N64 NTSC-J RGB Amp problems

Hi,

I have a Japanese N64 that was modded for RGB via wires connected directly from the video chip to the output pins.

I thought I would improve what was there by adding a pre-made RGB amp circuit, and I've had a go at installing it myself. However, when I test the N64, I get a blurry, overly white display (see attached image).

I've tried uninstalling and reinstalling the amp, even tried a new one but the same problem occurs. Does anyone have any suggestions of where I'm going wrong?

 

Are you using a c-sync scart?

 

I've tried a CSYNC PAL GameCube lead, as well as the lead that I've been using for my N64 up until now (presumably not CSYNC, and it has a switch on it that activates/deactivates an amp in the cable). Even tried a PAL SNES Sync on Luma Cable!

 

A unmodified PAL Cable wont work on a NTSC Unit as far as I know

 

Does anyone know where I can get an NTSC-J cable in the UK? I tried Retrogamingcables.co.uk, but their cables only work with American systems. I would have thought the RGB cable that came with my N64 (the one with the switchable amp circuit in) would be sufficient for the job, as it works without the amp installed.

 

Do you need a NTSC-J Cable?
Or a Cable for a NTSC system?
I have a Japanese N64 myself, and I use a NTSC rgb scart on my pal tv.
Unless you have an imported Japanese tv or video converter sat Up for NTSC-J scart, the cable you are looking for would be a regular NTSC rgb scart

Is it a THS7314 amp mod you have done?
Would you mind posting a couple of pictures?

 

US NTSC cable should work on a Japanese N64

 

Yes, it is a THS7314 amp - This one to be exact. I'm assuming that the RGB cable that came with my N64 (with the amp circuit) is an NTSC one, as it works fine when the N64 is modified with cables going straight from the chip to the video output (the old, no amp RGB modification). I'll take some pictures of my installation when I get home from work this evening - I've tried the install twice (I thought I'd messed it up the first time so I bought a new amp board and started again, but the exact same problem occurs).

Unfortunately, retrogamingcables.co.uk is sold out of their NTSC N64 RGB cables at the moment, so I'm a bit stuck for ordering a new NTSC cable (unless anyone can recommend another supplier?). Unfortunately, every other Nintendo system I have is PAL so I don't even have an NTSC cable on hand to test, other than the one that came with my N64 (and while I understand it to be an RGB cable, I don't know if it's CSYNC, Luma or whatever).

If it helps, my eventual goal is to use this N64 with my Framemeister (I have both a standard EUR SCART adapter and a powered one with Sync Stripper) - For now, I've just been testing it with my CRT and a modern television and the same problem occurs. I was concerned that it was my soldering that was at fault, but it's weird for the exact same issue to occur using two amp boards.

 

Sounds like a cable issue.
If I remember correctly you can modify a PAL Nintendo Gamecube Scart cable to use on a NTSC unit
(Yes - http://www.mmmonkey.co.uk/official-pal-gamecube-rgb-cable-on-ntsc-consoles/ )
However I understand if you are not wiiling to modify such an expensive cable.

In my case I had to cut the composite video signal trace (Pin 9), and then join it with Pin 3 (Csync).
Check the mmmonkey link i posted, it will show a picture of that mod a little further down the page

 

Thanks for the suggestion - My Gamecube RGB cable isn't an official one (it's a CSYNC cable from retrogamingcables.co.uk), and I'm not too confident about cutting the traces to enable CSYNC, or modifying the cable.

I've got in touch with retrogamingcables to see when he'll have the cables in stock, so I'll sit tight for now!

 

Alright, just be aware that it might still not work if you don´t cut the trace and join those pins, even though you get the right cable.

 

Of course - A Luma as Sync cable would do the trick, wouldn't it?

 

Yes Luma is on Pin 7, if I remember corretly and you would not have to cut anything.
What revision is your board?

 

I'd have to double-check on the revision - I'll take some pictures this evening and post up all the details here.

Really appreciate the help!

 

The board is an NUS-CPU-04, I've attached some pictures to show what I've done - The wires going to the video chip were what left over from the previous mod (I see they've lifted the pins).

Hope it looks ok!

 

Mod looks fine, however I would personally alway use the R8,R9,R10 points for the red, green and blue than soldering directly to the DAC.
Technically it should not make a difference though.
Why did you lift the pins on the dac?
With a 04 board, you are able to get Csync.
This post will help you in archiving so: http://assemblergames.com/l/threads/sync-on-n64-rev-04.49981/

 

I didn't actually lift the pins, that was done by the shop I got the N64 from in the first place, back in around 2009 I think.

I'm not too concerned about getting Csync, as I use a sync stripper with my Framemeister anyway (honestly, I'm not really electronically-minded so that linked thread goes completely over my head!). For now, I'll wait for my supplier to get some NTSC cables in stock, and take things from there

I'll update this thread with the results when I get an NTSC cable!

 

Sounds good!
Let us know when you get there!
And welcome to the forum btw

 

the mod does not work like you have it right there as the signals are either under or over clipped.

the lifted pin mod only works with the wires connected directly to the multi av.
the ths amp mod only works when the pins are connected to the board and you connect the amp to R8 R9 R10 like seen here: https://circuit-board.de/forum/index.php/Attachment/7561-N64-RGB-NTSC-jpg/?thumbnail=1

or to the caps infront of those spots like here: http://img4.picload.org/image/iwcci/n64-rgb-points.jpg

i personally use a ntsc-j board with ths amp mod and a pal gamecube cable. tested a lot of cables, with resistors, with caps, with nothing on the rgb lines and the best pictures was with caps as the gamecube pal cable has it. i also have installed a switch for selecting between c-sync or luma as sync signal.

you can try using a ntsc snes rgb cable, but i dont know if the sync will be right as the ntsc snes cable doesnt have 75 ohm resistor+220uf cap to the sync line like the gamecube pal rgb cable.

 

Thanks for the info - I'll try connecting to the R8,9 & 10 pins - Do I need to reconnect the lifted pins on the video chip to the board (and if so, what's the best way to do it?).

I got a new N64 NTSC RGB scart lead today, but no luck, so I'll try the other method!