Sega Blast City Nanao MS933 Lost red color and speakers sound issues (SOLVED)

[kyoken]

Hi guys I'm looking for some guidance to repair my Sega Blast City.

Check the values on the OSD panel and there's no cut on the red color, looks like for some reason the red is not getting through anymore.

I'm check around the forums and looks like probably the issue is that one of the transitors of the neck board that controls the red is gone or not working anymore, so the red color is gone.


There's also an annoying sound on the speakers like a buzz that didn't happen before or until I opened to inspect the chassis.

I'm looking for some advice from you guys to getting this fixed or any guidance.

Thanks in advance.

 

[rewrite]

Swap the red with either of the other two color transistors, if the problem color changes, you have your answer. If red is still missing, you know it's not the transistor.

Quicker to do that than just about any other troubleshooting so I would do that first, and see if it's something more complex from there.

 

[kyoken]

Thanks man so you know which transistor manage the red on the neck board? It's the Q302 or another?

 

[kyoken]

Also what's the best way to swap those do be need to unsoldering and solder in back in the other two?

 

[rewrite]

Thanks man so you know which transistor manage the red on the neck board? It's the Q302 or another?

Follow the red color gun pin back to it. Haven't seen a 2933 in a bit, probably labeled RK on the back. If you take a shot of the back of the neckboard it shouldn't be hard to figure out.

Also what's the best way to swap those do be need to unsoldering and solder in back in the other two?

Yes, desolder the red and either of the other two and then resolder them in opposite locations.

 

[kyoken]

Thanks brother I'll take a look more in detail tom and will provide a pic of the back neck board to check which transistor manage the red.

 

[kyoken]

Here's some pics of the neck board back.

 

[rewrite]

It should be 8 if I'm not mistaken. Annoying that they didn't label them nicely.

Check with your multimeter step by step back the the red line on the RGB connector.

 

[kyoken]

Can you point of where the 8 is located?

 

[kyoken]

My guessing is on q322 from the back board.

 

[rewrite]

Can you point of where the 8 is located?

It's silkscreened on the back of the neckboard, it's one of the connector pins. You'll need to trace it back.

You can guess, but if you happen to get it wrong and swap blue and green you won't have ruled out red. Better to take 3 minutes and check with the multimeter.

 

[kyoken]

Thanks brother I'm not very technical person will do my best to trace our.

Also do you know where can order those models specific of the transistor in case needed?

 

[rewrite]

Thanks brother I'm not very technical person will do my best to trace our.

Also do you know where can order those models specific of the transistor in case needed?

Set the multimeter to continuity. Start with one lead on the red RGB line going into the neckboard, and follow the traces and check with the multimeter to make sure you have continuity from part to part until you hit a transistor.

You can snag them here, it's just transistors, I'd grab a few extra:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2332490.m570.l1313&_nkw=2SC4001+&_sacat=0

I wouldn't shotgun replace them though. Take the bit of time to troubleshoot otherwise you'll waste a bunch of time and money hoping for one thing to work if it doesn't, y'know?

 

[nem]

Red is 30x
Green is 31x
Blue is 32x

 

[rewrite]

Red is 30x
Green is 31x
Blue is 32x

Thank you, I don't have one on hand, nor do I know them off the top of my head.

 

[kyoken]

Thank you!

Red is 30x
Green is 31x
Blue is 32

 

[rewrite]

So in this case swap 30x with either of the other two and fire her back up.

If you lose the other color and red comes back, you've found the solution.

 

[kyoken]

Ok guys so I swap one of the other's to 3022 and the red isn't back so I might think the oasis could be around the signal on the jamma harness.

I'm trying to get an spare for testing.

 

[erdrick1980]

I had the exact same issue on my blast with no red. It turned out for me it was the RED (pin12) wire on the jamma connector that came loose or broke. That damn magnet thing on those wires is so damn tight any wrong movement and rips it out.

Check that with flashlight and lighty pull on it see if it comes off or it's damaged.

 

[kyoken]

Thanks bro, I checked out and barely show the color now but it's damaged so I'm getting a new replacement soon.