SNES problem - fuse or voltage regulator post SuperCIC?

I went ahead and fitted a SuperCIC to my PAL SNES (standard revision, it isn't a 1chip) this afternoon and am having some issues.

In terms of fitting the superCIC, I already had the territory lockout switch and 50/60hz switch mods done, the aim for this was to only use the SuperCIC for tackling the CIC side of things. I wired it up as follows:

SuperCIC Pin 01 = Pin 18 CIC (+5v)
SuperCIC Pin 02 = Pin 07 CIC
SuperCIC Pin 03 = Disconnected/floating
SuperCIC Pin 04 = Disconnected/floating
SuperCIC Pin 05 = Disconnected/floating
SuperCIC Pin 06 = Disconnected/floating
SuperCIC Pin 07 = Disconnected/floating
SuperCIC Pin 08 = Pin 11 CIC
SuperCIC Pin 09 = Pin 02 CIC
SuperCIC Pin 10 = Pin 01 CIC
SuperCIC Pin 11 = Pin 10 CIC
SuperCIC Pin 12 = Disconnected/floating
SuperCIC Pin 13 = Pin 08 CIC
SuperCIC Pin 14 = Pin 09 CIC (GND)

This was from my thread here. So to clarify, I didn't run anything to the PPUs as the existing manual switch remained in place to control these manually, I disconnected the territory lockout switch, and didn't replace the power LED or wire anything back to the existing power LED.

I ended up removing the whole CIC chip and soldering a wire + 10k resistor between pad 8 from the CIC to a GND point (the above wiring also meant I have a a wire from the SuperCIC going to the same pad). At the same time I also bridged the points on the controller board to allow overseas pads on the machine.

I also made sure to discharge the voltage before I started.

When I tested it, nothing happened - plugged it in, switched on the power (everything was connected and screwed down except for the top plastic cover), no power LED, nothing on the screen (not even a black screen).

I checked everything and it looked like the ribbon cable to the controller panel was not inserted correctly, so I disconnected power and removed/re-inserted the ribbon cable (and this being said, on reflection I don't think I discharged any voltage before doing this...)

I then cranked out the multimeter - the PSU was outputting a touch over +9v AC (probably closer to 10 or 11v AC, keeping in mind that PAL SNES consoles take AC instead of DC from the PSU) and the voltage was running across the power switch without any issues. Voltage seemed to be going through the fuse, but I didn't check continuity, so I have a feeling I wasn't doing the right thing around the fuse when I had a look.

On the voltage regular things start to get weird - the heatsink was getting pretty warm (mind this is probably normal!), the input voltage was about the usual (around +7v DC), but the output voltage was tiny - the multimeter was reporting ~55mA instead of ~+5v.

So, I guess there are a couple of things here:

- Is the way I dealt with the SuperCIC causing an issue?
- Is it likely that the fuse is dead?
- Is it likely that the voltage regulator is shot?

I've got a spare 7805 lying around I could use as a replacement, but don't have a fuse (no troubles grabbing one though).

For those far more experienced than me, would be great to hear your thoughts!

 

Pin 4 and 7 shouldnt be floating for starters. They are inputs and there is code that is checking their value, leaving them floating will make the cic not work. Which might be your issue (held in reset?)

Just connect +5v to each of those and try again.

Also try adding a 100nf cap between vcc and gnd on the pic

 

Thanks for the advice Bad_Ad84 - I'll give that a whirl. Would it be possible to grab the +5v from pin 1 and connect that to pins 4 and 7 or should I run a fresh line from the voltage regulator? I'll also whack in a 100nf cap between VCC and GND (pins 1 and 14 respectively) and try again.

If this doesn't work I'll disconnect the existing switch on the PPUs and run the whole thing through the SuperCIC as stock. If you're right and it's being held in permanent reset mode would this explain the voltage regulator only pushing out a tiny amount of voltage on the output pin? When the CIC has pushed the console into permanent reset mode in the past I've negelected to measure the voltage at the regulator, but the behaviour was the same.

 

You can get it from pin 1 no problem.

I would think the output from the regulator should be 5v - even in reset, but its worth fixing this first.

 

Cool, thanks for your help mate!

I popped open the SNES today and redid the mod, this time doing everything by the book - I replaced the 7805 with a tested/worked one, wired in the PPU to the board, wired in +5v to the pins indicated and wired up the LED. With the wiring, I used a few of the alternative spots rather than directly soldering to all the pads where the CIC used to sit prior to removing it (pad 8 in particular was a bit of a pain). I triple checked all of the wiring from the pads to the IC and everything came up as connected. I also wired a fresh 10k resistor to GND (used the exposed metal near the edge of the PCB and checked continuity and double-checked that it was providing 10k of resistance - all good).

I also double-checked all the wiring on the controller board in care the ribbon cable got broken or bent out of shape, and everything checks out.

I also ran a continuity check on the fuse and it was coming up as connected, so that nixes that one.

When I was replacing the voltage regulator I also removed the old wires carrying +5v and GND to the previous switches and removed them, along with the switches.

Despite all of this, no changes. I measured again and the input voltage was around +6.6v, but the output was +77mV. I also checked the power getting to the IC, and it was measuring around 20mV.

The only thing I haven't done is wire up a cap between VCC and GND on the SuperCIC because I don't have any 100nF caps around. I was going to grab some for another project, so I'll order them in and see if that helps (don't think it will given the weird voltage output).

Any thoughts on anything I've missed? Am thinking of binning this one (well, stripping it for parts/spares) in lieu of any lightbulb moments and bugging you for a SuperCIC with the 50/60hz kit for a 1chip SNES I have and do everything as a standard mod.

... the problem is that it's annoying me that I can't nut out what's wrong and I don't want to move along to my next console without putting up a bit more fight

 

Sounds like there must be a short after the regulator?

You should be getting 5v out, which need fixing

Any chance of a high res pic of your work/mod/board?

 

I'll take some pics the next time I pop the SNES open, which realistically will be next weekend (don't often have time during the week to play with the soldering iron!). I'll also pop off the heatsink while I'm at it and have a few checks around the lines directly following the voltage regulator to see what might be obstructing the thing. Some close-ups of the CIC might also help in case something down there is shorted. It could even be something as simple as one of the legs from the CIC floating somewhere on the PCB for all I know!. Is it unusual for the 7805 to get quite warm? The heatsink was getting very warm after powering on for a short period of time on the old 7805.

 

They dump all the excess power as heat, so yes - getting hot is normal.

 

Just an update - the issue was my soldering Pad 2 of the old CIC had bridged to pad 3, and pad 11 had a cold solder join. Fixed it all up, and it's now all good!

The only cart that seems to be unhappy is my Kirby 3 SFC cart, but I have a feeling the edge on the cart may need some extra love (I've used iso, but will resurface with some Brasso and clean with iso again before using it - the same thing has worked a treat on a couple of other carts that were unhappy). Other carts using the extra pins on the cart slot seem fine though (including Street Fighter Zero 2).