Linear Technology 1083CP adjusting problem

trombone · 26th January 2006, 08:25 PM

I was always under the impression that these regulators worked or they didn't. Mine is kind of half way. I use it for a 6.3 filament supply. I recently had to rebuild the circuits around it, and all of a sudden, it puts out 4.3 VDC and won't adjust up or down from there. I'm assuming I made a mistake wiring the thing, but wonder: is it possible that it could work well enough to put out a voltage but that it can't regulate it? Or should I just keep looking for a wiring problem?

The question is compounded because I'm having trouble finding a new piece. Everyone seems backordered.

SY · 26th January 2006, 08:41 PM

Three possibilities occur to me:

1. You made a wiring error and everything will work once you fix it.

2. You made a wiring error and have transmuted a silicon chip to carbon.

3. You've got an oscillating regulator.

It's also possible that you're drawing more current than the device would like to see, possibly because of possibility 1.

Possibly.

EC8010 · 26th January 2006, 08:51 PM

Time for an oscilloscope...

trombone · 27th January 2006, 03:20 AM

Thanks guys. I did a little reading about LT regulators, comment about oscillating took hold. It was a bad bypass cap.

EC8010 · 27th January 2006, 08:56 AM

Excellent.

26th January 2006, 08:25 PM	#1
trombone diyAudio Member Join Date: Jan 2005 Location: Boston, MA	Linear Technology 1083CP adjusting problem I was always under the impression that these regulators worked or they didn't. Mine is kind of half way. I use it for a 6.3 filament supply. I recently had to rebuild the circuits around it, and all of a sudden, it puts out 4.3 VDC and won't adjust up or down from there. I'm assuming I made a mistake wiring the thing, but wonder: is it possible that it could work well enough to put out a voltage but that it can't regulate it? Or should I just keep looking for a wiring problem? The question is compounded because I'm having trouble finding a new piece. Everyone seems backordered. __________________ Trombone

26th January 2006, 08:41 PM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	Three possibilities occur to me: 1. You made a wiring error and everything will work once you fix it. 2. You made a wiring error and have transmuted a silicon chip to carbon. 3. You've got an oscillating regulator. It's also possible that you're drawing more current than the device would like to see, possibly because of possibility 1. Possibly. __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

26th January 2006, 08:51 PM	#3
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Time for an oscilloscope... __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

27th January 2006, 03:20 AM	#4
trombone diyAudio Member Join Date: Jan 2005 Location: Boston, MA	Thanks guys. I did a little reading about LT regulators, comment about oscillating took hold. It was a bad bypass cap. __________________ Trombone

27th January 2006, 08:56 AM	#5
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Excellent. __________________ The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...

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