Donkey Kong displaying all zero's

[jeff412]

I changed out 2P and 2R tonight. The zeroes are gone but now they are replaced with the lattice structure of the ramps. Sorry about the quality of the pic, but it's from my crappy cell phone.

Jeff

 

[braze]

I changed out 2P and 2R tonight. The zeroes are gone but now they are replaced with the lattice structure of the ramps. Sorry about the quality of the pic, but it's from my crappy cell phone.

Jeff

I would double check your work make sure you didnt lift any traces or a shorted
trace or something like that. Also see what it does with and without the RAMs,
swap the two ram chips just to see what changes as that might add a clue.
also make sure the gray cables are firmly seated between the boards.
Something for sure got worse after this

 

[jeff412]

Tested all traces. They are good. I'll go back and check the gray cables again in the morning. I have more 2114's, maybe one is bad.

Jeff

 

[jeff412]

Pulled the 2114's tonight and I had bent pin 10 on 2R when I inserted it. Correct that and now I'm back to all zeroes again.

Jeff

 

[ballytablewiz]

This should have been one of the first things you checked, so it almost goes without saying, but I'm not seeing any mention of it so...

Have you tried replacing the Z80A CPU? Or at the very least, cleaning it's legs and reseating it? I've had numerous DK-series boards that display all zeroes with a dead CPU. IIRC, they're normally white zeroes, but it's worth a shot if you haven't already tried.

 

[jeff412]

This should have been one of the first things you checked, so it almost goes without saying, but I'm not seeing any mention of it so...

Have you tried replacing the Z80A CPU? Or at the very least, cleaning it's legs and reseating it? I've had numerous DK-series boards that display all zeroes with a dead CPU. IIRC, they're normally white zeroes, but it's worth a shot if you haven't already tried.

I had not tried it, but I did this evening. I changed out the CPU with a new one. Still had all zeroes.

Jeff

 

[jeff412]

I received the HS Save kit today. When I plug it in I get the zeroes. It plays a musical tune about 3 times (didn't count) then goes into attract mode. I can see DK and mario and some barrels, but still all zeroes. What does the tune mean?

Jeff

 

[dezbaz]

I just started up DK (US set 1) in MAME

The first screen that appears after the nag screen is all zeros, it is many different colors of zeros

So your game is halting at that point

Is there a timer circuit?

That's all I have got, now an expert can chime in and complete the diagnosis

Pic above is a screen capture from my PC today during DK Startup

 

[dezbaz]

This thread is stickied on the tech section of the forum

http://forums.arcade-museum.com/showthread.php?t=177192

In particular I read this, and think that is the thing to check

Or even still ask womble himself what to look for


4) Get the logic probe on the CPU - check the clock pin - it should be very very active. Without a clock signal the board will do absolutely nothing.
5) Probe the RESET pin on the CPU - google the pinouts for that CPU to determine what it should be, on the Z80 a RESET pin thats low means the CPU is in RESET mode - ie its parked. A working Z80 should have this pin high! A pin with a line above its name in the datasheet means "active when not high".

 

[jeff412]

I just started up DK (US set 1) in MAME

The first screen that appears after the nag screen is all zeros, it is many different colors of zeros

So your game is halting at that point

Is there a timer circuit?

That's all I have got, now an expert can chime in and complete the diagnosis

Pic above is a screen capture from my PC today during DK Startup

That does look like what I'm seeing, but I do go into attract mode, so the game is not locking up. I can also coin up and start a game.

Jeff

 

[dezbaz]

That does look like what I'm seeing, but I do go into attract mode, so the game is not locking up. I can also coin up and start a game.

Jeff

Ok, I still suggest PMing Womble

 

[braze]

I received the HS Save kit today. When I plug it in I get the zeroes. It plays a musical tune about 3 times (didn't count) then goes into attract mode. I can see DK and mario and some barrels, but still all zeroes. What does the tune mean?

Jeff

When video ram fails the diagnostics, which we already knew you have video ram
problems, it writes a fail message ("BAD") on the screen, but since video is not
working correctly you cant see those letters. So an extra indicator the diagnostic
code also plays music indicating that video ram is bad.
Bad 2P plays music and flips the screen upside down.
Bad 2R plays the Boom (pound) analog sound.
You have some type of problem in the video ram access circuit, address decode
for it, or data buffers, or something. But it seems like it does not affect the
other rams or roms, so that might rule out common components to those.
If you have access to another DK/DKj/DK3 boardset, I would try swapping
the video board from another set and use that to determine if the problem is
on the video board or the CPU board as to narrow the scope down. Then
start following the circuits on the schematics.