N64 Internal RGB amp mod help.

I have followed the internal RGB amp mod on mmmonkey's website but i am unable to now get a display on my NTSC N64 console. Does anything look wrong in these pics at all??....





I can hear the 'thud' sound on my stereo when i turn the N64 off so it sounds like its getting audio possibly?

 

Ok school boy error i forgot to plug back in the memory expansion cart, but im getting what appears to be a black and white picture and its incredible dark...any ideas?

 

From the looks of things you've got some ugly solder joints everywhere and you really should use shorter wires of a higher gauge. That capacitor might be shorting on something for all I know but I'd like to think if it was the N64 wouldn't boot at all.

 

Thanks...i though that the soldering wasnt actually THAT bad!?

I must have the wrong resistors as i removed them and then i got a picture but was super bright.

In doing this the the pcb resistor at C109 where the yellow wire is attached in the picture above has come away from the board...but the N64 still appears to work. What do, or more to the point in this case what does that resistor actually do then if the N64 still works?

 

Hi,

The resistors look OK too (75 ohm / 2%), so it should work?

On second thoughts - are you sure they're resistors, 'cos inductors look very similar (with that "blue" colour).
Do you have a multimeter to test them?

Which Country are you in? I'm guessing you're using an RGB SCART cable?
Some SCART cables have extra resistors or caps in, and this give might problems with the RGB mod on certain TV's.
(There is a standard way of doing it, but not everything conforms to it).

btw, the IC is upside-down on the adapter! You've wired it correctly though, so it doesn't really matter.
(the white line on the IC should denote the pin 1 / pin 8 end. Ideally, this should match the "notched" symbol on the PCB itself).

C109 is a small Capacitor. It's used for "decoupling" for the +5V supply...

Decoupling caps are used to reduce noise on a supply. They are generally put close to every chip which uses that supply voltage.
http://en.wikipedia.org/wiki/Decoupling_capacitor

As long as C109 isn't shorted, the N64 will probably work fine without it as there are many other caps on the same supply.

OzOnE.

 

Might just be a decoupling capacitor which are usually necessary. I don't have the schematics on hand to tell you nor do I have an N64 in front of me to probe.

The soldering is decent and I have seen much worse it's just that anything short of "good" can easily be problematic and not actually form a connection. The fact that removing the resistors produced an overly bright picture is a good sign overall.

 

Thanks for the replies. Yeah I am based in the UK, I bought the resistors from eBay I just searched for 75k ohm resistors and they were the cheapest so bought them, but the colour bands don't appear to match the correct colour coding for a 75 k resistor shouldnt they be purple-green-black-gold, where the ones I received had more bands than that. I'm guessing I should just search for 75r resistors right.

You might be right on the resistors inside the Scart cable but the picture with the resistors attached to the IC chip was stupidly dark like you couldnt hardly make out anything on the screen and lacked any colour at all plus I should mention that the display wasn't stable was juddering/wavie. So the 75r resistor here will be fine?..http://mobile.maplin.co.uk/module.aspx?moduleno=341561

You think the N64 will be fine with our the cap at C109 position?

 

Ok just opened up the scart cable and it does appear to have some capacitors fitted...

 

you need 75 ohm resistors, not 75 k ohm... maybe that's your problem , 75000 is way more than 75

 

Yeah that will teach me to order late at night lol

 

Damn it, sorry!

Yep, those are 75K. lol
I don't know how I missed that?

I know my resistor colour code, but I forgot they are 5-band (if you leave out the "Brown" band, then it's only 75 Ohms)....
http://www.hobby-hour.com/electronics/resistorcalculator.php

Your SCART has similar caps to mine. Actually, I think my RGB cable is an old SNES one.
It should work OK with the caps in place when you get the 75R resistors.

I've had problems on some TV's though where the caps can create ghosting on the image?

The other important thing is that the cable has +5V going to pin 16 at the SCART end.
It usually goes through a resistor (likely the one in your last photo).

Without 5V on pin 16, most TV's will just display composite and not switch to RGB mode.
RGB via SCART still gets it "Sync" from the Composite signal on pin 20 (yellow wire).

