MOSFET burning up but similar circuit on another board is fine

[zacaj]

My theory: It limits the on time to something less than 100ms,

100ms is my worst case estimate but I know that something in the 50ms area (which is what I've scaled back to testing at currently) is reasonable. Much less and the solenoid doesn't fully activate.

The replacement IRL540L has a maximum on-resistance of 0.077 ohms when its Vgs is 5V. But the original STP22NE10l is worse at 0.1 ohms. But the original circuit might have used Mosfets selected (or survived) to be the best ones with a much lower on resistance.

I find that hard to believe

It is also possible that your coil is partially shorted. This would increase the current through it, and for DC use, may not affect the pull too much -- but it, and the driver, will run hot.

It could be, but shouldn't that show up in the resistance reading?

 

[(*steve*)]

It could be, but shouldn't that show up in the resistance reading?

It depends on your multimeter.

How accurate and repeatable are low resistance readings?

An error of half an ohm due to contact and lead resistance is not really unusual.

It would be interesting to see images of one of these commercial drivers that work with this solenoid.

 

[zacaj]

It would be interesting to see images of one of these commercial drivers that work with this solenoid.

Here's one: https://ksarcade.net/media/catalog/...8eab33525d08d6e5fb8d27136e95/s/a/samdrv_2.jpg

 

[(*steve*)]

How many solenoids does that one control?

 

[zacaj]

How many solenoids does that one control?

Probably 32? Maybe a few more. One per transistor along the bottom, but some (16?) are used for a lamp matrix

 

[(*steve*)]

Please point me to the specs of that unit

 

[BobK]

The coil is 22-550 which means 22ga wire 550 turns. At a one inch diameter that is 550 * pi inches or 1728 inches or 144 feet. 144 feet of 22 ga wire is 2,34Ω. So your measurement of 2Ω is well within the ballpark. Within the infield even.

Bob

 

[Terry01]

I just pulled a 74ACT04 from a board I got from an old Samsung TV I am taking apart. It was made back in 2003! I like getting the chips off the boards and using google to see what they are and what they do and try and figure out how they all work together. I learn better that way. Reverse engineering someone called it but I am just messing about. It'll be a long time before I can reverse engineer anything!

Anyways just thought it was cool that 1 of the searches on google brought me here!