I'm having trouble soldering these capacitors :( - Page 1
Forum section: electronics / beginners

author: LeWidget
author_rank: Regular Contributor
timestamp: May 26, 2014, 05:48:14 pm
content: Hey Guys,So I'm currently working on repairing an XBOX 230, which has the RROD. I open it up and come across these dodgy lookin' caps......so I decide to replace them. Unfortunately, I encountered a problem during the process. First of call, I couldn't melt the solder. I tried Flux, increasing soldering iron 400c+, cleaning tip, changing tips, using solder... nothing 'really worked' but sloooowly it softened... Unfortunately, I encounted another issue. I turns out the legs all broke off inside the hole. So either, I didn't melt it enough, or the legs were somehow damaged and broke off.Eventually, I got the legs out.. Massive Pain!! Used a sharp pointy iron tip and pushed/heating into the hole. (mostly worked), some I had to use a pin to push in the hole as I heated it up, mostly worked. Last hole I ended up hammering a pin into it. (not the best solution..).. all out..Cleaned up the holes/contacts with some wick & cleaned the board...~ Top of Board ~~ Rear of Board ~Sorry if the pics aren't clear. :\Now, onto the issue.I installed some new caps, and tried to solder them in, unfortunately though I can heat the leg of the cap, I can't seem to heat the contacts on the board enough to want to take the solderEven with a bit of flux or solder on the tip. Even though you probably can't see it clearly in the images, I can see the contact points still on the board.Does anyone have any ideas as to why this is happening ?Thanks,

author: mariush
author_rank: Super Contributor
timestamp: May 26, 2014, 05:56:30 pm
content: Your soldering iron is too weak.Need to raise the temperature of your iron tip a lot, because the copper all around the leads takes away the heat. Flux on the lead and pcb, put solder iron and apply solder.

author: dog80
author_rank: Regular Contributor
timestamp: May 26, 2014, 06:00:25 pm
content: It is probably a combination of a high thermal capacity, multi layer board and a crappy low thermal capacity soldering iron.In that case, use LOTS of solder on the tip of the soldering iron. This artificially increases the thermal capacity of your iron. Then clean off any excess solder.Or buy a better iron.

author: poorchava
author_rank: Super Contributor
timestamp: May 26, 2014, 06:09:29 pm
content: Or preheat the board with a heat gun. Either electronic hot air station or a hardware store one. But be careful, you want to slowly bring the board to about 100-140 deg. C, not char the pcb.

author: tszaboo
author_rank: Super Contributor
timestamp: May 26, 2014, 06:12:53 pm
content: Looks like someone forgot to make thermal reliefs on those caps. It is not your fault.

author: Huluvu
author_rank: Regular Contributor
timestamp: May 27, 2014, 06:15:39 am
content: ouch ... it looks like you removed accidentally the through hole vias (negative path)Those Board are really bad to rework and you have to use very good solder irons + know howYou can try to fix it by probing the board from that area to the next (big) negative path and attach a big copper wire to keep the resistance low.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 27, 2014, 06:58:32 am
content: Hammering to extract pins?You probably tore out the copper plating. No good anymore. As is, I see missing annular rings on the bottom side, which means you won't be able to solder those (at least not very well).Are Xboxen really so expensive anymore as to be worth it?Tim

author: w2aew
author_rank: Super Contributor
timestamp: May 27, 2014, 01:48:53 pm
content: Quote from: T3sl4co1l on May 27, 2014, 06:58:32 amDitto - looks like you likely tore out the plating inside the hole, thus likely removing the electrical connections to the internal layers of the PCB.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: May 27, 2014, 01:59:09 pm
content: Quote from: T3sl4co1l on May 27, 2014, 06:58:32 amI repair quite a few of them. They run from 179 to 300 UD dollars here. Depends on the system.Looks as if the above one is toast.

author: rob77
author_rank: Super Contributor
timestamp: May 27, 2014, 02:37:36 pm
content: looks like you destroyed the board - if you need to repair it then it will be quite lot of work - as it was suggested above, you need to add wires to compensate for the destroyed connection inside the hole. if you have access to another (same model, revision) xbox, then ring through that working PCB board to figure out what connection you have to wire up.and for the future:1. hot air2. soldering iron3. lot of patience4. forget the hammerwhen i'm desoldering big capacitors (was fixing a PC MB recently) i'm placing to board to and improvised stand with the capacitor facing down, then i'm slowly heating up the board to 180 celsius with a heat gun (little less than the melting point of the solder) and then, while keep heating with the hot air - just touching the leads with the soldering iron - the capacitor is taken out by gravity only - it literally falls off the board - you don't even need to touch the body of the capacitor.but do not overheat the board - it will be deformed otherwise.

