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  • Joined: 01 Mar 2020
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Issue with graphic glitches + lockup on SMS
Post Posted: Tue Jul 11, 2023 8:17 pm
Hey all,

I have a heavily modded SMS 1 (US NTSC) that has had a difficult to pinpoint problem with games, slowly over the course of having been on for a few minutes, it will first start to accumulate graphic glitches and then a complete lockup. It does this in multiple games, ie Sagaia, Out Run 3-D, Columns, among others.

This SMS has been had an FM mod added and an s-video mod done as well. The fellow who did the mods for me could not replicate the lockup/glitches, so we aren't sure what, if any, of these mods might have caused it or not.
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Post Posted: Tue Jul 11, 2023 9:41 pm
Hi!

This might be lots of things. Have you recapped the unit at all? If not, you might want to think about starting there, at least with a visual inspection of the capacitors if nothing else.

Otherwise could be a problem with the DRAM, either the chips themselves (they do fail) or the refresh logic which kind of fits the pattern in that as the DRAM warms up it loses its stored values more readily (although I think the time spans you mention might rule this out).

You could also see if any of the components appear to be getting unusually hot inside there from cold.

It may not be anything to do with the mods of course, but are you able to do any trial or error by disabling them at all to see if it makes a difference?

If you were able to eliminate the mods and capacitors I'd suggest maybe trying to speculatively replace some RAM. I'd say more likely system RAM than VRAM since you say the whole thing locks up.
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Post Posted: Tue Jul 11, 2023 9:46 pm
willbritton wrote
Hi!

This might be lots of things. Have you recapped the unit at all? If not, you might want to think about starting there, at least with a visual inspection of the capacitors if nothing else.

Otherwise could be a problem with the DRAM, either the chips themselves (they do fail) or the refresh logic which kind of fits the pattern in that as the DRAM warms up it loses its stored values more readily (although I think the time spans you mention might rule this out).

You could also see if any of the components appear to be getting unusually hot inside there from cold.

It may not be anything to do with the mods of course, but are you able to do any trial or error by disabling them at all to see if it makes a difference?

If you were able to eliminate the mods and capacitors I'd suggest maybe trying to speculatively replace some RAM. I'd say more likely system RAM than VRAM since you say the whole thing locks up.


Yes, I had my modder recap the system. I also had had him add the pause mod to it, but he tells me its not really possible for that mod to cause this sort of issue. I believe this system also had a voltage regulator put in on it.

Both of us did several length time lapse tests with it with multiple games. He NEVER could replicate it, and I could not always. Alot of times I would just leave a game on demo mode for 30-40 minutes and it would crap out, but sometimes it would go bad quickly. Was not any sure fire way to 'trigger' it that I could find.
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Post Posted: Wed Jul 12, 2023 7:58 am
Perfect! wrote
I believe this system also had a voltage regulator put in on it.

Can you elaborate on the "voltage regulator", I've not heard of that before on reference to an SMS?

Interesting that your modder can't reproduce the issue but you can, might suggest it's something environmental (or maybe just bad luck!)
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Post Posted: Wed Jul 12, 2023 8:41 am
if you have an EverDrive you could use this ROM to test RAM and VRAM.

I would wait for the system to be warm and going crazy already before running the test.
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Post Posted: Wed Jul 12, 2023 12:11 pm
willbritton wrote
Perfect! wrote
I believe this system also had a voltage regulator put in on it.

Can you elaborate on the "voltage regulator", I've not heard of that before on reference to an SMS?

Interesting that your modder can't reproduce the issue but you can, might suggest it's something environmental (or maybe just bad luck!)


I think he's talking about the 5V regulator/LM7805. A typical replacement in older consoles during a refurb. Usually not necessary, but doesn't hurt if you replace it since they're cheap.
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Post Posted: Wed Jul 12, 2023 2:42 pm
Maraakate wrote
willbritton wrote
Perfect! wrote
I believe this system also had a voltage regulator put in on it.

Can you elaborate on the "voltage regulator", I've not heard of that before on reference to an SMS?

Interesting that your modder can't reproduce the issue but you can, might suggest it's something environmental (or maybe just bad luck!)


I think he's talking about the 5V regulator/LM7805. A typical replacement in older consoles during a refurb. Usually not necessary, but doesn't hurt if you replace it since they're cheap.

Ah okay, thanks Maraakate. Sounds like a straightforward like-for-like replacement then, unlikely to be the issue.
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Post Posted: Wed Jul 12, 2023 11:08 pm
Maraakate wrote
willbritton wrote
Perfect! wrote
I believe this system also had a voltage regulator put in on it.

Can you elaborate on the "voltage regulator", I've not heard of that before on reference to an SMS?

Interesting that your modder can't reproduce the issue but you can, might suggest it's something environmental (or maybe just bad luck!)


I think he's talking about the 5V regulator/LM7805. A typical replacement in older consoles during a refurb. Usually not necessary, but doesn't hurt if you replace it since they're cheap.


Yes, I should have been more precise. My modder installed a Traco 2-2450 DC-DC switching regulator at the same time he installed the FM kit, but ended up putting back the stock one as the Traco caused some problems on some games that he WAS able to reproduce (on Columns).
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Post Posted: Thu Jul 13, 2023 1:25 pm
Perfect! wrote
Maraakate wrote
willbritton wrote
Perfect! wrote
I believe this system also had a voltage regulator put in on it.

