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.