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Old 9th Sep 2019, 3:36 pm   #43
ajgriff
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Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,587
Default Re: Defective/ fake LM317T

This is one of those threads that has generated so much noise that it's hard to see the wood for the trees. To my (simple) mind the following chronological extracts and the attached image crop may hold the clues needed to solve the mystery:

Quote:
Originally Posted by Jolly 7 View Post
The kit did not come with the insulated washer or mica sheet either. Removing the IC has caused damage to the board and it looks like it could be a write off.
Quote:
Originally Posted by Electronpusher0 View Post
It looks like the pot is just being used as a variable resistance, the bottom 2 pcb pads for the pot look joined together, in which case you only need 2 wires.

Peter
Quote:
Originally Posted by Jolly 7 View Post
Replacing the 10K linear pot with a 22K linear one and turning it clockwise gave acceptable voltage readings till around midway, but bizarrely the readings started to fall after that to reach 1.2V again.
Quote:
Originally Posted by ajgriff View Post
It looks to me as if the 'flying pot' might have been wired with the track ends connected to the negative rail and the slider to the Adj pin.

Alan
If I were the OP I would:

1. Remove the flying pot with its leads and put back the original.

2. Reinstate the supplied LM317 assuming it too hasn't been fried.

3. Make sure that any circuit board damage is made good and that there are no shorts or discontinuities.

4. Try again.

Alan
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