50/60hz issue on PAL Megadrive

Hi guys,

I was working on an original model PAL Megadrive today (modem port and all) and fitted a 50/60hz switch... everything is fine if I boot in 50hz, reset, then boot in 60hz, but when I try to switch from 50hz to 60hz, the picture rolls and it's running as slow as PAL50; I'm guessing it's a weird NTSC50 thing going on. Oddly enough, I disconnected the wires from the switch, and when I leave nothing connected to the common wire, it boots in 60hz.

The reason this is an issue is because it means the machine won't play PAL games in 60hz since it detects this as region protection and will refuse to boot if it's set to 60hz when it boots. Since it can't be switched on the fly from 50hz to 60hz, it's a big problem. Some solder has slid across both pads at the common end (i.e. where the middle wire attached to the switch goes), and since they were both connected anywho, I thought it wouldn't matter. Should I desolder the joint and put the common wire on JP4's or JP3's pad at the common end, or is something else up? Any feedback would be appreciated.

It's been a mixed day - my replacement SNES was kind enough to have that bugger of a 160-pin chip (making all the documentation on 50/60hz switches irrelevant), now this. At least the language switch on the Megadrive worked

desolder the wires, clean any and all solder connections, then touch a wire to GND (i.e. the large silver colored are at the back and the other wire end to the left side of JP2. also check that the cut between the JP2 spots is 100% through the trace. if that sets it to 50 Hz, and leaving it open sets it to 60 Hz (nothing connected to jp2 at all), the mod is working and either your switch is fucked or your wiring was wrong somehow.