Sega Genesis Console Issues

[vortalexfan]

Hello everyone, I recently acquired a mostly complete Sega Genesis console (all that was missing was the video hookups) and the unit has a generic run of the mill RF Adaptor built into it that is basically just like the one that the NES and the SNES use.

I went to try and hook up an RF Adaptor (the part with the long RCA plug-in on one end and coaxial input and output on the other end) that was from my NES and tried to operate my Sega Genesis with the RF Adaptor and I got clear picture and sound out of the unit except for the fact that the picture would bounce up and down repeatedly every couple of seconds and using different RF adaptor cables (I have two of the (S)NES RF Adaptor cables) didn't make a difference.

Also I was using the Coaxial input on the back of my 1974 GTE Sylvania GT Matic Console TV and I know for a fact that its not the TV itself causing the problem because when I hooked up an NES using its RF Adaptor the picture was fine and also when I hooked up a DTV Converter Box to the TV using the same Coaxial input cable on the back of the TV the picture is just fine.

Any ideas as to what could be causing this issue?

[freakaftr8]

Wonder if there's a possibility that there is too much AGC gain. I know some Zenith sets of the time had issues like this as well.
It may have something to do with the IF circuit and some signal processing that the TV does not like from the genesis.

[old_tv_nut]

This is likely a difference in the sync signal from the Sega compared to the NES. Some TVs with the early sync countdown circuits did not like the random interlace from some game systems. Zenith had a similar problem for at least one model year. The sync IC had to be redesigned to recognize non-standard sync and switch to non-countdown mode.