| Click here to select a new forum. |
| SE/30 recap - capacitor pads lifting, looking for advice |
Posted by: gsprod on 2026-02-15 07:02:17
Hi everyone,
I'm working on recapping my Macintosh SE/30 and I've run into an issue: when I remove the old electrolytic capacitors (3 so far), the solder pad lifts off the board with the cap.
I'm wondering if this is due to:
- the type/quality of flux I'm using
- my hot air temperature
-not heating long enough (or too long)
or if the pads are already weakened from electrolyte leakage
I'm using hot air, and I'm trying to be gentle, but the pads still seem very fragile.
Is this a common problem on SE/30 boards? What's the recommended technique to remove the original caps safely?
Any tips would be greatly appreciated - I'd like to avoid damaging more traces.
Thanks! |
Posted by: finkmac on 2026-02-15 08:51:03
it’s hard to say. Could be a combination of all those points.
Myself, I’ve never had a good time using hot air to remove caps…
I use the excellent and highly recommended method of cutting the capacitors with an hakko cutter and then removing the IC legs with a soldering iron and a bunch of no clean flux.
Generally that only results in +-1 lifted pad
per board |
Posted by: gsprod on 2026-02-15 08:56:31
Im going to try to that.. before un ruin the full mother board |
Posted by: ObeyDaleks on 2026-02-15 09:04:14
I use hot air almost exclusively for cap removal and I’ve not experienced this issue, but I would suspect that your technique needs some adjustment.
- Be patient and don't pull on the cap. Instead, gently nudge it to see if it's loose. Only lift it off once the solder is completely melted. It should come off with zero effort. You can also gently poke at the solder with your tweezers to see if it's fully melted.
- Make sure both pads are loose before lifting the cap. I use a medium size nozzle to heat the board evenly, but if you're using a very thin nozzle, you could end up with one pad melted and the other still attached. I have a suspicion that this might be your issue.
- If the pads are severely corroded, you can add some solder/flux to the pads first. This will dilute/refresh the old solder and push away some of the crud.
- Use low air flow and temp around 400 or slightly less. This is plenty to get the cap off without damaging the board.
- When cleaning the pads after removal, be careful and don't apply too much heat for too long. I use higher temps (400+) but spend very brief amount of time on each pad. IME, pad cleaning poses the highest likelihood of damaging the pads.
|
Posted by: bibilit on 2026-02-15 09:29:39
I use a side cutter plier to remove the head first.
Then remove the remaining legs, I have removed many (too many) capacitors, almost never had any issue. |
Posted by: superjer2000 on 2026-02-17 11:21:15
Needle nose plyers. Grab cap, push down and turn (twist) back and forth in very SMALL increments until the legs break off and then desolder the legs from the pads. Zero lifted pads with this method.
Reason it works: The legs are already weakened from the leaking cap and you are applying force on the plane the solder pads are strongest. You don't want to do anything that involves a lifting motion with these pads as the capacitor goo dramatically reduces the ability to melt the solder without overheating and damaging the pads.
I can clear a whole SE30 board with no damaged pads in about 5 minutes. |
Posted by: Aeroform on 2026-02-17 14:43:22
Another vote for the gentle twist method. Zero lifted pads since I started doing that. |
Posted by: Boctor on 2026-02-17 15:49:25
Have lifted no pads with the pure axial/twist method, even on the worst boards I've had. Gentle heating and attempting to walk off a capacitor has managed to do it, though. With a more precise preheater and hot air nozzle it should still be possible, but the flush cutters still sound the most tempting. |
Posted by: JC8080 on 2026-02-17 19:44:48
I have used the twist method, as well as cutting the cans off with side cutters, both are effective and I haven't damaged a pad doing either. As already mentioned, if you use either of those methods make sure not to lift at all while you are doing it, it's better to provide a little downward pressure just to make sure you aren't pulling up on the pad. |
Posted by: ymk on 2026-02-17 21:26:40
If you don't IR preheat the board, hot air can end in trouble.
