HP HP-97 - Page 103

HP-97 Component-Level Maintenance
Table 4-13. Logic PCA Troubleshooting Procedure (Continued)
STEP ACTION
6
Measure VSS and VB.
T.
Measure both the DC and
ripple voltage of VGG.
8.
Check waveforms &1, $2, SYNC,
RCD and STR (see figures 4-5
through 4-7).
If VB is not between 4.4 and
VSS Vdec, go to step 11.
If VB is between 4.4 and
VSS Vdec and VSS is between 6.0
and 6.5 Vdc, go to step 7.
If VSS is not between 4.4
and 6.5 Vdc, go to step
15.
If VGG=0, go to step 12.
If 0>VGG>-11 Vdec, go to
step 13.
If VGG =< =11 Vdc and ripple on
VGG > 200 mV, go to step 14.
If VGG =< =11 Vdc and ripple on
VGG =< 200 mV, go to step 8.
If all waveforms are satis-
factory, go to step 9.
If not, check for open or
shorted traces. Then re-
place one at a time the
ACT, PIK, ROM O, CRC, ROM 1,
ROM 2, ROM 3, ROM 5, ROM 6,
Q1, CRS, R3, C4 and R4 until
all the waveforms are cor-
rect.(Return to step 8 after
each replacement.)
4-35