Solder point retouching?

[devnulljp]

Quick question -- how do you retouch solder points on a PCB? I've got a pedal that looks like it may have had a battery leak or something--a little bit of crud on the board--and is not really functioning normally. There's a few of the solder points look a bit grunged/corroded and I'm hoping that's the problem and not something deeper. So I'm thinking to redo the points on the reverse side of the board...anything I need to do or take care of other than the obvious (don't melt the board)?
There's not a lot of lead poking through in most spots so what's the best way to apply the solder? (I've read I'm supposed to apply to the lead and have the solder flow around that, but there's not much there to work with...any hints for repair?)

Cheers

[-=Scorch=-]

Quick question -- how do you retouch solder points on a PCB? I've got a pedal that looks like it may have had a battery leak or something--a little bit of crud on the board--and is not really functioning normally. There's a few of the solder points look a bit grunged/corroded and I'm hoping that's the problem and not something deeper. So I'm thinking to redo the points on the reverse side of the board...anything I need to do or take care of other than the obvious (don't melt the board)?
There's not a lot of lead poking through in most spots so what's the best way to apply the solder? (I've read I'm supposed to apply to the lead and have the solder flow around that, but there's not much there to work with...any hints for repair?)

Cheers

make sure your soldering points are clean, and the soldering tip is clean and tinned. Heat the solder point and apply solder to it. Your soldering iron shouldn't be anything more powerful than 30 watts. This has to be done quick so you won't damage the components on the other side of the board. Clean the board again afterwards with some alcohol and a q-tip. The end result is your new soldering job should be shiny, not dull looking. good luck.

[devnulljp]

make sure your soldering points are clean, and the soldering tip is clean and tinned. Heat the solder point and apply solder to it. Your soldering iron shouldn't be anything more powerful than 30 watts. This has to be done quick so you won't damage the components on the other side of the board. Clean the board again afterwards with some alcohol and a q-tip. The end result is your new soldering job should be shiny, not dull looking. good luck.Thanks for the info - saved that for posterity too. Cheers.

[keeperofthegood]

:) I hate to bear bad news to you. Metal is fairly soft and porous. If you have had the contents of a battery leak and they have been on the leads of components, there may be a good chance they have caused corrosion up the leads and into the components themselves, if not through the leads. Also, a corroded lead is akin to a resistor if it still carries dc energy, and a capacitor if it no longer carries dc.

I would suggest though that you may have energy loss due to debris on the board, and a better first approach is to use a tooth brush and give the area a scrub and rinse (that's up from the q-tip and 'hol trick if that isnt enough cleaning) just being sure to use an infant toothbrush and scrub lightly (or any soft toothbrush like that). Production runs of pcb's use a lemon juice cleaner and water rinse so a wash wont hurt the pedal, just be sure to put it in the sun for the day to be fully dry.

However if a cleaning doesn't work, and if you have chemical contamination of your original solder, you will need to removed as best you can that original solder, heating and reflowing it just mixes that contamination in more, and a corrosive contamination (acid batteries are a thing of the past, it would be an alkali corrosive) simply continues that corrosive processes (not to mention, dirty solder itself wont form a good connection). There are lots of things made to remove dirty solder, but none really work very well, the bigger thing needed in doing is patience. If it was me, I would rapidly heat and remove the parts, clean with a rag the part leads one at a time seperate from the board and thouroughly examine them, and deal with removing the solder from the board seperatly. Cleaning dirty solder off a board is tricky, you do need to watch your heat, not melt the tracing off, and not cause solder bridges to happen.

:) and yea... I've done this all before too. I was the kid all the other kids brought their broken shizz to. I got almost everything to work again accept a buddies alarm/radio. Tea and radio's are not a good mix >.<

[devnulljp]

Thanks keeperofthegood, again good info. My prob is that the board is gooped on the other side so removing components isnt an option. However, good news is the pedal maker says he knows exactly what's wrong with it and will fix it for me...sounds like he maybe had a bad batch of components at some stage as he seemed to know exactly what the problem is from the description. Maybe not related to a battery leak after all. I sent it off to him a few weeks ago :)

But your info is definitely good and is going in the scrapbook (must remember not to pour tea in radio...gottit).
Thanks

[konasexone]

A flux pen is not a bad thing to own either. Flux is the key to good solder joints. Make sure to then clean off the flux after the job is done. I like to use Polyclens (the stuff you use for paint brushes) after I'm done with a board. It takes the flux off and stops its acidity from attacking your joints down the line.:wave: