of the thumbwheel switch assemblies (fig. 5-2) per

are properly seated.

table 5-4 will determine whether these assemblies are

functioning properly. If continuity per the table is not

5-11. Power Supply Out of Adjustment

obtained, replace the defective switch assembly. If

a. Remove power and remove the bottom cover of

continuity per the table is established and trouble

symptom remains, refer to higher category of

the modem. Observe caution in paragraph 5-5 for

maintenance.

operation of the modem with the covers removed.

a. Remove power and modem top cover.

b. Remove the alarm circuits card, A2A2A2A9 and

install the card extender in its place.

b. Check switch continuity in each dial position in

accordance with table 5-4.

c. Using the digital voltmeter to monitor the

appropriate connector pin (fig. 5-1), adjust each power

supply (A2PS1) voltage as required to obtain outputs

Figure 5-1. Typical PC card pin locations.

Change 2 5-3