N64 Internal RGB amp mod help.

Is that a good idea for Scart RGB UK setup? I though Luma was for S-video?

Ok i have found an old SNES scart cable that has a slider switch on the actual scart plug plastic housing that selects composite and RGB video. With this scart cable i am actually gettting a display on my Samsung LCD TV with the REV04 N64 and i dont appear to be getting the X Hatch problem!!!, dont forget atm on this REV04 N64 i have pins 7 & 9 bridged with just a wire (is that luma that Bad_Ad84 was suggesting?). What is different in this cable from my other 2 SNES scart cables thats allowing me to get a picture on the Samsung??

Ok a bit of a test, here is a vid of Super Mario 64 using the REV04 N64 (pins 7 & 9) using the Scart cable with the composite and RGB slide switch and me change the switch position...

http://www.youtube.com/watch?v=WqLWT59oBgY&feature=youtu.be

The REV04 (pins 7 & 9) is displaying a much crisper picture in composite mode!!! RGB mode there is slight ghost but the picture brightness is right and so are the colours are alot more pleasing, in the composite mode there is no ghost and the image appears to be crisper but the image it just a bit too bright (doesnt show well in the video clip and is actually brighter in real life) and the colours look more washed out. The actual ghosting might still be there but maybe because the picture is too bright it might hide the ghosting???

And this is the same but using the REV03 N64 (pins 3 & 9).....

http://www.youtube.com/watch?v=HgbCyrf4rB4&feature=youtu.be

The REV03 N64 has alot of display problems, in RGB mode it has ghosting and in the Composite mode has lines going across a section of the screen with some lines actually wobbling and still has the ghosting. The image appears to be alot Better on the REV04 N64.

Why is there alot of differencse in the picture quality between the 2 consoles, is this because i have pins 7 & 9 connected on the REV04 instead of pins 3 & 9 as on the REV03 N64?? What ill do next is get the RAW Sync SNES cable and try just the REV03 N64 with the same game (cant test the REV04 as that doesnt work with the other Scart
cables on the Samsung LCD).

To be fair on LCD displays its hard to tell if the signal is composite or RGB cos LCD screen make retro games look like arse no matter what. I'll probably do another vid of this test on my 28" CRT display aswell, that should really show the difference between composite and RGB!!

EDIT: OK just tried both REV03 and REV04 on my Hantarex CRT screen and changing the switch on the Scart lead from composite to RGB doesnt have any effect at all!!!.....

http://www.youtube.com/watch?v=K4afvUh0bFE&feature=youtu.be

Any ideas why it doesnt change over?

 

if you are connecting csync to the composite video pin - you need to cut the trace to composite video, else you arent actually doing anything useful.

luma works fine as sync source and is on all consoles (so no messing around rebuilding csync).

and yes pin 7 is luma, 9 is composite video. But you need to cut the trace going to composite video to actually be doing what you want to do.

If you were doing this mod correctly, composite mode would give you a black and white picture with luma and nothing with csync. It ONLY works as RGB correctly. The fact you have a picture in composite mode shows you are doing it wrong.

 

Ok some more info have tried the both N64 (REV03 & REV03) on a Hitachi 14" TV thats in the spare room still using the RGB/COMP slide switch scart cable and get a display with both N64s and the screen does change to Black & White on both N64's when i switch to composite! not sure why this didnt happen on the Hantarex!?. Cannot tell a difference between either of them despite them have different PIN bridged on the Multiout.....

http://www.youtube.com/watch?v=GLKB59kIlEY&feature=youtu.be

Also i can see a sort of ghosting problem across the screen on both N64s, can you notice it when Mario nods his head up and down right arcoss the screen??, its hard to make out in the vid what which the sync line rolling up the screen, any ideas whats causing this ghosting type issue....

http://www.youtube.com/watch?v=Op63LssolVE&feature=youtu.be

EDIT: Bad_Ad84, yeah i have cut the trace leading to Pin 9 labeled 'V' on Both N64s as best i could i am going to double check as i was a bit concerned as the trace is very thin and close to other traces so didnt go mad with it so maybe the trace isnt cut correctly.

From what you are saying using the the 14" Hitachi TV i should get a black and white picture on the REV04 N64 which has Pins 7 & 9 bridged (Luma) when switching the scart to composite, but i shouldnt get a display at all on the REV03 N64 as that has pins 3 & 9 bridged (C-Sync)?? As at the moment as you can see in the vid i posted im getting a black and white picture on both consoles when the scart is in composite mode!!

