Hot Air Station - Air Pump Failing

[stj]

Re: Hot Air Station - Air Pump Failing

flow is probably higher - it's a blower right behind the element - not like trying to push the air down a cramped hose first.

[caphair]

Re: Hot Air Station - Air Pump Failing

Just an update. The replacement pot failed yesterday. Didn’t last nearly as long as the original.

Symptoms were no air flow until fully on (same as original failure)
However out of circuit it measured smoothly in ohms range.

Is it normal for a pot to measure good but in circuit fail with current running though it?

[stj]

Re: Hot Air Station - Air Pump Failing

no, but you dont normally have much current flowing through pots - that's when you use a wirewound/reostat type.
how much current is yours being subjected to?

[caphair]

Re: Hot Air Station - Air Pump Failing

no, but you dont normally have much current flowing through pots - that's when you use a wirewound/reostat type.
how much current is yours being subjected to?

Not sure to be honest

[Agent24]

Re: Hot Air Station - Air Pump Failing

It's not common but yes, some bad components will test OK but fail under load. Try a new potentiometer. You might have just got unlucky.

Can you get a brand name one from Digi-Key instead of some generic thing from Amazon?

Also check, it's not perhaps some issue with the way it's mounted? Some pots may not isolate the wiper from the shaft, and if the body is mounted to a metal chassis that's also connected somewhere, like ground, you can get weird problems.

The original pot didn't have a plastic body, did it?

[redwire]

Re: Hot Air Station - Air Pump Failing

If this is the same mains AC dimmer circuit as in post #65, and the pot checks out, then the triac is suspect. It might have low sensitivity, needs high gate current to get it's lazy ass on.

I had a similar problem, first the pot went intermittent due to low quality chinese build. The carbon had cracked and it was sparking. I replaced it, added a series resistor... and after a month the triac gate shorted. It is possible a dud triac burns out the potentiometer, if it does not have a series resistor to limit current.
The potentiometer is typically a big 1W or 2W part for some reason.

[caphair]

Re: Hot Air Station - Air Pump Failing

I replaced the pot and it’s been working fine since but weird when testing with a meter that I didn’t spot any hiccups in it.