Hardware Volume Buttons Resistor

[XxShalevElimelechxX]

apologies for the late reply, just now saw this thread. here is a diagram of the three button lines and their corresponding test points, if necessary:

worth mentioning that the test points break out after the resistors and before the capacitors, so add a resistor to the line if jumping directly from the test points to the ribbon connector.

Wow, it really helps since my resistors haven't arrived yet (Probably because of the coronavirus), thank you very much!!

 

[FAST6191]

I too need to replace my volume resistors, they're on order. Any recommendations on the method? Was planning on doing it by hand since I'm worried a hot-air station is gonna cook the connectors. Obviously it's gonna be a challenge either way. Thanks.

You can put foil over the things you don't want to get too hot and make a hole for where you do want heat.
If you are not already versed in this sort of soldering and don't fancy grabbing some stuff from the pile of scrap to train up on I would give better odds at a foil shielded hot air going well than hoping your nice firestarter soldering iron gets things done.
You can also glue the resistor down, and then solder. Though for some of the really small surface mount stuff this can be more tricky.
Otherwise clean off the pads (wire braid works for me but solder sucker will probably get you most of the way there), tin one of them. Use a pick or something to hold down the resistor while you tack the tinned pad down. Flow some solder onto the other, add more to the tacked down one if necessary. Flux is generally your friend here, though you do then get to clean it off.

 

[marley]

Much appreciated. I'll try to rig up a heat shield and focus the hot air just in the needed area. Tight quarters, especially for the ones right in-between the connectors.

 

[vulp_vibes]

yeah, hot air is your best bet if you need to get in between the fan and button connectors. soaking the board with heat from far away is crucial here; you want the board itself to be significantly and evenly heated, so you can then quickly move the air in and apply as little intense heat as possible to reflow the solder without causing excess damage to the connectors. a tacky flux such as amtech nc-559-v2-tf is also invaluable, as it will keep components in place as the solder reflows instead of having to hold them in place with tweezers. cleanup isn't much of an issue with isopropyl alcohol and a toothbrush or the like, as long as it is done while the board is still warm and the flux hasn't solidified.

 

[marley]

Roger that. Resistors will be delivered today.

 

[FAST6191]

yeah, hot air is your best bet if you need to get in between the fan and button connectors. soaking the board with heat from far away is crucial here; you want the board itself to be significantly and evenly heated, so you can then quickly move the air in and apply as little intense heat as possible to reflow the solder without causing excess damage to the connectors. a tacky flux such as amtech nc-559-v2-tf is also invaluable, as it will keep components in place as the solder reflows instead of having to hold them in place with tweezers. cleanup isn't much of an issue with isopropyl alcohol and a toothbrush or the like, as long as it is done while the board is still warm and the flux hasn't solidified.

You would really heat soak something for a resistor on the edge of a device? Some multi pin chip, BGA or the like then sure but for a tiny resistor when you could well be in and out in 15 seconds?

 

[marley]

Appreciate the follow up. FAST6191, still recommending heat gun or soldering iron?

 

[FAST6191]

Either will be able to get it done, but a foil shielded thing with something like a proper hot air station is what I would go with as easiest. If all you had was a soldering iron, even a basic firestarter type, you could get it done but it would be more tricky and thus something you want to practice on.

Find something from the pile of scrap most of us have around and give a go at desoldering and then soldering a piece of similar size a few times. If you have something of similar size but with unpopulated sections then even better.

 

[marley]

Many thanks. I've got the "right" gear for either approach, but not a ton of experience with something this small. I'm a bit worried about being able to properly shield the connectors, but I'll have a look. Should I aim for air on the hot side and get in and out to avoid collateral damage to the corroding components? If so, what temp for 60/40 Kester?

 

[marley]

One more quick follow up... foil preferred over Kapton tape?

 

[FAST6191]

Temperature is usually a function of how close you hold the nozzle -- bust out a hairdryer and hold your hand a metre away, now move it in close despite not changing any settings.
Nice full fat eutectic lead-tin electronics solder will not need the highest temperatures though. If you have it low then you might well have it on for longer to melt things and that is when it gets more fun. Too high and you then start risking the bond between the copper and the board.

Foil reflects heat, kapton mainly blocks it but will do a fine job as well.

If you have doubts do find some old dead electronics and get some practice in.

 

[marley]

Yeah, will practice.

OK I've got rosin-core 60/40 or...

https://www.amazon.com/gp/product/B017RSGPI8/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

 

[marley]

Thanks everyone. I ended up having better luck doing it freehand. All is well. Appreciate all the advice.