 

Ok have just checked the Trace on pin 9 on the REV03 N64 and i was still getting a reading on the MM when testing from the PIN 9 to the pad at C13, so i cut the trace at where it says C13 as OzOnE suggested its a lot easier to cut as there are no other traces nearby and retested with the MM and no reading!!

But now when i connect the N64 up to the Hitachi TV i get no display on composite setting (great!) but when i switch to RGB i get a really fast rolling display, an ideas why the display is now rolling?

 

Hi,

I was wondering how the REV04 is working at all on your CRT assuming that the mainboard has the missing components like mine (and that you've C-Sync modded it).
Maybe yours does have the transistor etc, or maybe the CRT is picking up a weak sync signal from somewhere. Or, maybe the trace to pin 9 is still connected??

If it says "No signal" on the TV, then it's likely not getting a Sync signal at all (if it was JUST receiving C-Sync, the "No signal" message would normally disappear).
I'm still not sure how your CRT is working given the same SCART cable etc??

As @Bad_Ad84 said, try connecting pin 9 to pin 7 instead first. It will probably work just fine and at least get rid of the x-hatch on the Samsung.

Using C-Sync often improves the stability of the image on modern TV's since some of them prefer a pure sync signal without the extra image info.
It just depends on the TV, so try whatever works best. Using the Luma output is another option, since it doesn't contain the x-hatching pattern.
The only issue with using Luma is that if your TV is prone "crosstalk" between the RGB and Comp Video (sync) input, then you might get slight ghosting etc.

No, that's the original mod which connects the C-Sync output to Comp Vid on your SCART.
It sounds like you must have the extra components on your REV04 after all, but your LCD doesn't like your old SCART cable for some reason?
It probably has different / no capacitors in the new cable, or different resistors??

Yep, it looks like in your vid that the comp video output is too bright. There is slight ghosting in RGB mode, but there may be a reason for this...

Both consoles look pretty good to me, so you TV is doing a fairly good job of filtering comp video anyway.
But, here's what I don't understand - if you've successfully carried out the original mod (cut track to pin 9, then join pin 9 to pin 3),
you shouldn't be getting any image at all in composite mode!

I'll have to test my N64's because this is getting very confusing.
This is what you should be getting from each pin on the MultiOut (judged purely on their names, other pins omitted)...

1. R = RED ---------- Red image ONLY, no Sync.
2. G = GREEN ------- Green image ONLY, no Sync.
3. S = Comp SYNC -- Sync ONLY, no image info.
4. B = BLUE --------- Blue image ONLY, no Sync.

7. Y = Luma -------- Image info (B/W), AND Sync!
8. C = Chroma ------ Colour info ONLY, possible sync?
9. V = Comp VIDEO - Image (with x-hatching) + colour + Sync.


So, in the original mod, if you've cut the track to pin 9, there shouldn't be any signal on to pin 9 at all...
Then, when you join the C-Sync pin (3) to pin 9, it should output ONLY pure Sync to pin 9 (and hence, to the Comp Video pin on your SCART plug).

In composite mode, you shouldn't be seeing an image at all (and certainly not a colour image) unless your N64 is outputting full composite from C-Sync pin 3 as well ???

I'm guessing that the reason you're getting ghosting on your consoles is because the track to pin 9 is still connected!
On your Samsung, it obviously has problems with crosstalk between the RGB and Comp Video (sync) inputs. This happens on mine too.

OK, so I've read your latest posts, I'll skip to the important bit...

It sounds like the C-Sync output (pin 3) must be missing from your REV03 ?
Try bridging pins 9 and 7 instead, but it's possible you'll still get ghosting on the Samsung.

What does the REV04 do now btw?

If you don't have a pure C-Sync output from a particular console, then the only relatively simple way of obtaining it is by using a sync stripper (as @APE said).
You can tell from his modding experience that this is the only way to guarantee that the sync exists on all N64's ('cos all of them should have Comp Video outputs!).
The sync stripper does what it says - it removes the image information from the Comp Video (or Luma) output, so the TV only receives pure Sync on the SCART input (+ RGB).

You can cut where it says "C13" but just be careful there are no small bits of track that could contact the ground plane on either side.
(It's possible that the video DAC could be damaged if the comp vid signal is shorted to ground.)

I'm still working on a fix for all modern TV's (and many retro consoles) - HDMI...
I've finally found some open-source code on the Web for generating DVI signals directly from an FPGA (which will work via HDMI, but without audio as yet).

This function was normally reserved for the more expensive FPGA's (or Xilinx chips, which I don't use), but at lower resolutions the new code should work OK on a cheap chip!

