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Thread: Neo Geo CD (Front Loader), disc not spinning

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    Neo Geo CD (Front Loader), disc not spinning

    So this is my first post. Looking for some thoughts, suggestions on a work around for a disc spinning issue I am having with my CD Front Loader. About a week ago, I installed a new lens and everything was well. I played for a few hours and shut it down. The next day, the Neo CD kept crashing. The reason is that the disc would stop spinning randomly. At time I would turn it on and it would load the game with no problem. Other times it would not load the game at all as the disc would not spin. I ordered up another lens, swapt out the other thinking it may have been DOA but the same thing is happening. I opened it up, tweeked the pots a little but no go. I noticed that it would try to spin but something was keeping it from doing so. I took apart the drive and put it back together about 5 times. No go. When it tries to spin, if I give it some help, it runs and reads smooth, no problem. I have cleaned the spindle and all but it continues to do the same thing. I just onstalled the bios 3.3 on this thing and this machine looks clean with no scratches. I would hate to let it go for parts. Any help would truly be appreciate it.

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    Quote Originally Posted by Xian Xi View Post
    Check the lid/tray switch.
    I did not know the front loader had a switch. Ill look for it.

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    Let me know how that goes, I'm having a frontloader problem myself that I tried to post about earlier today. Something went wrong so I have to rewrite/repost it. Hope it gets sorted and it works! I really like the front loaders

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    Quote Originally Posted by Xian Xi View Post
    Check the lid/tray switch.
    Hello Xian, unfortunately I am unable to find the lid/tray switch you are referring to. Anyway you can point it out to me? Thank you!

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    Quote Originally Posted by CHAOS 0187 View Post
    Hello Xian, unfortunately I am unable to find the lid/tray switch you are referring to. Anyway you can point it out to me? Thank you!
    I don't have a front loader but you would be looking for a small switch or lever that the tray pushes so it knows that the tray is closed.

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    Quote Originally Posted by Xian Xi View Post
    I don't have a front loader but you would be looking for a small switch or lever that the tray pushes so it knows that the tray is closed.
    I did find a couple switches but they seem to be fine and intact. Back to square one on this.

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    Did you adjust the laser voltage on the new laser to approximately how the old one was set? What can happen is with these new lasers the voltage is set really high, and so the system works for a few days or a week and then the laser dies. Probably not your problem but I would certainly be checking that they aren't set too high before installing them. The other problem with the Neo CD that can cause this is a bad PSU (or bad connection on that dodgy 3 pin connector). You could try some deoxit or similar in the connector and make sure its making a good fit. Also re-cap the PSU, and check for the typical bad solder joint that occurs on one part of the heat sink with the edge of the PCB - I've fixed a few like that.
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

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    Quote Originally Posted by GadgetUK View Post
    .... Also re-cap the PSU, and check for the typical bad solder joint that occurs on one part of the heat sink with the edge of the PCB - I've fixed a few like that.
    I recently repaired a few dreamcasts where the disc would spin up and stop, the laser head would move too. But i found out the laser was not lighting up hence it wasnt seeing a disc and when I did a recap on the PSU the Laser would light and the system would work normally again. A cap change is never a bad idea anyways for older electronics, who knows!

    Best of luck.

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    Quote Originally Posted by GadgetUK View Post
    Did you adjust the laser voltage on the new laser to approximately how the old one was set? What can happen is with these new lasers the voltage is set really high, and so the system works for a few days or a week and then the laser dies. Probably not your problem but I would certainly be checking that they aren't set too high before installing them. The other problem with the Neo CD that can cause this is a bad PSU (or bad connection on that dodgy 3 pin connector). You could try some deoxit or similar in the connector and make sure its making a good fit. Also re-cap the PSU, and check for the typical bad solder joint that occurs on one part of the heat sink with the edge of the PCB - I've fixed a few like that.
    Thanks for the response. I will go ahead and take a look. BTW, do you know the voltage of what the laser is supposed to be set too?
    Last edited by CHAOS 0187; 09-18-2017 at 11:48 AM.

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    Quote Originally Posted by Geekman1222 View Post
    I recently repaired a few dreamcasts where the disc would spin up and stop, the laser head would move too. But i found out the laser was not lighting up hence it wasnt seeing a disc and when I did a recap on the PSU the Laser would light and the system would work normally again. A cap change is never a bad idea anyways for older electronics, who knows!

    Best of luck.
    Thank you. I will take a look.