You should be able to tell straight away when it's in RGB mode, 'cos the crosshatching / "running ants" patterning should disappear.

If you still get quite bad crosshatching even in RGB mode, then there's another mod you can do to the N64 to output the "Y" (Luminance) or C-Sync signal instead of composite.
EDIT: Oh, I see the other thread now about the C-Sync mod. Yep, it does remove the crosshatching problem on certain TV's, but most people don't need it.

Basically, just grab some 75R resistors and you should be good to go. :encouragement:

I wouldn't worry about C109 unless you're getting any noticeable image problems.

OzOnE.

 

Thanks man, got some 75R resistors today and now its all work. Now a slightly different problems im having, i didnt bother researching before hand so didnt know that REV04 NTSC N64s dont have C-sync so i already did the C-Sync mod. I have 2 N64's a REV03 & 04 which i have carried out both the C-Sync and RGB Amp mod now the REV03 N64 gives me a picture on my Samsung LCD or though it has the cross hatch problem, but i cannot get a display on the REV04 N64 on the LCD screen. Do you think me still getting a cross hatch display with the REV03 even though i have done MMMonkeys C-Sync mod is to do with me not getting +5v on pin 16??

Fathertime, over on this thread http://www.assemblergames.com/forum...GB-Mod-Poor-quality-image&p=627231#post627231 suggested linking Pin 7 & 9 up on the multiout pins not Pins 3 & 9 which should give C-Sync back to REV04 N64s!!, i have tried using pins 7 & 9 on my REV04 N64 but still dont get a picture on my LCD screen any ideas on these problems?

 

OK, so I thought I'd do a more technical explanation of composite signals and colour decoding since I find it quite interesting...

I'll try to explain it in terms of the C-Sync mod on the N64...

When RGB (via SCART) was first added to TV's, I believe it was mainly intended for overlaying things like Teletext onto the existing image (usually a Composite signal from the analog Tuner, phono AV, or SCART pin 20).

So, the +5V could be applied to SCART pin 16 ("Blanking") to quickly switch the TV to RGB mode for displaying the Teletext.

Some of you may be old enough to remember that you could choose "transparent mode" on Teletext - this would apply the Blanking signal only during the actual "text" parts, so it would overlay onto the original image.

Many TV's didn't switch completely over to RGB mode when the Blanking voltage was applied though.
Instead, they would "mix" some of the original composite video image with the RGB signal (making the RGB image / Teletext text itself look transparent).

Most modern TV's fully switch over to RGB when +5V is applied to pin 16, so you don't see the composite image at all.
Unfortunately, some TV's still have problems with this, and the Composite image still bleeds-through or mixes.

The x-hatching on Composite is caused by the way the colour information is encoded onto the original image, which is essentially the black and white image with the colour "modulated" onto it...

When in composite mode, the TV does it's best to filter out the crosshatching after it decodes the colour part, but you still see the effect on most TV's.
(it's quite difficult to completely filter it out)

So, if you're TV doesn't fully switch to RGB mode, or it doesn't properly filter out the "image" part of the composite when it extracts the Sync, you'll still see the x-hatching.
The C-Sync signal from the N64 is of course JUST the Sync (Vertical and Horizontal) without the image part, so you shouldn't get any of the x-hatching problems (when using it with RGB).

As a side note: what S-Video does is to separate the colour (Chroma / C) and brightness (Luminance / Y) signals on two different pins.
So, the Luminance / "Y" signal stays x-hatch free (and is black / white), the TV then simply decodes the colour info directly from the Chroma / "C" pin.

Composite video was a way of transmitting a colour signal using part of the original Black and White image bandwidth.
This made it cheaper / easier to add colour to the existing B/W broadcast system while still keeping it compatible with B/W TV sets.

For a great explanation on PAL Colour Decoding, have a quick look at this page (especially the first image)...
http://www.techmind.org/vd/paldec.html

Basically, the crosshatching you see on a composite signal IS the colour information...
The B/W image is actually modulated depending on the original "colour difference" signals (U / V).

So, for strong / bright colours the x-hatching is more pronounced. The page describes it best...