I'm dying to get this working soon. I just need to modify a few things in the existing code, then I can hook up an HDMI socket directly to my dev board.
We might finally have true digital upscalers for our retro gear and none of these analog issues. :tongue:

 

Thanks for the informative post OzOnE. Ok both traces where not cut correctly, and i really went to town on the 2nd console so am surprised at that!, anyway on both consoles i cut the trace near the "C13" across the trace 2 times next to each other just to make sure, after this i wasn't getting any reading on the MM. After this when i connected both consoles up to the Hitachi 14" CRT when i had the Scart lead in Composite mode on the REV04 N64 (Pin 7&9) i got a black and white picture, when switching to RGB i got a fast scrolling display, on the REV03 N64 (Pin 3&9) i got no display at all when in Composite mode (as it should be for C-Sync right?) on the Scart lead and when switching over to RGB again i got a fast scrolling display, so i dont think the REV03 console is missing the C-Sync on Pin 3 as you mentioned as i dont get a display when the scart is switched to Composite.So if both N64's give me a rolling display when hooked up to the hitachi and using RGB mode on the scart lead what is happening here??

I think i should explain my main CRT display i use for retro gaming, its a Hantarex CT 28 EQ. Though it does have a scart socket on it i could never get a RGB signal from the scart socket only a composite one despite the manual saying i should be able to get RGB from the scart socket. So instead im using the RGB D9 connection (looks like a VGA socket) on the Hantarex and made a D9 to Scart cable using just 7 wires, R, G, B, Ground, V Sync and H Sync from the D9 socket to the correct pinouts on the scart end, this could explain why when i mentioned a few posts back that the display wasnt changing at all when i was selecting composite and RGB on the scart lead as im guess the way i have wired up the D9 to Scart cable for the Hantarex it only uses RGB!??

Now when im using my RAW SYNC SNES Scart cable on the Hantarex i get a rolling display on both N64s now that i have made sure that the trace on pin 9 has successfully been cut (before i wasnt getting this rolling display, as the trace to pin wasnt correctly cut!) BUT using any of my other Scart cables i do NOT get a rolling display, any ideas why im getting a rolling display on the Hantarex when using the RAW SYNC scart cable but not the other scart cables give the information above?

I really appreciate your time in help me out with understanding these numerous problems im having here OzOnE

 

Ahh, I thought so. Again, the multimeter is your friend!

If you mean a "Black" image, then yes.
In composite mode, a proper C-Sync signal should make the "No signal" message disappear from your TV (well, on most TV's at least), but will give a Black / blank image.

Yep, the Hantarex accepts direct RGB only by the sound of it.
It's basically an arcade monitor, but it can probably accept both VGA modes (31KHz Hsync / 60Hz Vsync etc.), and "TV" modes (15KHz Hsync / 50 or 60 Vsync interlaced).
It likely ignores the +5V signal on pin 16 as well (that's what the switch on the SCART plug is doing).

The Hantarex must be accepting C-Sync via the H-Sync pin too I'm guessing?

Not sure what the problem is here unless the C-Sync levels are too low for RGB mode, or C-Sync is missing?

What does your Samsung TV do when in Composite mode? Does the "No signal" message disappear or stay on-screen?

You're getting a B/W image from the REV04 (pin 7+9), so that's correct for the Luma signal (Sync + B/W image, no x-hatching).
Don't know why it's not working in RGB mode? Again, the sync voltage level must be too low from Luma signal or something?
Maybe it's because S-Video signals essentially don't have the same filtering as Composite, and this is disturbing the sync on your TV (in RGB mode)??

I'm not sure which types of SCART cables you have now, it's getting very confusing.
Could you possibly take a photo of inside the SCART plug itself on both SCART cables to show the possible caps / resistors?

To make further debugging clearer, I just have to make one of my famous tables...

REV04 + Luma mod (pin 7+9) + Hitachi 14" CRT + New SCART cable...
Comp == B/W image (correct! Luma + Sync)
RGB == Rolling image (not good)

REV03 + C-Sync mod (pin 3 + 9) + Hitachi 14" CRT + New SCART cable...
Comp == Black image (correct! Sync only)
RGB == Rolling image (not good)

Again, it's very important to know the difference between "don't get an image" ("No signal" message remains) and "black image" ("No signal" disappears / blank screen)?

hmmm, the plot thickens. :confused-new:

The C-Sync mod is working on my REV04, but only because I joined pin 9 to that via next to R16.
Try connecting pin 9 to that point with the wire. I checked the signal levels with an o'scope and they seem fine.

