Sega MegaDrive seems to work but does not display video nor audio

Keeping on with my repairing spree, I've stumbled across a PAL MegaDrive which does something pretty funny...

I have it connected via an AV cable which outputs composite signal. It lights up the front led and the TV behaves like its receiving signal but nothing is displayed nor heard.

I've cleaned the cartridge, tested a couple of them but to no avail... checked with a multimeter the voltage regulators and are around 5v if my memory does not fail me... Also I tried RF and had the TV trying to find the signal in auto mode and found nothing.

I am at a loss with this since it has no movable parts... any hints on this?

 

Try and reflow the qfp sega 315 chips near the cart slot and check for bad traces. use some flux and a must is lead solder as thats what was used back then.

 

make sure the power supply is good and strong! try a different ac adapter, check solder connections on back of board and check for anywhere that may be shorting out. also clean the cart slot.