N Cook wrote in message
...
I need to get a rough idea of the amperage capability of a small 5V SM ps
before attaching it to its load, to simulate, just in case the regulation
is
kapput.
Does anyone know how the volume of the smps hf transformer is related to
power
throughput or any other method? It uses a TOP66 of sufficient rating to
drive a few hundred watts across but the ps is relatively low power , but
unknown rating.
The one in question is only about 20mm cube

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/






I've fathomed out how the ps works. The 5V regulator uses only a 100mA TO92
transistor because the error is fed forward via an optocoupler to the sm
oscillator.
The 5V line defines the output to +/-18V as well.
The original trouble was wavering 5V, which has returned, prior to replacing
some more caps . In the broken mode if say 2.5V on the 5V o/p then only
+/-10V on the unloaded +/-18V lines.

Scaling linearly, an at hand 70 W smps, with its 45mm cube transformer.
I would estimate volume for vol then this one with 20mm cube would be about
6W total. Allowing 1W for the few op-amp supplies and 2 relays then only 1
amp at 5V, its suppling 30 odd 74HC and 3 LSI.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/