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Failed voltage mod, but the A7v survived!

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Rob Cork

Senior Member
Dec 17, 2000
Woodcote, UK
Ok, I finally sat down to do the voltage mod, after much umming and ahhing. I spent ages trying to get one end of the resistor soldered on, and I succeeded after about 10mins, trying not to get the soldering iron tip too close to the smd resistors on the mobo. As soon as I'd done this, I bent the other leg of the resistor round to solder that, and pulled the other one off the mobo again! Agghh, that took me ages!! Plus, when I pulled it away, I could swear the smd resistor was about half the size it was - it's definitely smaller than the one above it, and I guess they ought to be the same size! At that point I said screw it, I've just melted a resistor on my £130 mobo, if I'm really lucky it'll still work but I'm not going near it with that soldering iron again.

It does still work perfectly, which has given me some confidence in the toughness of the resistors - despite my f***-up, they still work. I want to try the mod again, but has anyone got any suggestions to make the legs stick? I've put a small blob of solder on each leg, and I'm holding it in place while i heat it up with the iron (0.5mm tip). Do i need a heat sink for the 24k resistor while i'm soldering, like a piece of wire wrapped around it, tied to a heatsink? Anyone found an easy way to hold the legs in place while soldering? I really need those extra volts for the gig, any tips however irrelevent they may seem would be appreciated, thanks ;-)
haha. Try using a Third hand. Also, i carved some traces of my old mobo. do u think a 0.5mm tip will help me rebuild them?
If you want to repair traces you need one of those silver pens that people use for joining the L1 bridges, they were designed originally for repairing traces on pcbs. Now I wonder where I can buy a third hand, sounds useful.... ;P
Just spent another 1/2 hr trying - I'm using blu-tack to hold the resistor in place, and it works pretty well - the real problem is getting the solder to stick to the pcb. It melts, and flows into place and sets, but then just falls off. Maybe I need some special solder for small contact areas, or flux of some kind?
I did the voltage mod yesterday and it works fine. Use some flux it will make the solder flow. also use the finest solder u can, the stuff i have lookes like 0.5mm pencil lead. when i soldered mine I put some flux on the lead for the resistor and the tinned the lead wire with solder. I put the solder iron tip on the lead wire itself and heated not ever touching the MB , burnt my finger but for 1060mhz it was a worth a burn or two!
Thanks for the advice ElectricMan, once I get back to uni I'll go out and get me some flux and thin solder and try again. Third time lucky I hope (at least I still haven't killed it, so I must be doing something right :) )
Soldering Tip:
The resistor does not have to be on the board it self. You can use thin soft copper wire to connect to the board and place the resistor elsewhere, even better you can use variable pot.

You just cut the isolation of the wire tip (like 3mm from the end). Then pre solder the wire with clean Iron tip.

Use wet sponge or paper to clean your Iron, then put some solder on the tip and clean it again, then lightly put small amount of solder on the tip and you are ready

Then you stick the wire end in place and quickly heat the wire as close to the end as possible.

Your Iron should not touch the board just the wire. If you use this method you will not damage your board.
Remember the pad on the board needs to be hot enough to flow the solder otherwise you will end up with a cold joint. This seems to be what has happened in your previous attempts. Get it too hot, and you can pull the trace off the board. If you are not used to soldering in such tight places, perhaps your motherboard is not the place practice. You may want to consider taking your motherboard to a local radio repair shop to have the work done. Working on SMD boards is not for the faint at heart.

Thanks for the tips guys, I like Ericsson's idea about using copper wire to connect to the board - I'll see if I can find some thin wire lying around, and I'll give it a go. Colin - I appreciate the warning, and I think I do feel more confident now I've had a few goes at it and not blown my board. I've got pretty steady hands, so I know I can do it without touching the board so far, that ought to be enough to keep it safe. I double checked that resistor on the board, and it hasn't melted at all - guess I was just being paranoid :)

dont use a seperate solder and flux, find the electrical solder that is 'rosin core' or somehting like that...its much cleaner and gets the flux right where u need it..