OzOnE.

 

Ok then, right on the Samsung LCD screen on the REV03 N64 when in composite mode i get just a black display no 'No signal' message on the REV04 N64 i get a black and white picture. RGB mode gives me a fine picture on both N64s

On the Hitachi CRT on the REV03 N64 when in composite mode i get just the old school snow screen on the REV04 N64 i get a black and white picture. RGB mode gives me a fast rolling display on both N64's.

On the Hantarex, both N64's give me a display on either composite or RGB (does change) but if i use the RAW SYNC Scart cable on the REV03 N64 (C-SYNC) i get a rolling display but if using the REV04 (luma) i get a fine display.

I have 3 scart cables, 1 with the Composite/RGB switch, 1 RAW SYNC SNES Scart cable, and 1 bog standard SNES Scart Cable.

Below is 2 pics of the 2 scart cables (didnt bother including the composite/RGB switch scart cable as its basically the same as the bog standard one), The bog standard one (Left) and the RAW SYNC one (Right)........

TOP....



BOTTOM....



Not really sure why im getting a rolling display as the C-Sync N64 does appear to be using Pure Sync (C-Sync) as i dont get an display when in composite mode on the scart switch on my Samsung and Hitachi??

So on the REV04 in order to add C-Sync back it need to bridge a wire from Pin9 to the pad at R16??

 

It looks like both those SCART cables are pretty much the same.
They both have the 220uF / 10V caps on each R/G/B signal.
Then +5V goes direct to pin 8 (auto AV switch / 16:9), then across to pin 16 via a 75R resistor (RGB mode switch).

I think what is happening here is that the C-Sync / Luma voltage levels are too low for the Hantarex / Hitachi, or they need better buffering??

I'm fairly sure the Samsung would clear the "No signal" message with just the Sync input and no RGB stuff?

To confirm - are you saying that the way you're switching between Comp Vid and RGB mode was with the SCART cable with a switch on the actual plug?
(ie. it wasn't a separate SCART switch box or anything??)

btw, I would imagine the switch replaces the resistor in that cable?

My brain hurts now. There are 3 SCART cables / 3 monitors / 2 consoles / 2 different mods / RGB switches.
That makes around 72 different combinations. :biggrin-new:

OK, I have to admit, I don't know what's going on here. lol

I'd guess your REV04 has Q1 missing on the underside? (to the right of the MultiOut, just below the cart slot)?..
http://i1045.photobucket.com/albums...otherboard Revisions/NTSC/NUS-CPU-04_Back.jpg

(sorry, @Link83, I pinched your photo)

On my REV04, the missing components are C22, R14, R1, R15, R16, and Q1.

If they are missing on your REV04, you could try connecting MultiOut pin 9 to that hole where it says R16.
That should give you C-Sync, but it's definitely unbuffered then, which means it still might only work on the Samsung?

Not sure about the other problems. I'll have to have a think about it all.

When you say "old school snow screen", do you mean a normal colour composite image, or literally just snow (like an out-of-tune analog TV)??
I don't know why you'd be getting that from the REV03 / Hantarex unless the C-Sync output has loads of noise on it?

OzOnE.

 

This is my REV04.....



So i should bridge a wire from pin 9 to the pad next to where is say 'Q1'??

The only problem i want to sort out is why i get a rolling display, not really sure why before i cut the trace on pin 9 and enabled C-Sync i now get a rolling display

 

I know, not sure why you're getting that problem either. Let's see if the REV04 still works on the Samsung though...

Yep, desolder the small red wire then join pin 9 to the "R16" hole (not to the silver pad, to the via).

It will probably work fine on the Samsung, since mine does. See if it works on the Hantarex / Hitachi though.
Also, see if you notice a difference in image quality between the "9+7" mod, and the "9+R16 hole" mod.

OzOnE.

 

Ok ill give that a shoot tomorrow, so just a wire no need for a resistor from pin 9 to R16 via?

 

To do the perfect mod for samsung TV's the steps are:

i. Amplify the RGB lines with the THS7314 chip (as per http://mmmonkey.co.uk/console/nintendo/ntsc_nintendo_64_rgb_new.htm)

ii) Then cut the composite video sync trace (PIN9 on the multiout marked V) and run a wire with a 75ohm resistor in series from PIN7 on the multi out (marked Y) to PIN9. (almost like this http://mmmonkey.co.uk/console/nintendo/rgbntsc.htm#link83 but linking 7 and 9 with an added resistor instead of 3 and 9)

That's it. Perfect RGB picture on a Samsung and CRT too.

