Benzine
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| posted on 27/6/09 at 02:57 PM |
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Megasquirt soldering
I've got Megasquirt 2 V3 which I didn't solder myself. I've got a problem where the injection fuel pump doesn't prime then
turn off, it just stays on. I mentioned this to phil @ extraefi when I bought some sensors and he said
"It sounds like the transistors are faulty for the relay, resolder Q19 and Q2 as thats a possible cause, if not replace them, I will pop some
in the package for you,"
The bits showed up the next day (today)  and I've opened up the unit. From the back of the board I can see the 2 transistors he mentions.
There are 3 pins on each and the solder on both of them looks like they touch on a couple of pins... is this what will be causing the problem? If so
how do you go about removing solder? I don't want to bodge it up as I've very little soldering experience 
btw I'd email phil who suggested looking at the transistors but I'm guessing he works mon-fri so thought I'd try here first ^_^
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big_wasa
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| posted on 27/6/09 at 02:59 PM |
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Dont put to much heat into the board as it will lift the tracks.
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flak monkey
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| posted on 27/6/09 at 03:02 PM |
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Desoldering gun, available from RS components, and probably ebay too.
Heat the solder until it melts then use the gun to 'suck' the solder away.
You need a soldering iron with a very small tip to solder the transistors on the MS boards.
Sera
http://www.motosera.com
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big_wasa
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| posted on 27/6/09 at 03:09 PM |
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I use one of these. Less than £2 on ebay
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Benzine
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| posted on 27/6/09 at 03:11 PM |
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Thanks, so would the touching solder likely to be causing the issues?
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MautoK
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| posted on 27/6/09 at 03:22 PM |
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The characteristics of a transistor are most definitely compromised by solder bridges!
He's whittling on a piece of wood. I got a feeling that when he stops whittling, something's gonna happen. (OUATITW/Cheyenne)
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graememk
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| posted on 27/6/09 at 03:30 PM |
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I personaly would use de-solder braid, solder suckers can lift the tracks if you arnt carefull, failing that get someone to do it for you.
[Edited on 27/6/09 by graememk]
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Volvorsport
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| posted on 27/6/09 at 03:32 PM |
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ive got a solder sucker you can borrow .
www.dbsmotorsport.co.uk
getting dirty under a bus
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Benzine
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| posted on 27/6/09 at 03:37 PM |
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Sounds easy to mess up, I only have a bog standard soldering iron with a big end
ITT: someone does it for me  ^________^
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miikae
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| posted on 27/6/09 at 03:52 PM |
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You could try and do it yourself without and iron , good magnifying glass/eye glass, and a fine bladed modeling knife to cut away the excess solder,
just take care not to slip and cause more damage.
I have all the special de-soldering gear but too far away from you sadly.
Mike
If it can be done it i will be done .
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martyn_16v
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| posted on 27/6/09 at 03:55 PM |
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You can try just using the iron to melt the offending solder bridge. Heat up the joint until the solder melts and drag the tip of the iron between the
pins to break the join. It won't be the prettiest pair of joins after but at least you can test it all. Once you're happy you can (get
someone to) tidy it up if needs be.
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BenB
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| posted on 27/6/09 at 06:20 PM |
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If you apply a dry soldering iron to the solder bridge the end of the soldering iron will wet itself with the solder. Then flick it off into the bin
and repeat
No solder sucker device needed... Just be careful where you flick it!!
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02GF74
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| posted on 27/6/09 at 07:18 PM |
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I have not managed to lift tracks on a GTP board but have with the cheaper resin type boards - damn, forgotten what they are called.
locost way it to melt the solder then tap the board so that the solder drops off the board.
if you iron has large tip then take care.
the alternative would be to snip the leads and solder onto them but that is not ideal.
if your transistor pads are beige by solder, then as ^^^, it is unlikley they will operate as per design.
the short may have damaged them so may need replacing - try and reomve the solder bridge as per benb advice and see it it works.
if not, you'll have to replace the transistor.
a solder sucker is a fine tool - unfortunately you are way too far away for me to do help do this for you.
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Macbeast
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| posted on 27/6/09 at 07:26 PM |
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Maplins (open on Sunday ) probably do a solder sucker. But you would be better with a small soldering iron too - 15W with small tip.
I've never had much luck with desolder braid. Problem with just heating solder and flicking off is you don't know where it will end up -
possibly bridging something else.
I've often cleared bridges with a sharp knife or a small file.
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