Author Topic: LB/RB & Both Joysticks not functional, and Y is "pressed"  (Read 1742 times)

Offline InternetC

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LB/RB & Both Joysticks not functional, and Y is "pressed"
« on: July 27, 2020, 09:09:25 PM »
So I'm repairing a controller for someone who sent it in for "bad drift" but there's obviously something else going on here.  I can pin it down to the motherboard with the joysticks as I swapped boards with a known working one and it does not have these issues.  The only thing I can physically see is some damage to the board that was caused by the RT and LT buttons.   I tested the controller with the back plate on and they can't touch the board, so someone must have had it off and pressing it, a lot, which would then make me think someone was trying to fix this same problem before and this is not what's causing the issue.

One other thing I just noticed is that C20 next to the left joystick is corroded.  Also C31 and C30 look a little corroded as well.  I'm guessing this is it?  Know the part number for them so I can stock up on some?  Anything else I should troubleshoot/check?










Offline RDC

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Re: LB/RB & Both Joysticks not functional, and Y is "pressed"
« Reply #1 on: July 27, 2020, 10:03:52 PM »
The POTs of the sticks aren't soldered in.
Screwing up is one of the best learning tools, so long as the only thing you're not learning is how to screw up.

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Re: LB/RB & Both Joysticks not functional, and Y is "pressed"
« Reply #2 on: July 28, 2020, 09:56:26 AM »
The POTs of the sticks aren't soldered in.

I thought I might get this response lol.  I will solder them back on and show that that's not the issue.




Offline RDC

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Re: LB/RB & Both Joysticks not functional, and Y is "pressed"
« Reply #3 on: July 28, 2020, 03:18:24 PM »
Never implied it was the issue, as you did say they were not functional. It's just what was blatantly obvious from the pics, all POT leads desoldered = sticks that will not function, and floating Analog lines can cause all manner of weird issues. Had you said they were jammed in the down/right position and wouldn't move from there and had them desoldered for some reason, we could have gotten off to a better start. ;)

Both sticks jammed down/right like that would be the grounds for all the POTs are open (really long shot) or that the AN+ (1.8v) is not getting to them.

The 3 caps in question are all decoupling on the AN+ line. That U8 there at C30 and C31 is where the AN+ comes from. Just remove them all for a test and see if the Sticks act any different. They are just for decoupling, so anything from 1uF to 1nF would be fine there. I'd toss a 1uF and a 0.1uF at C30 and C31 then another 0.1uF at C20 if removing them gets the sticks going again.

Y being pressed would have to be either a short on that Y button line or something pulling it down. Worst case the MCU is fragged. Could be some corrosion somewhere, around J6 or hiding under that BGA causing it. Kind of need to just start chipping away at the issues and see what we can get going.
« Last Edit: July 28, 2020, 03:21:29 PM by RDC »
Screwing up is one of the best learning tools, so long as the only thing you're not learning is how to screw up.

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Re: LB/RB & Both Joysticks not functional, and Y is "pressed"
« Reply #4 on: July 29, 2020, 10:50:06 PM »
Agreed, I should have been more thorough :)  Thanks so much for the response.  I will check next week when I get back from vacation.  Is it too much to ask for links to the capacitors?  I'm having a really tough time figuring out even what they're called and where to find them.  1uf and 0.1uf comes up with some really weird pieces.  Sorry for my ignorance to motherboards.  I'm a newbie.

Offline InternetC

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Re: LB/RB & Both Joysticks not functional, and Y is "pressed"
« Reply #5 on: July 29, 2020, 11:25:51 PM »


Also, while I got you here, separate issue.  I have no idea how to interpret the pcb scans/traces and info posts. 

Where do I connect the middle pin of the left joystick's Y-axis pot on the model 1708?




Offline RDC

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Re: LB/RB & Both Joysticks not functional, and Y is "pressed"
« Reply #6 on: July 30, 2020, 02:35:36 PM »
The Capacitors are Ceramic, Surface Mount. Physical size of them is 0402. Any place like Digikey, Mouser or the like will have them. They don't have to be anything special in this case since they are going on the 1.8v rail, so any rated over that is fine.

1uF - https://www.digikey.com/product-detail/en/kemet/C0402C105K9PACTU/399-4873-1-ND/1090868
0.1uF - https://www.digikey.com/product-detail/en/kemet/C0402C104M8PACTU/399-7764-1-ND/3471487


Wire LSY to TP63 there. - https://www.acidmods.com/forum/index.php/topic,43981.0.html
Screwing up is one of the best learning tools, so long as the only thing you're not learning is how to screw up.

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Re: LB/RB & Both Joysticks not functional, and Y is "pressed"
« Reply #7 on: August 15, 2020, 04:54:54 PM »
You are way too knowledgeable and helpful! Lol

Anyway, I did as you said. Removed C30 and C31, nothing.  Then removed C20 and the joysticks are back to functioning! And Y and RB/LB function as well now.  That's one little important bugger right there.  So my question is, how important is it to replace them? I'd assume they're there for a reason.  I will probably just buy the ceramic capacitors and put them in anyway but just curious.  Thanks again for the help!  Idk who you are, but you are my hero.

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Re: LB/RB & Both Joysticks not functional, and Y is "pressed"
« Reply #8 on: August 15, 2020, 04:57:08 PM »


Also, which one would you recommend throwing on C20?

Offline RDC

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Re: LB/RB & Both Joysticks not functional, and Y is "pressed"
« Reply #9 on: August 15, 2020, 05:04:57 PM »
Answered all of that in reply #3. ;)
Screwing up is one of the best learning tools, so long as the only thing you're not learning is how to screw up.

 

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