repair advice (machine was never grounded)

[algorithm]

I got this japanese electronic, I have many japanese electronics running on 120v just dandy normally.
This 1 in particular, seemed to progressively get worse the longer it was plugged in.
1 terrible flaw with this specific piece is there is no fuse.
also, the machine required a ground, but there are not ground slots in japan normally.
I know definitely this piece was used without grounding it ever before it got to the states. I received it with a little adaptor to bypass ground from the previous owner.

It had a problem when it was purchased, but it got worse and worse.
It has a panel of buttons with a display, and the buttons trigger randomly and sporadically, LEDs seem to go out and come on regardless of button presses...

What would happen if something was run for nearly 20+ years without it grounded?
& Then was grounded while powered after all that?

Thanks ahead of time!

[SeanB]

If it is grounded now the problem is likely unrelated, unless the socket outlet itself is faulty and is not actually grounded.

Likely the power supply capacitors are showing age and gradually failing and need to be replaced. This causes extra ripple on the supply rails and will give symptoms like you describe with digital selection of inputs and such. Open it up, post some pictures and it is likely an easy repair.

[algorithm]

If it is grounded now the problem is likely unrelated, unless the socket outlet itself is faulty and is not actually grounded.

Likely the power supply capacitors are showing age and gradually failing and need to be replaced. This causes extra ripple on the supply rails and will give symptoms like you describe with digital selection of inputs and such. Open it up, post some pictures and it is likely an easy repair.

Ok, great, thanks for the information.
When I tested the PSU all lines were good, but when the PSU is plugged in, all lines get lost except for the 5v.
Does this mean that the faulty capacitor is after the PSU ribbon cable? On the relative board connecting?

I will say if I remember correctly the caps on the PSU in question looked like the bottom seal might have leaked.
Although when testing the PSU without a load, everything was great.
Its been a while also, but the ESR reading seemed to check out iirc...

The PSU ribbon goes to the motherboard, the board has tons of SMD caps.