can a interior plane sustain... swiss cheese damage? (welding machine) - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: September 02, 2025, 09:44:51 pm
content: I gave it another crack, and I noticed that near where I fixed a burnt resistor, grounds are not what they should be. For instance, there is no ground connection for a CD4093 and a few 2N transistors that should be connected to ground.This failure shorted a IGBT, a NMOS and a power resistor on another board. On this board it damaged I believe a 2N gate and a 1.5k resistor (burn it half).Anyway, apart from a small crater under the resistor, there was no signs of damage. However, based on some available schematics, several parts do not appear to be linked to ground/common on this PCB. It has a ground plane and a power plane (15V).I am working on mapping it out, but as far as I can tell, this damage is akin to say.. swiss cheese-the yellow circles are missing connections, the red circles are OK connections. R7 is the resistor that burned/explodedHow do you get that distributed damage to open all those nodes? Like I said, the PCB looks fine from top and bottom.taken from miller welds forumQ1 common, Q2 VDD, Q3 common, Q3 emitter, 4093 ground, Q33 emitter, Q4 and R6like what the hell is going on down there in the plane??I thought about just using a buncha jjumper wires but it feels pretty sketchy. Also, I don't see damage using a flashlight to look at the ground pads (+ shapes) that are not connected.

author: Nominal Animal
author_rank: Super Contributor
timestamp: September 02, 2025, 09:56:06 pm
content: Impossible to say, because this is what I see:Why is it so hard to just upload the frigging images? Do you intend to remove the picture after you've gotten your answer, so that nobody else can gain from the discussion?

author: coppercone2
author_rank: Super Contributor
timestamp: September 02, 2025, 10:02:51 pm
content: yeah maybe you should take medication instead of accusing me of insane shit, I never removed any imagesi.imgur.com/xpu3D7z.jpegyour browser is not displaying things properlywhy don't you check with the quote button instead of trying to start an argument? Why should I go out of my way for people running broke systems? maybe you should complain to the forum administration about your browser not working instead of spreading venom. maybe they can make a text only mode that gets rid of forum interactivity features that have been normal for15-20 yearsnow for gutted browsers

author: Nominal Animal
author_rank: Super Contributor
timestamp: September 02, 2025, 10:19:32 pm
content: Good luck with that attitude.

author: PCB.Wiz
author_rank: Super Contributor
timestamp: September 02, 2025, 10:26:55 pm
content: Quote from: coppercone2 on September 02, 2025, 10:02:51 pmThat is not an image, it is alink to another website, which then seems to need another click.That's not a great way to use a forum.

author: coppercone2
author_rank: Super Contributor
timestamp: September 02, 2025, 11:39:31 pm
content: Quote from: Nominal Animal on September 02, 2025, 10:19:32 pmthe only person with an attitude problem is you, you literallyaccusedme of some sort of conspiracy to hide information because your browser is not working

author: Nominal Animal
author_rank: Super Contributor
timestamp: September 03, 2025, 12:03:07 am
content: Quote from: coppercone2 on September 02, 2025, 11:39:31 pmConspiracy?What the hell have you been imbibing? I recommend you take a break from that shit, it's making you incoherent and paranoid.No, it's just a pattern that you see when silly newcomers ask about stuff here, and when they get an answer, they hide their tracks by deleting the post and pictures, so that their employer and coworkers don't find out they asked outsiders about work stuff. They always use external services to host their images, so that even if the administrator of the site reverts the text of their posts, they are assured that at least the images are gone. Most often, you see this with software code related questions, with the code snippet shown as a screenshot image instead of text within...tags.Besides, services like imgur.com are known to delete images for their own reason (too high load, not accessed often enough, or just because). By uploading the images to this forum, you ensure that does not happen, and the images stay with the post.The one exception I myself have, is with SVG images (that I use for schematics and diagrams that are much better as scalable vector graphics than as pixmap images). For one, they're not allowed to be uploaded; for two, theyshouldn'tbe allowed in the same domain as the HTML content unless fully trusted, because they may contain JavaScript and are thus an XSS vector. From an unrelated domain, there is no viable attack vector at all with current browsers, due to them blocking JavaScript across unrelated domains (necessary to stop XSS-related attacks). I maintain those SVG files atmy own host, with the same kind of responsibility and assumptions Dave has for content here. (That is, unless I die unexpectedly, I consider it my responsibility for maintaining those files at their current URLs for the foreseeable future.) This has been discussed in detail and demonstrated here on this forum, in a forum image upload/maintenance/format-support related thread a couple of years ago.

author: coppercone2
author_rank: Super Contributor
timestamp: September 06, 2025, 08:35:17 am
content: caught it, it looks like arc light inside of a circuit card. The thermal relief near the via's is acting like a fuse and there is nearly invisible damage occuring inside of the PCB that disconnects the via from the traces. I caught a white glow for a split second when I some how turned on a IGBT with a voltmeter for a connection to the interior planeI wonder how many SMPSU were deemed too hard to repair when people got overwhelmed by thoughts of drifted or damaged passive parts, when the real problem is just a 'fuse' built into the PCB near the viaand for the post above, an accusation is an accusation. no wall of text can change that