How to break ultrasonic welding - Page 1
Forum section: electronics / repair

author: @rt
author_rank: Super Contributor
timestamp: January 31, 2017, 08:10:33 am
content: Hi Guys,I have a couple of linear PSUs for retro computing I’d like to replace the smoothing capacitors,and perhaps even the whole PSU, but preferably save the plastic enclosure.Is there a common way to open them other than the obvious butter knife?Cheers, Brek.

author: james_s
author_rank: Super Contributor
timestamp: January 31, 2017, 08:15:51 am
content: I sometimes have luck using a bench vice with a rag to prevent marring the plastic. Squeeze it from opposite corners and some enclosures will crack open along the welds. It's tricky though and some stuff is virtually impossible to get apart without mangling it.

author: Towger
author_rank: Super Contributor
timestamp: January 31, 2017, 08:26:05 am
content: High impact shock. Aka whack the item along it's seams with the head of a large screwdriver or some such object.

author: @rt
author_rank: Super Contributor
timestamp: January 31, 2017, 09:58:17 am
content: I don’t see it being so easy somehowhttp://www.amigahistory.plus.com/commodore/cd32powersupply.jpgNothing to loose though I suppose.I’ve spend enough time & money on the machines, I’ll never be happy with the stock PSU.

author: Gyro
author_rank: Super Contributor
timestamp: January 31, 2017, 10:06:29 am
content: Just double check that itisultrasonic welded. Rub over the label on the underside with something hard to look for screw holes. Also look under any rubber feet, another favorite hiding place.

author: @rt
author_rank: Super Contributor
timestamp: January 31, 2017, 10:08:07 am
content: I’ve got one that has been neatly broken, and the PSU replaced,I just don’t know how they did it.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 31, 2017, 10:27:16 am
content: Quote from: wilfred on January 31, 2017, 08:30:56 amThey don't usually break that quickly, but I've never had that technique fail, and I've taken alotof things apart

author: amyk
author_rank: Super Contributor
timestamp: January 31, 2017, 10:39:37 am
content: Quote from: wilfred on January 31, 2017, 08:30:56 amThe ultra-sonic screwdriver.

author: @rt
author_rank: Super Contributor
timestamp: January 31, 2017, 10:40:22 am
content: The thing is you’d usually care about the guts,but here I care about the case, and the guts are secondary... but will try.

author: thom
author_rank: Contributor
timestamp: March 14, 2023, 06:25:41 pm
content: reviving this old thread to share some info I just stumbled upon. no, this doesn't affec tultrasonic welds, but most of the time these power bricks aren't welded shut, but held together with a solvent.if oyu don't care about the smell, wick some gasoline into the seam, wait 30 seconds, then wick some more into the seam and wait another minute or two, and it will cleanly pull apart. there are sprays you can buy that do this as well with less smell but they aren't as strong so your mileage may vary.

author: richnormand
author_rank: Unknown
timestamp: March 14, 2023, 06:34:27 pm
content: I usually use the combo of a vise or a C clamp and listening at the source of the cracking sound.Then, a 1" wood chisel with a hammer to go around. I find the screwdriver methods leaves to many damaged spots on the enclosure.Sometime you have to repeat the whole process several times, but it works at the end. Small increments and patience are the key.Looking for hidden screws and, in a couple of cases, going to a friend to xray the piece! One handy tool is a diamond wire saw to get in the seam and cut there to weaken the cornerswhile being carefun not to damage the insides. Diamond wire method is much more controllable than using a Dremel.

author: cantata.tech
author_rank: Regular Contributor
timestamp: March 14, 2023, 09:58:26 pm
content: Quote from: @rt on January 31, 2017, 08:10:33 amI don't know if this is common, I doubt it, but the obvious tool would be an ultrasonic plastic cutter.

author: tunk
author_rank: Super Contributor
timestamp: March 14, 2023, 11:03:30 pm
content: I think I read it on this forum:Place two 3-4mm drill bits (or similar) on the seams and then put it all in a vice.This will concentrate the pressure on the seams.

author: abdulbadii
author_rank: Frequent Contributor
timestamp: March 14, 2023, 11:58:00 pm
content: supposing have handy DC motor with its gears to be a grinder, driller, etc, and spudger(s), highly recommended many of it :get 1 mm (or less) thick grinding discjust start grinding with it onto part that seems to be the easiest/weakest to open then continued by use of spudgerpry it up mildly strong to judge finding the screwed fastened partif meet a hard/impossible part repeat using grinder just for it, then back use spudgerit'd be most of time, succeed finishing such task

author: Swake
author_rank: Frequent Contributor
timestamp: March 15, 2023, 10:06:08 pm
content: I hope that after 6 years he managed to crack it openBut thanks for the tips

author: WattsThat
author_rank: Frequent Contributor
timestamp: March 15, 2023, 11:05:33 pm
content: If it has been ultrasonically welded - Place item on a solid surface. Insert a new, heavy duty utility knife blade sharp edge into the seam and smack with a hammer all along the edges. Repeat until it opens. It will. Cleanly. Battery packs are where I learned this. Works for PSU bricks as well.It sounds dangerous and probably is if you’re an all thumbs kind of individual. But, it works well with little to no damage of evidence of opening. Re-close with MEK or appropriate solvent cement.

author: wraper
author_rank: Unknown
timestamp: March 15, 2023, 11:20:02 pm
content: Quote from: WattsThat on March 15, 2023, 11:05:33 pmOnly if you are almost blind and don't see a shit. This does not work without significant visual damage. Also it does not work well on stronger welds. Solvent method allows to take power bricks apart with zero damage. You can take it apart, glue it back and there will be no way to find it out by looking on it.

author: Original
author_rank: Contributor
timestamp: March 16, 2023, 04:39:04 pm
content: Like #15 and also put it in the freezer. The colder it gets the easier it will crack open. If attacked correctly, you will not even need a hammer. Wear gloves watch the sharp edges!

author: wraper
author_rank: Unknown
timestamp: March 16, 2023, 05:11:50 pm
content: Quote from: Original on March 16, 2023, 04:39:04 pmFreezer helps and I've done it before. But solvent works better and there is no chance enclosure will crack in a wrong place. Also you don't need any blade shit. While cold, put is on some semi-hard surface and smash it with a mallet all around on the seam until it cracks. Blade only does more damage as it's not really pushing pieces apart but only mauling the seam.