Removing damaged mosFETs to repair ESC - RC Groups
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Mar 26, 2012, 08:13 PM
Psalms 23:4

Removing damaged mosFETs to repair ESC

I was told I might have better results in the DIY Electronics section.

Is it possible to get a burned out ESC to work again by removing the burned out MOSFETs, and also removing the corresponding MOSFETs on the other two "lines"? Will I need to add resistors or something to make up for the burned out MOSFETs?

Here's the link ~
Last edited by miniprinter96; Mar 26, 2012 at 09:18 PM.
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Mar 26, 2012, 08:44 PM
Registered User
The simple answer is it should be possible to remove the bad FETs and if there are enough FETs left to form a complete a bridge it will still work but at a much lower current rating.

The actual answer is, there is not one chance in a hundred you will get it to work.
Mar 26, 2012, 09:00 PM
Psalms 23:4
What would I need to do to have a chance at it working? It's not good for much of anything right now...
Mar 27, 2012, 05:28 AM
g0t rabb1t?
ABLomas's Avatar
Because i had lots of dead ESC's (bought entire batch of crappy HK SS, fried some when reflashing firmware, overloaded them, etc), i repaired some of them...
Actually, most of time it's not enough to replace dead channel (if one FET dead on channel, most likely that all will be dead, so better replace them all), sometimes You need to replace many parts (and sometimes burning FET's simply make hole in PCB, those ESC's are good only for spare parts).

Try this:
- take hot air gun (something like - noname brands cost ~10$ here), put it to middle heat
- strip off heatshrink from ESC, take off alu plate, put it horizontally (not on angle), on corner of chair (or other surface)
- heat dead FET's on ESC for ~10 sec, with distance at about 3cm. Try to move FET off (carefully) while blowing air on it. If it moves easily - pick ir off (not with fingers - hot), pick others. If not - heat 5 more seconds and retry

That way it's easy to de-solder entire ESC's and no need to put entire ESC with plastics parts into oven (at least, it helps to avoid smell). I guess, You know how to solder FET's back to plate? ;-)
Mar 27, 2012, 07:46 AM
Psalms 23:4
Here's a diagram of what I'm thinking. The filled in MOSFETs are the burned out ones. If I would remove the ones with the X, and move the lower right yellow MOSFET to replace the top left MOSFET, would it work? All the MOSFETs have the same number on them, so they should be interchangeable.
Mar 27, 2012, 10:54 AM
g0t rabb1t?
ABLomas's Avatar
Very strange configuration (all my ESC's (except some very low power - 6A or smth) had another arrangement - in 3 rows).
ESC model?
Mar 27, 2012, 10:58 AM
Psalms 23:4
Here's the link to the ESC ~

I switched the MOSFETs, but it just makes a jittering sound. I'm not sure if all my solder connections are solid.

How do I test a MOSFET to see if it still works?
Mar 27, 2012, 01:34 PM
Oxford Panic
AndyOne's Avatar
MOSFETS most often fail to short circuit between source and drain. Just check the resistance making sure you get the meter the right way round otherwise you will be checking the parasitic diode instead.

Mar 27, 2012, 03:02 PM
g0t rabb1t?
ABLomas's Avatar
Link does not work.
Are You sure they got only 2 rows of FET's?
Mar 27, 2012, 03:46 PM
Psalms 23:4
They were set up in 3 rows, just running vertically instead of horizontally. The colors are coded for each phase.
Mar 30, 2012, 11:03 PM
Registered User
Scuse jumping in. Possible the mosfet driver has released the magic smoke? (Super magic smoke is invisible) EDIT: Maybe you've 2 drivers per phase. one driver per 2 mosfets. didn't look at schematics sorry if obviously not. I repaired one yesterday and that was the problem, so this caught my attention. It also took out a via that pulled the gate low; or high, didn't look.

It would jitter and pull 0.5A on every throttle pos

GL huntin'
Apr 01, 2012, 09:50 AM
Suspended Account
Here's the simple answer: Don't buy JUNK from Hobbycity, go for Castle Creations and employ Americans. Not only are you unable to solder on those things due to the size and not having milspec (you do know what this is, right?) soldering equipment but they were designed to crap out early to force a repurchase to begin with!

Not only are the CC units overload protected but they have higher resolution and quicker response time. If you want your kids to live in cardboard boxes, just keep buying the imported filth and have another Big Mac.

I cannot believe the stupidity of screwing around with an $8.42 item to begin with!
What's wrong with you people? 2 buyers had FIRES, what do you need a smack on the nose?
Last edited by Tx_Heli; Apr 01, 2012 at 09:56 AM.
Apr 01, 2012, 10:22 AM
g0t rabb1t?
ABLomas's Avatar
Originally Posted by Tx_Heli
Not only are the CC units overload protected but they have higher resolution and quicker response time. If you want your kids to live in cardboard boxes, just keep buying the imported filth and have another Big Mac.
.... like CC never die or work better...
They use the same Chinese components. Differencies are simple - better QC and firmware.
And because CC firmware (and software) is useless for multicopter ppl (ok, dunno about heli) compared to custom firmware, what's left? QC?
I would buy 10x HK ESC for 1x CC price and have others as spare ;-)

Tell us about "higher resolution and quicker response time" please, thanks.
Apr 01, 2012, 11:59 AM
Suspended Account
Had plenty of their CRAP in the past, only thing that solved the issues on a Blade tail motor was a CC10 which was PROGRAMMABLE thru the USB port. Their $8 6A ESC's (which they now don't carry anymore) burned out on average every 3 weeks. The CC10, that's when the problems stopped.

I've got 5 years of disappointment with their damned ESC's thanks. You're not "resoldering" anything on that board but if you do, please let people you fly with know! Weird shorting issues which will glitch receivers and cause other issues and possibly people/property damages....

Now that's real SMART for $8, isn't it? 'Nuff said.
Apr 01, 2012, 12:03 PM
Suspended Account
Buy a kite.

Why you should even argue with me when a review on that thing shows one buyer had a FIRE on his
kitchen table from it is absurd at best. What do you people do for a living anyway?

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