Author Topic: [Help] 1st soldering job gone wrong, can it be salvaged?  (Read 876 times)

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Offline kikomir

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[Help] 1st soldering job gone wrong, can it be salvaged?
« on: Tue, 29 September 2020, 01:24:06 »
Greetings everyone. Long time lurker around here but only now posting. I tried doing a custom board by soldering but I messed up the soldering and am now asking for help to diagnose the problem and fix it if possible (waiting on a new PCB to be shipped would again take a very long time, months even). The PCB is an XD60 rev.3.

The problem is on one column I get 2 keys registered per 1 key pressed:

7 and 8 registered when pressing 7
U and I registered when pressing U
J and K registered when pressing J
N and M registered when pressing N

All are on the same column - diode/resistor numbers 36, 37, 38 and 39. I would be very grateful if someone can help me out how to diagnose and fix this problem as I am lost right now. Some photos on the following link but I can snap more if needed. 36, 37, 38 and 39 are extra messy because I tried desoldering them one by one to find out where the problem lies. There are washers under all stabilizer screws and the soldering iron had a temperature of around 300-350. The PCB itself was tested before soldering and it worked flawlessly.

https://imgur.com/a/2yjs3bp

Any help is greatly appreciated.

Online yui

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Re: [Help] 1st soldering job gone wrong, can it be salvaged?
« Reply #1 on: Wed, 30 September 2020, 10:01:17 »
my guess would be that you overheated a diode that is now shorting, or that your flux is conductive and shorting with something, at 1st glance i see nothing wrong with your solderling
vi vi vi - the roman number of the beast (Plan9 fortune)

Offline kikomir

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Re: [Help] 1st soldering job gone wrong, can it be salvaged?
« Reply #2 on: Thu, 01 October 2020, 08:11:56 »
I cleaned the PCB with isopropyl alcohol to clean the flux but it didn't help. What can be done about a overheated diode?

Online yui

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Re: [Help] 1st soldering job gone wrong, can it be salvaged?
« Reply #3 on: Fri, 02 October 2020, 00:44:44 »
you can test them with a multimeter without one you are kinda out of luck, you need to test in diode tester mode if one way they have a low-ish reading and the other a very high (should overload) reading, if so they are ok, if it is 0 or close both way then it is dead
Although yesterday i said that because i saw nothing wrong with your soldering, but it make little sense that it would be that given the symptoms... to me it screams that you shorted 2 rows together but i do not see where...
vi vi vi - the roman number of the beast (Plan9 fortune)

Offline leetuser

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  • Location: Herndon, Virginia
Re: [Help] 1st soldering job gone wrong, can it be salvaged?
« Reply #4 on: Mon, 12 October 2020, 17:23:52 »
Nevermind
« Last Edit: Mon, 12 October 2020, 17:25:37 by leetuser »