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Forum Index : Microcontroller and PC projects : Is it worth fixing?

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MOBI
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Joined: 02/12/2012
Location: Australia
Posts: 819
Posted: 06:47pm 09 Apr 2015
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Hi all,

I have (had) a CGCOLORMAX1 and accidentally (why would you do it on purpose?) dropped a jumper lead from the IO pins to a spot on the board where it could do the most damage. Stupidly, I had power applied to the board.

Testing shows power supplies to be in the right places but it looks like the PIC32 is cactus.

Is it worth replacing the PIC? or is the repair process too fiddly. There are quite a few smd components near the PIC.

If it is not worth fixing, does anyone recommend a cheaper and simpler replacement board?
David M.
 
jman

Guru

Joined: 12/06/2011
Location: New Zealand
Posts: 711
Posted: 09:09pm 09 Apr 2015
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Hi
Fix it.
I have one these boards so I took a quick look and I reckon
to replace the PIC is totally doable

Regards
Jman
 
WhiteWizzard
Guru

Joined: 05/04/2013
Location: United Kingdom
Posts: 2933
Posted: 10:14pm 09 Apr 2015
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If you think it is the PIC, and have one spare, then I would personally do a quick swap over.

I am sure you know how to do it (or have your 'preferred' method), but in case not, then this is the way I would approach it:

Use a sharp scalpel blade to cut along all the rows of pins close to the main body of the PIC (i.e. cut out the black bit!). This results in rows of pins left soldered to the board which can now very easily be removed with an iron and solder braid.
Once all the pins are removed, use the solder braid + iron to remove any 'excess' solder - this will flatten all the pads (ready to accept the new PIC).

I use this approach whenever there are other SMDs in close proximity (as you mention). IF no nearby components then I use a gas powered heat-gun and a pair of tweezers (but this method can lead to 'scorching' of the PCB depending upon it's composition).

Good luck . . . . . (and let us know how it goes!)

WW

 
MicroBlocks

Guru

Joined: 12/05/2012
Location: Thailand
Posts: 2209
Posted: 02:14am 10 Apr 2015
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Which PIC is on that board. I might have a spare lying around looking for a good place to work. :)
.
Microblocks. Build with logic.
 
bigmik

Guru

Joined: 20/06/2011
Location: Australia
Posts: 2949
Posted: 02:29am 10 Apr 2015
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Hi Mobi,

If it were mine I would fix it.. What have you got to lose? (about $10 from RS Components with their free shipping... I havent looked the exact price up but will be within a dollar of two either way...

I would use my hot air gun (rework station) to remove the old chip and clean up the pads with solder wick then solder the new chip..

If you are stuck or dont feel confident drop me a PM.

Regards,

Mick


PS.

Maybe change the VCap first just in case..

Mik
Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<
 
CircuitGizmos

Guru

Joined: 08/09/2011
Location: United States
Posts: 1427
Posted: 05:03am 10 Apr 2015
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Is it worth the cost to you of shipping back here? (US) Would be a factory fix.

Micromites and Maximites! - Beginning Maximite
 
MOBI
Guru

Joined: 02/12/2012
Location: Australia
Posts: 819
Posted: 02:05am 14 Apr 2015
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G'day all,

@CG - thanks for the offer - If I can't get it working, I'll purchase another.

Thanks everyone for all the tips.

I have removed and replaced a 100 pin pic32 before

but that was on a breakout board and there were no

smd components in close proximity. I used the

scalpel method.

I have a spare PIC32MX795 512L-801/PF but have to

check if it is a direct pin for pin replacement

otherwise I order a couple. My guessing is that it

is as I wired up a MM in modular form using a 795

and it all worked.

I have to do a bit more diagnostic checking before

willy nilly ripping the PIC out. something pretty

catastrophic has happened though because PicKit3

doesn't even recognise a target PIC.

I'll take a few photos along the way. My main

concern is my failing eyesight. Even stereo

goggles are not as effective as they used to be.

I've got a couple of Senate submissions to write

so it might be a day or three before I get to do

any more testing.

PS - That was a couple of days ago and I have finished the Senate stuff, so I'll see

what I can find tomorrow.
David M.
 
MOBI
Guru

Joined: 02/12/2012
Location: Australia
Posts: 819
Posted: 05:49pm 15 Apr 2015
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Hi all,

We have a happy camper here. Replaced the PIC32 chip and all works just fine.
I did have a heart stopping moment when I connected power to the board after replacing the chip and nothing worked. Like Charlie Drake's politically incorrect song of yester year "my boomerang won't come back", "if you want your pic 32 to work, then first you have to flash it."

The replacement procedure was as the various advice given:

- use a sharp scalpel to cut the PIC pins as close to the PIC as possible and then,

- use a not too hot soldering iron to clean the remaining legs from the board.

- apply a film of flux paste to the pads and level the solder left on the pads once again with a not too hot iron.

- apply a small dob of heat sink paste to hold the chip in place

- align the chip and carefully run the iron over the chip legs.

Aligning was a little tricky as the pads were slightly hilled with the previous solder.

I took some photos, but they really don't show more than I described. If you have a board, then you'll know what it all looks like.

My main concern was my eyesight but using stereo goggles with both lenses (full strength), a bright fluoro up close and about 15 minutes of muttering mild oaths, all was success.

I'll do a I/O check on all pins but I'm pretty confident everything will work.

Thanks again for all advice and encouragement.
======
I forgot to mention that before I started the operation, I ran the cro over the xtal and the frequency and voltage were as per specs, so I was pretty sure I had cooked a vital I/O pin.

It is nice to have a back up again.
Edited by MOBI 2015-04-17
David M.
 
WhiteWizzard
Guru

Joined: 05/04/2013
Location: United Kingdom
Posts: 2933
Posted: 08:33pm 15 Apr 2015
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Nice going MOBI - and glad you have it back . . . .

WW
 
paceman
Guru

Joined: 07/10/2011
Location: Australia
Posts: 1329
Posted: 03:53am 16 Apr 2015
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Well that's pretty encouraging David. So far I haven't managed to kill a chip but now that I've said that I probably shouldn't have! I'll give it a go now too if it happens.

Greg
 
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