Pptc Resettable Fuse

Do re-settable fuses change value or deteriorate over time? Hobart welder here uses them to protect the Darlington transistor output for the wire feed motor. The PPTC is 1.85 A and measured current varies in that range so the PPTC cuts out. Darlington transistor is 2N6388 so it should handle higher current safely. Considering replacing the PPTC with 2.5 A.

 

No.
You never replace a fuse with a higher value than the one fitted by the manufacturer of the product.
The fault causing the higher current needs to be isolated.

 

Yes. They tend to get weaker. But as Eldon correctly noted, you never, as in never ever, replace with a higher value. Fuse are safety devices - there to protect the equipment from excessive current situations that could cause fires or worse - death!

Just because the transistor can safely handle more current, that IN NO WAY means all the other components in that (and connected) circuits can.

 

Normally I agree but from my google searches I'm finding these machines have issues with PPTC used here. On user had only 1 1/2 spool of wire through it before encountering problems. There probably should have been a recall. There's nothing wrong with the motor or the cable. I've had the motor and gear box apart, cleaned and lubed though it didn't really need it. I find that no wire in feed the current drain is 1 A approx. Wire installed and max feed it increases to as high as 2.75 A well above the PPTC. Most of the time the welder won't be operating a full capacity but I couldn't get it below 1.65 Amps at anytime. I consider that borderline.
Both Darlingtons and PPTCs are on order.
Sad news today is my Tectronix scope quit today. Can't get a base line on it.

 

And were those google people qualified electronics technicians? Or just people who do things like wrap tinfoil around fuses, stick pennies in fuse boxes, or bypass circuit breakers altogether?

I say again, just because the transistor can handle more current, that does not mean the entire circuit can. Go ahead and replace the transistor but use the same value breaker.

That's my advise and I am sticking with it. I believe it would be irresponsible of me if I condoned the use of a higher value safety device.