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I'm working on a Dukane MCS350 rack and found the main 24V PS was at 32 volts. Seemed like a problem because 24V goes to relays, regulators, consoles and I didn't want components to be stressed and fail. True, board regulators get the volts down but it means there’s that much more overhead to dissipate.
I took the supply apart and it's just a transformer, bridge rectifier and big capacitor. No regulation. I opened up the transformer and there are no voltage adjust windings.
So now I'm considering replacing the stock supply with a Power One 24V 4A linear.
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A second problem: I found the 120VAC neutral is hardwired to the safety ground inside the supply. This means part of the return current from the hot side flows back through the safety ground. I plan to separate the two and connect safety ground to the chassis.
Next I need to consider the other grounds: DGND, AGND. In my opinion these should be connected, but at one point such that digital current does not flow through AGND and muck it up. Also, I think DGND should be connected to safety ground so that the electronics don’t float and drift up to some tingly voltage. Seems like the analog card would be a decent place for both connections.
Thoughts Anyone?
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