SMS power issue: Must stand on its rear in order to turn (and stay) on

[joe-musashi]

Hello guys. I am new to this forum, and also to this world of soldering and technical restoration of consoles.

I still have my childhood Sega Master System (the model that is rectangular and red/black + it takes both cartridges and cards). It holds a special place in my heart. It must stand on its rear to be able to turn on (and stay on). If I turn it on this way, I can sometimes gently lie it down into the normal position without it going out. I would love to be able to fix this issue on my old machine. I have opened everything up, and I am ready to test the various components as needed. But I do not know where to start?

[bust3dstr8]

Reflow the solder on the power jack and retest.

[joe-musashi]

Thank you very much for your advice. I will start with the power jack. You suggest that I reflow the solder. Could I also 'just' take the jack up, clean/suck up the existing solder, and then solder it back in. To reflow I gather you need some kind of oven-equipment that I do not have...

[bust3dstr8]

You can remove the old solder if you like. The quickest way is to dap some flux onto the old joints and then melt the
solder again, adding fresh solder if needed.

[joe-musashi]

You can remove the old solder if you like. The quickest way is to dap some flux onto the old joints and then melt the
solder again, adding fresh solder if needed.

OK - thank you again. And thank you for your patience with me as I am a total soldering-newbie. I have done some further research along the lines of your suggestion. Could this be the plan:
1) Apply flux from a tube on both sides of the power jack joints
2) Instantly heat it up with a heat gun / hot air gun? For how long? Approx. 15 seconds on each side (until the old solder, covered in flux, begins to melt)
3) Let it cool of
4) Retest

If fresh solder is needed, it is applied afterwards - as a separate process?

[bust3dstr8]

Apply flux only to the leads on the solder side of the pcb.

Heat the flux and solder with an iron until it is shiny and molten.

The iron tip may wick some of the solder away from the pcb while you are heating it,
if this happens feed fresh solder into the joint at this time.

The leads will cool in seconds and should be shiny and smooth.

[Tokimemofan]

Resolder the power port, if that fails your power supply has a broken wire at one of the strain reliefs, a common problem with paired wire power supplies and to a lesser extent coaxial ones too.

[joe-musashi]

Resolder the power port, if that fails your power supply has a broken wire at one of the strain reliefs, a common problem with paired wire power supplies and to a lesser extent coaxial ones too.

OK - thank you both. I will focus on the power port/jack. This info was just what I needed to get started.

[InsaneDavid]

For whatever reason I notice this a lot with Genesis systems as well. I'd assume it comes from general wear due to age but I think it mostly has to do with people storing systems with the cables or controllers attached, as is often the case when found in storage somewhere. The tug and pull of the attached cables ends up breaking the solder points. Many, many, many Genesis systems with unresponsive or screwy controller functions have been repaired by a quick reflow.

[joe-musashi]

I have tried to reflow/resolder the power port. It has three points (?) that I first brushed with flux, and then heated up with my soldering iron one-by-one until the solder melted (flowed?). I could apply some additional new solder to one of the points.

It did not solve the problem. The machine still works like before: You have to tilt it vertically (with the power port towards the floor) in order to get the green LED to light up.

I repeated the reflowing process. Still the same result. (I have attached an image of the power port soldering side).

I have a multimeter. Is there somewhere I should test for a broken connection? What is next step? Replacing the power port? Can I use the multimeter to test whether it is the power port or not...?

Thank you for your help. I have just had my first soldering experience since my early youth

[FABombjoy]

Other possibilities include:

1: Break in power cable - the pressure of having the SMS sitting on it helps complete the circuit. Have you tried a different power supply?

2: Dirty power jack. A business card cut lengthwise and rolled into a tube makes a good power jack cleaner. The part of the jack that makes contact with the outside of the power supply DC plug can get a decent amount of build-up on it over the years.

3: Broken power jack center pin. On the back of the power jack you can see where the center pin is connected to the part that's soldered to the PCB. Sometimes they just get a bit loose, and soldering that attachment can make them usable again without having to replace the whole jack.

[joe-musashi]

Other possibilities include:

1: Break in power cable - the pressure of having the SMS sitting on it helps complete the circuit. Have you tried a different power supply?

2: Dirty power jack. A business card cut lengthwise and rolled into a tube makes a good power jack cleaner. The part of the jack that makes contact with the outside of the power supply DC plug can get a decent amount of build-up on it over the years.

3: Broken power jack center pin. On the back of the power jack you can see where the center pin is connected to the part that's soldered to the PCB. Sometimes they just get a bit loose, and soldering that attachment can make them usable again without having to replace the whole jack.

OK - thank you. I will try to clean it inside with something like a business card tomorrow. I do not think it is in the cable, because it works when I am holding the power base (now stripped down) and tilting it backwards (so it works without the base sitting on the cable). It is almost like the down-pull of gravity does something to something somewhere on the board. In the event I need a new power jack, is it possible to get one? I have been Googling for it, but without luck.

Can I use the multimeter somehow to establish whether it is the power jack or not?

// EDIT: I have used the multimeter on the power jack. When I touch the inside of the jack with the red probe and the middle pin (of the power jack) with the black probe I get continuity. Also when I touch the two other pins of the power jack there seems to be continuity. Could this mean that the power jack actually does work, and the error must be somewhere else...? Where is the next place to test? The converter (attached to the heat sink) seems also to be alright with regards to continuity...

// RE-EDIT: Oh well, I got it. It actually was the power cable . In the process of reflowing the power button, thinking about all your suggestions and testing everything again, I accidentally wiggled the power cable in a way that immediately powered up the system.

Thank you for your time guys. I'm moving on to the unresponsive control sticks etc. Thank you for helping me into this world of restoration. I am certainly having a great time!!!

[joe-musashi]

I just wanted to return here to my first post and say thank you for your kind help. I started not so long ago with my childhood SMS that had power cable troubles. With your help and patience I fixed that and now I have modded the console (AV, PAL/NTSC switch) and built an arcade stick for it into a coffee table. It is nothing much, but for me it is a childhood dream coming true (the arcade stick part..). So thank you all.