"The net result is that the picture transmitted is effectively a black-and-white picture but with areas of fine patterning the strength of which is proportional to the saturation of the colour portrayed. Of note, U-axis colours (pure yellows or blues) appear as diagonal stripes \\\, while V-axis colours (pure reds or greens) appear as diagonals ///. Mixture colours, such as orange (red+yellow) give rise to a superposition of the two, ie cross-hatching. These patterns can be seen on a black-and-white monitor fed with a colour TV signal."

So, if the phase of the x-hatch in the image part itself goes negative relative to the reference, this denotes more voltage on the "U" signal (and vice-versa for the "V" signal).

(probably not 100% accurate, but you get the idea)

To decode the colour (U/V) signals, the TV needs to synchronize it's internal reference signal to the original carrier (4.43MHz in the case of PAL)...
It does this by using a short "colour burst" at the start of each horizontal line and uses that as a reference frequency for the rest of the line.

In a PAL Composite signal, it also swaps the phase of the "V" colour signal to help reduce noise or drift in the carrier signal (the opposite phases tend to cancel out any noise etc).
This is where PAL gets it's acronym from (Phase Alternate Line).

This is why NTSC Composite signals can sometimes have problems with the colour drifting (it doesn't alternate the phase AFAIK).
That's also why you often see the "Tint" control in NTSC mode on your TV.

NTSC officials stands for "National Television System Committee", but I like to call it...

"NEVER THE SAME COLOR"! :biggrin-new:


OzOnE.

 

If you've done the C-Sync mod, you shouldn't really see any crosshatching at all since you've removed the Composite signal from the equation?
The C-Sync mod also means that you probably won't get an image at all with a simple phono Composite cable, is this correct?

Also, if you've done the mod and +5V was missing from pin 16, you shouldn't get any image at all (no Composite signal, only C-Sync).

There is possibility for some confusion here though - on mmmonkey's guide, you'll see that the N64 has these signals...
(assuming this is an NTSC N64. Pinouts included for my own sanity)...

1. R = RED
2. G = GREEN
3. S = Composite SYNC (C-Sync).
4. B = BLUE
5. G = GND
6. G = GND
7. Y = Luma (S-Video Y)
8. C = Chroma (S-Video C)
9. V = Composite VIDEO
10. +5V
11. L = Left Audio
12. R = Right Audio

http://www.mmmonkey.co.uk/console/nintendo/rgbntsc.htm#fourx

...Remember, when they say "C-Sync" mod, it's actually on the "S" pin and not the "C" pin!

Are you sure the original track to pin 9 was cut properly and tested with a multimeter before hooking up pin 9 to pin 3?

Do you know if it definitely has +5V on pin 16 of the SCART? I'm assuming you're connecting all these N64's using the same SCART cable?

When you say LCD screen, are you talking about the same Samsung LCD TV each time?

If all the connections test OK, then I can only assume that the REV03 console actually outputs Composite VIDEO from pin 3 instead of raw Composite Sync??

Basically, if you've done the C-Sync mod and still get an image via an old N64 phono cable (three plugs), then that would prove the assumption.

EDIT: Yep, it's worth trying the link between 7 + 9 instead. That would give a B/W Composite signal + Sync.
Presumably, it wouldn't have x-hatching then? You'd still be getting a Composite signal instead of raw C-Sync with that method, but it might work OK.

OzOnE.

 

Ok i have just tried a phono cable (3 pins yellow, red, white) on my Samsung and i do still get a picture on the REV03, so your saying i shouldnt be getting a display if the C-Sync mod was carried out!? . What do you think the problem is here, do you think maybe the trace leading to Pin 9 ( (labled V) hasnt been cut correctly??...i was trying to be really careful as the trace is really quiet thin so didnt want to cut any other traces leading to pins on the Multiout socket is there a safer location to cut this trace leadind to pin 9??

Yeah im still getting a picture..but then from what i stated above this might be why if the trace hasnt been cut correctly...one thing i should mention when i have the Scart cable hooked up to the Samsung LCD as soon as i turn the N64 on the Samsung switches to the RGB channel this would indicate that pin 16 is connected up right?

I will have to test with a MM to confirm this, which i try tomorrow. Im crap with MM what setting should i use for this test please?

