power supply wattage calculation?

[Mugiwara303]

hello guys  i have a very old psu and i want to know how mayn watts can deliver, nothing is written on it, it outputs multiple voltage values, thanks in advance

[Rerouter]

as its a very old one, the very first thing you can look at is the fuse, this will tell you your absolute maximum,

next up would be to measure its output voltage and connect a load until the output begins to droop, for this set it to the highest voltage it can output, as for a transformer based one this should reach the regulator drop out voltage earlier. then from your load you work out the wattage you where pulling, (V * I), so now you know your max wattage, and finally set it to a lower voltage and put a larger load across it to try and pull around the same amount of current as the earlier test to see whether it is current limited, thermally limited (if you hear relays clicking as you adjust the voltage it may not be this one), or wattage limited (If SCR mains controlled)

[Mugiwara303]

It doesn't have a fuse, it's so basic just a transformer and 4 diodes and a capacitor, what kind of loads should I put that draws lot of current?!

[ivan747]

Post a picture with a ruler, maybe we can estimate.

[SteveyG]

You could also load it up, look a the voltage drop and estimate from there.