Debug for NeoCD

[smkdan]

Since I got confirmation on a CD system coming (many thanks to ckchan) I thought I would get some stuff sorted in advance. It's needed to fix a few issues above but I can prepare a few things for it.

^My current progress on the selftest to include. Since the CD systems never get tested it would help if your console suddenly starts resetting or doesn't start at all. Trying to make it as robust as I can here i.e. it doesn't need any functioning WRAM to test itself whereas the regular tests will be stuck in a reset loop. The bonuses of the CD mean that it can test a few other things that you can't really do in a cart system (without extra modding). There's more I can test but a lot of the details are still unknown. At any rate it should help in diagnosing a flawed/dead system.

 

[NeoTurfMasta]

Very cool! This will definately help me diagnose my screwy TL board. In other news, my final bios adapter board is scheduled to be delivered Tuesday. I'll have one out to you Wed morning.

 

[smkdan]

5 CD-Rs later: http://smkdan.eludevisibility.org/ngcd/img/t.JPG(the system is fine,false VRAM error has already been resolved)

I have dozens of discs I'll never use so I fixed up mostly everything that emulation didn't catch. It's a bootable test disc that you can use in an unmodified system but it's not as good as the test you'd get from a new BIOS for a few major reasons. If there's enough desire for a bootable test disc with this, A/V tests (colorbars,sound etc.) and all of that then I might get around to cleaning it up a bit and uploading an ISO, otherwise I'll just leave it alone.

I can move onto other other stuff when I get some time with the adaptor.

 

[Xian Xi]

Nice progress dude. Keep it coming.

 

[NeoTurfMasta]

http://www.neo-geo.com/forums/showthread.php?t=210857

News on the NeoBiosMasta for you guys wanting to mod your CD systems for this.

 

[smkdan]

And as soon as NBM arrives I can try a new CD file loader and see what it does for times (and get the MS2/KOF99 bug sorted). Not expecting much if anything, but we'll see. Testing is mostly finished, the bootable CD-R works fine now. Cheat engine coming up later.

@NTM: when I can confirm the BIOS works on my toploader, I'll upload a Z if you could test that. It'll be alot less hassle for you if I can atleast confirm the BIOS works on a real neo instead of just emulators.

 

[Lochlan]

THIS is the kind of thread that belongs in "best of," you've all been fooling yourselves with "teh drama."

 

[NeoTurfMasta]

@NTM: when I can confirm the BIOS works on my toploader, I'll upload a Z if you could test that. It'll be alot less hassle for you if I can atleast confirm the BIOS works on a real neo instead of just emulators.

Can do, I'm soon going to be sending back the Toploader to Murray so all I'll have access to is the Z and Front Loader.

 

[Murray]

Can do, I'm soon going to be sending back the Toploader to Murray so all I'll have access to is the Z and Front Loader.

But of course I'm happy to do testing on the TL when the time comes.

 

[smkdan]

I started working on a web page for this here for general info and also pics like this for each board revision. I labelled as they appear in the test menu. I'll take a decent photo of the CDM 4-2 I have access to and label that too, ideally one for each board revision for quick identification.

For BIOS: PAR style cheat engine is there too, here is a start for the MS1 entry:

Pretty drab, but it functions. Progress should continue at a decent enough pace so the time NBMs start going out, the BIOS should be on fairly decent shape.

 

[smkdan]

Since getting the adapter, I can try these on a toploader but there seems to be a problem with using the BIOS I've been given in a 4-2 board. My patched BIOS didn't get the system to recognize the CD, so I put in the original untouched TOP.BIN I've been given and it does the same thing there. The drive spins for a little bit, but doesn't recognize the disc at all. Opening/closing tray makes it spin again but no onscreen prompts or anything. "TRACK" changes from 0->1->0 and "INTRO" is set to 5 for whatever that does.

The BIOS in the original system is TOP-SP-2 I think. I don't know what this one is, but I'm stuck unless I can at least try it on a SP-2 dump. The system worked 100% before and everything outside of disc I/O works fine. If the revisions (each toploader PCB has a different BIOS revision) involved SNK changing the disc I/O code that would cause the issue. If I get an untouched SP-2 ROM running and it causes the same problem then the CD drive is dead, however that happened. I took alot of care when handling it..

