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Old Jul 29, 2001, 08:27 PM
Terry Dunn
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United States, TX, Lubbock
Joined Jan 2001
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Can my ESC be fixed?

I was recently given a zagi/Aveox ESC where the negative battery lead had been separated from the board. The problem is that the etched part of the board where the lead is soldered delaminated is still connected to the lead. I can post a pic if necessary. Do any of you EEs out there think it is repairable?
Thanks,
Terry
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Old Jul 30, 2001, 02:46 PM
Space Coast USA
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Contact Steve.

stevem@fesi.com

hoppy
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Old Jul 30, 2001, 03:07 PM
MK
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You should be able to CA the delaminated trace back on to the board.
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Old Jul 30, 2001, 04:11 PM
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Agra, Oklahoma
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Quote:
Originally posted by hoppy:
Contact Steve.

stevem@fesi.com

hoppy
Please - don't. I would love to help but have called it quits on the ESC repair sideline.

Yes it is repairable, and please don't ever call me an EE

The CA trick will work but do not solder it after doing this as the CS will not take the heat and the trace will come loose again.
Alternate method would be to epoxy it down - you can even get a little sloppy and cover the trace.

Good luck!

Steve

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Old Jul 30, 2001, 06:27 PM
Space Coast USA
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Ok Steve, sorry to hear you've decided to "retire". I'll withhold any further referals . Thanks for your past help!!
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Old Jul 31, 2001, 08:52 AM
Terry Dunn
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United States, TX, Lubbock
Joined Jan 2001
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Thanks for the replies guys. No worries Steve. When I was racing RC cars, I used to airbrush bodies for free. It didnt take long for it to get out of hand. I know where youre coming from.

Anyway, I just want to make sure I explained this situation correctly. The part of the trace where the negative lead is soldered separated from the rest of the trace and is still soldered to the lead. So I guess the real question is:
" Is there another place on the board where I can attach the negative battery lead?"
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Old Jul 31, 2001, 09:20 AM
MK
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How about at the point where the trace broke off?
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Old Jul 31, 2001, 09:41 AM
Terry Dunn
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United States, TX, Lubbock
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It broke off right at the edge of the transistor. I cant see any part of the trace left there.
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Old Jul 31, 2001, 01:38 PM
rebmeM roineS
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Rockingham, Perth - Western Australia
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I would offer to do this for you, but im in Australia, so the turn-around could be quite long, upto a month I guess, depending on the postal services involved.

If your not confident doing it yourself, and dont mind the possible wait, I may consider it if your interested.
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Old Jul 31, 2001, 02:02 PM
Terry Dunn
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Thanks again guys.
Looking at it closely, I found a piece of copper that appears to go through to the other side to feed the BEC. It's hard to tell, but I think that youre right MrBungle about the trace going to 3 legs of the MOSFET. Im going to get out the multimeter when I get home to see if I can confirm that. If that is the case, I think I can handle the solder job. Otherwise I may take you up on your offer.
Terry
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Old Jul 31, 2001, 02:32 PM
rebmeM roineS
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OK im 100% certain thats where to solder now (yellow dot), Ive just had a look at the datasheet for the IRF7805 Mosfet, which are likely the ones used on that speedy, if not they would surely have the same pinout. The three legs next to the Gate are the Source and the 4 on the opposite side are the Drain on this datasheet.

I have Surface mount rework gear I use, so if you do decide to get me to do it for you I would be removing the Mosfets, laying down some new copper clad, and then replacing the Mosfets. That way the legs dont have to take the strain from the Batt lead.

Im off to bed now it's 3:30am! gotta be up at 7 :/
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Old Aug 01, 2001, 12:51 AM
rebmeM roineS
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Looking at your photo, it appears that the lead went to the 8pin SOIC Mosfets on the edge of the board where there is not alot of copper, if you have a look closely you might see if the trace did actually go under the Mosfets to those legs there, you will then probably be able to solder onto the legs on the Mosfets where the Yellow dot is in the pic below. Im pretty sure of this because the mosfets are connected on the other side to the area in the center where the Red dot is, and all the copper there appears to be connected to the blue lead for the motor. I cant really tell because the pic is so small, but Im sure it wont be going to the same legs on the mosfets that the motor is connected to So please check carefully where the trace went before soldering onto the legs. It looks like theres another small trace running along the edge of the board where the Yellow dot is, try not to solder that when you solder onto the legs. that smalltrace is going to the gate of the Mosfet, the 1st leg closest to the area that the lead was originally, so you want to solder onto the remaining three legs, not all 4.
Yeah its Dodgy but if your carefull you will do it. This can definatelly be fixed, just have to be absolutelly sure where its going, im feeling confident with the yellow dot. Good luck



grrrr posting images takes me far sometimes..lol
try #12, I cant see what im doing wrong, its no different to the way ive posted other images, trying html code now
try #13 YAY!! UBB can bite me! lol

Oh yeah I just thought of something else, check that there are no via's(a small copper plated hole approx .5mm dia going through to the other side of the board) where the copper was that the lead went to originally, I cant see any in the pic but there may be one or two there.

[This message has been edited by MrBungle (edited 07-31-2001).]
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Old Aug 02, 2001, 09:34 AM
Terry Dunn
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United States, TX, Lubbock
Joined Jan 2001
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Thanks a million guys!! I think it's gonna work.
A check with the multimeter confirmed the trace goes to those 3 legs of the mosfet and to the other side of the board. I coated the gate leg and its trace with a thin layer of epoxy then made a solder bridge across the other 3 legs. I soldered the battery lead there and then added a jumper to the other side of the board. The bench test seemed to show normal operation. I'll throw it in my zagi to see if it will still hande operating currents. The photos are fuzzy but they show the fix...the dashed yellow line is the added jumper:


[This message has been edited by mopar_man (edited 08-02-2001).]
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Old Aug 02, 2001, 11:38 PM
rebmeM roineS
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Rockingham, Perth - Western Australia
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Congrats Terry

Dont forget to throw some heatshrink over it to hold that lead firm, it wont take much to break those legs off the mosfet. Maybe even put a drop of thin CA where the silicone insulation runs along the board before shrinking.
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Old Aug 03, 2001, 12:54 AM
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United Kingdom, England, Burnley
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Hi Mopar !

Smear the wire ends and reworked components with epoxy, after testing the ESC, and before recovering with heatshrink . . .
That'll hold it all tight . . .

Keven.
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