Motorola R-2001A Service Manual page 83

Test Paragraph
5-137 DVM DC mode is inoperative
5-138 No horizontal sweep
No vertical display
5-138
5-138
No vertical sync
Table 5-6. System Troubleshooting (Cont)
Fault
5-40
Troubleshooting Procedure
NOTE
The DVM AC signal from the external input is
multiplexed with the other signals to be mea-
sured. Thus only short bursts of the input signal
will be observed at TP8.
If signal is not present at TP8 replace the
Scope/DVM Control module.
3. If the signal is okay to TP8 of A3, replace the
Processor I/O module (A7).
1. Check for the DC input level attenuated by
factors of 10 to less than 1 volt at pin 22 of the
Front Panel Interface module (A12). If not
present or if greater than 1 volt, replace the'
Front Panel Interface module.
2. lfthesignalisokayfromA12,switchtotheAC
mode and apply an AC signal to the DVM in-
put. Proceed from step 2 under DVM AC
mode inoperative.
1. Check for a voltage level between -2.0 VDC
and +2.0 VDC at TP4 of the Scope Amplifier
module (A2). Ifthevoltagecannot be brought
within range with either the vertical range
attenuator or the vertical position control
replace the Front Panel Interface module
(A12).
2. If the voltage at TP4 is okay replace the Scope
Amplifier module (A2).
1. Check for the input signal at TP4 of the Scope
Amplifier module (A2). If not present replace
the Front Panel Interface module (A12).
2. If signal is okay at TP4 replace the Scope
Amplifier module.
1. Check for the presence of sync pulses at pin
12 of the Scope/DVM Control module (A3)
and for a nominal zero volt sync present level
at pin 76. Ifeithersignal is not present replace
the Scope/DVM Control module.