[G4] Power supply woes

[Doug McNutt]

At 10:24 -0400 10/11/05, jim carbone wrote:
>Here's what is says on the fuse, "250V 8A 51S" I don't know what the "51S" stands for.

It is an 8 ampere fuse which will safely switch a 250 volt AC power source. The S probably stands for 'slow blow" which is the opposite of the fast fuses typically used on electronic equipment. It may have been chosen to support the harmless inrush current which charges the filter capacitors as power is applied.

>Anyone with similar troubles in the past that can help me get up and running fast? Time is so important to me right now that I'd even just overnight a new PS here if that meant I could save a few days of hunting down and blowing out more fuses.

It is unlikely that the fuse or a power surge is at fault. Either 1) something is drawing too much current at the output side  or 2) the power supply has a failed capacitor, diode, or switching transistor. (1) is unlikely because the power supply is probably current-limited by design.

The fastest way up to speed is a replacement supply. It would be smart to start up first with unnecessary equipment - a second disk  - disconnected.

Finding internal maintenance information of the power supply is next to impossible. You may find a part number on the controller chip. If so it can be Googled and you might find suggested circuitry from its manufacturer. An isolation transformer on the workbench is a requirement for working with the cover off. The first parts of the power converter are directly connected to the power line and it is unsafe to measure with any grounded equipment like an oscilloscope.

-- 
-->  The best programming tool is a soldering iron <--