Color problem with arcade games, supergun, and PSU?

[retrogamingjohnny]

Hey guys how's it going? I couldn't find the answer to my problem after reading many old posts and doing some
search so forgive me if I missed.
So here is the issue: When I connect my supergun to any arcade game pcb, the image is too bright
with a lot of color loss due to the brightness


I am using a Sony BVM monitor and the games look
perfect when I use any home console. This is a shot of Magician Lord for the AES and it looks
perfect

Of course these images look a lot worse than on screen, but it gives you the idea. This problem only occurs when
using the supergun with arcade games. I have tried lowering the brightness, contrast, increasing, decreasing the
RGB values on the BVM, but that still doesn't look right. Lowering the brightness
just make the image darker, but the color loss is till there.
I am not sure whether the problem is with the supergun, the power supply, the scart cable or anything.
Here is the supergun from an European store called Smallcab

This is the website for the supergun http://www.smallcab.net/index.php
It outputs Scart signal and I am using a Scart to bnc adapter for the BVM.
from this seller http://www.ebay.com/itm/Female-RGB-Euro ... 2c8567b4c7
I hook up my consoles to the same cable and they look perfect.
I am using this arcade PSU

This is the website for the PSU http://www.ebay.com/itm/120966942326?ss ... 1439.l2649
I have it in 110v setting. I tested the PSU and the voltages are in the proper range.
Measuring the voltages on the rom chips of my SF2
board, they read 5.01v so that should be right.
I have also tested the boards with my ATX power supply and get the same thing.
Does anyone here has the same supergun? Any idea what the cause is?.
I'd appreciate the help.

[muckyfingers]

You have to lower the gain for the RGB colors on the Supergun itself, usually 3 potentiometers, 1 for each color.

[Fudoh]

yes, definitely. Your voltage levels on the RGB lines are too high. Arcade levels are about 3x the consumer levels.

[retrogamingjohnny]

You have to lower the gain for the RGB colors on the Supergun itself, usually 3 potentiometers, 1 for each color

yes, definitely. Your voltage levels on the RGB lines are too high. Arcade levels are about 3x the consumer levels.

Thanks guys for identifying the issue. Now I am much relieved to know what's causing it.
I did some searching and found that 1K ohm is the right rating. Can you confirm that
or what rating would you use? So I can get 3 one of these right?

this is the listing url http://www.ebay.com/itm/1-2-5-10-20-50- ... 417b859e06

I found this wiring example

, but in this case the middle wire will go to one of the RGB signals right?

I also found this on ebay, not sure if it would work for this but it caught my attention

This is the url http://www.ebay.com/itm/12-24V-3X3A-Dim ... 1020751109
It is for led, but will it work on the supergun? Just curious because it would
be useful if it can be used for this.

Thanks



-retrogamingjohnny

[Fudoh]

The lower one is nothing for you - wrong voltage levels.

Also the smaller trim pots don't need a ground line, so they usually just have an input and an output. 100 to 300 ohm is the range you LIKELY need, so 1K is not neccessary.

[retrogamingjohnny]

The lower one is nothing for you - wrong voltage levels.

Also the smaller trim pots don't need a ground line, so they usually just have an input and an output. 100 to 300 ohm is the range you LIKELY need, so 1K is not neccessary.

I found this this:


Specifications:
Adjustment Type Top Adjustment
Number of Turns 25
Power 0.5W
Resistance 100 OHM
Series 3296
Tolerance ±10%
Sub-Series 3296W
RoHS
Lead Free

How do the number of turns and tolerance rating look?
There is a bunch of other ones, but this is the most economical.
Will it do fine or would you recommend any particular one? Thanks.

[Zets13]

Are there no RGB pots already on the supergun itself?

[Fudoh]

100 ohm max. resistance isn't strong enough. You need a minimum of 100 ohms and a max of AT LEAST 300 ohms.

I checked the manual of the supergun and there are no resistors. Major design flaw. It's easiest to add them to the cable instead of the supergun.

[retrogamingjohnny]

Are there no RGB pots already on the supergun itself?

Not that I am aware of. It has these optional RGB ports for future
add on

[Fudoh]

That's just another output option if you don't want to use the Scart socket. It's more complicated to add the resistors between this output and the Scart connector next to it than it is to simply add them to the cable. Both works of course. If you feel better by using non variable resistors, just get a few 220 ohm and a few 75ohm ones. The 220ohm might work already and if not then you can still put the 75 ohm in line.

[retrogamingjohnny]

100 ohm max. resistance isn't strong enough. You need a minimum of 100 ohms and a max of AT LEAST 300 ohms.

I checked the manual of the supergun and there are no resistors. Major design flaw. It's easiest to add them to the cable instead of the supergun.

Will this work?


500 OHM Linear Taper Rotary Potentiometer B500 Pot

Manufacturer: ALPHA
Manufacturer Part No: B500 OHM 17mm
Comes with Dust Seal

Specifications
Adjustment Type: Top Adjustment
Power: 1/2W
Resistance: 500 OHM OHMS
Type: Linear
Type B

You suggested at least 300 ohm, so I am guessing 500 would be ok? Will this type of pot work?

