How to determine smps power rating

[harp]

So, I have old smps NEC psu, who not work correctly... it has no label table of declaration, and I supose that is from some printer or so.
The output is 34v.
Switching element is STR16006
Mains caps are 2x 470uF/250v
Output caps is 10000uF/40v

I dont know a topology, only have interest to know in which way should determine power for what designed for.

[PeteS in CA]

So, picking out a few bits and pieces:

It looks like the TDK transformer has an 8823 date code, i.e. 23rd week of 1988.
The switch device may be a clone of the MJ12006, an 8A, 450V NPN transistor, designed for switching power supply use.
I don't see an output inductor, so I think the topology is discontinuous flyback.

Putting these latter two together I'd guess the power rating would have been 100-150 watts. Given that its some 35 years old, it is possible that the electrolytic capacitors have dried out and/or the aluminum oxide dielectric has thinned, making re-forming advisable.

[harp]

Thank you, so about 4A output is answer.

Have you maybe aplication/test circuit for MJ12006 / STR16006, I try to find some info but nothing.
The thing is that board of psu was cracked apart and with desoldered all 4 small caps, so, before anything to do with troubleshooting is to find proper value of this four caps. I put some random caps, they fit into silk screen size but psu it not work reliable (safe).
I think that older technician may be familiar with this STR16006 circuit.