Voltage regulators run very hot (C84, J99)

[jsiwek]

Is it normal for the voltage regulators to be too hot to touch for the C84 and J99 boards? I built three C84's and two J99's, and all the test voltages are correct for all the boards. It would be hard to believe that I did something wrong or had bad parts on all 5 boards, but I just wanted to check to make sure that it is normal for the regulators to run that hot.

Thanks!
Jim

[tpryan]

The regulators should get warm, but not too hot to touch. Keep in mind that the higher you set the operating voltages the cooler the regulators will run.

[jsiwek]

Thanks for the response, Tim...

I set the voltages for the three C84's to the suggested +18V/-18V and +20V/-20V for both J99's. I can touch the heatsinks briefly but they are too hot to leave my finger on for more than a few seconds.

All the voltage measurements are correct and they all work & sound great. The regulators on my three A12's run much cooler. I've checked my work & everything seems to check out. It would seem odd that I would have made the same mistake on all four modules since they where each built individually.

I have a laser temperature sensor, but it is at my office. I will take a temp measurement to see how hot it really gets.

Thanks,
Jim

[jsiwek]

I took the temperature measurements and the voltage regulators for the C84's (the hotter of the two) are running at about 65 C, well within their spec range (125 C), so no worries.

I guess I didn't realize how hot 65 C (150 F) feels to the touch.

Side note, I saw some questions about hot John Hardy 990C's, I measured them at running at 50C, and he burns them in at 100C.

Jim

[bkspero]

Remote reading (IR) temperature meters (and I am presuming that is what you mean by a laser thermometer...as they often have laser pointing indicators) can have a fairly wide angle of detection. If you are 12 inches away, the sensor may be analyzing an area as much as 2 inches in diameter. Some average the reading over the field of view and some bias the output to the peak.

So its possible that your perception is accurate and that the IC is hotter than 65 deg C (150 F), but the sensor is reading an averaged temperature over the IC and some of its surroundings.

Probably not the case, as 150F is pretty hot, but worth the small investment to think about it.

[jsiwek]

Thanks, yes it is an IR sensor. It seems to have a pretty narrow focus. Taking the measurements within an inch or two of the component, it will measure 20 degrees F difference between pins of the regulators (ie, on one pin, the temp will read 130F, the next pin over will read 150F) so I think it is probably close enough to know that everything is within the heat toleances of the components.

Thanks!
Jim