dk board help

dirt

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i just got a dk board yesterday and its not working right. it is missing the chip at 5a. i pulled the 5a chip out of my good dk board but it still has something wrong with it. i checked the braze technologies dk tech page and i dont see the same thing that i have on this board. does anybody have an idea what is wrong with it? here are some pictures of what its doing.

IMG553.jpg


IMG552.jpg


IMG551.jpg
 
I don't think it is a voltage issue but check the voltages on the rom chips. It looks to me like a ROM problem and I would check all of the roms. There might be added files to the other roms so that 5a chip might be a duplicate file causing the problem. try verifying the roms, rom files, rom voltages, rom sockets, rom programs, and finally rom traces.

If that doesn't bear any fruit I would look at the address lines and check all traces real good in the outdoor sunlight. That way you can hold up to the light and see the traces thrugh the board. I would bet there is some other line (trace) shorting to another.

Could be a bad ram but I really don't think so but it is possible and should be checked.
 
I don't think it is a voltage issue but check the voltages on the rom chips. It looks to me like a ROM problem and I would check all of the roms. There might be added files to the other roms so that 5a chip might be a duplicate file causing the problem.

its not the 5a chip i installed causing the multiple images. this is what is on the sceen without the 5a chip.

IMG556.jpg


i will check the voltages on the chips as soon as i get out to the garage today.
 
First one I seen like that. If you can't fix it my repair shop can for $65.00 which includes shipping back to you.
 
Does anyone know what would cause the multiple images on this board?

Usually it is a ROM problem, the program is not being read or processed correctly. Clock signals can do strange things if they are not correct. Buffers, address lines, clock signals, Roms, and voltages should be checked.

You now need a logic probe or some other test equipment.
 
Actually from the image it looks like a address decoding problem to the character RAM. Character address bit 3 probably as the same sequence of 8 characters are being blitted to the screen over and over again each row.
 
Actually from the image it looks like a address decoding problem to the character RAM. Character address bit 3 probably as the same sequence of 8 characters are being blitted to the screen over and over again each row.


how would i go about checking that? i would like to fix this board myself if at all possible. not because im cheap but because its something i have wanted to try and learn for a long time now. keep in mind i have very limited electronics background. im a construction worker so be gentle with the lingo. haha
 
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