Cutting corners  - Page 1
Forum section: electronics / general

author: GigaJoe
author_rank: Frequent Contributor
timestamp: July 17, 2025, 02:49:16 am
content: is that seem direct technique applied ...and on serious side - what it is supposed to do?

author: cunningfellow
author_rank: Regular Contributor
timestamp: July 17, 2025, 03:53:11 am
content: I'd guess it was a two step process.Cut trace and connect somewhere else to try fix fault.Find out it did not fix fault.Reconnect original path.

author: Ian.M
author_rank: Super Contributor
timestamp: July 17, 2025, 07:48:08 am
content: If that's a power rail, someone without a thermal camera was probably looking for a short, so cut the track without much thought where to cut, then was too lazy to do a neat repair directly across the cut.

author: wraper
author_rank: Unknown
timestamp: July 17, 2025, 08:33:24 am
content: Likely it was cut for diagnostic purpose during repair.

author: Analog Kid
author_rank: Super Contributor
timestamp: July 17, 2025, 08:40:36 am
content: Quote from: Ian.M on July 17, 2025, 07:48:08 amFrom the looks of it, a blob of solder probably would've done the trick here. You can see where they used a Dremel cutoff wheel to cut that trace. Zzzzzzzit. Done.Still, that wire jumper looks fairly neat.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: July 17, 2025, 02:37:24 pm
content: This is one of very disastrous design , at my amateur look .. it 90-x something taiwan made \ design power supply , and that line rolling to opposite side of board to opamp input .. most likely sense wire. and it actually production version, a few that fail - all has the same . one looks like older don't have one ...Certanly it not a power trace overheated, as it need to replace at full . and trace cutted by some impact movement not like dremel ...with 12V output , a great designer add 400V MOV on output ( That exactly was in his mind ... unknown) , some transistors has a black pcb around - miscalculation of heatsink. one resistor 1w completely burn pcb around on all boards, at least need 5W ; overal design unstable ... oscillating with 50uf on output ( i need to find stategig place to put cap at very beginning of where it emitting . dont have a schematic and kinda lazy to trace one .. )

author: SteveThackery
author_rank: Super Contributor
timestamp: July 17, 2025, 02:42:31 pm
content: That's a perfectly OK repair. The only thing I would do extra is a couple of blobs of glue to keep the wire flat and secure.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: July 17, 2025, 04:06:35 pm
content: that my point ... it not a repair ... it manufacturer process flow .. at least 6 failed and dozen working same thingi ...unless the explanation are - they cut for some adjustment during manufactured process then restore it .... im speculating ...

author: wraper
author_rank: Unknown
timestamp: July 17, 2025, 05:59:31 pm
content: I noticed this trace was cut in 2 places. Does this trace touch or is located close to some metal part?

author: Analog Kid
author_rank: Super Contributor
timestamp: July 17, 2025, 06:01:26 pm
content: Quote from: GigaJoe on July 17, 2025, 04:06:35 pmItisa repair, to what kind of defect we don't know.QuoteWe have no idea if it's a manufacturingflawor not. You're just speculating here.(BTW, I take it that English is not your first language)

author: Analog Kid
author_rank: Super Contributor
timestamp: July 17, 2025, 10:08:36 pm
content: Quote from: wraper on July 17, 2025, 05:59:31 pmHey, points to you for spotting that; I missed it. Which explains why the long wire and not just a blob of solder over the top cut.

author: GigaJoe
author_rank: Frequent Contributor
timestamp: July 18, 2025, 02:01:52 am
content: damn .. 2 cuts ...it actually the edge of board , basically connectors output and the metal case in let say couple's mm from this line ...and it seems high impedance one ..( usually im typing with a blind eyes, shorting words, gobbling some, etc ... as it bad as is , consider it a broken english .. so in my mind it was a "Manufacturing process flow" , where one word was skipped distorted a meaning ... )

author: GigaJoe
author_rank: Frequent Contributor
timestamp: July 23, 2025, 01:58:22 pm
content: mystery solved .... unused binding post possible to shear with board ... hm

author: Analog Kid
author_rank: Super Contributor
timestamp: July 23, 2025, 05:54:32 pm
content: Quote from: GigaJoe on July 23, 2025, 01:58:22 pmEh? what does that mean?

author: wraper
author_rank: Unknown
timestamp: July 23, 2025, 07:53:12 pm
content: ^I guess there is a metal rivet nut or something similar under the PCB which may rub against the trace. An oversight during PCB/enclosure design.

author: Analog Kid
author_rank: Super Contributor
timestamp: July 24, 2025, 07:01:02 pm
content: Quote from: wraper on July 23, 2025, 07:53:12 pmHmm; I don't see that from the picture posted, where I'd expect to see some damage from that rubbing.It just looks like a repair that was done by cutting that trace, though I don't understand why it needed to be cut in two places.

author: wraper
author_rank: Unknown
timestamp: July 24, 2025, 08:23:57 pm
content: Quote from: Analog Kid on July 24, 2025, 07:01:02 pmOp said it's like that on every board. It won't necessarily leave marks, as it depends on board flexing, vibration. It may be even not touching the board in most cases. However if solder mask is all that protects the trace from shorting, you need to do something about it.

author: Analog Kid
author_rank: Super Contributor
timestamp: July 24, 2025, 09:22:15 pm
content: OK, so it really is "dodgy technology".