# Controller oh oh :s



## crackerjackz (Jun 26, 2009)

Having been unlucky 2 months ago blowing up my charger from water infestation I was able to fix it after about 10 hours of work .... now I think I have my work cut out for me
 ....

My Curtis 1239-8501 has met an end while driving at full throttle :s somehow a loose washer had the guts to go were it never should have .... onto my motor lugs ... result it got welded there and the pack fuses blew . 

Welded contactors / blown fuses and broken controller 

Opened it up and if not all ... a lot of mosfets are blown ... pictures worth a thousand words 




























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## crackerjackz (Jun 26, 2009)

My question to anyone keen on mosfets/ électronics is this .... there on two codes on the mosfets spread out across the boards ..

Irfs4127 And irfs4127
P243d. P305d
By II Ej59

What is the difference between the two ? The only code I find online is irfs4127 but the rest of the codes don't match up ?? 

Anyhelp as always .... much appreciated



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## lastcyrol (Dec 12, 2015)

This is the same transistor. Only different production dates.
According to the datasheet here (page 9) the first one is produced in the 43-rd week in 2002 and the second one in the 5-th week in 2003. That is if I am not mistaken.


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## ken wont (Jul 6, 2016)

With that much damage to the mosfets, the circuit board is probably beyond repair.


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## crackerjackz (Jun 26, 2009)

ken wont said:


> With that much damage to the mosfets, the circuit board is probably beyond repair.




Well that's what I thought at first glance which is why I called Curtis instruments to get new boards .... after 4 company transfers the answer is still ... they only sell complet units :s .... 

So now the board repair has to look doable :s lol .... when i look carefully I see about max visibly 30 blown mosfets ... the controller is still loading ect but gives a short on motor code so I'm hoping fixing only the mosfets will curé the controller ..... 


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## bigmouse (Sep 28, 2008)

Here are some troubleshooting tips to find out if it's worth trying to replace the FETs on the board:

Take a multimeter set to diode mode and do the following:
Put the black lead on the B+ terminal and the red lead on the B- terminal
If you read a dead short, then you have a high side and low side "switch" shorted on at least one phase. If you read something around 0.6-0.7V, then you likely have one switch shorted (though you could have one on more than one phase). If you readh around 1.4V, then you have either nothing shorted, or the shorted parts have fused and gone open circuit.

Regardless of what you measure, you'll need to narrow it down to which switches are shorted. To do this, leave the red lead on B- and touch the black lead to each phase out. Do the same again, but with the black lead on B+ and the red lead to each phase out. This will check all 6 switches. Record any switches which read shorted (0 volts, or close to it).

It looks like they're using 100 ohm gate resistors (which is actually pretty high) and a 10k pull-down. This should make it relatively easy to figure out which specific FETs are shorted. Normally, not all are. Measure the gate to source resistance on each switch. If you happen to measure a shorted one, it will read shorted, or close to 0 ohms. If you happen to measure a good one, you'll read at least 100 ohms. Desolder or cut the source lead on all the shorted ones. You'll know you got the last of them when the switch passes the diode check described above.

Once you've narrowed it down, completely remove all the shorted MOSFETs from all phases but leave the good ones on the board. Do this until you measure 1.4V or so during the diode check on the battery terminals. Once you do, you can try powering it up enough to see if the faults go away. If they do, then you probably only need to replace the MOSFETs. If you still have unexpected faults, then something else is damaged and you'll need to either replace the inverter, or do some more digging.

I'm not sure what it involved in powering up a Curtis controller, whether high voltage is required or not, but be super careful, especially if there's soot all over the place.


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## arber333 (Dec 13, 2010)

Yes, but clean the schorched areas first, so you can see other things, like physical damage... Use nitro solvent with brush and rinse the whole plate. Leave it to dry and then you can start diagnosing it.

A


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## crackerjackz (Jun 26, 2009)

Gees that's really good info  ... thanks ... ill let you all posted when I finally get time to check it out more  


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## WolfTronix (Feb 8, 2016)

I will also throw in some helpful troubleshooting tips for repairing power MOSFETs / diodes...

http://www.wolftronix.com/amc230_514/index.html

Specifically, MOSFETs and diodes can be damaged in such a way that they pass the diode test, but conduct well below the break down voltage.

Hope that helps,
Wolf


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## hmincr (Jan 20, 2012)

Wolf/Wolftronics

I know nothing about electronics and was trying to think of a way to ask for some photos showing different parts/sections of a controller.

YOU sir, have done such a fine job of documenting this controller troubleshooting and repair, I now feel I can approach a non working controller I have that is a BLDC type, and possibly find the faults and maybe even repair it. I do realize this is a different controller than what I have, but, it surely can't hurt to give it a try.

I thank you immensely for this documentation.

Harold in CR


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