At 15:06 -0700 8/6/10, willy wrote:
>I need to identify a P.S. mod. 699-0133,
>the label on side says; Dyna Comp Inc,
>+5V 4A,  +12V 1A,   -5V .25A,  -12V .25A
>It is sick so I need schematic.
>Thanks


That looks like 36 watts which is tiny by modern standards. Give us a hint 
about what it's from. Did it come from Apple?

But schematics for such things are rare indeed. Using an isolation transformer 
the first thing to check is the rectified line voltage which ought to be a few 
hundred volts. Input capacitors can be shorted causing a fuse to pop or the 
bridge rectifier can be kaput.. After that it's either a failure of the high 
frequency power transistor that drives the power transformer or the integrated 
circuit that controls it. Even if you had the schematic finding those old parts 
can be a nightmare. Sometimes you can read the part number of the controller 
chip and find a datasheet for it. It's likely that the recommended circuit for 
the chip looks a whole lot like the final product.

If you're lucky you might find a bad solder joint. In those days reflow 
soldering tended to be set for the small joints. The larger ones didn't get hot 
enough and proceeded to develop cracks. Fixable with a soldering iron and some 
rosin flux.
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