author: LeWidget
author_rank: Regular Contributor
timestamp: May 27, 2014, 04:10:41 pm
content: Hey Guys,Thanks for all the feedback. Looks like I have a fair bit to learn. I spent a couple hours on it, using hot air gun, soldering iron, fluxes and solder.. could make that last one budge :\. Didn't think I did damage to the other holes.. they seemed to come out much much easier, I only used the hammer on the last one.Ahh well, iirc I think I only payed $10 for it (with power unit and remote). Really thought it would be a straight forward processI might have a closer inspection soon, see if it is completly gone. in the meantime, I might look at a better flux. Can anyone recommend some decent but cheap flux that might help with hard to heat situations ? alot of what I came across seems pretty pricey for a small amount.. not sure if that's normal or depends on where you ship.I came across a place in Sven Hills (can't remember the name) that advertised ChipQuik for $25.. not sure if it's any good or not. I was looking as the paste type rather than liquid... or would liquid be better ?Thanks again guysRegards,

author: rob77
author_rank: Super Contributor
timestamp: May 27, 2014, 04:42:30 pm
content: even if the plating is not completely gone, it's damaged. those computer boards have usually 8 (or more) layers. if the plating was destroyed even partially - some of the layer might be disconnected from the plating. you simply have to replace those connections with wires - and to find the needed connections you need another very same board to measure.or just opt for the "i feel lucky" option : solder the caps in and connect the negative of the cap to the closest accessible negative plate on the board. but you might introduce (not necessarily) more damage to the device this way.and by the way - the flux does not improve the heat transfer, the flux is there to improve the "wetting" of the soldered parts by solder. the solder itself is improving the heat transfer from the solder iron tip to the heated joint. - that's why others suggested a big solder blob to help heating through the joint.

author: kony
author_rank: Regular Contributor
timestamp: May 27, 2014, 04:45:32 pm
content: Quote from: NANDBlog on May 26, 2014, 06:12:53 pmOr wanted to keep parasitic inductance and resistance of cap connection as low as possible, which is good idea for filtering output of core voltage SMPS. I'd expect them to be connected without thermal reliefs even on internal power layers too.

author: rob77
author_rank: Super Contributor
timestamp: May 27, 2014, 05:08:17 pm
content: actually... i had a closer look at your photos... there is fairly good chance that you can fix it.all 4 caps are in paralel and there are lots of vias around them... and it looks like it's enough to solder the negative leads on the bottom and the positive leads on the top side.you'll have to keep the leads longer on the caps (have them "floating" above the board on longer leads) in order to be able to solder the positives from the top (destroying the designer's intention to minimize the inductance) but there is a good chance that it will work.

author: rexxar
author_rank: Frequent Contributor
timestamp: May 27, 2014, 06:35:14 pm
content: Quote from: rob77 on May 27, 2014, 05:08:17 pmBut there's no traces going to the pads on either side, they have to be connected to an internal layer. The through hole plating is gone, so there's nothing to make contact with the inner layers anymore.

author: rob77
author_rank: Super Contributor
timestamp: May 27, 2014, 06:43:09 pm
content: look better ar the photos - there are tons of vias on the outer layers, and it's more than clear that the top big copper plate is the positive and the bottop cooper plate is the negative there is very good chance that those vias are redundant to the plating in the holes for the capacitors.or do you think those vias are shooting through the whole board shorting the capacitor ?

author: rexxar
author_rank: Frequent Contributor
timestamp: May 27, 2014, 07:56:41 pm
content: Quote from: rob77 on May 27, 2014, 06:43:09 pmLook at the big pins on the inductors, he's flipped the board over the X axis. In both pictures, the pins closest to the inductors are isolated from the large copper pour.You can clearly see that the vias are connecting the two sides together. If the top and bottom pours were at different potentials, there would be isolation around the vias. Since there's not, the two sides are electrically connected.

author: rob77
author_rank: Super Contributor
timestamp: May 27, 2014, 08:18:01 pm
content: Quote from: rexxar on May 27, 2014, 07:56:41 pmsorry, didn't noticed he flipped the board... you are right. my apologies sir. i should have pay more attentionso the only way is to ring through a same board and find where to connect the negative leads.