I was thinking about connecting the pots this way with wires.

What do you think?
Then I'll encase the supergun with some sort of junk console shell like some users have done, but that's for the future.

Thanks

[muckyfingers]

NO! You'll kill your Supergun, nothing should be soldered to the 5V line for RGB. If you want to wire it to the supergun you need to cut the traces for the RGB lines on your Supergun from the Jamma harness side, pins 12,13, and N.





Example: Cut the trace for the R line from Jamma board to one side of the potentiometer, ground to other side, and R out to the middle. That output then goes to otherside of the trace you cut from your Supergun. Though like Fudoh said it would probably be easier to do it to the cable.

[Fudoh]

omg

[muckyfingers]

So here is an example of the R line with a picture, the red mark is where you need to cut the trace.

[system11]

Post a photo of the back of the PCB please.

Looks like it already has output resistors, I see three 220 ohm ones right next to the scart connector... If the output level is too high the easiest change would be to simply swap them out for 300 ohm for example.

[retrogamingjohnny]

Post a photo of the back of the PCB please.

Looks like it already has output resistors, I see three 220 ohm ones right next to the scart connector... If the output level is too high the easiest change would be to simply swap them out for 300 ohm for example.

Here is the back of the supergun




Let me know. Thanks.

[retrogamingjohnny]

NO! You'll kill your Supergun, nothing should be soldered to the 5V line for RGB. If you want to wire it to the supergun you need to cut the traces for the RGB lines on your Supergun from the Jamma harness side, pins 12,13, and N.





Example: Cut the trace for the R line from Jamma board to one side of the potentiometer, ground to other side, and R out to the middle. That output then goes to otherside of the trace you cut from your Supergun. Though like Fudoh said it would probably be easier to do it to the cable.

Wow, I am glad I shared the plan first. I think I want to it to the cable then. I really do not want to do cuts on the supergun. Could you show me how to do it to the cable please, with diagram if possible. If you need me to open the cable and show pictures of it, let me know. Thanks.

[RGB]

Anybody else noticed how thin the +5V and +12V traces from the PSU connector to JAMMA connector are ? And they are single layer, too

[CkRtech]

Wow, I am glad I shared the plan first. I think I want to it to the cable then. I really do not want to do cuts on the supergun. Could you show me how to do it to the cable please, with diagram if possible. If you need me to open the cable and show pictures of it, let me know. Thanks.

If you don't want to make changes to the board, I would make a breakout box and feed your R,G,B lines to the breakout box along with ground. Tie up each of the RGB lines to its own pot (along with ground), then run the pot output to the TV. Essentially, you would create your own box similar to the one you showed that was for LEDs, however it would instead be for your video lines. You are basically offloading functionality that should, in my opinion, be built into your Supergun.

Having the breakout box close to the supergun would make it easier to tweak as you would want to see your display as you make adjustments.

If you wanted to still use that SCART cable, you could put the box at the end of it (behind the TV) and feed the R,G, and B lines into the box at that point. Sync and stereo audio would go straight in, and the BNC connectors for RGB would go to your box.

So...if you go the route of keeping your existing SCART to BNC/RCA cables, you could...

Materials needed:

Buy 6 female BNC panel mount connectors like...


Buy 3 adjustable pots (mentioned already) in this thread

Buy a small, plastic project box (or re-use a box you already have)

Buy BNC cable (male to male) for your R, G, and B line box output.

Other items: Solder, soldering iron, wire, drill, drill bits. Colored knobs for the pots are also optional.

1: Drill three holes in one side of the case and three holes in the other side of the case. Drill them to fit your panel mount BNC connectors.
2: Drill three holes in the top of the case for your pots. Pots tend to have a little tab at one point of the base, so you may need a small hold for that tab to fit into as well (it keeps the entire pot from turning when you turn the knob).
3: Connect one side's RGB lines to the input of each of the pots (solder). One for each color.
4: Connect the other side's RGB lines to the output of each of the pots (solder). One for each color.
5: Connect the grounding tab from the input panel mount connector to the ground on its appropriate potentiometer. Connect the same pots ground to the output BNC connector on the opposite side of the box.
6: Close the project box.

Steps 3 to 5 may require some solder stealth if your box is small.

From there, wire up your SCART to BNC cable to the TV (for audio Left, Right, and the sync signal). Connect the R,G,B lines to your box's inputs. Connect your male to male BNC connector to the RGB output of the box, and then connect the other end of that BNC male cable to your TV.

You could also buy extender cables for your RCA stereo audio and your single BNC (Sync) connector as well. This would let you float the box out from behind the TV a bit so you could adjust your signals.

[system11]

Yeah the three 220 ohm resistors are already in-line on the scart output. If you want a quick and easy potential fix just replace those three with 300s.

Note that if you do break out the video signal before those using the RGB terminals on that supergun, if you fit some pots you want them to act as trimmers not potential dividers so just use an outer and the inner pin. Also note that at minimum adjustment you will actually be sending a stronger signal than you are at the moment, which could damage some equipment.

