13-01-2017, 07:56 AM
Hi Haydon / Lou,
The attached document shows LM723 (IC1) pin voltages for normal operation at outputs of 10 V and 14 V, i.e. when the supply is working properly.
It's a pretty standard configuration driving a composite Darlington configuration consisting of a TIP31C feeding 5 x 2N3055s in parallel. You can find examples of this configuration on the internet, but there is one important difference. The Frequency Compensation pin is being used for Remote Shutdown, via a diode from pin 13 of IC2D to the frequency compensation pin of the LM723 (yes, pin 13 on both ICs.) I have a strong suspicion that the fault is actually related to IC2.
Best wishes,
Lew.
D-3800_LM723_Normal.pdf (Size: 41.64 KB / Downloads: 887)
The attached document shows LM723 (IC1) pin voltages for normal operation at outputs of 10 V and 14 V, i.e. when the supply is working properly.
It's a pretty standard configuration driving a composite Darlington configuration consisting of a TIP31C feeding 5 x 2N3055s in parallel. You can find examples of this configuration on the internet, but there is one important difference. The Frequency Compensation pin is being used for Remote Shutdown, via a diode from pin 13 of IC2D to the frequency compensation pin of the LM723 (yes, pin 13 on both ICs.) I have a strong suspicion that the fault is actually related to IC2.
Best wishes,
Lew.
D-3800_LM723_Normal.pdf (Size: 41.64 KB / Downloads: 887)