Since there are a large quantity of them, the idea is to build a power supply tester to handle:
- At least Indigo, Indy, and O2 PSUs, in some sort of modular way
- Testing all possible voltage rails simultaneously under load. Somewhat arbitrarily: 3.3V @ ~11W, 3.3Vsb, 5V @ ~30W, 5Vsb, 12V @ ~20W, -12V @ ~2W. Not full load, but good enough to tell whether it would actually behave while powering a machine
- Providing visual indication of low voltage, high voltage, or OK status, per rail
- External outputs for measuring voltage and ripple per rail, with some amount of idiot proofing
- Repeatably surviving a short-through of the high-side switching voltages or mains to the PSU output
- To try and protect the PSU from itself, in terms of its AC input current
- Providing an excuse to start doing electronics again after a decade or so
Anyways I am at the step where I have designed the load boards and have just sent one off to OSH Park. The load boards are per rail, and:
- Provide input protection (somewhat excessively)
- Indicate the range of the voltage
- Connect it through to a resistive load bank
Once the load boards and main board are working in a satisfactory way, I will put them in a nice custom metal enclosure from Protocase.
I will try to post updates here occasionally so that it doesn't look like all those SGIs will just be gathering dust forever! Meanwhile, some of them are also getting cleaned off.
Positive load board: top / bottom. I think it turned out nicely.