Donkey Kong Dead Screen

Hammerheadx

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I'm having more and more issues with DK.

After doing a cap swap I lost the walking sound for Mario and picked up a slight ringing in the speaker. Read some here to replace Q4 and Q6. Before I could get to that repair, my screen went to a garbled mess and wouldn't play. Again reading here it sounded likely a new Z80.

I replaced both transistors and Z80 and now the screen is black. Marquee lights up, I hear the degauss coil and the Mario jump noise, but no neck glow, no picture and no playing blind.

HELP!
 
I'm having more and more issues with DK.

After doing a cap swap I lost the walking sound for Mario and picked up a slight ringing in the speaker. Read some here to replace Q4 and Q6. Before I could get to that repair, my screen went to a garbled mess and wouldn't play. Again reading here it sounded likely a new Z80.

I replaced both transistors and Z80 and now the screen is black. Marquee lights up, I hear the degauss coil and the Mario jump noise, but no neck glow, no picture and no playing blind.

HELP!

Are you sure you put the z80 in the right way? The new z80 good?
 
Sounds like you had a monitor problem and a pcb issue. In regards to the monitor, if you aren't getting neck glow, either you installed something wrong or it is going into high voltage shutdown. You need to check the B+ and make sure it is set at 108v DC. Easy to do. Just be careful. If you aren't sure how to do that, just ask.
 
Sounds like you had a monitor problem and a pcb issue. In regards to the monitor, if you aren't getting neck glow, either you installed something wrong or it is going into high voltage shutdown. You need to check the B+ and make sure it is set at 108v DC. Easy to do. Just be careful. If you aren't sure how to do that, just ask.

How do I do that? Where's B+?
 
The is a B+ test point right next to the back "leg" of the big white ceramic resistor, but you can actually just test it off the back leg. The best way is to use some double ended alligator clip leads and with the monitor off, connect on to that leg and to the red lead of your multi-meter and the black lead of the multi-meter to any metal part of the chassis. Make sure it is set on DC volts and then turn the monitor back on. Should be dialed in right around 108vdc. There is a pot that will likely have glue on it. You need a non-metallic screwdriver to adjust it with, but be very careful with the monitor on. Easy to hit something you don't want to. If not comfortable you can turn it off before adjusting and just adjust in small increments. Safety first if you aren't comfortable. Sometimes after a cap kit and changing components, I have seen the b+ get out of whack. Had one end up around 140vdc. Little adjusting and monitor works like a charm. This is the first thing I check when a monitor goes into complete shutdown, other than rechecking my work to make sure nothing was put in backwards and checking for cold solder joints.
 
Okay, let's say the B+ is out of wack, wouldn't the game still play blind if everything else is correct?

No wait, on Nintendo cabs if the monitor doesn't work, nothing works.

Yet, the marquee does light up.

I'm confused.
 
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Okay, let's say the B+ is out of wack, wouldn't the game still play blind if everything else is correct?

No wait, on Nintendo cabs if the monitor doesn't work, nothing works.

Yet, the marquee does light up.

I'm confused.

The audio comes from the monitor, so I don't think you'd hear the game, but I could be wrong.
 
Probably, the voltage is pulled off a resistor on the main chassis, i think it grabs 12 or 16vdc. I don't know if all voltage goes away when you get shutdown, but i don't think it does. It would be easy to measure though.
 
Probably, the voltage is pulled off a resistor on the main chassis, i think it grabs 12 or 16vdc. I don't know if all voltage goes away when you get shutdown, but i don't think it does. It would be easy to measure though.
Thanks! Definitely has me wondering now. Might have to do a couple tests the next time I have one on the bench.
 
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