Section V Model 140A
Table 5-4 (cont?d)
Table 5-4. Troubleshotting the Low Voltage Supply (Cont?d)
Supply Symptom Procedure Indication Conclusion
-12.6V output Low 4. Replace collector of Q183 Output rises Q183 OK
(cont?d) and short emitter of Q183 to
Output remains low Q183 shorted
base
5. Short emitter of Q185 to Output remains low Q185 shorted
base
Output rises CR184 shorted
+1oov High or Low 1. Check -lOOV and -12.6V Normal Trouble in +lo0 volt
output supplies supply
Voltage
Abnormal Trouble in -100 or -12.6
volt supply
High Output 1. Remove the WHT-GRN wire Output drops Q141 OK
Voltage from the edge of the printed
Output remains high Q141 shorted
circuit board
2. Replace WHT-GRN wire. Output drops Q143 shorted
Short emitter of Q142 to base.
Output remains high Q142 shorted
Low output 1. Short emitter of Q142 to Output rises Q141 OK
Voltage collector
Output remains low Q141 open
2. Short emitter of Q143 to Output rises Q143 open
collector
Output remains low Q142 open
+250V High or Low 1. Check -100, -12.6, and Normal Trouble in +250
output +lo0 supplies
Abnormal Trouble in -100, -12.6,
Voltage
or +lo0
High Output 1. Measure voltage across Greater than approx CR146 open
Voltage CR146 6.5~
Approx 6.5~ or less CR146 OK
2. Remove green wire from Output drops Q121 OK
edge of board
Output remains high Ql2l shorted
3. Replace green wire. Output drops Q123 shorted
Short emitter of Q122 to base.
Output remains high Q122 shorted
Low output 1. Measure voltage across 0 volts CR142 shorted
Voltage CR146
Approx 6 volts CR146 OK
2. Short emitter of Ql22 Output rises Q121 OK
to collector
Output remains low Ql2l open
3. Short emitter of Q123 Output rises Q123 open
to collector
Output remains low Ql22 open
01638-1 |
ACEC