I'm surprised a BVM doesn't have a set of proper RGB level inputs though, maybe it does? If that's the case you could build a cable for whatever connectors it uses and wire them straight into those RGB terminals on the PCB without any resistors/etc.

[retrogamingjohnny]

Wow, I am glad I shared the plan first. I think I want to it to the cable then. I really do not want to do cuts on the supergun. Could you show me how to do it to the cable please, with diagram if possible. If you need me to open the cable and show pictures of it, let me know. Thanks.

If you don't want to make changes to the board, I would make a breakout box and feed your R,G,B lines to the breakout box along with ground. Tie up each of the RGB lines to its own pot (along with ground), then run the pot output to the TV. Essentially, you would create your own box similar to the one you showed that was for LEDs, however it would instead be for your video lines. You are basically offloading functionality that should, in my opinion, be built into your Supergun.

Having the breakout box close to the supergun would make it easier to tweak as you would want to see your display as you make adjustments.

If you wanted to still use that SCART cable, you could put the box at the end of it (behind the TV) and feed the R,G, and B lines into the box at that point. Sync and stereo audio would go straight in, and the BNC connectors for RGB would go to your box.

So...if you go the route of keeping your existing SCART to BNC/RCA cables, you could...

Materials needed:

Buy 6 female BNC panel mount connectors like...


Buy 3 adjustable pots (mentioned already) in this thread

Buy a small, plastic project box (or re-use a box you already have)

Buy BNC cable (male to male) for your R, G, and B line box output.

Other items: Solder, soldering iron, wire, drill, drill bits. Colored knobs for the pots are also optional.

1: Drill three holes in one side of the case and three holes in the other side of the case. Drill them to fit your panel mount BNC connectors.
2: Drill three holes in the top of the case for your pots. Pots tend to have a little tab at one point of the base, so you may need a small hold for that tab to fit into as well (it keeps the entire pot from turning when you turn the knob).
3: Connect one side's RGB lines to the input of each of the pots (solder). One for each color.
4: Connect the other side's RGB lines to the output of each of the pots (solder). One for each color.
5: Connect the grounding tab from the input panel mount connector to the ground on its appropriate potentiometer. Connect the same pots ground to the output BNC connector on the opposite side of the box.
6: Close the project box.

Steps 3 to 5 may require some solder stealth if your box is small.

From there, wire up your SCART to BNC cable to the TV (for audio Left, Right, and the sync signal). Connect the R,G,B lines to your box's inputs. Connect your male to male BNC connector to the RGB output of the box, and then connect the other end of that BNC male cable to your TV.

You could also buy extender cables for your RCA stereo audio and your single BNC (Sync) connector as well. This would let you float the box out from behind the TV a bit so you could adjust your signals.

Hey CkRtech thanks very much for the detailed write up. I like it. I made this visual aid


Are there any errors from the what I understand?

Also please answers these few questions that I am bit unsure:
Will three of these M/M RG59 Coaxial cables do fine?


Will this type of pot do?

500 OHM Linear Taper Rotary Potentiometer B500 Pot

Manufacturer: ALPHA
Manufacturer Part No: B500 OHM 17mm
Comes with Dust Seal

Specifications
Adjustment Type: Top Adjustment
Power: 1/2W
Resistance: 500 OHM OHMS
Type: Linear
Type B

For the female BNCs I should use these types that have a ground tab right?


I really appreciate the help. I will commence this project once I'm sure I understand it. Thanks.

[CkRtech]

Looks pretty good. I don't know the pinout of the pots off the top of my head, but I think someone else covered it here. Your illustrations are basically the same design I mentioned. Make sure you get those grounds connected properly - You could drill your holes first and wire up a single color and test it out just to see your work in progress.

A lot of people use 1k pots on their superguns. You already have some built-in resistors in your supergun, so you are adding to them. 500 will probably be plenty. I think I had to go rather high (but still under 500 ohms total resistance) with my Capcom CPS2 board.

Let us know how it goes and feel free to ask questions.

[retrogamingjohnny]

Looks pretty good. I don't know the pinout of the pots off the top of my head, but I think someone else covered it here. Your illustrations are basically the same design I mentioned. Make sure you get those grounds connected properly - You could drill your holes first and wire up a single color and test it out just to see your work in progress.

A lot of people use 1k pots on their superguns. You already have some built-in resistors in your supergun, so you are adding to them. 500 will probably be plenty. I think I had to go rather high (but still under 500 ohms total resistance) with my Capcom CPS2 board.

Let us know how it goes and feel free to ask questions.

Thanks. Yes I was considering the 1k pot. Might as well go with that. Can you verify whether the M/M coaxial cable will work? I am thinking about using a carboard box for the project since I am planning on using junk console shell to house the supergun once I have everything down.

[CkRtech]

I think you will be ok. RG59 is typically used for video. Keep it short if possible.

[retrogamingjohnny]

I think you will be ok. RG59 is typically used for video. Keep it short if possible.

Good I just ordered the parts. Haven't ordered any extensions. I'll leave that for the future. I ordered 1k pots though for the heck of it. It will take a few weeks to arrive since I ordered overseas for the cheaper. I will keep my progress updated.