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Connecting an Arcade PCB to a CRT TV


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Your TV likely has hpos, vpos and vsize in service menu.

 

 

Sent from my iPhone using Aussie Arcade

 

Yeah but most of the TV's I get come from the side of the road without remotes. I've found finding the service codes a bit of the a pain for the cheap Chinese made TV's.

 

Thanks for the link @Frank_fjs, I 'll order a couple of those for the test bench.

I was thinking about seeing if I could replicate what Nintendo has done on the Donkey Kong PCB's but for the money this is a quick and simple solution.

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Connecting an Arcade PCB to a CRT TV

 

For Jamma attenuation I use 500 ohm pots on the Jamma RGB lines outside the TV. They interact with the 75R terminations to form a voltage divider. For sync I use the same principal but with 1000 ohm resistor.

 

Frank uses a more robust solution on his superguns.

 

 

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I like the idea of being able to tweak the values so I might make up a small Vero board with the four pots as mentioned.

 

eA84qfH.jpg

 

I'm re doing my test bench setup tonight after not being happy with it for a while, for the primary Jamma setup I'll use a 4PDT to turn the mod on and off so I can hook up normal.arcade PCB's as well as B&W (Composite Video input) PCB's.

 

 

1lpmTpI.jpg

 

There'll be two Jamma rigs using the two TV's I modded, the left one will be able to take a composite signal using the switch.

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@redferatu

 

What model Sony?

 

 

Sent from my iPhone using Aussie Arcade

The Sony I was talking about is a Kv-Sw29m31

 

https://www.manualslib.com/products/Sony-Trinitron-Kv-Sw29m31-3685766.html

 

I also have an LG. I haven't looked right into this one, but I think I have a few rgb options for it.

 

https://www.manualslib.com/download/763632/Lg-Rt-29fa30v.html

 

I also have this cool 7 inch sony trinitron that was used for booking flights. It has no video input, they worked of a modem. I'm pretty sure it'll be rgb somewhere inside but I can find a manual yet.

 

I also have a konka I'll look into.

 

Sent from my HTC 2PZF1 using Tapatalk

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Connecting an Arcade PCB to a CRT TV

 

Ah yeah, BX-1, BX-1L and BX-1S stubbornly refuse to mod.

 

It sucks too because there are variants of this chassis around the world that are factory Scart but I haven’t found the secret.

 

 

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If you mod it with the Mux method you only need a single point switch to disable blanking which will stop the RGB signal.

 

 

Sent from my iPhone using Aussie Arcade

 

 

 

Doh, the mod has already been done and tested, will definitely do the mux option in the next one.

 

 

The other TV doesn't have a blanking option so I may do another 14" for the right side using the mux mod so I can run two Spacies L-Shapes at the same time.

Running two identical PCB's on the bench simultaneously will hopefully make some repairs quicker when I can compare the signals between both boards at the same time.

The other benefit is that I can have one board soak testing wile working away on another.

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I grabbed a 21" TV from the stash and had a quick look at the schematic.

It's a Sany CP-21SW1, link to mamual here...

 

https://elektrotanya.com/sanyo_ac3a_chassis_cp21sw1.pdf/download.html

 

The OSD out goes through a transistor, resistor and inductor on each of the lines that are powered by the VDDA output on the same chip.

 

Ufe9P3M.jpg

 

I'm not sure what the VDDA is/does at this stage but I'm guessing that it won't interfere with the mux method. They go through caps just after the inductor and then through some 5.6k resistors before going into the Jungle Chip.

 

5AiAPul.jpg

 

The Blanking also gets a feed.from the H and V Sync, not sure if that will affect anything, I'm guessing if a composite signal is connected it will automatically blank...:unsure

 

MF2lsv6.jpg

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For the OSD Mux I would consider cheating.

 

I’d remove R221, R222 and R223 and inject 75 ohm terminated RGB into the RGB circuit, maybe on the text header via 1K resistors.

 

For blanking I would tie 5V to a 3900R and to the leg of resistor R850 farthest from the micro controller IC801. Use a switch on this line if you want to disable.

 

 

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Thanks Mark, this monitor will be used in a dedicated Spacies cocktail so permanently connected to RGB is fine.

I just finished setting up the first monitor on the test bench so I might have a go at this tonight.

Did you mean 390R resistor?

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Nope, I meant 3900. Same value that R850 is.

 

Something of a similar size should be fine.

 

The TV has an inbuilt voltage divider using R850 and R851, both 3900. This means that 2.5V is going to the jungle because the micro controller chip will be outputting 5V from pin 39.

 

I’m not sure exactly the blanking voltage for this chip. By sending 5V into a 3900R onto the leg of R850 farthest from the micro controller we will be sending 2.5V to the jungle.

 

 

Sent from my iPhone using Aussie Arcade

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Connecting an Arcade PCB to a CRT TV

 

Blanking voltage should be from 1.2V to 3.3V according to datasheet.

 

So that should help you work out what resistors will work on your 5V line.

 

 

Sent from my iPhone using Aussie Arcade

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