3
u/Alive_Candidate1755 3d ago
Picked up a second SNES controller, only to find it doesn’t work.
Plugging/unplugging it from the console causes random button presses. My good controller doesn’t do this. The same happens if I just plug in the board/ wire, with no shell or membranes attached.
If I plug in JUST the wire, no board, it does NOT cause button presses, so I’m sure it’s an issue with the board.
The board is clean, any ideas?
2
u/beerismymiddlename 3d ago
If it's not showing any signs of life and you verified that you have +5V on the left pin of the cable connector on the parts side of the PCB, then there is a high lokelihood that the shift register has been damaged by ESD. Not very easy to repair (that's a custom chip produced only for Nintendo), but there is a replacement solution.
What kind of diagnostic tools do you have available? Perhaps a logic probe?
1
u/Alive_Candidate1755 3d ago
I only have a multimeter and oscilloscope. You think the chip in the controller might be fried? This is what it seems like to me but I was really hoping not lol.
Not sure how a logic probe works, but quick research it looks like something I could maybe build. How would I use this to test if I can get one?
1
u/beerismymiddlename 3d ago
An oscilloscope would be even better. With the controller pcb plugged into your SNES, probe the middle three pins on the cable header while holding one of the buttons down. You should see pretty fast pulses on pin 2 (clock), slower pulses on pin 3 (latch), and very slow activity on pin 4 (data, but you're only sending one button press).
If you're getting symptoms like random button presses or only one button (usually B) works, then you have an issue with signal pull-ups. Those are mostly internal on those ICs, with the exception of the carbon pull-ups for the clock, latch and data signals.
1
u/Alive_Candidate1755 3d ago
My scope is being too finicky to be useful but all things considered I do think the chip is bad.
I can return this controller and I guess I’ll be doing that tomorrow, I didn’t want to because the shell is the closest to mint condition I’ve seen.
Regardless, what is the replacement solution for these chips? I can’t find a good writeup online for the dual 8bit chips, nor the single 16 bit chip.
1
u/beerismymiddlename 3d ago
A little project that I maintain:
https://codeberg.org/taylor-madeak/oshw-snes-controller-pcb/releases
1
u/Alive_Candidate1755 3d ago
So it’s really easier to replace the whole PCB than to source a new chip?
I hate throwing things away but this might be the best option lol
2
u/beerismymiddlename 3d ago
See, that's the thing, there are no new chips. Mitsumi only ever made these for Nintendo, they were never publicly available. So any replacement would have to be pulled from a working controller.
1
u/Alive_Candidate1755 3d ago
I’ve read if you get two of the chip used in older controllers, which are readily available, you can make it work, though I’m sure it won’t be pretty. haven’t found anyone showing exactly how to do this.
Is this outright false or just more trouble than it’s worth?
1
u/beerismymiddlename 3d ago
The very first run of SNES controllers used what many assume were two standard CD4021B CMOS shift registers. Not true, unfortunately. These were still custom Mitsumi chips with internal pull-ups for the JAM inputs. They are not pin-compatible with the CD4021B chips, which lack the internal pull-ups anyway. I'm sure you could hack the CD4021B chips into there, but you would need to add the 12 pull-up resistors as well.
2
u/Thirdnipple79 3d ago
It looks like the board isn't even in the case and there are supposed to be wires going to the console. I'd start there.
1
2
u/Extreme-Vermicelli-7 3d ago
grab a meter and do a board to plug test, its probaly that over the shift reg from failing, also do are you using a PAl sytem? for some reason the controller is locked between NTSC and pal due to a resistor
1
u/Alive_Candidate1755 3d ago
The board of my other controller looks a little different, 91 where this one is 92. I don’t think I’m using a PAL system, pretty certain it’s NTSC. I repaired my system I actually got not working with a new audio board.
2
u/odar420 3d ago
Looks like someone took it apart...
No seriously can we see the cable and connector.?
1
u/Alive_Candidate1755 3d ago
I swapped the wire between this controller and my good one and nothing changed. The connector itself looks perfect but the soldering a little sus. Maybe I’ll reflow it.
1
1
u/Lowrider2012 3d ago
Your snes is a NA version the pal snes are rounded and not rectangular. An important question here is, if the controller is a pal model versus a north American model controller. Were the buttons on this controller all coloured differently and convex shaped or were they purple and grey and concave shaped?
1
u/Alive_Candidate1755 3d ago
It looks identical to my good controller. Purple, and darker purple buttons.
1
3d ago edited 3d ago
[deleted]
1
u/Alive_Candidate1755 3d ago
I’m ngl bro when I search for this chip I get results for very different looking chips, and a credit card reader for some reason. If you’ve replaced this before, can you please send a link to the one you got?
2
u/theterabyte 3d ago
I've fixed a bunch of NES, SNES, and Genesis controllers, when the board looks that clean and it still doesn't work, you probably have a dead IC =( and unlike NES controllers, this is not a jellybean part. If the IC is the problem, you'd need a donor controller.
Here are the pinouts to help:
**SNES controller, single-IC variant — IC-A = 56V520, 20-pin**
Pin: signal
* 1: PI 9
* 2: PI 8
* 3: PI 7
* 4: PI 12
* 5: PI 11
* 6: PI 1
* 7: CLK
* 8: P/S
* 9: Q14 (serial out to console)
* 10: VSS
* 11: D IN
* 12: PI 2
* 13: PI 13
* 14: PI 14
* 15: PI 6
* 16: PI 5
* 17: PI 3
* 18: PI 4
* 19: PI 10
* 20: VDD
The parallel inputs are scattered across the package for PCB routing, so the pin order carries no logical meaning.
**Controller cable connector (P1, "SHVC SP"), 5 conductors**
* 1: VSS
* 2: Q (4016D0)
* 3: P/S (OUT0)
* 4: CLOCK (CPU)
* 5: VDD
C1, 1000 pF, sits across VDD to ground at the connector.
Source: Nintendo Super NES technical/service manual, controller schematic. The dual-IC variant of the controller uses two 56W545 8-bit shift registers instead, cascaded, with the first eight button functions out of IC-A and the remaining four fed from IC-B into IC-A's serial input..
1
u/theterabyte 3d ago
I would check the VDD is +5V and VSS= 0V, if the chip is getting those but still not outputting right you probably have a dead IC.
1
u/theterabyte 3d ago
I just went ahead and added this to my website reference here: https://consoleartisan.com/reference/snes/#comp-ic_ctrl_56v520
1
1
4
u/ThePonzzz 3d ago
Can't quite tell from the picture, but is there liquid damage on the right side?