Anyone using a CMVS-RGB pcb for MVS SCART/RGB?

[xodaraP]

That's correct I'm using a straight through cable which is what the AES uses. What cable is the PCB expecting?

I picked up the sync signal before R13 and this works on my PVM but not on a standard TV, it is too weak.

Colours are also very dim so all signals from this PCB are too weak.

 

[SVM]

I'm using a straight through cable which is what the AES uses.

That's the way it's meant to be.

I picked up the sync signal before R13 and this works on my PVM but not on a standard TV, it is too weak.

Colours are also very dim so all signals from this PCB are too weak.

Strange...

Could you upload some photos of your pcb, please?

 

[xodaraP]

Will do. It's installed which makes it more difficult.

I do have a second PCB (when I ordered parts it was cheaper to order several sets) so I might try that too and see if I get a different result.

 

[xodaraP]

I'm using a straight through cable which is what the AES uses.

That's the way it's meant to be.

I picked up the sync signal before R13 and this works on my PVM but not on a standard TV, it is too weak.

Colours are also very dim so all signals from this PCB are too weak.

Strange...
Could you upload some photos of your pcb, please?

You say the way it is meant to be is using a straight through cable for the AES, but then you say others have had issues with sync on straight through cables.

Can you explain what cable you are using that works?

 

[xodaraP]

Ok so I used another PCB and I'm getting the same issue. I took some measurements of voltages on a white screen so all colours are in use:

Input:
RGB: 2.068v
Sync: 4.28v

Output:
RGB: 0.86v
Sync: 0.07v

Sync is definitely not making it through correctly. I have confirmed continuity on all components as well. The reason it works on the PVM is you have the option of internal sync. If I use sync from the board it doesn't work at all.

Connecting it before the 75R will not help, I get a similar voltage on the other side of the resistor.

Colour is very strange, I'm getting blue, some green but no red as far as I can tell. All colours are there on the output from the PCB so may have come disconnected on the output video connector. I'll need to double check.

Photo of the PCB will be up shortly.

 

[SVM]

You say the way it is meant to be is using a straight through cable for the AES, but then you say others have had issues with sync on straight through cables.

Can you explain what cable you are using that works?

No, I said ONE user had that problem.

Therefore a straight through cable is still the right decision.

 

[xodaraP]

Ok, it doesn't matter in this case because I'm not getting sync from the RGB PCB. I have beeped out quite a lot of the circuit and it's working.

2 boards have the exact same issue so it isn't a build issue. All parts were ordered from Mouser including the 7374 so I don't believe it's a component issue.

 

[SVM]

Sorry, but if the components are ok than there is not much I can do for you... :-/

Are the resistor values correct?
R1: 9.53KΩ
R2, R3 & R4: 7.5KΩ
R5, R6 & R7: 1.2KΩ
R8: 620Ω
R9, R10 & R11: 5.1MΩ
R12: 10KΩ
R13, R14, R15 & R16: 75Ω

Are GND and 5v connected to the pcb?

If yes, the only solution would be to play arround with the resistor values at the input side (R1 & R8 for sync; R2 & R5 for red; R3 & R6 for green; R3 & R7 for blue).

But I realy don't know why the pcb "behaves" in that way, because the video DAC values are the same for every MVS (to my knowledge)...

Sorry...

 

[xodaraP]

Do you have your connections for RGB to the JAMMA pins or the resistors? And which side are you taking them from?

The issue I seem to be having is red and green are mixing together somewhere. If I have red connected by itself or green connected by itself on both input and output side, I get the same colours, dim and yellow.

I've metered out for shorts, beeped out the JAMMA edge to confirm nothing is connected incorrectly there, unless they're reversed on the board for some reason but even that doesn't explain why they're mixing.

Thank you for your help it's very frustrating when things don't work and make no sense lol

 

[SVM]

Do you have your connections for RGB to the JAMMA pins or the resistors?

To the JAMMA pins.

The issue I seem to be having is red and green are mixing together somewhere. If I have red connected by itself or green connected by itself on both input and output side, I get the same colours, dim and yellow.

Than there must be an issue with the bypass pcb... Would you be so kind to upload some photos (maybe 4 eyes see more than 2)?

it's very frustrating when things don't work and make no sense lol

I totally understand.

 

[xodaraP]

You'll have to excuse my very bad reflow job on the 620ohm resistor and on the connections for inputs/outputs, I've been soldering and desoldering random wires to test stuff all day @Frank_fjs has also been helping and has made some suggestions but nothing has worked so far.

I'll fix it once it's working properly and I permanently put everything in place.

 

[xodaraP]

Wire colours for reference:

Red - Red
Green - Yellow
Blue - Black
Sync - White

 

[SVM]

The parts seem to be correct...

Where do you grab your 5v from? Could you test an alternative spot, please?

I've "measured" my outputs with a white screen, too (even if I know that it is not the right way to do it with a multimeter ):

RGB: 1.76v
Sync: arround 0.07v

 

[xodaraP]

Shouldn't it be 0.7v not 0.07v?

I know there’s proper ways to do it but at least of I’m getting roughly what I’m expecting I know I’m on the right track. Your RGB lines are twice the voltage of mine so that explains why it’s dim.

The 5V is coming direct from the PSU, I have a connector with 1 input and 4 outputs (1 going to power switch, one to board, one to video connector and one to LEDs)

I'm not sure an alternative connection is going to be an improvement since it would have to come from the board itself.

 

[SVM]

Shouldn't it be 0.7v not 0.07v?

As I said, its hard to tell with a multimeter (the values are shifting arround). One would need to measure it with an oscilloscope ...

The 5V is coming direct from the PSU

Than it should be ok.

What still bothers me is that your red and green signals are mixed together. But on 2 pcbs it is relatively impossible that 2 IC have an issue...

 

[Nic034]

Hi XodaraP, all,

Note : I've successfully tested and mounted on gamma board (MVS and cps2) Tim Worthington av-driver board, this one can also be used from your stuff.
https://etim.net.au/shop/shop.php?crn=211&rn=556&action=show_detail

This board is great and for compatible for multiple purpose, as CMVS-RGB pcb's available on internet are crappy or TTL levels delivered are incorrect.Great results with CPS2 with custom supergun : no more video noise (even a few), RGB levels and sync are perfect. I've used a 220ohm resistor (also great for CPS2) on RGB lines before av-driver pcb instead of multi-gang pot ready to use avaliable by Tim shop and video ground / 5v from jamma to power the board.

jamma : http://etim.net.au/av-driver/arcade/
jumpers : http://etim.net.au/av-driver/jumpers/

Thanks to Tim for his great job.

Best regards,
Nico

 

[Frank_fjs]

Good point there @Nic034

The AV driver is multi purpose in that you can configure RGB attenuation and has superior sync processing.

 

[Nic034]

Hi Frank_fjs

Thanks for feedback too.

I confirm this, it's a greatboard and with a great price.
I'll try it on other hardware soon and will provide feedback (old supernes mini us, for RGB cleaning and sync restitution)

Best regards,
Nicolas

 

[xodaraP]

The 5V is coming direct from the PSU

Than it should be ok.
What still bothers me is that your red and green signals are mixed together. But on 2 pcbs it is relatively impossible that 2 IC have an issue...

This is the thing that’s really annoying me. I’ve checked every single connection for a bridge and it isn’t there. But if I connect either green or red by itself, I get yellow, so it’s bridged.

I’m going to restart the whole circuit again next weekend.

 

[xodaraP]

The eTim board looks great but I’m really disappointed he hasn’t included attenuation on the inputs and you’re expected to calculate this with horrible multi gang pots.