HP 6654A - Burnt Resistor

[Centmo]

I started noticing a magic smoke smell coming from my HP 6654A, so I opened it up and traced it to R690. Now, the manual is awesome and tells me exactly what the part is so it would be easy for me to replace it. However, resistors don't just randomly overheat without a different underlying cause. Does anyone here have experience troubleshooting/repairing this type of power supply? It would make an effective doorstop, but I'd prefer to keep using it as a power supply. Thanks in advance.

[fzabkar]

I would check CR700. It appears to be involved in crowbar protection. CR700 may have sacrificed itself and, in so doing, it may have damaged its gate resistor.

[bbqws60]

check c694 

[Swake]

If this is indeed crowbar related then the root cause of the issue might also have been external. For example, when the PS is used to charge a battery and it gets inadvertently connected inversely or the PS is configured to output a much lower output voltage that the battery it is connected to.