Motorola R-2001A, Service Manual

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5-118. Extended Alignment Procedure
5-119. DVM
1. Remove the top and bottom covers of the-R2001A.
2. Connect the R2001Atoa primary power source and turn it on. Allow approximatly 15 minutes warm up
before proceeding with the alignment procedure.
3. Short the center conductor of the DVM Input Jack on the front panel to ground. Connect an external
DVM with a floating input between pin 1 and pin 6 of J3 on the bottom side of the motherboard.
4. Adjust the Coarse and Fine DVM Zero potentiometers on the Front Panel Interface board (Figure 5-17)
for a reading of 0 ±0.5 mV on the external DVM.
Figure 5-17. DVM Input Buffer Alignment Points
5. Remove the ground from the DVM Input and connect the DVM Input to TP 12 of the Scope/DVM
Control Board. (Figure 5-18)
Figure 5-18. Scope/DVM Control Test Point Numbering
6. Disconnect the external DVM from pins 1 and 6 of J3 and connect it to TP 12 of the Scope/DVM Control
Board and chassis ground. Note the DVM reading for TP 12.
7. Reconnect the external DVM between pin 1 and pin 6 of J3. The external DVM should show a reading
equal to one-tenth the voltage at TP 12 noted in paragraph 5-119.6 plus or minus 10 mV. If the reading
falls outside this range it will be necessary to physically disconnect the front panel from the chassis in
order to adjust the DVM Input Gain Potentiometer on the Front Panel Interface Card (Figure 5-17).
Adjust the DVM Input gain for a reading on the external DVM equal to one-tenth the voltage noted for
paragraph 5-119.6. Reconnect the front panel to the chassis.
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