RGB mod French N64 (How to restore RGB circuit)

I was wondering how to restore the RGB on a french N64. I've heard you can do the mod similar to NTSC models but also have heard mixed reports of different image (better contrast). But anyway I want to challenge my soldering skill a bit more at least. So now the big question:

How can I restore the RGB circuitry? From what Ive heard you it's easiest tot take SNES parts for a restoration, if so what parts (I have a junked SNES with faulty chips so those parts wouldn't be a problem)?


Also as a side question, why is the circuitry different in the regular mods and the "restored" circuitry.

 

Could you be looking for this?

 

Yes! Thanks!

Does anyone know if those part are in a SNES (and what those parts are marked as)?

 

Depends on which SNES version you have.

You could probably find the transistors in any version SNES marked BR,BQ or LY. Nintendo seems to use any of those in place of each other but not mixed with each other. You could also easily find the 47pf caps in any SNES version, directely connected between each RGB pin of the multi out connector and GND. Just use a multimeter to trace from the RGB pins of the multi out connector to the small SMD caps nearby to find them.

It would be better if your donor SNES is a PAL 1CHIP though as the RGB circuit between the SRGB chip and multi out connector is identical to the NUS-001(FRA) N64. It has the transistors and capacitors mentioned above plus the 39 ohm resistors but instead of the 75 ohm resistors in the diagram that sanni provided above it uses 100 ohm resistors.

R47 and D4 on the diagram are for the +12v circuit of the multi out connector. You could leave those out if you don't mind switching aspect ratio and/or RGB channel on your TV manually or if your display device doesn't support that function anyway. If you do want to complete that circuit then unfortunately you will have to find those components elsewhere as that circuit and components in the SNES are quite different from the NUS-001(FRA) N64.

EDIT: Just checked and even on the older PAL SNSP-CPU-01 board there are just enough 39 ohm resistors and more than enough 100 ohm resistors for what you need. The resistors are marked 390 and 101 respectively.

 

Just got everything I didn't have in house from fleabay and did the mod but for some reason nothing beyond Q1/2/3 don't get voltage.

These is the voltages I get at the Q's when the N64 is on (and I do get sound over scart and over composite I get everything)
~4V
__ I____
I. . . . . I
~2V ~0V

But the prong of 0V goes to the resistances and caps. It almost seems the 2V should be connected. And to my continuation tests it should be good...

Why is this and how can I fix it?

 

What parts did you use in the end? Did you take the transistors from the SNES or get them from ebay? Also a photo of your mod would help in finding the problem if possible.

 

RGB output on SNES is not quite as good as composite (!), however of course RGB on N64 is better.

 

Transistors and SM caps where from the SNES all else from ebay. And I know it's not the cleanest mod, but damn those things are miniature!

@bacteria:
You mean component right? (and even then I don't think so)

 

Please don't take this to heart but the easiest thing for you at the moment is to slap that board (as is) in a antistatic bag and send it to a professional modder.

I'm sorry to put it so bluntly but I just really don't know how else to put it into words without going into a long drawn out post/tutorial on basic soldering and the right tools for the job.

In all fairness I can remember doing worse jobs than that early on. You just need some practice, some good tools and probably a magnifying glass if you find small components difficult to work with.

On a side note, were the transistors that you took from the SNES definitely marked BR,BQ or LY?

There are also quite a few dual diodes on the SNES that use the same package as the transistors and could be easily confused without looking closely at the package markings.

 

Yea they weren't marked that way, completely forgot that... Time to switch them out.

(and yes, I currently dont own a soldering tools for such parts except a magnifying lense/light. So I'm well aware that the soldering looks like utter crap at best)

 

Make sure that you move that 39 ohm resistor on the far right in your picture. It looks like it is touching a via hole on the board (probably GND).

I wouldn't worry too much about how it looks. It's those dry joints that you need to be careful of.

 

That fixed it, just a stupid oversight (also those transistors look placed look far better, without those blobs of solder). And I was also looking at that resistor, but it wasn't a problem but moved it a little to be sure.

 

Glad you got it working.

One more thing. The correct cable for that circuit is in the link below. Credits to viletim for the diagram.

http://members.optusnet.com.au/eviltim/gamescart/snespal.png

 

checked the SCART cables I've got with the schematics and they don't match.

Instead of 75 ohm between the R/G/B signals and ground I've got 220 uf caps on the signals without anything in the scart head linking the signals to ground. The 5V line has the 180 resistance but also a connection by another 220 uf cap (which misses the 75 ohm resistance also).

so for extra clarity, pin 7/11/15 have a 220 uf cap, without anything linking them to ground. Pin 16 has the 180 ohm resistance but is also connected to pin 18 by another 220 uf cap. Also pin 18 is directly connected without a 75 ohm resistance.

So is this case of structurally different but functionally the same or should I mod these leads to fit the schematics?

 

Not functionally the same unfortunately. It should work but you will get an impedance mismatch and the signal levels will be too high also which will give a bright over saturated picture.

The circuit that you restored in the PAL NUS-001(FRA) N64 was designed to be used with the PAL SNES scart cable. I would imagine that Nintendo had originally intended for people to use the already widely available (in France) official PAL SNES scart cable with their new N64 but then they changed their mind and decided that people didn't really want RGB anymore and released the N64 without it.

Either modify the cable that you have or save that cable and get PAL SNES cable. The cable that you have may come in handy for other consoles like the NTSC SNES or PAL Gamecube.

Although to be honest it doesn't seem quite right for either. Are you sure it is wired that way? There shouldn't be a cap between pin 16 and 18. although I can't see it making much difference if that is the case to be fair.

 

I already thought the signal was brighter than usual. But seeing as I have 3 of those leads (for SNES/N64/GC) I just have to mod 2, which shouldn't be hard.

And yea I'm sure, it a bit of weird cable.