Donkey Kong text issue

AtomicBomb

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I've been fighting with a DK board for a little while. I went from no boot at all to a playable board with no sprite issues, but the text is garbage. It kinda shows up in weird patterns. Some letters are correct, Os, and Is, but most letters show up as 2 characters before what they should be. The N and D in Nintendo shows up as L and F respectively. These characters are stable and consistent. I've re-burned all the eproms, changed out the Z-80, all the 2114s that make up the CPU ram (3a-4c), the character ram, and the object ram. What else could be causing this strangeness?
 

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I'd be checking the low address lines on my eproms if it was me.

Check for one that stays low or high (at the chip pin) and work backwards from there.

Do you have a logic probe or analyzer that you can use?

It could be a bad socket or trace giving you trouble.
 
I had some time to screw with this today. Pulled out my o-scope and probed all of the proms, which all seemed to be pulsing nicely. I swapped out the 8035 chip on the processor board, and on the video board changed the HD10124s at H3 & 4, HD1025s at F3 & 4, and the heat sinc'd chips at E & H2. Still no change in my characters being a mess. I'm going to borrow a friend's board to at least determine which of the two is bad, but with how much work I put in, I'm getting pretty frustrated.
 
Looks like you are messing with sprites and color, not characters. The characters are generated by roms 3n, 3p and use the 2114s next to them on the video pcb. Check the schematics for this area of the vid pcb.
 
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The frustration continues. Additional symptom not mentioned above is the construction site planks are funky. See photo

I tested against a known good board, and confirmed my problem lives on the video board. I tested the proms 2N, 3N, and 3P in the good board, and they're good. I'm focusing on the 3N/P area so I started changing out just about everything associated with those roms. I have changed 1-5S 2R, 2P, 2M, 4M, 4N, 4P, 3M, 3L, and my problem still exists.
 

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Yeah the issue is the address bus logic driving the 3n 3p roms, not the roms themselves. Grab a logic probe and start poking around for stuck bits.
 
The frustration continues. Additional symptom not mentioned above is the construction site planks are funky. See photo

I tested against a known good board, and confirmed my problem lives on the video board. I tested the proms 2N, 3N, and 3P in the good board, and they're good. I'm focusing on the 3N/P area so I started changing out just about everything associated with those roms. I have changed 1-5S 2R, 2P, 2M, 4M, 4N, 4P, 3M, 3L, and my problem still exists.
Did you ever resolve this problem. I have the exact same problem.
 
I did not see it covered in a video. The issue was that it was displaying text on the screen that would be 2 characters off, like an address line was stuck. I replaced all of the ROMs already.
 
"The issue was"

So just to be clear, did the ROM swap resolve this issue, then? Or, are you still having the problem?
 
Here is what it is doing. Some sprites (text) display correctly. When they are wrong, it is two characters less than what it should be. (C becomes A, F becomes D, G becomes E, N becomes L, O becomes M, R becomes P, and S becomes Q.

I have attached an image showing the problem.
 

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C = 0x13 = 8'b00010011
A = 0x11 = 8'b00010001

O = 0x1F = 8'b00011111
M = 0x1D = 8'b00011101

DA1 is stuck low at 3N/3P
Most likely the 2114 at 2P is bad.
That fits for all the test cases. DA1 only pulses low on 3N and 3P. I have replaced both of those chips and no change.
 
I will replace the 2114. The transceiver seems to be working fine. I will post back my result.
 
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