Altair 680 power supply...

dwight elvey dkelvey at
Sun Jan 17 10:46:51 CST 2010


 I just came on an unusual problem. I'm fixing a

power supply with +12 and +5 outs. It uses 2

723 regulators. The one on the +12 was blown.

I bought another 723 regulator and it didn't

seem to be working.

 I checked the voltages and noticed that the

5 volt one that is working fine, has a Vref of

about 3 volts while the new one has a Vref

of 7 volts.

 Looking at the specs, it is suppose to be 7 Volts.

Looking at the resistors on the board, the

board expects 3 volts.

 Has anyone seen these with different reference

voltages before?

 I'll have to change the feedback resistors ( not

a big deal ) but this is a strange one.


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