AES flickering / tearing screen

Toomanymikes · Mar 2, 2017

Hi there
I picked up an Aes a few years ago from fellow forum member IDCHAPPY, its a low serial no (5500) has been modded for rgb and has unibios 3.0. Happy days.
Unfortunately it's now unplayable as it's developed a really bad flickering / screen tearing effect when I turn it on. I have taken it apart and all the traces look good (the traces under the board where the rgb mod link cables are have been cut) and there are no other obvious things that make me think it could be the board. I spoke to Razoola about the bios in case it was that but he says it won't be, and I'm certainly going to take his word as correct

I poked and prodded all over the board to see if that made any difference but it hasn't changed it. It seems to be only at certain points of games - samurai spirits is fine until you get to the character select screen then it goes nuts. Interestingly, when I turn it on without a cartridge I get a white screen, no colour diagnostic at all.

I'm thinking it could be one of a few things:
the scart cable
The rgb mod
The TV not picking up the signal (it did before though)
The power pack
Something I'm missing on the aes
Basically I'm completely clueless!

I would love to get some advice (or just commiserations) from anyone than can give me a few pointers or has had similar problems. I miss my aes!

pulstar · Mar 2, 2017

So the picture starts off fine and is solid until you get to certain screens in the game? Sounds like it could be a sync problem.

Check the scart cable, especially the sync pin. Also, what RGB mod has been done to the machine?

Toomanymikes · Mar 2, 2017

Hi Pulstar
Thanks for getting back so quickly. I'm gonna be honest with you, I'm a total newb when it comes to circuit boards and wiring so I wouldn't know where the sync pin was but I'll do a search and check it out. I think it's a rgb bypass mod - the only change I can see is 4 new wires on the underside of the board, but all the capacitors and resistors are still in place on the top side.

pulstar · Mar 2, 2017

Pin 20 on the scart is the sync. Seems strange why it would only now develop a fault so it might end up being a dead end, but worth a quick look. It could need a resistor on the sync line or a sync stripper, but again it would be weird if the setup hasn't changed and has only now started doing it.

Toomanymikes · Mar 2, 2017

OK, the plot thickens. I opened the din connector end and pin 7 - composite sync is not connected. Pin 3 composite video is connected to scart pin 20. I cut the cable at pin 3, held it against 7 and it gives a more stable picture (after a bit of wiggling, but the colours are all messed up. Time for a new cable perhaps?

wyo · Mar 2, 2017

You could use process of elimination to determine the culprit. Try another cable/TV/PSU/AES.

Post a video of what it looks like and someone should be able to give you a more definitive answer.

Toomanymikes · Mar 3, 2017

OK, I have attached a typical image of the problem - the sound doesn't get affected at all, its just the image.
here is a video link:
https://vimeo.com/206636751

Im interested to see if it is just the cable (please let it just be the cable) so im up for a bit of experimenting. I nipped out and stocked up on resistors - got about 400 of the various buggers now - what sort of resistance should I be adding to the csync line?

pulstar · Mar 3, 2017

I take it this is exactly the same setup as before, when it used to work? Like wyo said, it might be worth trying a different TV, cable etc as well.

Try with a 75 ohm resistor on the sync line and see what happens then, not sure it will do much but worth a try.

Toomanymikes · Mar 3, 2017

Thanks, I'll give it a go. This is the same setup but it's always been a little off, even when I had it in a crt. It has become unusable now though.
I'll try the resistor as linking the scart pin 20 to the cdin pin 7 made the image stable, but it also made weird colour effects.

Xian Xi · Mar 3, 2017

Use a sync cleaner, 1st gen AES systems have shitty RGBS output out of the box.

Toomanymikes · Mar 4, 2017

So I hear! I have experimented with linking a resistor to the csync line which has made the image rock solid but I'm getting weird colour effects on the games. I have bought a stereo rgb scart cable from retrogamingcables.co.uk, the guy I spoke to there says the csync comes from pin 7 rather than pin 3 so I'll give that a go and let you know how I get on!

pulstar · Mar 4, 2017

Have you got a pic/video of the strange colour on the games? Is it a bleached effect or over saturated or simply the wrong colours?

Neo Alec · Mar 4, 2017

I don't think adding a resistor to the sync line will help. Xian's idea about a sync cleaner is better. Have you tried a different TV?