If the Samsung LCD switches over to the RGB channel when powering on the N64 this would confirm this right?. Yeah im using the same Scart cable on both N64's

Yeah same LCD, both N64's work fine on my CRT display, its just the Samsung LCD that im only getting a display with the REV03 Nintendo

I would really like to get the correct C-Sync mode to work (pin 3 & 9) if i can.

 

I'm not sure about the REV03, but on my REV04 you can follow the track from pin 9 down to where it says "C13" and connects to a silver test pad.
It might be easier to cut the track right between the "C13" text?

Personally, I wouldn't do any of these mods without a multimeter. It's amazing what you can actually use it for.
For example, I used ONLY a multimeter and a few datasheets / pinouts to reverse-engineer the entire N64 schematics a few years back.

You need to set the multimeter to "ohms" / resistance. It's great if your meter has the "diode" check / beeper on it though.

If it doesn't have a beeper mode, it will probably have different ranges for resistance like 200 / 2K / 20K etc.
Just set it to 2K or something like that to check for continuity between two points on the N64...
A direct connection between two points will have a few low resistance of only a couple of ohms (or close to zero ohms).

You can use that to see if the track to pin 9 is properly broken, but any resistance check MUST be done with the N64's power turned OFF!

The other possibility is the REV03 consoles just connect the Composite VIDEO connection to both pin 3 and pin 9.
This sounds unlikely though, 'cos the other revisions seem to have a separate C-Sync output.

The TV switching to RGB is probably a good sign that the +5V is on pin 16.
It's very likely that you have +5V on pin 16 if you're using a SNES RGB cable like I am (and your TV says "RGB").

(Extra info here, probably not necessary)...
But, the SCART pin often used be many TV's to auto-switch to the SCART input is pin 8.
The voltage on pin 8 also determines which aspect ratio the TV switches to...
Around 5-8 Volts switches to SCART + 16:9 widescreen. Or around 9-12 Volts switches to SCART + 4:3 "normal" screen.

OK, just to clarify...

REV03 = RGB working, but x-hatch patterning.
REV04 = No image at all?

Here's a quick test for the REV04 - does your Samsung TV still say "No Signal" even with the REV04 plugged in, or does it just give a Black image?
(A handy tip is to turn on the "Blue Screen" option if your TV has it, that way you know if it's getting any kind of Sync signal at all).

If you're getting a "Black" image from the REV04, it sounds like it's outputting C-Sync to the SCART, but for some reason the TV isn't switching to RGB mode?
Does the TV still say "RGB" with the REV04 connected?


So, there are a few different scenarios here (assuming N64 is already RGB modded)...

N64..............SCART
R-----------------R
G-----------------G
B-----------------B
Comp Video-------Comp Video
NO +5V on SCART pin 16 == Composite image, evil X-hatching! :mad-new:

N64..............SCART
R-----------------R
G-----------------G
B-----------------B
Comp Video-------Comp Video
+5V on SCART pin 16 == RGB image, possible X-hatching - Comp VIDEO is used for Sync! :moody:

N64..............SCART
R-----------------R
G-----------------G
B-----------------B
Comp SYNC-------Comp Video
NO +5V on SCART pin 16 == Blank / black image :concern: - TV in Composite mode, but C-Sync signal has no image info!

N64..............SCART
R-----------------R
G-----------------G
B-----------------B
Comp SYNC-------Comp Video
+5V on SCART pin 16 == RGB image, no X-hatching :love-struck: - TV in RGB mode and only needs sync from C-Sync signal!


You can see that standard RGB still gets it's Sync signal from a separate pin (the R/G/B signals themselves ONLY carry the image info).
Many TV's used to work fine when the Sync for RGB was taken from the usual Composite signal, but modern TV's seem to have trouble with x-hatching bleed-through or "wobbly sync".

(that's probably why most Sky boxes turn off the RGB outputs when you press the "TV" button, so they don't interfere with other inputs).

We should be able to figure out if your consoles have proper C-Sync and +5V outputs. My guess is that they should do?

btw, if you want a very basic oscilloscope (for LOW voltages), did you know you can use your sound card!?...
http://www.zeitnitz.de/Christian/scope_en

If you get really stuck, the above software and a modded jack connector will be good enough to tell you which signals are Composite, which are RGB, and which are Comp-Sync.

