SparkFun Forums

[Steffen595]

Hello,

by accident I put 9 V onto the 3.3V in port. Did I blow it up? Micro SD card with firmware was in as well, its gone. Red LED flashed, and then it went quiet...
edit: logomatic that is

Steffen

[MichaelN]

Are you refering to this?
http://www.sparkfun.com/commerce/produc ... ts_id=8627

Exactly which pin on which connector did you connect 9V to? If it was the battery connector (JP2) chances are you just damaged the regulator (U2) - a cheap & easy fix. However, if you injected 9V directly into the micro, there's a good chance it's fried...

[JJ]

It's somewhat possible you only fried the power LED. See if the CPU still runs.

[riden]

It's somewhat possible you only fried the power LED. See if the CPU still runs.

If the OP applied 9v to VCC, the chip is almost certainly fried. The processor will be long gone before the LED gets damaged. The LEDs have current limiting resistors.

[Steffen595]

there is these pins, from left to right, GND, 3.3V, USB, Batt. So I put the 9V into the 3.3/GND, used wrong plug on my power supply. Sh*t. Can I solder a new CPU on? Or better don't try?

[MichaelN]

If you have the ability to de-solder and replace the chip, then go for it. The replacement chip is a lot cheaper than a new board:

http://search.digikey.com/scripts/DkSea ... &k=lpc2148

A hot-air tool would be best (I think Sparkfun sells a Chinese unit - these are quite useable). If you don't have access to one, look up a product called "ChipQuik" (http://www.chipquikinc.com/). This allows the solder to melt at a very low temperature, and you can remove the chip just with a soldering iron.

It would probably be advisable to replace any of the other components you suspect are damaged at the same time (eg the regulator).

[Steffen595]

ordered a new one already, but may as well try.

there is another thing, says 12000 AB something, may be the quartz, gets quite hot, looks quite troublesome....

[ktownsend]

ordered a new one already, but may as well try.

If you don't already have the minimum equipment (hot air rework station and a decent adjustable soldering iron), it'll cost you less to order a new one, and is probably a lot more 'certain'. I think Sparkfun uses lead free solder which also requires a higher temperature to work with (I usually keep my iron around 400°C but different people will tell you differently). Lead-free solder doesn't remain 'liquid' as long as leaded so it can be tougher to remove anything but discrete components with just an iron.

That said ... if it's already dead and you've ordered a new one ... you've got a great PCB to learn to solder SMT parts with, so have at it! The only way to learn how to solder and rework boards is by doing it. It's a lot less terrifying than people think, and you get the hang of it pretty quickly ... especially if you've got nothing to lose.

[Steffen595]

yepp, may as well try. So if I get it to work, I have one to spare. Suppose only Farnell to get the 2148 in Australia, AUD 25.

The quartz: well, if controlled by the CPU which is now fried, no wonder it goes berserk, maybe won't have to fix it. Guess I just get some of this desoldering copper stuff, should do the trick. Did some SMD soldering a while ago.

[MichaelN]

I didn't realise you were in Australia too. Farnell are getting better with their prices, and the free shipping on all orders means I order a lot more stuff from them these days...

[Steffen595]

there is always www.futurlec.com.au and ebay, just got 2 1GB micro SD cards for price of one 1 GB, free shipping from Hongkong. Only thing, it takes a while. So you would have to plan your projects a bit ,-)
10 LM35s for price of 4 on farnell....

Anyhow, lets see what I can do to the logomatic...

[ktownsend]

yepp, may as well try. So if I get it to work, I have one to spare. Suppose only Farnell to get the 2148 in Australia, AUD 25.

Ug, Farnell. I find their prices so inflated here in Europe that I order from Digikey and even with the 19.6% tax at the border I end up way ahead. Maybe they're a bit better in Australia, but I honestly don't think I've ever ordered from them here (probably 25-30 Digikey orders last year, and maybe 4-5 from Mouser when Digikey didn't work out).

Honestly, I wouldn't bother ordering a new LPC2148 if you've already ordered a new board since you don't know what's dead and it's likely just a waste of money. But have fun trying to soldering and desoldering the chips. Discretes cost nothing and are easy to practice with ... QFPs are what takes a bit of practice to get used to (though it's not complicated).

Try getting some of the resistors off, for example, and then solder them back on. Should be an easy and harmless way to built some confidence soldering SMT stuff. If you want to make it a lot easier, I'd order a flux pen. Makes getting the solder to reflow MUCH easier. Kester 2331-zx is my personal favourite (I think Sparkfun even sells those?), but anything should be fine. You just put a bit of flux on the joints before trying to get the solder to 'reflow' again.

Here's a video I made where you can see some flux applied and a solder bridge removed (though I was being lazy and should have cleaned the tip between every pad ... the last one didn't want to co-operate because there was already some solder on the tip. The smoke is cause by the flux, though ... it would be much harder to work without it.

http://www.youtube.com/watch?v=-T3DdG_7jAM

PS: Ironically, I think that's even an LPC2148 in the video.

[Steffen595]

if you were in Germany there is www.reichelt.de, but they only do Germany I am afraid. Are quite good and quite cheap.

In Australia there is only Jaycar. Then Farnell and RS, latter seems to be even more expensive. Anything else, better order from Hongkong. Little electronic shoppe around the corner asks 80 cent for a resistor, normally about 8 cent...

You are right, no idea what else is gone on the logomatic, new one is AUD 80 incl shipping, the 2148 is AUD25. Worst case, I just put it on, hope it works and it conks out straight away because something else is dead.

[MichaelN]

Farnell in Australia have been getting a lot better - for my last project the prices were comparable with Digikey for about 30-40% of the parts, and cheaper in some cases. The free shipping and next day delivery is great too.

Sometimes they have clearance stock that is really cheap - I got heaps of heatshrink tubing for $0.02 / 4-foot length the other day (sorry, I bought all 75 pieces of it).