Need help finding RGB traces.NTSC tv

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Rang_86

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Hi, I need help on a project I'm doing. I want to use my SHARP 13J-M100 Tv (only has RF and composite in) for the MVS's RGBS. I can't find any schematics online and am a little puzzled by the unlabeled circuitry. I want to tap into R, G, and B, and find where sync goes BEFORE the amp's that drive the guns, I think. I know all TVs eventually convert their signals to RGB at a point. I found one large IC on side of PCB (a DIP) "X2933CE" and on the solder side a surface mount one. The PC board attached to back of the filament bulb is labeled with GND, SCREEN, H, RK, GK, BK.

I set the set to a snowy picture and attached a probe to Earth ground and experimented with traces. Tapping RK made the white spots cyan (G+B) and so forth. Tapping SCREEN made some small noise and small sparks jumped and the picture became almost completely black with some white spots. Grounding H did nothing unless I also tapped RK or GK or BK and the screen would become whatever color I touched with a static display, three horizontal stripes of varying brightness of that color. I touched various pins along the IC most had no effect, some mesd up horizontal hold, another made rainbows. I continued until I touvhed the probe to two at once and the TV shut down and would restart for five minutes.

I'm a little scared to monkey around blindly any more.
Any help is appreciated :)
 
ttooddddyy

ttooddddyy

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Rang_86 said:
Hi, I need help on a project I'm doing. I want to use my SHARP 13J-M100 Tv (only has RF and composite in) for the MVS's RGBS. I can't find any schematics online and am a little puzzled by the unlabeled circuitry. I want to tap into R, G, and B, and find where sync goes BEFORE the amp's that drive the guns, I think. I know all TVs eventually convert their signals to RGB at a point. I found one large IC on side of PCB (a DIP) "X2933CE" and on the solder side a surface mount one. The PC board attached to back of the filament bulb is labeled with GND, SCREEN, H, RK, GK, BK.

I set the set to a snowy picture and attached a probe to Earth ground and experimented with traces. Tapping RK made the white spots cyan (G+B) and so forth. Tapping SCREEN made some small noise and small sparks jumped and the picture became almost completely black with some white spots. Grounding H did nothing unless I also tapped RK or GK or BK and the screen would become whatever color I touched with a static display, three horizontal stripes of varying brightness of that color. I touched various pins along the IC most had no effect, some mesd up horizontal hold, another made rainbows. I continued until I touvhed the probe to two at once and the TV shut down and would restart for five minutes.

I'm a little scared to monkey around blindly any more.
Any help is appreciated :)
Click to expand...

After that Im suprised the set is still working, amazing.

If the IX2933 is similar to the IX2938 (I imagine it is) the RGB outputs are on pins 42,41 & 40 respectively. There will be 4.7K series resistors off these pins if Im correct. Lift these and introduce the rgb there.

H-sync is pin 1 and V-sync pin 2, they each connect to collectors of NPN sync amp transistors. If all this matches up give it a go.

AV switching is pin 6 (low for AV)

Good luck and dont blame me if you stuff up :make_fac:
 
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ToeJam

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Any update or screenshots I am very intrigued to see this working. :spock:

Possibly using a NTSC TV as an arcade monitor without a JROK, now that's interesting! :buttrock:

-ToeJam
 
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Rang_86

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might take a while....my supergun isn't finished and my PS2 is in pieces, plus i'll need to get a low power iron (40W too hot) and some heat sinks. When I'm done i'll post it though.
 
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Rang_86

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ttooddddyy said:
H-sync is pin 1 and V-sync pin 2, they each connect to collectors of NPN sync amp transistors. If all this matches up give it a go.
Click to expand...

uh is there anyway to put composite sync to any input on the X2933? Or is there a way to build your own sync stripper/splitter cause3 i can't find any lm1881 at local shops.
 
ttooddddyy

ttooddddyy

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No the IX2938 inputs seperate v and h sync- no composite in. (we need to confirm that we are talking about similar ICs 2933/2938 before proceeding with this- see diagram below)

How old is the set? Im not familiar with the model (being an NTSC TV designed for the US market) I am responsible for tech support of the Sharp product in Papua New Guinea, the company I am with are the appointed Sharp agents here.

The sets I deal with are PAL or multi-system, for the SE Asia-Australian markets.
However the IC you mention I think maybe similar apart from the system switching on the version for this region. Does this match up? If so will make a decent scan of the block and schematic (with some notes) and email it.

IX2938.jpg


Do you have a TB1226 "jungle" IC 801 (56 pin) or something similar on your set.
 
Last edited:
ttooddddyy

ttooddddyy

PNG FTW,
Joined
Nov 29, 2001
Posts
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ToeJam said:
Any update or screenshots I am very intrigued to see this working. :spock:

Possibly using a NTSC TV as an arcade monitor without a JROK, now that's interesting! :buttrock:

-ToeJam
Click to expand...

Its not difficult.(in most cases)
 
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Rang_86

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although the numbers on my chip are close the x29333CE is different, it is 56-pin DIP. I tried grounding pins 1 and 2 to see if it would affect the syncs like you said, but it didn't. I experimented some more, nothing I did would affect the picture (when plugged in to my PS2 composite) until I hit one that made the picture go black until I reset it. This is very frustrating.....if anyone has any ideas please share, I'm saving XRGB as a last and very costly resort.
 
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