EDIT:

Oh, sorry, I missed that. Does it look like both are working in RGB without x-hatching on the CRT??

hmmm, not sure about that then.
The only thing that makes sense is that the value of resistor on pin 16 of the SCART plug is a bit too high to switch the Samsung to RGB?
It sounds like +5V is there, otherwise the CRT probably wouldn't switch to RGB mode (unless it can be manually switched to RGB ??)


OzOnE.

 

Something that would help me figure out what is going on: BlockABoots are you an American or are you living in PAL land?

After having done this mod a few times the only thing I can really suggest is using composite video with a sync stripper in the SCART cable itself. The SNES SCART cable I bought from the UK wasn't wired for every connection on the MultiAV output and I ended up using composite video for sync which works great with no cross hatching I can see on my Sony PVMs. I didn't want to cut out composite video entirely as the chances are that one day the N64s I modify for people may end up into the hands of people who are either entirely ignorant of RGB or are ignorant that the N64 is modded and assume it doesn't work when they use composite video on their TV and it greets them with a black picture.

There are probably SCART cables out there wired to use the C-SYNC connection but I'm not about to buy 20 cables from 20 suppliers just to find out. Bad enough I dropped $20 on one cable to find out it was insufficiently shielded.

 

@APE - Yep, I think many people don't know about RGB and that it needs the proper RGB SCART cable if the console has been C-Sync modded, or they won't get a picture at all.
I don't think there's any easy way to tell which SCART cables are be pre-wired to use C-Sync on the N64 unfortunately. BlockABoots is in the UK btw.

@BlockABoots - I've just tested my REV04 board (NTSC) and realized the problem (as far as the Samsung is concerned)...
The REV04 is missing ALL the parts for the C-Sync output!

If you follow pin 3 of the multi-out, it goes to C22, then R14. These are missing on my REV04, as well as the buffer transistor Q1, and R15/R16.

So, if your REV04 is missing these too (likely), I don't know how the hell it's working OK on your CRT?

I'll just try modding mine to see if I can get C-Sync to work OK. I actually glanced at this while Googling earlier, but didn't take any notice...
http://www.mmmonkey.co.uk/console/downloads/retroaccess n64 csync.pdf

I might be able to get it to work with just a resistor / cap and no transistor.
(I have x-hatching on my TV too via RGB, it's a Samsung of course) :rolleyes-new:

EDIT: OK, my REV04 is working with C-Sync now - no more x-hatching!
I didn't bother with the buffer transistor, just a 75R resistor between the via (hole) above R16 on the board and pin 9 on the MultiOut (not recommended).
(This is not the silver test pad above Q1, but the actual hole next to it).

I can't guarantee this will work on all TV's, and you should really add the full transistor circuit + resistors / cap.
It's stable on my Samsung LCD though.

As for your REV03, I'd imagine you need to check if the track is cut properly. They're a bit tougher than they look (I've just modded mine).

OzOnE.

 

The scart cable im actually using is a SNES RAW Sync cable, from Retro Console Accessories on eBay, http://stores.ebay.co.uk/Retro-Accessories?_trksid=p2047675.l2563. I have also tried another SNES cable that i used to use aswell both of these give the same results on the REV04 N64.

@OzOnE - Why would you say that the REV04 shouldnt be working on my CRT TV, do you think its some sort of sync issue on the Samsung thats causing this?, i have used the same components for the mods on both my N64's it must be something to do with the C-Sync mod then yes? On my Samsung LCD when i have the REV04 N64 connected up i get the 'No Signal' message on the screen BTW.

So i need to bridge pin 9 on the Multiout and the hole next to the silver test pad above Q1 via a 75R resistor? I should remove the wire i have connected to pin 3 and 9 on the Multiout? Any pictures to correctly show this would be appreciated

Does actually carrying out the C-Sync mod improve the picture quality any if using a CRT based display as i though i read that it made the picture sharper? Or is it just solely to remove the X Hatch problem on Samsung's?

 

use luma instead of csync