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    Quote Originally Posted by CHAOS 0187 View Post
    Thank you. I will take a look.
    So I scraped the holes on the PSU tip with a small screwdriver and also squeezed it with small wire cutters and it fits tight now. I tried out the system and still the same issue. After powering it on and off and trying to get it the disc to spin, it started spinning. Been playing it for hours have turned it on and off and still working. This really has me bugged out cause I can't seem to figure out what the heck is wrong with it.
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    Could be the caps on the PSU. Try booting a disc from cold (eg. when its been powered off overnight and PSU unplugged). If its not booting discs, then just leave the lid / tray open with no disk. Leave it powered up sat there doing nothing for 20 minutes, then stick a disc in and see what happens. If it starts working when warm its most likely caps (probably in the PSU).
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

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    Quote Originally Posted by GadgetUK View Post
    Could be the caps on the PSU. Try booting a disc from cold (eg. when its been powered off overnight and PSU unplugged). If its not booting discs, then just leave the lid / tray open with no disk. Leave it powered up sat there doing nothing for 20 minutes, then stick a disc in and see what happens. If it starts working when warm its most likely caps (probably in the PSU).
    Ok, so I took the unibios off and put the regular bios in prior to running your recommended test. I then did the test and after a little bit of trying to get it to read, it started to work. I let it sit for a bit and I got error 0002. I think the laser needs adjusting. Wish I knew what each pod is for as there are three. This is all I could find.
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    Last edited by CHAOS 0187; 09-19-2017 at 07:51 AM.

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    Surprised to see 3 pots on the pickup assembly =O

    For a new laser I would set all 3 pots the same positions as the old laser was set to (measure their resistance with multimeter and adjust to get resistance as near as possible)

    EF = Error Focus Balance - best way to adjust that would be to monitor TE / TER signal on a scope and pause CD track. Then you need to adjust the pot until the pulse has equal positive and negative peaks of that pulse.
    Laser power pot is pretty much all you would need to tweak on a dying laser. Best way to adjust that is by monitoring the RF level on scope and start around 500mV and increase until it reads a pressed CD and perhaps a CD-R (if you plan on using CD-R). I am not sure what the correct RF level would be for the Neo CD, guessing between 500mV and 1.2v, but starting lower and working upwards will maximize the laser life. If anyone has a service manual for one of these let me know please =D

    The Focus bias again related to focus and would only need adjusting if it was having trouble focusing - again you might be able to tell that from the RF level on a scope, but there are probably other test points better suited to adjusting the focus bias pot.

    The best way to adjust any of these pots is whilst playing an audio CD. And there's another point - if the system crashes or resets etc whilst playing an audio CD - its not the laser or drive PCB as that wouldn't cause a reset. You would either find the audio stops or stutters etc. But in summary - set them the same as the original laser, and only tweak the laser power pot if need be.

    The other possibility is the tracking needs adjustment - there should be more pots on the drive PCB?
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

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    Quote Originally Posted by GadgetUK View Post
    Surprised to see 3 pots on the pickup assembly =O

    For a new laser I would set all 3 pots the same positions as the old laser was set to (measure their resistance with multimeter and adjust to get resistance as near as possible)

    EF = Error Focus Balance - best way to adjust that would be to monitor TE / TER signal on a scope and pause CD track. Then you need to adjust the pot until the pulse has equal positive and negative peaks of that pulse.
    Laser power pot is pretty much all you would need to tweak on a dying laser. Best way to adjust that is by monitoring the RF level on scope and start around 500mV and increase until it reads a pressed CD and perhaps a CD-R (if you plan on using CD-R). I am not sure what the correct RF level would be for the Neo CD, guessing between 500mV and 1.2v, but starting lower and working upwards will maximize the laser life. If anyone has a service manual for one of these let me know please =D

    The Focus bias again related to focus and would only need adjusting if it was having trouble focusing - again you might be able to tell that from the RF level on a scope, but there are probably other test points better suited to adjusting the focus bias pot.

    The best way to adjust any of these pots is whilst playing an audio CD. And there's another point - if the system crashes or resets etc whilst playing an audio CD - its not the laser or drive PCB as that wouldn't cause a reset. You would either find the audio stops or stutters etc. But in summary - set them the same as the original laser, and only tweak the laser power pot if need be.

    The other possibility is the tracking needs adjustment - there should be more pots on the drive PCB?
    Thank you for all of the info. I appreciate it. Unfortunately, I dont have the tool necessary to read the laser with. I will try going off the old one, which is what I originally did. I did not see any other pots, just the three. I forgot what the tool to test the pots is called. I will do a search and get back to this thread to update you if I come across a solution.

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    Angel's Love Slave
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    No worries! You could work out if its the laser or not by just testing the audio CD player for a period of time - that shouldnt crash even if the laser plays up. If the laser is the problem I would expect problems playing some audio tracks.
    My YouTube channel contains some MVS repairs and stuff:-
    http://www.youtube.com/user/GadgetUK164

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