[HECnet] VS4000/60 power supply dead... or not?

[Clement T. Cole]

Yes They are wire wound power resisters that are made taking wire wound around a ceramic base.  From your markings it would mean it is rated @ 2watts within 10% of the rated value of 15000 ohms (i.e. at least 13500 ohms and not more than 16500).  These values tell you the maximum current / voltage etc that can be running through it before it will burn up.  But the reason why those resisters are mechanically off the board is because they do get very hot as they typically do carry a lot of current and put off a lot of heat as they drop the voltage at that current. 

You can try to test it with a DVM on resistance mode but it's going to tell you the impedance of those two points in the circuit so if anything is parallel  with the resister you will pick up that also. 


Sent from my iPad

On Feb 15, 2016, at 1:53 PM, Jordi Guillaumes i Pons <jg at jordi.guillaumes.name> wrote:

>>> 
>>> Some things never change.. ;)
>> 
>> ATX PSUs are far more abundant. ;)
> 
> 
> Well, I have replaced the fuse and it is still dead. I have double checked the PCB and I have found a part that seems to be charred.
> 
> http://i.imgur.com/4hpUKpb.jpg
> 
> I’m not sure what the big grey things are. I’d guess those are some kind of resistors (labeled 2W10% 15K), but I have not seen something like that before. If so, the one horizontally in the pic seems to be burnt. The PCB is charred underneath it, and no current goes thru it accordint to my multimeter.
> 
> On the other hand, I will have a stupid trouble: I can’t remove the PCB from the chassis, because one of the TORX screws is… well… screwed. The turndriver does not fix onto its head. I guess I’ll have to do a compraption taking a derivation from the (suposed) resistor out of the PCB. Unless there is any kind of magic for a broken screw head (and no, I can’t vandalize this one).
> 
>