MEGA DRIVE CLONE - DOIN SOME MODS ON IT

Hi everyone, I recently got this jap mega drive 1 and it revealed was a fuckin clone...damn! but was one of those early clones which are quite nice replicas of the original: it got motorola cpu, sony cxa video encoder, zilog z80, etc
console had a ntsc master clock (53.69..), 5 pin composite av output, a 4.43 oscillator connected to cxa for pal color, and it was stucked to jap language + 50hz.
What I did was removin the 5 pin din and put a 8 pin as it got the 3 pins free for r,g,b lines already connected to the cxa, and rgb was ok.
remove the 4.43 oscillator and connect pin 6 of the cxa trough resistor and capacitor to pin 50 of 315 clone chip to get right color subcarrier as a japanese unit (also feed 5v to pin 12 of cxa). This connection bring jailbars as an original mega drive (!). it was useless as I use rgb but want to do some testing...
Not having the jp1/2 jp2/3 pins I lift the correct pins of clone chips and got 2 switches 50/60 and jap/eng.
They work nice, but there are some problem with 60 hz, in fact some games like sonic 1 and 2 if you power up the console at 60hz you got some glitches in the upper part and occasional slowdown, the effect is the same of a regular mega drive unit when you power up sonic at 50hz and then you put 60hz during gameplay, pretty the same identical effect. some other games works perfectly and I also tried to overclock with different mhz and console works nice (I tried 10mhz, 12mhz and 13.6).
there are also strange things, with a japanese cart of badomen I got rollin in 60hz (using the same rom with the everdrive got me no problems) and also with some usa konami games I can't go trhough the region lock and I am stucked with the konami logo.
I really would like to fix these things, specially the 60hz problems, anyone has experience in these kind of clones?
here's a photo of the infamous clone pcb

 

I solved the thing, all I had to do was liftin pin 26 of the 315-5309 clone chip

 

strange thing: overclock not working well anymore, it crashes with some game at even 10 mhz

 

Usually clones are small versions using cheap components; you sure this is a clone? It looks a bit different to normal MegaDrive boards but quite large. Curious.

 

Depends on how old they are - early on, there were clones that were pretty much identical to the originals except that the chips were copies with different part numbers. The sort of machine you are talking about it much more modern, built when it was practical to shrink pretty much the whole system onto a single chip.

 

exactly, the one I own is a clone but a nice replica of a real mega drive and everyhthing works very nice, I'm curious to record some tunes to do some comparisons with the original yamaha chip

very curious about the overclock problem, when pin 26 of the 315-5309 clone chip was not lifted I could overclock till 13 mhz without any crash, now it crash also with 10mhz