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-   -   mosfet question (https://www.badcaps.net/forum/showthread.php?t=71803)

Brucetafer 09-12-2018 08:40 PM

mosfet question
 
I have a seadoo RS1 seascooter that is stuck on and its pretty basic inside.. I have narrowed it down to a mosfet that is totaled, showing open on all 3 legs. part nmber is FB3306 on both but one has 012p and the other 904p under the part number.. does that make a difference or are they the same thing??

I would take a picture but they one is barely visible under mag glass..

R_J 09-12-2018 08:49 PM

Re: mosfet question
 
1 Attachment(s)
Should be the same, seems to be IRFB3306,
904 = 2009, 04 work week, P = lead-free
012 = 2010, 12 work week, P = lead-free

budm 09-12-2018 10:08 PM

Re: mosfet question
 
So it does not even show S-D body Diode?
S/G and D/G should show open circuit for sure.

Brucetafer 09-12-2018 11:45 PM

Re: mosfet question
 
Quote:

Originally Posted by R_J (Post 850259)
Should be the same, seems to be IRFB3306,
904 = 2009, 04 work week, P = lead-free
012 = 2010, 12 work week, P = lead-free

wow, that's sad to know they are putting 10 year old stuff into a 1500 dollar underwater seascooter that could potentially kill you.. this one is stuck in full blast and it damn near dragged me to the bottom at 110 feet.. scary shit... thank you for the super fast reply!

Brucetafer 09-12-2018 11:47 PM

Re: mosfet question
 
Quote:

Originally Posted by budm (Post 850272)
So it does not even show S-D body Diode?
S/G and D/G should show open circuit for sure.

what does that mean? im looking at them now and don't see anything other than r7 j9 and the other says 0C or OC NN both have the I *Diode sign* R

budm 09-13-2018 12:59 AM

Re: mosfet question
 
"I have narrowed it down to a mosfet that is totaled, showing open on all 3 legs."
When measure the resistance between Source pin and Gate pin it should show open circuit, same result when measure between Drain pin and Gate pin, and when you measure in diode mode it should show like diode between Source pin and Drain pin.

Brucetafer 09-13-2018 02:19 AM

Re: mosfet question
 
Quote:

Originally Posted by budm (Post 850288)
"I have narrowed it down to a mosfet that is totaled, showing open on all 3 legs."
When measure the resistance between Source pin and Gate pin it should show open circuit, same result when measure between Drain pin and Gate pin, and when you measure in diode mode it should show like diode between Source pin and Drain pin.

oh right, of course, the one is dead short on all 3, doesn't matter which way I test it... i also hooked it up to my component tester and it shows 1 resistor of .2 ohms. the other one is showing diodes as it should.. at least my component tester said it was good.. im going to replace both anyhow, just want to make sure im ordering the correct part..

budm 09-13-2018 10:46 AM

Re: mosfet question
 
So the MOSFET is SHORTED, not open circuit, just trying to get the correct data.

Brucetafer 09-13-2018 12:24 PM

Re: mosfet question
 
Quote:

Originally Posted by budm (Post 850370)
So the MOSFET is SHORTED, not open circuit, just trying to get the correct data.

Yes one is completely shorted, and the other has an open gate.

https://www.digikey.com/product-deta...PBF-ND/2096585

that's what I ordered..

budm 09-13-2018 02:03 PM

Re: mosfet question
 
Well the Gate better show open, the resistance be between GATE and Source pin or Drain pin should show Open, if it shows resistance then it is bad.
MOSFET typical failure mode is shorted.
Info about MOSFET:
'Gate construction: AGTE is physically insulated from the channel by an oxide layer. Voltages applied to the gate control the conductivity of the channel as a result of the electric field induced capacitively across the insulating dielectric layer.'
https://www.radio-electronics.com/in...s-tutorial.php
https://www.elprocus.com/mosfet-as-a...free-circuits/

Brucetafer 09-13-2018 10:05 PM

Re: mosfet question
 
Quote:

Originally Posted by budm (Post 850413)
Well the Gate better show open, the resistance be between GATE and Source pin or Drain pin should show Open, if it shows resistance then it is bad.
MOSFET typical failure mode is shorted.
Info about MOSFET:
'Gate construction: AGTE is physically insulated from the channel by an oxide layer. Voltages applied to the gate control the conductivity of the channel as a result of the electric field induced capacitively across the insulating dielectric layer.'
https://www.radio-electronics.com/in...s-tutorial.php
https://www.elprocus.com/mosfet-as-a...free-circuits/

thanks so much bud, Its been YEARS since I went to school for this crap, i don't remember much of it.. but yes, gate was open, but with tons of resistance, and it was open S-G and shorted D-G so both were trashed.. just scares the hell out of me to use this scooter ever again, figured it would fail in a shut off situation, not go full throttle until it dies... I guess I could make some waterproof mag deadman switch on the handle like a treadmill..

budm 09-13-2018 10:14 PM

Re: mosfet question
 
"shorted D-G so both were trashed" That can be real bad for the device that drive the GATE since the Voltage of the Drain pin will be dumped into the output of the GATE drive device, you need to trace out where the trace from the Gate goes to so you may be able to check the Gate drive device.

Brucetafer 09-13-2018 10:45 PM

Re: mosfet question
 
yeah that goes straight into the motor, which caused it to run away.. the board is SUPER basic, If i can get a picture ill post it so you can see..

budm 09-14-2018 12:26 AM

Re: mosfet question
 
I am talking the Gate pin which should get the drive Voltage from Gate driver circuit, if the driver circuit is damaged and you do not replace it the your new MOSFET can be damaged.

Brucetafer 09-14-2018 08:42 AM

Re: mosfet question
 
Quote:

Originally Posted by budm (Post 850487)
I am talking the Gate pin which should get the drive Voltage from Gate driver circuit, if the driver circuit is damaged and you do not replace it the your new MOSFET can be damaged.

so after removing all the caps and 2 rectifiers, one is fried, one cap is half of its rating and the main cap 3300uf 50v was only 110uf... so my guess its that it was toasted from too much current.. as soon as i get the new parts ill chime in if its fixed.

momaka 09-14-2018 01:24 PM

Re: mosfet question
 
Would really be interesting to see some pictures of the board and also what cap brand is used in this seado. 110 uF for a 3300 uF cap is pretty bad. Could be why the MOSFETs failed too. Or the other way around too, of course.

Brucetafer 09-15-2018 11:32 PM

Re: mosfet question
 
Quote:

Originally Posted by momaka (Post 850630)
Would really be interesting to see some pictures of the board and also what cap brand is used in this seado. 110 uF for a 3300 uF cap is pretty bad. Could be why the MOSFETs failed too. Or the other way around too, of course.

they are junk chinese, can't even read the brand its so badly printed.. no bulge or leak.. I replaced with nichicon and checked everything and seems to be close to spec.. im just waiting on the mosfets to come in..

Brucetafer 09-20-2018 11:06 PM

Re: mosfet question
 
1 Attachment(s)
received the new ones, and they sent 3306G which no idea the difference.. Installed the new mosfets, and the unit worked for 1 second, then died, now is shorted out, and drawing tons of amps.. this is the best picture i can get with the power outage.. the other side is only the mosfets and 2 sets of wires that control the deadman magnets..

budm 09-21-2018 10:28 AM

Re: mosfet question
 
What is the P/N of U4?

Brucetafer 09-24-2018 08:11 PM

Re: mosfet question
 
Quote:

Originally Posted by budm (Post 852108)
What is the P/N of U4?

S2104 IC.

https://www.infineon.com/dgdl/irs210...53567633f727a1


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