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  • Joined: 20 Dec 2010
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**FIXED** SMS Distorted Image then Died (Can it be Fixed?)
Post Posted: Mon Apr 24, 2017 4:07 pm
Last edited by TheSegaDude on Fri Jun 02, 2017 11:10 pm; edited 1 time in total
Hi all,

I'm looking for some help.

I recently bought a used SMS 1. I was playing the built in Snail Maze game and everything was sharp and crisp for a while.

*My CRT TV and SMS power cable and video cable are good. I tested with another SMS.

After about 2-5 minutes the image started to distort. It would get hazy as ripples of distortion would pass over the image. Over about two minutes the image would worsen to the point were you can still see but it was getting very hard to play the game. Then the distortion would start to fade away and until everything was clear and crisp again. It would cycle doing this; from good image to bad image.

I used the SMS for about 60-90 minutes at which point it powered off on it's own and now it will not power up again at all.

I opened it up and looked at the board. Everything looks good and very reasonably clean. There were no obvious signs of damage. In a few spot I saw some flux that could be cleaned up. All solder joints looked factory and none looked in dire need of re-flowing.

I did purchase a cap kit and I'm currently waiting for it to arrive.

I thought I'd detail what I know so far and see what you guys think. I'd like to bring this SMS back to life.

Thanks!
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Post Posted: Mon Apr 24, 2017 9:20 pm
Caps are the most likely problem, it remains to be seen if anything was damaged in the dying moments.
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Post Posted: Tue Apr 25, 2017 1:34 am
Hmm, good point. I hope no damaged was caused.

We'll see if the cap kit will be enough. I don't have a lot of soldering under my belt but I think I can do this. I'll report back when I get it done and we'll see what happens. I got a shipping confirmation today for the caps.
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Post Posted: Sun May 14, 2017 1:54 pm
OK, I finished installing new caps. Below are the ones I did:

SEGA M4, POWERBASE/NTSC, 837-6067 & 837-6405

CA1
CA20
C1
C4
C20
C22
C25
C28
C49
C119
C120
C121
C122
C123
C124
C131

I am still new at soldering but I think the work I did was OK. Correct cap in the right spot with the correct polarity.

When I try to power up the SMS the same things happens as before the cap kit.

Dead... no sign of life.

The green SMS light does not light up and looking at the TV screen there is no indication of any signal being received. (the TV and cables work with another SMS)

I'd love some help figuring out the next steps. How do I find out what else might be broken?

I'd love to be able to bring this SMS back to life.

I've attached images of the front and back of the PCB in case that's useful.

https://console5.com/wiki/Sega_Master_System
https://console5.com/wiki/File:Sega-Master-System-Cap-Map---837-6067.png

Thank you!!
SMS PCB 01.JPG (3.82 MB)
SMS PCB 01.JPG
SMS PCB 02.JPG (3.71 MB)
SMS PCB 02.JPG

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SMS Distorted Image then Died (Can it be Fixed?)
Post Posted: Sun May 14, 2017 5:04 pm
If the green LED is not lighting up there's no power on the PCB. The problem could be the power adapter socket, voltage regulator or the power switch. A faulty PCB trace or ferrite bead are also possibilities but lets start with the likely components first.

Start by checking that your power supply is OK and not flaky if you haven't already.

If the power supply is OK then check that you have power at the power adapter socket on the PCB. Your power adapter voltage (9V) should be present at the pins when the power supply is connected to the SMS.

Turn on the SMS. Check if you have power at the voltage regulator. The voltage regulator has 3 pins labelled I, C and O. Your power adapter voltage (9V) should be present between the I and C pins.

Check the voltage regulator output. There should be 5V between the C and O pins.

Also check that The C pin should be connected to the PCB ground.
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Post Posted: Fri Jun 02, 2017 11:09 pm
Fixed!

So it turns out it was the voltage regulator. I've read that this is a very common problem for a system that wont power on.
I ordered a replacement 7805 from Console5 and after replacing the old NEC 7805 the Master System powers up again.

Obviously I was really happy to see this. It meant two big things for me.

1) I found the broken component.
2) I installed the caps correctly.

So as it turned out, I didn't need to do a full cap kit but it's done now and a lot of new live has been put back into this SMS. Very cool.

@asynchronous Thanks for taking the time to really spell out what I had to do. I'm sure all you guys who know what you're doing are getting tired of saying the same things over and over but it really does help.

I could not have done it without your help. Thank you!
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Post Posted: Sun Jun 04, 2017 12:32 am
Great job! I've had a few where the 7805 needed replaced but the RAM and other things were cooked... so it's good to hear a success story. :)
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Post Posted: Sun Jun 04, 2017 2:33 pm
Is it possible to replace dead RAM on old consoles like these?

Which parts/components are just not replaceable anymore?
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Post Posted: Sun Jun 04, 2017 6:10 pm
RAM may be replaceable, as is the CPU and video encoder, the rest is all proprietary anyway.
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**FIXED** SMS Distorted Image then Died (Can it be Fixed?)
Post Posted: Tue Jun 06, 2017 2:02 pm
Sweeeet
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Post Posted: Tue Jun 06, 2017 2:15 pm
Yeah man! It is totally sweet :)

Anyone out there with a broken console and is new to soldering?

I really do recommend that you try fixing it yourself. It's not entirely easy but I feel anyone with a bit of patience will be able to do it.

*I also recommend buying de-soldering iron. I found that removing the components is by far the hardest part.
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