How can I solder damaged soldering pad in the trace of bridge diode? - Page 1
Forum section: electronics / beginners

author: bshi02
author_rank: Regular Contributor
timestamp: June 04, 2024, 01:50:50 am
content: I desoldered Ceramic Capacitors(C804 and C805 1kV 1nf in the below schematic) which is right beside bridge diode(TS4B05G) of 21inch CRT TV(220v 80watts).But Unfortunately,the thickness of these Ceramic Capacitors' pin is thick and so tough,and It already have been bent in the PCB of 21inch CRT TV,While I desoldered these Ceramic Capacitors,Some of its soldering pad was torn apart(damaged).As soon as I confirmed that its capacitance was almost the same as 1000pf with LCR T4 meter, I narrowly resoldered these Ceramic Capacitors back to PCB,But there was already hardly any pad left in one of soldering pad(which is just above D815 and it is C805 in the schematic).So I Scraped off the varnish from its trace and It exposed some of copper and I soldered to connect it to pin of Ceramic Capacitor by applying heavy doses of solder like below picture.I confirmed that it has continuity with its adjacent components But As far as I know, Fairly high amphere and high voltage flows in the trace of bridge diode,So I doubt that It is really enough just soldering exposed some of copper to pin of Ceramic Capacitor with heavy doses of solder..

author: aliarifat794
author_rank: Regular Contributor
timestamp: June 04, 2024, 01:31:43 pm
content: Clean the repaired area with isopropyl alcohol and a soft brush to remove any flux residues. This will help in ensuring a good connection and prevent corrosion. Since the pad is damaged, ensure that the solder joint is mechanically secure. If the capacitor lead is not firmly attached, it might cause intermittent connections.

author: bshi02
author_rank: Regular Contributor
timestamp: June 04, 2024, 08:51:23 pm
content: Quote from: aliarifat794 on June 04, 2024, 01:31:43 pmBy the way,I Scraped off the very little varnish from its trace and It exposed tiny copper and I soldered it to connect it to pin of Ceramic Capacitor.But Now I think I should have Scraped off more varnish from its trace as much as I can,Because Fairly high amphere and high voltage flows in this trace...

author: MathWizard
author_rank: Super Contributor
timestamp: June 05, 2024, 08:39:39 am
content: Yeah you can get trace/pad repair kits or supplies, with new pads and glue/etc.But yeah I'd just scrap back the trace a few millimeter's or a cm , 1/2" on the trace, and take some fresh/clean solid copper wire, of a suitable size for the trace, and just make a little ring/hook as a pad around the diode leg, and a straight part going out onto the trace. And with flux get it nicely soldered, then clean the whole area real good after, with ISP, to keep the high isolation.

author: MrAl
author_rank: Super Contributor
timestamp: June 05, 2024, 10:32:07 am
content: Hello,#26AWG bare tinned wire is good for this purpose, as mentioned wrap one end around the lead, run the remaining length to the trace, solder, clean. A decent wire is 'wire wrap wire' which is nice and thin. Strip a short length to bare wire.#22 wire is approved for military applications, but sometimes you just have to use thinner wire.

author: bshi02
author_rank: Regular Contributor
timestamp: June 05, 2024, 01:55:29 pm
content: Thank you very much for reply!Currently I don't have 26AWG or any thick wire, So Firstly I'll scrap back the trace few more millimeter and I'll make use of lead of 1w carbon resistor in order to run one end of ceramic capacitor's lead to the trace by soldering.

author: MrAl
author_rank: Super Contributor
timestamp: June 06, 2024, 08:49:36 am
content: Quote from: bshi02 on June 05, 2024, 01:55:29 pmHi,If the 1 watt carbon resistor lead is thin enough that should work. Just have to make sure it does not touch any other traces and no accidental solder bridges

author: kevin.gibbs
author_rank: Regular Contributor
timestamp: October 02, 2024, 01:18:11 pm
content: This connection is sufficient because a large current does not pass through this capacitor.The photo does not show the holes for the parts well. You don't need to do anything additional if the holes are metalized. If there is no metallization, you must also fix the capacitor with thermal adhesive for mechanical strength.