Barn Raid Mr.Do!
- Thread starter Purity
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favouredson
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Have you tried manually resetting the Z80?
If will narrow things down somewhat if the game boots by doing this.
If will narrow things down somewhat if the game boots by doing this.
Nope, but I'm willing to give it a try. I'm pretty new to this so am not sure of the best method to manually reset the z80. If I put a switch across the reset switch (pin 26) and the ground (pin 29) and activate it for a second or so would that do it?
I think I understand the conecpt that you have to get it to go low for a moment then high?
Purity2013-09-20 23:00:43
I think I understand the conecpt that you have to get it to go low for a moment then high?
Purity2013-09-20 23:00:43
RGP said:
My logic probe is also a logic pulser, so I could do that. It's the same one as Lukes
He doesn't explain how he goes it though. I can see a croc clip on the pulse connector on the probe. Where does that lead too - ground i assume?
Purity2013-09-21 11:07:15
Lee said:
Thanks, but I have a working boardset
I've used the ouput pin on the 555 timer to change the output on the reset pin of the z80 from it's high position to low then back to high, and it has not booted the pcb
Purity2013-09-21 22:24:23
Purity said:
I have a similar issue with a mr do pcb I have. The reset line is a continuos high instead of low then high. I've replaced and checked all of the reset line and I just can't get it to work as it should.
When I pulse the CPU reset line low the game boots (with errors lol) but it does play with sound on the plus side.
Well you've got further than me. I've pulsed the CPU reset line low, and my PCB stays exactly the same.
I think I've narrowed this down to some issues with the HM6148P ram, or 6116 ram, but it's really a bit of trial and error at the moment. I don't have the equipment to figure out exactly where the issue is
I think I've narrowed this down to some issues with the HM6148P ram, or 6116 ram, but it's really a bit of trial and error at the moment. I don't have the equipment to figure out exactly where the issue is
RGP said:
Just seen this. Nothing so complicated needed and using a pulser may give you false results.
If your /RESET pin is being driven high then you just momentarily pull it low with a wire to GND. A logic pulser applies logic HI pulses and depending on the construction may go to Z state when it's not pulsing high so it's not a reliable method of grounding a high driven signal.
trm2013-11-06 13:23:43
Just catching up with this thread - I didn't see it hidden away in Members Machines.
If you want some help troubleshooting this start a thread in Tech and I'll work through the schematics and fix it with you.
If you get the screen shown in the photo at absolute start-up then I'd not bother poking around at RAMs because the game is crapping itself before it'll be needing RAM.
First thing we need to establish is that the CPU is getting a proper power-on-reset and has connectivity to the program code ROMs. You've already tested the ROMs so we know they're good, so we're halfway there already
If you want some help troubleshooting this start a thread in Tech and I'll work through the schematics and fix it with you.
If you get the screen shown in the photo at absolute start-up then I'd not bother poking around at RAMs because the game is crapping itself before it'll be needing RAM.
First thing we need to establish is that the CPU is getting a proper power-on-reset and has connectivity to the program code ROMs. You've already tested the ROMs so we know they're good, so we're halfway there already
Ok dude, thanks. There is already a tech thread:
http://www.ukvac.com/forum/help-me-fix-a-mrdo-pcb_topic335423.html
http://www.ukvac.com/forum/help-me-fix-a-mrdo-pcb_topic335423.html
Been a busy boy with the Mr.Do
The monitor bezel artwork was competely wrecked:
So I decided to remove it and will replace it with a repro perspex one, but will use the original glass below as it comes up really nice when clean, with the crumbling paint removed:
Control Panel stripped down and re-coated, ready for repro artwork:
Coin door and marquee brackets nice and tidy and back together:
Got a couple of Universal Mr.Do PCB's. One is ready to go, the other needs work
As you may know I have issues with the monitor so that's still work in progress
But things are getting there
Purity2014-03-09 13:21:33
The monitor bezel artwork was competely wrecked:
So I decided to remove it and will replace it with a repro perspex one, but will use the original glass below as it comes up really nice when clean, with the crumbling paint removed:
Control Panel stripped down and re-coated, ready for repro artwork:
Coin door and marquee brackets nice and tidy and back together:
Got a couple of Universal Mr.Do PCB's. One is ready to go, the other needs work
As you may know I have issues with the monitor so that's still work in progress
But things are getting there
Purity2014-03-09 13:21:33
Really coming together now