On Jun 3, 2010, at 7:11 PM, Stewie de Young wrote:
The MDDs PSU have fuses in as well. Replacing the fuse sometimes works but usually points to something else amiss like capacitors as Deaner says. One caveat though if you are going to attempt to fix these yourselves is to take care inside the PSU. Even turned off and disconnected , these retain enough zzzz's to give you a nasty jolt.
The primary voltage is 120 in North America and 230 most places elsewhere.
The PSU is auto-switching and the secondary voltage on the caps is 325 volts with enough energy to cause more than a nasty shock.
Fuses are usually found in the primary circuit, but not in the secondary circuit.
The fuse is there to protect the PSU from a converter failure (one of the four diodes) or an inverter failure (one of the switching transistors).
The output of the PSU is protected by a "crowbar" circuit which temporarily places a short across the output, thereby causing the inverter to stop.
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