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What have I fried ?
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Post What have I fried ? 
Well, was going to try the new firmware for v3.
But soon after I had uploaded new firmware I suddenly heard spark sounds and a fried smell came out.
I turned off power as soon as I could. When I opened the case I found the cause.

While waiting for the new fix/update for v3, I installed a hard rev limiter module. Whilst doing, I soldered a thicker gauge wire to the pin on the Molex where +12V comes in.
Appearantly my soldering wasn't good here. So most of the strands had come undone, and was lying up against the components marked with read in the image below. Some strands were off course still on the Molex pin, so there was 12V on all strands.

Now, what can I have fried with this 'operation' ?!
The unit no longer works, and doesn't communicate with the Configurator any more.
I'm hoping that what I have damaged is replaceable. But, I need help in figuring out what components I most likely need to change now.




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Ouch- that does sound bad. You will want to replace D2, D3 and D4.

See schematic here http://www.autosportlabs.net/asl_dist/mjlj/mjlj_v3_sch.png) and the BOM here http://www.autosportlabs.net/asl_dist/mjlj/mjlj_v3_bom.txt.

Unfortunately, It's likely the PC board traces have been vaporized as well- you may need to manually patch up / re-route the traces using jumper wires.

One thing you could do to verify if the controller is basically 'alive' is to bypass that part of the power supply circuit and feed in voltage from a 9v battery right into the input of the voltage regulator. If it works then it holds promise for repair.


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Thanks Brent !

I checked the board visually - and the traces looked alright at a first glance.
I'll feed power and see if the controller is working.

Could I use 12V directly with a regulated power supply, or should it be 9V ?

I'll change D2, D3 and D4 after also checking the traces and see what that gives me.
If things look too 'cooked', I think I'll just a go for V4 unit instead.

Thanks again Brent, and I'll post when I've tried.


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And, an additional question:

I've now inspected the board. All traces look solid.

But, when doing so - it seems to me that D2 and D4 already are wired directly to the +12V pin ?!
The trace on the underside looks to me to connect the +12V pin and the same side of D2 and D4 that I had marked were in contact with the strands in the initial post.

Could they really have been damaged then ?

And, how about D5 ? That's the third one that the strands likely were in touch with on the side closest to the Molex.

Thanks in advance.
I'll check later to see if the controller is alive.


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Well, I fed power to the voltage regulator as per the enclosed image.
I at the same time connected it to the PC and started the Configurator software. Nothing. COM port was the correct one.

And, all traces look as before the incident.




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Does the voltage regulator output 5V? If you verified the voltage regulator is outputting the proper voltage to the various components (oscillator, processor, etc), then perhaps the original shorting problem caused 12V to be injected into areas of the board where it could not be tolerated, damaging multiple components in the process.

Double check your regulator is outputting 5V and let us know.


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Here I have marked what I've measured with +12V to the regulator.




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Well, I'm replacing all components.
Since I'm still a newbie at this to be honest - instead of trying to figure out what possible could be the exact cause(s) and the time it would take, I'm just replacing everything.

I've removed everything but the MAX232, since it wasn't sitting in a socket, and now I wonder:

1. Is it likely that the MAX232 was damaged?

2. If it is damaged, if I replace everything but it - will I damage anything else when powering up ?

3. Or can I first leave it in and replace everything else and see if it works without replacing it. And, if it seems it (too) is damaged just replace it then ?

This is obviously since there are so many pins from it to remove solder from, and remove it without damaging the board. And the hasle of trying to get all holes free of solder so that the PCB accepts the new MAX later.


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Patriq, from you measurements it looks like your voltage regulator isn't working properly/has blown. You can find data sheets off the interent for most components. For the max232 you can find one here http://www.datasheetcatalog.org/datasheet/texasinstruments/max232.pdf and it shows that max voltage is 5.5v, so looks like that may have some damage too.

The best thing to do is defo change the voltage regulator first with all other chips off the board and double check your still getting 5v then add new chips. Most of the basic components should be fine such as resistors and diodes, they are quite robust.

To get the old chips off the board the most ideal way for the price is to get yourself a solder sucker, this one would be ideal http://www.maplin.co.uk/Module.aspx?ModuleNo=96859 or similar. Basically you set the piston, then put the heated end of it, which has a hole over the leg of the component on the board, then push a button and it sucks up the molten solder from the board. Easy and the board isn't damaged.

Hope this helps
Ryan


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Thanks Ryan !

That pump should do it !
I have one that is unheated, and that I have tried without success before. I've only used copper wick this time.

I've already removed all components. Only the MAX remains. But, I'll go about it and remove it too.


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Proper de-soldering tools are extremely handy- especially those with built in pumps. It eliminates the need for de-soldering braid and reduces prolonged heat on the board, avoiding damage.


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Tried to order the pump. It was 12.95 I think. P&P to Norway was 40 !!!

Sent them an e-mail to confirm if this really is correct......

And, yes - I've missed a proper de-soldering tool to be honest. I have a pump, but non heated. It hadn't had the best of experiences with it so far.

Thanks again guys.
Will report back when package with new components from Brent has arrived and I've tried them out.


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Well if you can't find one in Norway then i'll post one out to you. Got to be cheaper that way. 40 is rather expensive Very Happy


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ELFA is the Norwegian (Swedish) alternative for these parts.

There is a shop in Oslo

ELFA
Sandakerveien 76F
0484 Oslo
Telefon: 800 81 135
Telefaks: 800 81 136
07.30–16.30 mandag–fredag

https://www1.elfa.se/elfa~no_no/b2b/start.do

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Hi Svein !

I answered your e-mail too.

Well, Elfa has similar but professional units. They start at 250 and then up....
Wink
I'm not prepared to pay that much. Although I've bought much of my supply and tools there.


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