Hi everyone,

New to this forum and amateur in electronics, but do understand most of the basics.
I am trying to fix this fruitmachine (bandit). the hoppermotor won't run, because a mosfet (BUZ71) has burned out. A few resistors around this mosfet were bad as well so I have exchanged them for new ones, but for the mosfet I am having problems finding a compatible one, because I don't have enough knowledge about the things.
However, I have found a BUZ11 (in the same package) in my collection of odd parts. I have got the datasheet of both and they look very much the same. The BUZ11 handles a higher current which seems fine for a motordriver, but I am not sure about the capacitance. I have attached both datasheets.

Could anybody give me an idea if I could go ahead soldering the mosfet in and give it a go?

Any comment is appreciated

tia
Gerard

 

I don't see the data sheets. Check again?

You didn't mention what exactly the MOSFET does. Is it for an H-Bridge application? Generally, a higher current device will work, but check the Vgs (ON) voltage of both to see if they turn on in the same manner. The gate capacitance may be a factor - it depends on how quickly the device needs to turn on and off.

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As far as I can make out from the board this mosfet switches the hopper motor of the machine, which is a 24V 20W motor and needs to run for 10-30 seconds to dispense all the coins out of it.

I couldn't fix the attachments to the original message anymore, but I have attached them to this message (I hope)

thanks
Gerard

Attached Files

	buz11.pdf (266.6 KB, 2 views)
	buz71.pdf (270.6 KB, 2 views)

 

They are pretty similar, the main difference I can see is the BUZ11 is slower, has more capacitance and a higher current rating than BUZ71.

The speed won't matter if it's just being used as a low speed switch but if it's doing something like PWM the capacitace could be a problem for the driver.

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Thanks for looking into this,

Is there any chance it would not switch on? I cannot measure on the live board since it is deep in the guts of the machine and the cables and connectors are not long enough to get it outside the machine.

Gerard

 

It should turn on, the threashold voltage is the same as the BUZ71.

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