The fans that were in look as though they were 6V ones in paprallel , so
being overdriven when taken to 12V explains the knackered state of them.
No labels, but 3V starts the working one and takes .1A at 6V and at
physical size 60x60x10 is probably 6V,0.1amp rating. Not that they were
the originals as the fixing bolts were hacksawed to length and the
housings are for 20mm thick fans. What I thought was a fudge diode under
the collector pin of a TO92 was in fact a 6.6V zener, in the fan control
circuit on the SMPS pcb. That fudge diode has no marking on the overlay
but was of the same series as other zeners on that board and the TO92
uncropped long legs, to accommodate this zener , and all looked original
manufacturer's PbF soldering. So overall quite a mess. At least I now
know what zener sets the PTC sensing line, 2 of them in series one on
the SMPS rectifier heatsink and one on the PA . And which one sets the
12V as uses 28V supply it is quite critical. Now to find what this 6V6
zener function is, will change it to 3Vzener and suck it. So far the fan
control circuit has stuck resolutely to about 5.5V starting voltage via
the TO220 pass transistor.
The replacement fans I put in there are 12V
I suspect the pcb was designed for 2 fans in series,24V , 12V each,hence
28V supply, as in the earlier 1062 amps