I just purchased a used BK 4003A function generator. Everything is working fine but I have noticed that there is an area about the diameter of a red bull can on the top right side of the case that gets hot to the touch. It is not so hot that I cannot maintain skin contact. There is a brownish discoloration about the size of a quarter on the exterior of the case above that point.

Is this normal heat from the power supply or is it something that I should be worried about?

 

It is probably nothing, I'm betting this function generator has an internal power supply, which means it has a spot where the excess voltage is dumped as heat. If it is very old at all (which it probably is) this heat will discolor the plastic.

If in doubt you could open it up and take a look see.

http://www.testequipmentdepot.com/b...ors/4003.htm?gclid=CLucivzMhaMCFQG3sgod8QKTaw

There is supposed to be a manual available at the above site.

 

Yes, it does have an internal power supply. Thank you for the quick response.

 

Unfortunately, the B&K manuals never tell you anything about the internal construction and schematics are rare if they are not nonexistent (I've looked at most of the current B&K manuals and I don't remember seeing any schematics).

 

You might have a "leaky" capacitor in the power supply section. That would cause excess heating.

Posting high-res photos of that area would help to figure out what the problem might be.