Anyone happen to have a TOP-SP-2 dump they are willing to share? I'm stuck without it.

 

[NeoTurfMasta]

Thats crazy if they changed the bios on different revisions. I'm fairly certian the bios I dumped was from a 4-2 and it works on Murray's 5-1. I'll be able to check for sure what board I have on tuesday. If anything, I can send you my spare toploader cd pcb.

 

[smkdan]

I cleaned the CD ribbon cable connectors and lens, but it didn't change anything. It doesn't matter what the disc is, it will do the same spin up for 3-4 seconds and then turn off the motor. If this is a familiar tech problem, suggestions would be appreciated ofcourse. Nothing much happened to the drive when the BIOS was being installed though..

If you can confirm that the BIOS I got from you is a 4-2 then I hope I'm capable of repairing whatever damage happened to it. I wasn't anywhere near the MGA chip or CD connector when installing this. I appreciate the offer for the drive PCB but I hope alot of money isn't burned over this.

The label on each BIOS is different which implies they changed *something* even though the interface from user perspective is unchanged. Just hoping that the BIOS was not SP-2 or else I have repairs to do. If the BIOS you dumped was SP-1 or SP-3, then hopefully a simple swap will address this. I'm not taking chances trying to dump the SP-2 in my system.

 

[NeoTurfMasta]

If you want to make sure its the bios revision or not, just remove the NBM and solder back down the original.

If it is the CD drive board, I have no problem shipping you my spare. Its from my junker top loader anyway. I'll get all the info together on Tuesday.

 

[smkdan]

I don't have access to my soldering stuff for the time being but I concluded that the BIOS itself is not at fault because:
-It is confirmed working in a 5-1 which has the exact same chipset. Type of RAM is the only thing separating the two.
-It correctly detects that a disc is not inserted. Atleast it pops up with "CD" and some Japanese text after it when a disc isn't placed inside. It just fails to read off the disc.
There's no reason to believe that the BIOS is the problem. It seems to work as expected but it won't read any discs at all.

neogeocdworld has a troubleshooting section on the laser. One of the issues listed is alignment of the photodiode which has the exact symptoms I am having with presence detection of disc OK, but no recognition. I made a note of the original position of the alignment screws and messed around with it, but no success. Also double checked all 18 connections on the ribbon cable and continuity is good so they're all reaching the drive PCB just fine.

I'll play with it a bit more tomorrow and see how it works out.

edit: I got it playing pressed audio CDs but I have to set it to near-maximum laser current to get it to work. It worked before with my CD-R games but not anymore, it struggles to just display the number of tracks on the game disc. It won't actually start. Max laser power won't play any games but atleast I know what the problem is. I can't afford to spend all that cash on the original ones so I'd be better off ordering a new laser assembly and using 1x CD-Rs I guess.

 

[slugger_dan]

i'm back from swapping in a new laser (as in brand new from a local electronics shop) and while it does work it pretty much struggles to read the discs like the old laser did. I don't know anything about laser calibration or whatever but I can only guess that it's either the focus and tracking pots needing to be calibrated for a new head or the drive PCB is busted. It properly detects when no disc is inserted and the actuators inside the head are doing what they are supposed to.

On the upside, a 16 year old laser was replaced with a brand new one so that has to count for something in terms of life epxectancy.

that thing cost quite a bit but atleast one variable is cut out. If much more cash has to go into this then I suppose the cost/benefit with the next gamble has to be weighed up with just cancelling the project. I'll keep trying pot settings in the mean time.

 

[smkdan]

The frustration is actually starting to get to me, I mean with throwing down the cash for a system that doesn't last more than 2 weeks with a $40 laser replacement and replacement consoles running $100 shipped minimum. Yeah, vintage disc based consoles come with these sorts of problems but I didn't expect it to die so soon. I can program a decent test routine with good-enough knowledge on how the main PCB works but what good is it if I can't diagnose the most problematic part of the console? I might think of something later, but in the end if it means buying another system then I'm finished here. I'm basically throwing money away at that point for something which is supposed to be just a hobby and the stress isn't all that good either.

