Konami track&field missing red

GoneMad

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Another T&F thread. This one is my good game pcb. Turned it on and everything was grey/blue/yellow. Took me a few to click in, went to the back of monitor, adjusted the red drive and cutoff and the controls worked. Monitor confirmed to be working with another pcb.
Anyone know where I should be looking to trouble shoot this? Do erproms controls colors as well as graphics? Or would this be a single component that went tits up? Any help would be appreciated. Thanks
IMG362.jpg
 
Anyone know where I should be looking to trouble shoot this? Do erproms controls colors as well as graphics?

Not exactly an EPROM, but a close relative: a bipolar PROM. However, I have my doubts that it is to blame. I'd first check/clean the edge connector (obviously, check the pinout and focus on the connection for the red video signal). After than, I'd carefully follow from that connector on the PCB traces and looking for any damage or a bad via.
 
Not exactly an EPROM, but a close relative: a bipolar PROM. However, I have my doubts that it is to blame. I'd first check/clean the edge connector (obviously, check the pinout and focus on the connection for the red video signal). After than, I'd carefully follow from that connector on the PCB traces and looking for any damage or a bad via.
I have already checked connection from the monitor chassis to the harness, it is good. I will look at the rest of what you say here and hopefully I will find some thing simple.
Thanks
 
ok, i gave the edge connector a good scrub with an eraser, checked all the traces and seem ok. Fired it up and no change. Turned off and checked for connection right from the red coming off the monitor chassis straight to where it goes into the first resistor on the pcb. Checked the four resistors in the red and they all tested good and followed the traces right to where they lead into the 6331 chip at 1F. This chip also has 316B16 stamped over it.
 
ok, i gave the edge connector a good scrub with an eraser, checked all the traces and seem ok. Fired it up and no change. Turned off and checked for connection right from the red coming off the monitor chassis straight to where it goes into the first resistor on the pcb. Checked the four resistors in the red and they all tested good and followed the traces right to where they lead into the 6331 chip at 1F. This chip also has 316B16 stamped over it.

As well as checking the traces visually, did you use continuity (or resistance) mode to verify electrical continuity between the edge connector and the appropriate leg on each of those 4 resistors in the DAC ladder?

Do you have an o-scope or logic probe to check for activity on the red outputs of the color PROM (the one labeled "6331" on the schems)?
 
As well as checking the traces visually, did you use continuity (or resistance) mode to verify electrical continuity between the edge connector and the appropriate leg on each of those 4 resistors in the DAC ladder?

Do you have an o-scope or logic probe to check for activity on the red outputs of the color PROM (the one labeled "6331" on the schems)?

Yes. I find it easier just to do continuity check. Gives a much truer result. I don't have a scope but I did just hook up the logic probe. I found the inputs and outputs of the 6331 and also the LS298 that seems to be feeding to it from 16D. What sorta confuses me is how these pins should be probing. They mostly seem to be probing very very rapid. No high or low or just beep beep, just very rapid machine gun-like.

You can see here on page 2
http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/Track and Field Schematics.pdf
 
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I found the inputs and outputs of the 6331 and also the LS298 that seems to be feeding to it from 16D. What sorta confuses me is how these pins should be probing. They mostly seem to be probing very very rapid. No high or low or just beep beep, just very rapid machine gun-like.

Yeah, attached is the region we're discussing.

What going on here is: On the left (input) side of the 6331 are the 5 address lines. These represent the "index" for the desired color. This is happening for every pixel on the screen,as the scanline goes left to right across the screen thousands of times per second (about 15000 times each second, actually). The entire screen is being re-drawn about 60 times each second. As long as there is something "interesting" being shown on the screen (i.e. not a solid color, or relatively few colors), there should likely be activity on ALL of these input lines... and all of the output lines.

Speaking of the output lines, what the PROM contains is data which converts the 5 input address lines into the signals necessary to make the actual desired color on the screen. There are 8 outputs. You can see them grouped into two outputs for blue (D7 & D6), 3 for green (D5, D4 & D3) and 3 for red (D2 D1 D0). This means the hardware is capable of generating 4 different levels of pure blue, 8 levels of green, and 8 of red. Mixing these all together ever possible different way is 4*8*8=256 different colors possible. However, the hardware can't display ALL of those 256 colors, because there are only 5 input lines to the PROM. That means that they chose 2^5=32 colors from the 256 possible.

Anyhow, did I understand that you found activity on all of the outputs of the PROM (D0-D7)? Specifically those for red (D0-D2)? If so, things don't seem to add up. Those 3 digital output are converted to an analog voltage level by those 4 resistors connected to the output, and that's all there is to it. Make sure the other end of the 1K resistor (other than the end connected to the red output pin) is connected to ground.
 

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Anyhow, did I understand that you found activity on all of the outputs of the PROM (D0-D7)? Specifically those for red (D0-D2)? If so, things don't seem to add up. Those 3 digital output are converted to an analog voltage level by those 4 resistors connected to the output, and that's all there is to it. Make sure the other end of the 1K resistor (other than the end connected to the red output pin) is connected to ground.

Double checked that just to confirm. Activity on D0-D7(pins 1-7 +9). Also double checked continuity between the the ground end of the said resistor to ground on edge connector. Confirmed. Resistor values check good. Sigh
 
Oppolo, why did you delete? You made me second guess myself. I went out to shop and took a second glance. My nice new rebuilt G07 was sitting in my Pac and not the T & F and my WG4903 sitting where I thought the G07 was. Did a quick swap and had a nice crisp unstoppable scrolling picture on the T&F. I will check out that 4903 and see what's up with that. If the G07 is going to scroll in the T&F but it works fine in my pac, I must get the red issue fixed in that 4903. Thanks Darren and Oppolo for everything.
 
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I deleted because I saw in the first post that you already checked the monitor with another board. I'd check the red transistor on the neck board on that monitor in question.
 
Cracked joints on the T&F pcb? What are header pins? I'm not familiar with pcb repair but my PC 10 has a similar color issue.
 
Glad you got it fixed... just a little confused, as the original post seemed to rule out a monitor issue...
It really had me because when I pulled it out and hooked it up to my test rig, it was ok. I put it back in the T&F, no red again. Grabbed the RBG connector and wiggled it, VOILA, red on and off. Took the chassis off and grabbed the magnifying glass and could see the cracks, especially on red.

Cracked joints on the T&F pcb? What are header pins? I'm not familiar with pcb repair but my PC 10 has a similar color issue.
It's the connector where the Red/Green/Blue/ and sync hook onto the chassis. On some chassis, these connectors are notorious for getting bad joints. I usually reflow them, but must have missed on this one.
 
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