Consider getting a Framemeister. It's great for all your systems on modern TV's.

Toomanymikes · Mar 4, 2017

I have but they are impossible to get for a good price in the UK. Then again it's neo geo land so nothing is cheap! &#55357;&#56832;

Neo Alec · Mar 4, 2017

Solaris Japan is where to buy Framemeisters from. Try the AES on a CRT if you can.

GadgetUK · Mar 4, 2017

I would start by replacing the electrolytics for R,G,B and Sync. Unless they were previously swapped out when it was RGB bypass modded? I had similar sync problems starting on my old AES until I swapped out those caps.

Toomanymikes · Mar 4, 2017

I don't think they were swapped out, they still have the original glue on them like the crystal. I'll give the new cable a go first before I start hacking up the board- I was reminded of how rubbish my soldering skills are when I added the resistor to the c din connector pin this morning...

Toomanymikes · Mar 7, 2017

OK, so I had a feeling this wouldn't be simple. I got the csync cable today which sorts out the sync problem but has the same messed up colours as the cable I modded to run off pin 7.
Sooooo, the way I see it is this:
1.The original cable is OK
2.The rgb mod to the console didn't change the sync output
3.The power pack is not a problem
Which leaves three options:
1.It's the TV
2. It's something up with the neo geo itself - recap perhaps like GadgetUK suggested
3. The sync is crap like Xian Xi suggested
Because I'm a cheap ass Scot I'm going to go cheapest option first - sync splitter. This may be a dead end too but it's easier than recapping the neo for now...

Toomanymikes · Mar 14, 2017

Update time- I wired the sync stripper from the cdin pin 3 into the scart pin 20 and it has sorted the sync problem but it's still got the crazy colours from when I rewired the cdin pin 3 to pin 7. This is the same effect that I had with the cable from retrogamingcables.co.uk. Here is a video of the resulting colours:
https://vimeo.com/208387167
I now think that it's the neo or the TV and not the scart cable (damn)
Has anyone seen something similar to this? Recap the neo perhaps?

GadgetUK · Mar 14, 2017

Yeah, I cannot see the video - but the thumbnail shots work for that video, so I can see the picture looks OK. Since colours are wrong I still suspect caps. The reason the sync stripper is working is its probably able to filter out noise, or it might be that you are taking sync now from composite video and that signal might be passing through the related cap OK. Caps I reckon! Assuming its not something wierd like a strange palette RAM fault, or the R,G,B lines mixed around on the SCART connector - but if you've not messed with the connector and swapped colours it's likely caps.

When I re-capped my AES I measured the old caps and they were marked 100uF and all of them were bad - high ESR and they measured something like 20uF if I remember correctly. I swapped them out for 470uF I think - following XianXi advice I think.

Toomanymikes · Mar 15, 2017

I was thinking the same but don't have a tester to hand to check the caps so can't be 100% sure. The only thing that causes me doubt is that the colours were OK before I started to experiment with the sync from composite video. I have a suspicion that it may be the rgb mod that is causing the issue as I have never seen one like it on any forum post before - all of the original caps and resistors are still in place. It could be because it is an early version of the board and there are no examples of the mod online, or it could be a red herring...

pulstar · Mar 15, 2017

Take a photo of the mod. Although it might look different to the mods online, it may be doing the same thing but with traces cut instead of components removed.

Xian Xi · Mar 15, 2017

Try a different TV like a tube(CRT). If the picture looks good there then you know it's an LCD compatibility problem.

Toomanymikes · Mar 15, 2017

Here are a few photos of the board, caps and rgb mod with cut traces. The mod looks like nothing i have seen on the forum but then again i am no expert. Have you guys seen a mod like this one before?
It turns out that its a rev 3-4 board and the caps are 100uF, not 470uF, and the resistors are 68k not 75k, so recapping would be a good move.

i dont have a CRT to test it on, may have to look around for one...

Toomanymikes · Mar 24, 2017

Update time: I managed to get hold of a Sony trinitron (thanks Gumtree) and tested the neo. Picture was rock solid but the colours were all messed up with no limited reds and a green band across the screen about one third of the way up. I opened the cable up, resoldered the connections but no change, so I desoldered the sync splitter and bypassed it- it now works perfectly! Joys.
Thanks for all the help folks, it is much appreciated!

AES flickering / tearing screen

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