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Model 3 wont boot

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Kev A View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Topic: Model 3 wont boot
    Posted: 26 Nov 2018 at 9:55am
Having a bit of a problem with my Daytona 2 stack, (For background it did always have a faulty video ram) but played OK with only minor glitches, and given the cost of video boards I decided to live with it.

For a while now its been having trouble booting requiring a couple of power cycles to start up, I originally thought this was PSU related but have swapped out the PSU with no improvement, checked the chips are getting 5.1v etc.

Anyway most of the time now it just boots to a black screen but sometimes comes up with this error message, and unable to access the test menu....



BACKUP RAM : UNREADABLE .. HALTED.

I'm guessing its terminal, having played around model 2 stuff even a completely borked video board will boot, but I don't have much experience with model 3 stuff so any ideas if its the video or CPU board that's causing it?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bonehead Quote  Post ReplyReply Direct Link To This Post Posted: 26 Nov 2018 at 10:05am
My guess is it’s the cpu board as I have one that won’t boot properly and I have tested a working cpu and all is ok.
I could be wrong but that’s my thought.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote keropi Quote  Post ReplyReply Direct Link To This Post Posted: 26 Nov 2018 at 10:17am
could that backup ram error mean that some sort of sram or rtc clock is dead so settings can't be read and the board stops booting? I could check this first as the cpu seems to pass the tests...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Posted: 26 Nov 2018 at 11:35am
Well glad to hear its probably the CPU board, if the worst come to the worst it will be cheaper to replace.

Any idea where those components are, would they be near the battery?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote obcd Quote  Post ReplyReply Direct Link To This Post Posted: 27 Nov 2018 at 9:09am
If there is a battery on the board I would measure it's voltage. It's pretty old hardware and if the battery is totally dead it could prevent the cpu from properly reading the nvram resulting in your error. Also check if it hasn't leaked and maybe coorosion damaged a pcb trace.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Posted: 27 Nov 2018 at 10:05am
I replaced the battery as the old one measured 2.8v, It doesn't look like to me like there has been any leakage. I have reflowed the solder on the battery holder pins, and the supercap,(I have read a bad supercap can cause Naomis to black screen so have ordered a replacement)

I have tested continuity on the traces running under the battery and around the supercap on both sides and cant find any broken traces, here's a couple of pics. I have identified a few of parts and labeled them...








Edited by Kev A - 30 Nov 2018 at 9:59am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 27 Nov 2018 at 10:22am
Have you de-soldered the super cap to check it? Last one I replaced looked fine, but was badly corroded underneath. If this has happened to yours, it may have damaged traces.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Posted: 27 Nov 2018 at 10:31am
Yeah I took it off to check and re do the solder, looked ok, don't suppose I could use a normal cap to test, or is there something special about the super cap?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 27 Nov 2018 at 10:37am
Can't speak for model 3, but on a regular NAOMI 1, I'm pretty sure all the super cap does is allow the coin battery to be changed, without wiping the settings RAM. I believe you can remove the super cap and the board will run fine without it.

Edited by big10p - 27 Nov 2018 at 10:37am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Posted: 27 Nov 2018 at 10:56am
Yeah I couldn't find much info on the supercap regarding model 3, but I assume its similar to the Naomi, it doesn't boot either with the supercap removed but I think I will replace it anyway when the new one arrives, its easy enough to get to so may as well. If that doesn't work I'm kind of out of ideas where to look next, I think the chances of me being able to sucessfully replace any of the surface mounted components is pretty slim.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Posted: 29 Nov 2018 at 4:54pm
Supercap replaced and still no change, think I'm going to double check all the continuity in that area, if the battery is installed should I be seeing voltage on the vcc pins of the srams all the time?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote big10p Quote  Post ReplyReply Direct Link To This Post Posted: 29 Nov 2018 at 5:23pm
Originally posted by Kev A Kev A wrote:

Supercap replaced and still no change, think I'm going to double check all the continuity in that area, if the battery is installed should I be seeing voltage on the vcc pins of the srams all the time?
I imagine so, else the settings would get wiped.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Posted: 29 Nov 2018 at 8:26pm
Ok so I got 3v on the vcc pins of the srams nearest the battery, increasing to 5v when booted ao im sure they are getting power. Also double checked continuity in that area and dint find anything. Short of replacing the srams im not sure there is much else I can try.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vamino Quote  Post ReplyReply Direct Link To This Post Posted: 29 Nov 2018 at 8:31pm
Daytona 2 is the game that shows if your boards are 100% stable and error free. Boards that I thought were OK wouldn't boot Daytona 2 or would randomly throw various errors. 

I'm with Bonehead, that fault looks to be a CPU board issue. I had a stack that would play Sega Rally 2 but had issues with Daytona 2.

I did come across this guide on my travels surfing the internet, maybe you could ask the author of that guide for some pointers?



Edited by Vamino - 29 Nov 2018 at 8:32pm
Insert Coin[s]
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Kev A View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Posted: 29 Nov 2018 at 10:20pm
Cool thanks for the help guys, hopefully have a quiet day at work tomorow and i can read theought that guide. Looka like it may be usefull. Interesting you have had stacks that would play SR2 but not daytona, as thats what it was running originaly and apart from a slight graphics glitch was working ok
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Post Options Post Options   Thanks (0) Thanks(0)   Quote robotech Quote  Post ReplyReply Direct Link To This Post Posted: 30 Nov 2018 at 12:37am
All the naomi boards i have owned i removed the supercap
I dont know what it does as they all work fine without it

Another cpu board shouldent be too expensive unlike the step 2 video boards
Unless you want to put the hours into that cpu board for fun/enjoyment

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Posted: 30 Nov 2018 at 9:21am
Originally posted by robotech robotech wrote:

All the naomi boards i have owned i removed the supercap
I dont know what it does as they all work fine without it

Another cpu board shouldent be too expensive unlike the step 2 video boards
Unless you want to put the hours into that cpu board for fun/enjoyment



Its just to provide power to the srams when you change the coin battery, so Sega making things overcomplicated.
To be honest it was a long shot being the only thing in that area that is easily replaced and their tendency to leak I thought it was worth a try.

Bonehead is going to look through his spares to see if he has a spare D2 stack for me, I have ordered 2 srams, but I'm a bit worried about installing them, but then if the boards buggered anyway it might be a good chance to learn.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Posted: 06 Dec 2018 at 5:16pm
Bit of an update here, got a faulty SR2 ROM board from Mo, and swapped the ROMs over to my Daytona board (turned out the ROM board was busted but the ROMs are fine) and whilst I'm still getting a black screen when I first power it on, after leaving it a couple of mins and cycling the power it boots up and plays fine. So I'm a bit unsure what to think. But at least its playable again.



Edited by Kev A - 06 Dec 2018 at 5:16pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote robotech Quote  Post ReplyReply Direct Link To This Post Posted: 06 Dec 2018 at 8:38pm
If you have a hot air station the s rams are very easy to replace
You can use that chipquick stuff if not but i would buy one of those cheap ebay hot air stations 505d i think mine is
great tool to have if you are trying to repair surface mount stuff
Worth a try if the boards knackered anyway

Edited by robotech - 06 Dec 2018 at 8:39pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Kev A Quote  Post ReplyReply Direct Link To This Post Posted: 06 Dec 2018 at 8:52pm
I keep looking at those hot air stations. Glad to hear they work well enough. I have ordered some srams and was going to attempt changing them over using chipquick. But now its sort of working again im kinda hessitant.
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