I never twist. Dual irons is my favorite method for caps. |
Posted by: shirsch on 2026-02-18 06:42:45
If you don't IR preheat the board, hot air can end in trouble. Truer words were never spoken. My batting average on hot-air reflow (either direction) was miserable until I picked up an IR pre-heater. It is possible to work without one, but YMMV. |
Posted by: superjer2000 on 2026-02-18 06:54:44
I never twist. Dual irons is my favorite method for caps. I used to do the two iron method and also have a good set of soldering tweezers. The additional time and risk to the pads when caps are leaking are just not worth it vs the next to zero risk (and actually zero risk for me- I haven't lifted a pad in literally hundreds of smd can replacements) gentle twist method - even if the twist method is sometimes looked down on). For beginners especially though anything but the gentle twist method isn't a good idea. |
Posted by: s_pupp on 2026-02-20 18:38:13
Another vote for very gentle clockwise-counterclockwise alternating twisting movements while gently pushing down. The legs of even new SMD aluminum caps are susceptible to metal fatigue. |
Posted by: GRudolf94 on 2026-02-21 17:36:50
I like flush cutters to snip them above the base. My reasoning is that twisting is no different from pushing the caps from side to side, which puts a load on the pads that they were not meant to support, and the compromised bonding between copper and fiberglass caused by the corrosion could make that happening easier. I have gotten boards to repair that people tried twisting caps off of, and ended up tearing pads away. |
Posted by: ymk on 2026-02-21 20:29:36
I have gotten boards to repair that people tried twisting caps off of, and ended up tearing pads away.
Same here. It's only in the vintage Mac world that this practice is considered sane. |
Posted by: Boctor on 2026-02-21 21:41:41
So in theory, all we'd have to do for it to be considered sane in general is to twist SMT electrolytics off of all kinds of PCBs? |
Posted by: ObeyDaleks on 2026-02-22 09:10:33
The twist and snip methods rely on the pads being solidly attached. If there’s already damage to the pads, they absolutely can come off when shearing forces are applied. I would say the snip method is probably safer as long as you’re cutting parallel to the leads (as opposed to perpendicular where you’re pulling on both leads). First time I’ve ripped pads off was when using the twist method on an LCII that had significant cap damage. I ended up ripping off like 5 or 6 pads in a single session. Yes, I did push down while twisting. After that experience, I never used that method again and switched to hot air. |
Posted by: superjer2000 on 2026-02-22 15:22:59
The twist and snip methods rely on the pads being solidly attached. If there’s already damage to the pads, they absolutely can come off when shearing forces are applied. I would say the snip method is probably safer as long as you’re cutting parallel to the leads (as opposed to perpendicular where you’re pulling on both leads). First time I’ve ripped pads off was when using the twist method on an LCII that had significant cap damage. I ended up ripping off like 5 or 6 pads in a single session. Yes, I did push down while twisting. After that experience, I never used that method again and switched to hot air. That's too bad you lost so many pads with the "twist method". I haven't lost a single one and have dealt with some really brutal boards. Where people have lost pads doing this I think (not saying this was your case) that they are reading too much into "twist". To be successful you are "twisting" back and forth an almost imperceptible amount, increasing that amount by a further almost imperceptible amount each time. It should take a couple of minutes or more to get a cap off.
I think people just get impatient and then give it too much of a twist and there go the pads.
I will again maintain that using this method properly applies forces on the plane the pads are strongest. |
Posted by: Boctor on 2026-02-22 16:01:18
Well said about the actual rotation distance, that's an important clarification I never mention. You'd want to fatigue the legs and nothing else. They usually break farther up, with the force concentrating at a thin/weak area that's not right on the pad. |
Posted by: Fred1212 on 2026-02-22 16:53:56
I've found its the amount of cap goo leakage that affects the pads causing them to lift with either method |
| 1 > |