 

OK, that might be an idea then. Maybe the resistor is needed for the proper signal level?

This is the same as the Luma mod of course, but with the added resistor.

If you want to try the REV04 C-Sync mod too, just put the resistor between pin 9 and the R16 hole instead.

OzOnE.

 

I have never had the resistor and it works fine (including my samsung).

You do not need the caps in the scart cable, but you do need a 75ohm resistor to ground on each RGB line (else the picture is too washed out - tested with a legit snes rgb cable vs 3rd party without resistors).

 

So the 75R resistors i have attached to the THS7314 chip then will do i dont need any more if i remove the caps from the scart lead?? At the moment the picture brightness is more or less perfect, if i remove these wouldnt it cause the picture to become brighter more saturated? Also do having these cap in the scart lead cause and video interference no matter how small?

I shall try the resistor instead of a wire and see if i still get the rolling display. In soldering terms is it looked down upon if you just use a resistor to bridge, in other words no wire at all just the resistor?.

As i was thinking for my final N64 machine ill just use a resistor to go from the MultiOut pins to the THS7314 chip and cover them in heat shrink...or would the resistors get too warm/hot if covered in heat shrink?

OzOnE, so you have tested the Pin 9 to R16 method and in your opinion it is perfectly safe to do this?, its not going to burn anything out from what you can tell?...after all you should know if you've reversed engineered the N64 lol

 

If I take out the 75ohm resistor in series from PIN7, the image is too bright.

This is using an official Gamecube RGB cable which has some additional components.


With the resistor is looks perfect:



Again this may depend on the RGB cable you are using. In my case its an official Nintendo RGB cable. Maybe try it without the resistor and if it's too bright, put in the resistor.

 

The official SNES rgb cable has 75ohm resistors on each of the RGB lines - which gives the correct brightness. GC cable doesnt have this IIRC

No, you need the ones in series and then the ones to ground too.

 

Well, I've done the mod on my REV04 and tested the actual voltage levels and everything is OK so far, but you should really use a resistor between the points just to be safe.
The main problem is that without transistor Q1, the C-Sync signal is not buffered, and some TV might "load it down" too much.
I don't think this will damage anything even without a resistor, it just means you might get a rolling image.

Yep, @Bad_Ad84 is correct - the general idea is that there are series resistors coming from the amp (like you have), then resistors going from each R/G/B pin in the SCART down to ground.
This is so each signal is strong through the cable itself, then gets "terminated" properly with the resistors at the SCART end (supposedly stops ghosting, and makes the voltage levels correct).

(I'm not sure if this means that the amp is supposed to output twice the normal voltage for this to work properly? I haven't tried the different methods, I just used whatever works for my N64.)

The caps are there to "AC couple" the signals to the TV. This means that they block possible DC offsets from the N64. Pretty much all TV's should have AC coupled inputs anyway though.
It depends though - I think I tried removing / shorting the caps many years ago and it made the picture much worse on certain TV's. This was probably due to the lack of an amp in the N64.

@BlockABoots - the main thing is to get your REV04 working first. Try the 75R resistor between pin 9 and R16, it should be perfectly safe to do, but I can't guarantee that it will work on your Hitachi / Hantarex.
Worth a try though. It's OK to solder the resistor between the two points as long as it's properly insulated (heatshrink or whatever), and is mechanically sound (won't be moved around and snap / short out etc.).

@fathertime - that pretty much confirms that your TV (or many TV's) are mixing the comp video input with the RGB input...
If you're using the Luma mod and your TV is definitely in RGB mode, the image brightness shouldn't change at all when using the resistor?

It's possible that the TV is using the comp video input as a clamping "reference" for the RGB input, or it's taking the level of the sync from the comp vid input as the base black level?

ie. The only thing an RGB input is supposed to take from the comp vid input are the Sync pulses, but it sounds like it's not as simple as that.

btw, I'll be testing the HDMI code today. I've managed to translate it OK for my FPGA. Let's hope. :very_drunk:

EDIT: I don't mean to hijack this thread, but just wanted to let you know - The HDMI code is working!! :encouragement: :applause:

The HDMI socket is connected directly to the FPGA (no other chips needed), now I just need to hook it up to the N64 code and figure out a simple scan doubler.


OzOnE.

 

this is great news OzOnE. i am waiting for your HDMi project. also please test your setup without a scan doubler too, native at 240p. it might be supported on TVs too and feel more "retro".