Simple Controller

[WALLSHIRTS]

This is a question for Hugh Norwood.
The LM317 shorted out to the metal case, and the replacement isn't working. I'm getting full voltage at the output and at all three pins of the LM317. Also the potentiometer has no effect. I'm not sure what voltages I should be seeing. Any ideas as to what could be wrong?
Thanks, Mal

[B.Meldon]

As these cost under £5 is it worth trying to sort it out??

https://www.ebay.co.uk/itm/401000177231

A common issue that makes these fail is using one without any additional short circuit protection.
A simple 1a thermal cut out shouldl do the job.

[Graeme Dunbar]

It may need other work too. By itself the LM317 voltage regulator goes down only to about 1.25 V and most railway controllers using the device include a couple of diodes in series with the output to drop that excess voltage.

There are other options for overload protection, with a bit more work. One is Foldback Current Limiting where the current drops to a low safe value until the short of overload is cleared.

There is something of a subsection of the Electronics SIG (the same people, just different hats) interested in gathering up DC controller circuits, if interested.

[Hugh Norwood]

This is a question for Hugh Norwood.
The LM317 shorted out to the metal case, and the replacement isn't working. I'm getting full voltage at the output and at all three pins of the LM317. Also the potentiometer has no effect. I'm not sure what voltages I should be seeing. Any ideas as to what could be wrong?
Thanks, Mal

Sounds like something else has gone west

If you would like me to look at it, send me a PM