1. Home
  2. Electronics Repair
  3. Autopsy on the body of a voltage regulator

Autopsy on the body of a voltage regulator

Well sort of as still functioned and no downstream damge, but replaced of course anyway. USA kit 120V, powered up in UK at 240 V this LM317T set for 15V out survived 40 or 50V instead of 25V at its input. Clamped to heat sink with a thick Ali bar pulled against the body so sandwiched between 2 bits of ali. The grey PTFE/Teflon or whatever it is insulator was "welded" to the metal of the V Reg and all lettering disappeared from the other face. Anyone else seen this before, no explosive eruptions from the body at all.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

formatting link

Reply to
n cook
Loading thread data ...

hmmm, the 317 data sheet from national doesn't list an absolute V max input but does list a input output max differential V of 40V so for a

15V output you should be good to a 55V input. Still if it were me I'd try to knock down the input DC somehow. If you go thru the numbers for heat/thermal transfer you're probably right at the limit. That maybe the reason you've "welded" the insulator and "cooked" off the lettering. Try to get a sense of the temperature of the device, I suspect you will find it's a bit on the toasty side.

tomh

n cook wrote:

Reply to
tomh

of

explosive

I just cracked it open and it looks or rather looked perfectly healthy

Reply to
n cook

You must have a lot of free time on your hands! :-)

Dave

Reply to
Dave D

So I can take it on good authority that the Lincoln Lab does no research.

Reply to
n cook

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.