The NEW Build Your Own Arcade Controls
Main => Main Forum => Topic started by: GMZombie on January 17, 2020, 04:09:00 pm
-
Ok i have a dk3 board that im trying to get working. Here is what ive done so far.
Hooked up to system no video or audio.
Changed out 4 40 pin single wipe sockets for dual wipe.
Changed out a few smaller sockets on the cpu side as well.
Changed the z80dma chip
Tried without the dma chip.
I have 2 good verified rp2a03 chips in the system.
Probed the 8mhz crystal and no pulse.
Probed z80 clk pin pulse is there. Also at z80dma. Voltage at vcc pins are 5vdc
Pretty sure I checked 21mhz clock and there was no com pulse there but at the rp2a03 chips.
So it seema like its not even starting so where should I start?
My next steps is to replace the z80 chip and get a new dk3 chipset but I dont want to just replace blindly.
Any help would be great.
-
So it's dead, but you're getting 5v on the Z80? Did you check the board for cold solder joints (especially at the power headers), or broken traces? That should be one of the first things you look at.
Also, what's pin 26 (reset) doing on the Z80? If it's toggling every few seconds, then your board is stuck in watchdog and I would test the CPU board ROMS in a programmer.
-
It doesnt look like it has any cold solder joints but ill relook when I get back tp the shop on Monday. Unfortantly i dont have a programmer at the moment. Its one of the things i need to get next. I blew up my old willem. Ill check the reset pin also. What Programmer would you reccomend?
-
Everything looks good solder wise. Pin 26 is showing high on my probe. So that would say its in watchdog correct?
-
What Programmer would you reccomend?
I'm not too sure, I have a TOP3000 which is pretty low in cost, and works well for me. It should support the 2764's ROMs on the CPU board.
Everything looks good solder wise. Pin 26 is showing high on my probe. So that would say its in watchdog correct?
Is it toggling High/Low every few seconds? If it's just stuck, then it's probably not even getting into watchdog reset. I mean, the fact you have no video or audio whatsoever means it's probably not even getting that far...
When you swapped out the Z80 did you inspect the socket at all?
-
I didn't swap out the z80 but i in fact replaced the z80dma chip. I replaced all 4 40 pin sockets on the board with double wipes. Ues it is stuck high no pulsing
-
Ohhhh, sorry I misread.
You might need to verify the Z80-A isn't fubar'd then. Completely stuck high, and no video and audio sounds to me like a CPU problem.
-
Changed the z80 cpu with a known good one and im gettingnhigh on pin 26 still.
-
So I guess the next step should be to take a look at the ROMs on the CPU board. First try pulling them, cleaning the legs, then reseat.
If no progress shows you might need to spring for a programmer and start testing.
-
I have ordered a programmer. Didnt have a whole of of money so i bought a willem 6.0 parralel port one. Should suffice to read and write those chips. Ill let u know what i find
-
ok so i have verified chips are clean and just the same as they are on mame for the cpu side. im going to check the other side as well. anythign else i should be looking for.
-
Also checking around crystals im getting a low pulse on my probe but no pulse just low at the crystal
-
Anybody? Im still stuck here.