Can you elaborate on the "voltage regulator", I've not heard of that before on reference to an SMS?

Interesting that your modder can't reproduce the issue but you can, might suggest it's something environmental (or maybe just bad luck!)


I think he's talking about the 5V regulator/LM7805. A typical replacement in older consoles during a refurb. Usually not necessary, but doesn't hurt if you replace it since they're cheap.


Yes, I should have been more precise. My modder installed a Traco 2-2450 DC-DC switching regulator at the same time he installed the FM kit, but ended up putting back the stock one as the Traco caused some problems on some games that he WAS able to reproduce (on Columns).


Honestly, the blind replacement of LM7805 is superflous. I see this done quite a lot on Atari 2600s and seems to make no difference.

The only time I've ever had to legitimately replace one is when I accidentally plugged in an AC adapter.

It may be entirely possible that the modder got ham-handed with replacement of components and now it is causing problems.

I will say that I tried the FM kit many years ago and it caused some weird problems that didn't crop up immediately. I gave up on it and removed it. It was causing strange issues when used with my Pro Action Replay.
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Post Posted: Thu Jul 13, 2023 1:30 pm
Another possibility is the capacitor replacement. Did he follow the schematic or pull each one individually and order them?

The reason I ask is that the schematic may have mistakes or that parts were superseded to fix issues and are not documented. It may be in your interest to find another known working unit of the same revision and compare the capacitors.

I'm assuming he only replaced electrolytics, yes? There is no need to replace the ceramics in most situations.

The S-Video mod is quite reliable. Did he do the simple mod that involves NPN transistors and resistors? That's the only one I've ever done and never had a problem with it on the few units I've done.

If you suspect a component is out of tolerance an old school TV/radio repairman trick is to get a heat gun and move it around and see if things get funny. If it does then use "freeze spray", freon, or a can of computer duster upside down and spray components. If it magically starts working again where you spray this is where the faulty component is located. Don't get crazy with the heat gun at maximum setting and don't hang out in one spot too long. Constant movement is key.
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Post Posted: Tue Jul 18, 2023 11:10 pm
I ran the latest version of the ram test program - passed multiple times. At the suggestion of my modder, I also tried 'shake' testing the cart to see if it was intolerant toward the cart being slightly moved in the cart slot - also nada.

Now I am running a few games in demo mode for several hours to see if it happens then. It rarely happened when I first started a game, it was almost always minutes into gameplay once the system had warmed up.

Maraakate wrote
Another possibility is the capacitor replacement. Did he follow the schematic or pull each one individually and order them?

The reason I ask is that the schematic may have mistakes or that parts were superseded to fix issues and are not documented. It may be in your interest to find another known working unit of the same revision and compare the capacitors.

I'm assuming he only replaced electrolytics, yes? There is no need to replace the ceramics in most situations.


I asked him about this point specifically and he says he replaces them one by one with a matching cap based on what was removed. He's been using the cap kits from console5
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Post Posted: Wed Jul 19, 2023 2:58 am
How much you wanna bet it’s the pause mod sending spurious NMIs.
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Post Posted: Wed Jul 19, 2023 9:49 am
SavagePencil wrote
How much you wanna bet it’s the pause mod sending spurious NMIs.


The games should work fine even if one keeps on bashing on the Pause button, or does the pause mod works differently?

Also, to see if the console receives NMIs even if nobody touches the Pause button, you can test that with SMS Test Suite: the Pause button will light up for ~3 seconds when an NMI is received.
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Post Posted: Sat Jul 22, 2023 11:25 am
sverx wrote
SavagePencil wrote
How much you wanna bet it’s the pause mod sending spurious NMIs.


The games should work fine even if one keeps on bashing on the Pause button, or does the pause mod works differently?

Also, to see if the console receives NMIs even if nobody touches the Pause button, you can test that with SMS Test Suite: the Pause button will light up for ~3 seconds when an NMI is received.


Here's the pause mod: https://www.smspower.org/Development/JoypadPauseButton
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Post Posted: Thu Dec 14, 2023 5:10 pm
Reviving this old thread, though I am going to replace this system with a SMS II soon, it would be nice to figure out what was causing this. I finally caught it doing the glitches on video. It happens after the demo, but about 15 min of letting Outrun 3-d demo, it started it. It does it on other games of mine - ie Sagaia, Columns, a few others.

https://drive.google.com/file/d/1a22Z7wkLvyLiQAxSkyBXtwhDG8qVbu_J/view?usp=drive...
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Post Posted: Thu Dec 14, 2023 9:40 pm
Have you looked at the solder joints for the cartridge port? The later revisions tend to develop cracked solder joints and that can possibly cause issues like this.

Also, why are you replacing it with an SMS II and not another original model?
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Post Posted: Fri Dec 15, 2023 12:40 am
ApolloBoy wrote
Have you looked at the solder joints for the cartridge port? The later revisions tend to develop cracked solder joints and that can possibly cause issues like this.

Also, why are you replacing it with an SMS II and not another original model?


Mostly for space reasons, my current TV stand it will fit a little better.

Thanks I will check that out on the cartridge port.
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