Pissing and moaning aside, here's some good news:

-The resetting MVS problem is due to the system instantly restting if backup RAM is touched at any point. Doesn't matter what the game does with it, it instantly resets the entire system if what would normally be the MVS backup RAM is accessed. Simple enough, I just patch out each access to backup RAM at runtime. Tedious and error-prone as Murray put it but I don't have any real alternative. It will definitely fix the MVS reset issues though.
-CDDA died in certain games, but it was an easy fix.

 

[NeoTurfMasta]

I have a spare drive laser/assembly and controller board that I'll box up and send today or tomorrow. If I get my IDC adapters in today I'll throw together a new CD NBM extension as well. Thats the only thing I'm waiting on now...

Sorry for the problems, I'll help any way I can and I'm sure several others will as well.

 

[NeoTurfMasta]

@snkdan

Drive and controller board shipped today. Expect it mid next week.

 

[smkdan]

Thanks for the CD assembly it'll definitely help figure out what's up.

I saw the video of the installation and now I have to question the state of the PCB. It seemed to fit in so easily there, but I need to apply about 30lbs of force over multiple attempts to get mine sort-of flush with the PCB. It's why I was uncertain with an earlier post in your thread. I hear cracking noises but I guessed it was just the PLCC socket. I do know an otherwise good CDROM stopped working after that even with a new laser. I will get around to inspecting the PCB more thoroughly soon. The new PCB/drive coming will definitely rule out one or the other though.

Other news:
-Murray confirms SS and KOF99 are fixed with MVS resets so the fix is actually really simple. I fixed MS2 in the same manner and might upload another ROM when a few more are fixed.
-A/V tests are in, just simple color bars/audio tests like in MVS
-noticed that CD games sometimes load alot of unnecessary data for slower loads and more work for the drive. SS1 has hundreds of kbs of dead space in GFX alone when starting up. When the CD works in the system here, there can be multiple things to experiment with in improving loads.

 

[smkdan]

NTM: if you wouldn't mind testing this on your modded Z that would be great. If you can play turfmasters and MS2 on that with no resets then it means getting MVS working on all games will be very simple.

Also, try the turfmasters cheats and see if they work out on your system. 'power multiplier' is the important one since it patches the program itself. If you can do 600yard drives then it's working. That one is very simple but other game enhancements might follow later on. Stuff out of reach with cart systems can be done here aslong as I feel like implementing. BIOS space is the only limitation as to what can be done to a game (which sucks as it's not alot, but plenty can be done still).

 

[NeoTurfMasta]

NTM: if you wouldn't mind testing this on your modded Z that would be great. If you can play turfmasters and MS2 on that with no resets then it means getting MVS working on all games will be very simple.

Also, try the turfmasters cheats and see if they work out on your system. 'power multiplier' is the important one since it patches the program itself. If you can do 600yard drives then it's working. That one is very simple but other game enhancements might follow later on. Stuff out of reach with cart systems can be done here aslong as I feel like implementing. BIOS space is the only limitation as to what can be done to a game (which sucks as it's not alot, but plenty can be done still).

Okie..

MS2 MVS mode no longer resets. Turf still resets when put in MVS mode.

The cheats work great on NTM. Insane drives!

 

[smkdan]

I missed a few things on turfmasters. Obvious mistakes, it is probably fine now.

I clearly messed up with the installation since 3 combinations of lasers/drive PCBs do not work on this. The actual installation went pretty smoothly and everything else works fine, but it can't read game discs and can't play CDDA without corruption + long delays. Ribbon cable continuity is good despite looking a bit rough, no gouged traces on main PCB, MGA <-> connector traces look fine, no scorches on board, no mess of solder anywhere, ESD was certainly not a problem, excessive flex was not a problem. Maybe the PCB stress when forcing the PLCC socket into it killed the NEO-MGA, I don't know. Whatever it is, it's my own fault since it worked before this without issue. I am open to suggestions, but right now the plan is to try to fix up and lingering bugs with whatever I have now and discontinue it.

E: missed something really stupid: don't need a working system to implement most cheats so there's not much reason to kill it. Loading times etc. I can't do without one, but enhancements/cheats I can do in emulation. Would kind of suck to be unable to use them myself but I can keep working on it regardless even though I miss out on a few things I'd like to add.

 

[werejag]

any more progress?

 

[sonofx51]

The whole idea of this debug bios makes me want to pick up a CDZ again.