Sega Master System Mystery Issue

[crabhammer]

I just picked up a SMS from GoodWill today. It didn't have the RF, A/V or power supply, but I have a spare 9V, 1.2A wall-wart that fits. I have cleaned the hell out of the console and the games, but each time I power on the system, I get the boot screen, then a screen saying

WELCOME TO THE SEGA
MASTER SYSTEM.

TO PLAY, FOLLOW THESE
INSTRUCTIONS:

1. TURN OFF POWER ON POWER BASE.

2. INSERT CARD/CARTRIDGE INTO SYSTEM.

3. TURN POWER BACK ON,AND....
ENJOY!!!

...and I can't get it to read a game. Every few power cycles I get a different error screen, but nearly every time it's the above screen.

I can't find any shorts or open connections on the motherboard and the cart slot seems to grip the cart pretty well.

I can usually find the source of the problem, but this one has me banging my head on my workbench. 

[crabhammer]

I finally got it to let me play about 7 minutes of Astro Warrior before it went back to the ENJOY!!! screen and I think I'm making some progress. I'm now getting a SOFTWARE ERROR screen every 3rd or 4th try. I still have no idea where to start here, though. I wish it was an obviously blown capacitor or a dead 7805 regulator....

[atarileaf]

I have a SMS that was always either giving me software errors or defaulting to the built in Super hang on/Safari Hunt. When I could get a game working it would seem to freeze or lock up after a few minutes. I never did figure out what the problem was and ended up getting a power base converter for the genesis which seems to work great.

I'd be interested if there are any experts with insight on this myself. I always wondered if it was a power supply issue but I only had the one so wasn't able to test that theory.

[crabhammer]

I thought it might be a supply issue as well. I managed to track down a bag full of Sega adapters from the local Goodwill and I can say with 100% certainty it isn't a supply problem. I've tried 4 different wall-warts and all of them give me the same result. The very same adapters work well with my Sega CD and Genesis 1.

Where I think the issue lies is with the electrolytic capacitors. I mean... this thing was manufactured around 1987 and they've got to be causing some sort of issue. I haven't been able to find a pinout of the cart connector anywhere to find the voltage supply pin for the cart. I have a strong hunch that the cartridge isn't getting power while the rest of the unit is.

When I get this SMS running again, I'm going to post up a "fix it" thread and maybe help anyone else out of this dilemma. Every SMS "fix" I've seen is for a blown 7805 regulator...

[atarileaf]

If you haven't already, try posting this at Atariage. There's some pretty smart technical people there that might be able to point you in the right direction.

[crabhammer]

I always forget about AtariAge. Maybe someone there has had the same issue. Thanks for the reminder! 

[crabhammer]

I just took a jog through the AtariAge forums and found this.
http://atariage.com/forums/topic/212713-sms-software-error/?hl=%2Bmaster+%2Bsystem#entry2765052

This is nearly identical to the issue with my SMS. I'm going to try to reflow the solder around the pin connector and check the traces around the connector. I'll post after it's done.

...I hope this works.

[crabhammer]

UPDATE: I took a peek at the backside of the SMS motherboard and found 18 cracked solder joints on the cartridge slot connector. Solder work is decidedly in order.

EDIT: I got the resoldering done and I am VERY happy to report that I now have a 100% working SMS. 

[soera]

Good job! If you decide to start delving into SMS console modding, let me know. I would love to have this : http://www.ebay.com/itm/SEGA-Master-System-I-Pack-Modified-Audio-Video-RCA-50-60Hz-Mark-III-Switch-/111009810354?pt=AU_Consoles&hash=item19d8b347b2

[crabhammer]

I saw that listing. I'm planning on giving my SMS an s-video output.

As far as the switches go, I can do the 50/60 hertz switching, but I don't know what use that would be to me.

I haven't looked into the Mark III switch mod very much and I haven't a clue to what it does. 

[sin2beta]

As far as the switches go, I can do the 50/60 hertz switching, but I don't know what use that would be to me.

It's mainly if you are wanting to go deeper in the library. There were some games made specifically for the European market. These were designed for 50 Hz. I don't know which are best at this speed. However, there are some.