Beginners trace repair question. - Page 1
Forum section: electronics / repair

author: MrZwing
author_rank: Regular Contributor
timestamp: January 05, 2017, 07:11:18 pm
content: Helloi'm trying to fix a keyboard for an old vintage computer since especially one of the keys did not work as it should.now when i took it apart i found this on the trace to the key (see image)my question if you veterans can see if this could be the cause and if the trace is broken/oxidated. if so how can i fix it properly any suggestions?/MrZ

author: dan3460
author_rank: Frequent Contributor
timestamp: January 05, 2017, 08:34:45 pm
content: What I have done on similar occasions is to scrape some of the solder resist from each side of the trace that is firmly attached, then with a fine wire solder the missing part. After confirming that the solder repair is working, I use a little of transparent epoxy and brush a think film over the repair.

author: tautech
author_rank: Super Contributor
timestamp: January 05, 2017, 08:46:08 pm
content: Quote from: dan3460 on January 05, 2017, 08:34:45 pmThis ^^^With the finest wire you can manage to work with forthisrepair as you need to keep it low profile so not to affect the membrane above it.You can get conductive pens with silver (I think) and that would be quite satisfactory to the low currents used in keyboard switching circuits. When dry coat it with some lacquer/varnish to ensure it gives long life.

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: January 05, 2017, 09:25:57 pm
content: These is a pen type application for traces on ebay or aliexpress for drawing circuits by hand on paper to test your circuit, this could work.

author: cheeseit
author_rank: Regular Contributor
timestamp: January 05, 2017, 09:29:24 pm
content: Judging from the image, and if this affects especially one key, if the trace was bad wouldn't this affect more keys and maybe consistently? Could worn conductive carbon rubber be the reason?

author: MrZwing
author_rank: Regular Contributor
timestamp: January 05, 2017, 10:07:02 pm
content: Thank you for all the replies.Well since this is one of the arrow keys that i need to navigate on the computer (atari 1040stfm) i haven't been able too see with other keys that doesn't work. but there is only a couple of keys connected too this trace so they is possibly out as well. but i will try and repair it with a thin wire and see if it will do the trick. should have some really fine gauge in my workshop.

author: tpowell1830
author_rank: Frequent Contributor
timestamp: January 05, 2017, 10:15:06 pm
content: Check the trace with an ohmmeter in order to be sure it is open. The suggestions above are all good for repair if it is indeed broken.PEACE===>T

author: Fisher77
author_rank: Regular Contributor
timestamp: January 06, 2017, 04:12:30 am
content: It should look something like this, except thinner wire in your case.

author: DaJMasta
author_rank: Super Contributor
timestamp: January 06, 2017, 08:07:40 am
content: Quote from: joseph nicholas on January 05, 2017, 09:25:57 pmIn the same vein, you can get little containers of solder resist to cover over your repair if you don't want to use epoxy or similar.

author: vealmike
author_rank: Regular Contributor
timestamp: January 06, 2017, 09:30:03 am
content: Quote from: DaJMasta on January 06, 2017, 08:07:40 amMy wife has several of these in varying colours. Weirdly she uses them on her fingernails.

author: MrZwing
author_rank: Regular Contributor
timestamp: January 06, 2017, 01:38:07 pm
content: I have Used son very fine sand paper and looked at it with a loupe and there is definitely a break in the trace. i could be gaped with some solder but i think it would be a better job done if i take a think wire as well and not leave anything for chance. need to buy some flux before i do anything though so i get a clean and proper solder joint.might go to a beauty shop and see if they have anything in "solder mask green".

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: January 06, 2017, 01:44:45 pm
content: Not to get off topic too much, but do you really need to make a repair? I mean, I was able to score 5 old PS/2 keyboards at the local recinto ferrial. The one I'm typing this note on is an old IBM (not mechanical). May be one could find an old membrane to replace yours. This type of keyboard is not really much of a collectors item an they all feel and work about the same.

author: Basileus
author_rank: Regular Contributor
timestamp: January 06, 2017, 02:05:02 pm
content: Quote from: joseph nicholas on January 06, 2017, 01:44:45 pmimho, this repair is quite easy and fun. I would love to do it. Cant see why he shouldnt repair his keyboard.

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: January 06, 2017, 02:43:02 pm
content: He should. I don't see all the back and forth from the op on a trival repair.

author: vealmike
author_rank: Regular Contributor
timestamp: January 06, 2017, 03:05:21 pm
content: Quote from: joseph nicholas on January 06, 2017, 01:44:45 pmThe Atari 1040 had an integral keyboard.

author: MrZwing
author_rank: Regular Contributor
timestamp: January 06, 2017, 06:11:54 pm
content: Quote from: vealmike on January 06, 2017, 03:05:21 pmindeed but also it's a fun thing to do just to repair what you have... and it is a "bonding process" between me and the computer.