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nam9

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This is the Sync output from a bootleg Cadillac's & Dinosaurs board:

1.png

As is this:

1.png

Resulting in this:

2.png

The game is running fine behind all this. Sound is good, controls sound responsive, even colours look ok.

So.. no expert, but... Vertical sync looks to last over 1ms. Periodicity of the horizontal sync looks fine... but amplitude of each pulse varies wildly over time...
(Video link: https://photos.app.goo.gl/n9Bw2hFmhU09VCsg1)

Since this board is a boot I have no schematic per se... so I looked at the CPS1 schematic to see how sync was implemented on the original:

3.png

In the original, H&VSync is output from the PPU, then combined. (H17 is an inter board connect).
I traced sync back from the jamma edge to pin 5 of a 74LS368 chip. Pin 1 is N/C, so all signals on pin 2, 4 & 6 are being inverted
(Again, if my understanding here is correct...)

4.JPG

This is the input on pin 4 (HSync also fluctuates). I can trace this inout all the way back to the FPGA unit on the PCB.
Looks like it is outputting an already combined sync signal:

5.png

Here is something interesting though. This is the input on Pin 2:

6.png

Looks like CSync as well? Differences - HSync is stable (the display is too squashed to properly show this).
VSync... well... it looks to last over 3ms...?

So. I fed the above input into the Jamma Sync circuit... (Cut pin 4 on the 74 chip, jumpered Pin 2 to Pin 4).
The result looks good! Bar the extended VSync pulse the HSync peaks are stable (they look different below, but it's just the display):

7.png

And the picture now looks like this:

2.png

(Ok, its the same picture.... but you get the idea.)

I'm not sure if i have made the problem better or worse... or what the problem here may actually be.
Does this look like anything other than a Sync issue? Would this all be down to problems with VSync timing?

This page is worth a read regarding Sync issues: That syncing feeling: classic arcade games that won’t stay still

I have emailed Chris there with this same issue, but would be interesting to post here too.

The board itself is clean and looks in good shape. I am running it out through a HAS supergun into a CRT.
I also have an Extron RGB unit, but it will not lock on to a Sync signal from the board.

Thoughts?
 
I've run into a screen that looks like that a couple of times and it's turned out to be that the video ground pin on the board isn't connected.

On my supergun it doesn't seem to pose a problem but on my Astro City I end up with a screen that looks exactly like yours. The solution was to run a jumper wire between the video ground pin on the edge connector and one of the main ground pins.

Apparently it's more common on bootleg boards for that pin not to be connected, I ran into the issue on a System 16 adapter as well as a SF2CE bootleg which I would hazard a guess is very similar to your C&D

Video ground is pin 14 parts side
 
I've run into a screen that looks like that a couple of times and it's turned out to be that the video ground pin on the board isn't connected.

On my supergun it doesn't seem to pose a problem but on my Astro City I end up with a screen that looks exactly like yours. The solution was to run a jumper wire between the video ground pin on the edge connector and one of the main ground pins.

Apparently it's more common on bootleg boards for that pin not to be connected, I ran into the issue on a System 16 adapter as well as a SF2CE bootleg which I would hazard a guess is very similar to your C&D

Video ground is pin 14 parts side
same issue here with my very first SF2CE I got, also a bootleg, PCB looked kinda identical to my C&D bootleg I once owned.
Check video ground and run a jumper wire from pin 14 to pin 1/2
 
Are you sure? I'd run another wire across anyway because that's what your issue looks like
 
post a foto of the gameboard please - there are many versions!
 
IMG_3561.JPG


@stj PCB looks like this one (I didn't think to take a full shot):

download.jpg
 

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Looks like video ground is connected on the PCB, have you tried a jumper wire on the Jamma connector as well?
This will make sure your video and chassis is proparly grounded :)

I used to own an exactly the same C&D board and my buddy had an identical Punisher board.
Both work perfectly in various cabs.
 
You mean to jumper pin 1/2 to 14 on the jamma connector as well?

I'm using @RGBs HAS v2 with this board...
 
pic's too small to make out the chips.

there is one type that has the sync coming directly from a pld near the center of the board,
the pin gets overloaded and the output screws up.

i have a few of them - maybe a dump will show up one day to program some new ones.
 
Sync on this board is output from the FPGA, then inverted by a 74 series IC near the centre of the board.

I'll take a better pic when I'm home.
 
You mean to jumper pin 1/2 to 14 on the jamma connector as well?

I'm using @RGBs HAS v2 with this board...
Exactly that, just makes sure of a good ground and if it doesn't fix anything, it certainly won't make it worse
 
Hi, i experienced the same issue on almost all cps1 bootlegs pcb, i always thought the issue was due to a not "strict" standard sync signal like most bootleg pcbs generates, since them correctly play on my arcade monitor, but they never stay in-sync on my sony pvm monitor on my test bench, so i never think about going deep analyze the issue until a captain commando bootleg come to my bench for a quick repair.

That bootleg played well, but it was completely mute, no audio effects and music at all, it missed few capacitors in the audio section, easy fix ...

With my surprise that board perfectly played the game on my sony pvm, so i started populating the pcb with the missed capacitors, and once finished the job, i powered-up the board and the sync issues were back, and the monitor didn't correctly display the image anymore ... gulp!

As soon as i can i'll made some investigations on these sync issues that affect these bootlegs.

I'll let you know.
 
Poor grounding perhaps?
This. These boards don't sync on my Astro which doesn't have video ground connected up (as many cabs don't) but it does on my Supergun, simple solution is to run a small jumper wire from the video ground pin to one of the ground pins on the edge connector

I have the same issue with my system 16 adapter
 
the monitor cabling should *always* have video ground, so should jamma connectors - it's to minimise noise/interference on the image.
 
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