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Comments on Troubleshooting Table for LM723 Regulators
As you can see, there are, potentially, a lot of things to worry about. The LM723 is
rarely used these days unless a specific feature requires it. I don't want to scare you,
but anybody who troubleshoots a number of old-style regulators has to understand
the circuit thoroughly, so he can tell immediately when he looks at a couple voltages,
whether he is on the right track. He has to have the concepts behind the chart built
right into his head, or it would take forever to troubleshoot a basketful of bad mod-
ules. (Okay, he or she. . . .)

Figure 14.6. Full-Wave Rectifier.

Table 14.6 Troubleshooting Full-wave Rectifiers
Indication of Trouble Possible Cause Solution
Input amplifier runs badly. Anything? Apply Vi, = +O. 1 to +IO VDC
and troubleshoot it
per the procedure
above, for inverting
op amps.
Output amplifier runs badly. Anything? Apply Vin = -0.1 to -10 VDC
and troubleshoot it
per the procedure
above, for inverting
op amps.
Bad diodes? Check for reversed or
shorted diodes. Watch
A 1 output with scope.
Bad AC response. Diodes too slow? Check out diodes in
little sockets; com-
pare to known good
diodes.
Amplifier too slow? Check amplifier with
large and small AC
signals, fast and
slow.
Bad DC errors hot. Diodes too leaky? Compare leakage to known
good diodes.