Can GE 20GT612 Be Fitted With RGB Mod?

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DotMatrixMoe
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

Post by DotMatrixMoe »

Right here, hopefully.

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DotMatrixMoe
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

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I did a bunch of research on the neckboard and yoke (just in case I have to go that route), and I'm skimming through the schematics. To avoid the pinch of death, I'm thinking I can use lower resistor values inline to the neckboard and tap into its signal via motherboard (coming out the jungle IC). I may have to create a switch circuit so only one rgb signal is shown at a time. And I'm going to have to test with a pot to see how bright it can go.

Wish me luck, rubber here is my friend.
(Parts may be coming next week. USPS is lousy!)
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DotMatrixMoe
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

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DotMatrixMoe wrote:Right here, hopefully.

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And what do you know, if the pins I found are actually outputs, then I already found my resistor values.
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

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I'm only actively researching, so when I'm confident in my information, I'll redraw a neckboard schematic (follow my idiocy at your own risk) and go ahead with the dirty, yet somewhat convenient mod.
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Syntax
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

Post by Syntax »

Your going neck board I'm leaving.
Crap set crap mod, total waste of money and time.
Go get another set.
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

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Syntax wrote:Your going neck board I'm leaving.
Crap set crap mod, total waste of money and time.
Go get another set.
Bit harsh, though true. Was shopping for CRTs already online, but none are in a reachable distance :( .
I'll see what I can do, thanks for the tips at least. I appreciated the patience you had.
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

Post by DotMatrixMoe »

Continuing on with the mod, because the television looks lovely...

I will NOT be soldering directly in the neckboard, and instead remove the SMD resistors inline the Jungle IC to inject my signal. That way, my inputs can go through the circuitry.

If necessary (probably), I will make a tiny board with a signal amplifier, line the output with 75 ohms, and then a 1K pot to adjust the voltage the tube expects. I want to be able to use other inputs, so I'll line it up with a 9 pin switch and feed the jungle's output with the same resistance the board original had.

This is all according to my research so far, and will soon follow as planned.
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

Post by DotMatrixMoe »

According to reading 20 pages of the RGB mod and some arcade forums, I figured this diagram should work.
Only think I see iffy about my work is the termination to 75ohm in input, but the datasheet of the Texas Instruments chip apparently expects 75 ohm terminated 0.7v.
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I appreciate the tips on RetroRGB which advised to filter power with a capacitor. And I decided to remove the SMD resistors because that's the farthest from the other circuitry that is regulating voltage. I don't know if the potentiometers are of use yet, but I'll see once I adjust them.
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

Post by DotMatrixMoe »

DotMatrixMoe wrote:According to reading 20 pages of the RGB mod and some arcade forums, I figured this diagram should work.
Only think I see iffy about my work is the termination to 75ohm in input, but the datasheet of the Texas Instruments chip apparently expects 75 ohm terminated 0.7v.
Spoiler
Image
I appreciate the tips on RetroRGB which advised to filter power with a capacitor. And I decided to remove the SMD resistors because that's the farthest from the other circuitry that is regulating voltage. I don't know if the potentiometers are of use yet, but I'll see once I adjust them.
Just a disclaimer, this has NOT been validated yet. Do not attempt before a confirmation message or a complete log in my first message. Also, don't try this unless you don't have a full color OSD.
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

Post by DotMatrixMoe »

Correction, the output resistors are 1.6k Ohms and not 16k
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

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A part of me thinks amplifying the voltage of the RGB lines may not be necessary. But of course I could be wrong.
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

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There are inline resistors on my neckboard. They may become a problem. So if I have to, I'll hook 'em up to a potentiometer.
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

Post by DotMatrixMoe »

I won't make an update in a while, but stay tuned! I'm planning to also pick up a Trinton next month, so I can compare both the neckboard and OSD RGB mods for myself. The neckboard one will be in a arcade cabinet that I was designing before this mod. :)
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Re: Can GE 20GT612 Be Fitted With RGB Mod?

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My parts has arrived, finally! Teaches me not to order from China during a global pandemic... :roll:
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