HP 141A - Troubleshooting the

Section V
Table 5-5
Model 141A
Table 5-5.
Troubleshooting the Low-Voltage Supply
SUPPLY SYMPTOM
-12.6
I - 100 I +loo I +250
I I
No current limiting
Q421 not protected
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
22
22
22
0
0
0
0
0
18
17
0
14
14
9
0
5
4
1
0
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
ok
142
136
0
113
110
69
0
63
29
12
60
119
117
111
110
106
ok
96
94
93
93
93
92
81
80
75
28
ok
ok
ok
ok
ok
ok
ok
ok
144
135
0
145
140
75
0
77
75
75
77
-
280
282
194
200
218
198
274
292
295
2 94
286
295
55
55
200
114
ok
ok
ok
ok
ok
ok
ok
ok
344
335
0
342
327
184
0
185
167
163
168
-
PROBABLE CAUSE OF TROUBLE
Q483 open
(B - E short)
CR425 open
Q444 open
(B - E short)
Q443 short
(B - E - C)
Q423 open (B
- E short)
CR426 short
CR425 short
Q422 open (removed)
Q421 open (green lead open)
CR426 open
CR445 open (cause Q421 short)
Q421 short
(E - C)
Q422 short
(E - C)
Q423 short (E - C)
Q421 open (removed)
F421 open
Q442 open (B - E short)
Q441 open
(base disconnected)
Q481 short
(C - E causes Q484 B - E short)
Q482 short (C
- E causes Q484 to fail)
Q484 open (removed)
Q482 open (removed)
Q482 short (B
- E)
Q481 open
(base lead open)
Q483 short (C
- E)
Q484 short
(C - E)
Q461 short (C
- E)
Q462 short (C
- E)
8464 open (E
- B short blows F461)
Q441 short (C
- E)
Q443 open
(B - E short)
Q462 open (B
- E short)
Q463 short (B
- E blows F461)
Q463 short (C
- E)
+lo& removed from -1OOv supply
Q461 open
(base lead open)
Q461 open (removed)
02567-1
5-7