Repairing the Surprise Box Broken JD40

[urbancamo]

OK, so when I received the surprise box I happened across a broken JD40 - there was a helpful note on the bottom explaining that the teensy didn't work and that the space bar stabilizer had not been installed before the switches were soldered to the PCB and therefore could not be installed without unsoldering every switch!

My soldering skills are fairly ninja - although my tools less so. I used de-soldering braid and coated the switch solder points in flux before heating the braid over the solder points to suck up as much solder as possible. The two legs of each switch are different - one is a flat, thin prong and one a square leg. It was quite easy to confirm that all the flat prongs were free by wiggling them and I started to get a little movement in the PCB relative to the switch plate. I probably should have been a little more patient but in the end I levered the PCB off gradually with a reasonable bit of force. The downside of this approach is that some of the pads on the PCB have been lifted where the solder was holding firm on the other side of the board.

The upshot of this is that I will have to manually check connectivity between each switch pad and the other end of the PCB trace, repairing where necessary. At least the diagnostic approach will be very straight forward, if a little laborious.

The other interesting part was removing the Teensy. Given the hole sizes and the proximity of the pins at 0.1" pitch I didn't hold much hope out that I would be able to remove it whole. The alternative approach was to work from one end and use a small pair of snips to get in and cut the legs between the Teensy and the JD40 PCB. In the end I resorted to breaking down the Teensy using the snips (well two pairs actually, I broke the first pair!) and then slowly uncovering the individual pins. I have yet to remove them - it is a particularly three-handed job (anyone who has done any soldering knows that the whole process is designed for three handed people at the best of times) so I'll leave it until I've replaced my soldering iron (the end of which just plopped off - thankfully not on to anything to precious!)

I'm pretty sure I have some teensy's kicking around so will be looking to get one back on the board. I should then be able to diagnose each of the PCB switch pads before soldering the whole kabudle back together (and remembering to install the spacebar stabilizer!

Regards, Mark.

With the PCB removed:

repair3.jpg (208.83 KiB) Viewed 2433 times

Teensy off the board - just the pins remaining:

repair4.jpg (236 KiB) Viewed 2433 times

Copper rings around some of the switch pins indicating where a little too much force was used!

repair2.jpg (263.65 KiB) Viewed 2433 times

This is what a 'deconstructed' Teensy looks like!

repair1.jpg (150.69 KiB) Viewed 2433 times

[chzel]

My soldering skills are fairly ninja...

http://lydz25.deviantart.com/art/Ninja- ... -334288378

Poor little teensy...looks like it met the ninja above!

[Muirium]

Ah, copper rings around the legs, I know that story. My desoldering "skills" are so low on the spectrum that it's insulting of me to even use the word in their presence. So, yes, I saw that delicious JD40 when I opened up the Surprise Box and knew to leave it the hell alone! Note the red SA set on it. It's a near complete custom keyboard, besides all the take apart work needed to get there. I knew it would soon find a home.

[flabbergast]

I was also removing a teensy from a board once ... I ended up snipping all the legs through the black plastic that's between the PCBs. Then I had to remove the remains of the pins from both the Teensy and the PCB - but I actually ended up with a functional Teensy. I also lifted some pads.

BTW this is how you can tell cheap PCBs from the better ones - the better ones (apart from usually being ENIG plated - the contacts look golden) survive desoldering a few times even after a few years.

Finally - I recommend getting at least a solder sucker (a.k.a. desoldering pump) for desoldering switches - I've used both a braid and a sucker and I can tell you that it's way easier with a sucker.

[andrewjoy]

It did not look that bad when i took a gander at it but i did only take a quick look, man that board has been skull fucked

Possibly get it in an ultrasonic cleaner to see whats left of the pads ?

[urbancamo]

I'll give it a clean yes - I have to say that it looks a lot worse in the pictures than it is in reality.
I'll have to manually wire a few pads up but most have survived intact.

I love your colourful terminology however!
Mark

[Redmaus]

The teensy part made me laugh pretty hard...

I definitely know what its like to have a hard time desoldering switches, broke a few alps switches trying to get them off some cruddy chicony board.

[7bit]

A 980x190px crop would make an excellent header image.


The note and the stabiliser are from me, same for the key caps, but you would have guessed that.

[andrewjoy]

I love your colourful terminology however!

Hey thats a technical term!

You have

Damaged , Buggered , screwed , fucked and then skull fucked, oh and after that comes China Esport