AES Scrolling screen when white or flashes.

[Retrogamer]

I just bought a bulk lot of broken consoles for a pittance and included was a AES that was supposedly not working at all, but I tried with another power supply and it fires up and works for the most part, but whenever the screen turns white or flashes white the screen scrolls until the white goes away like the vertical sync is all off. I have encountered this problem before with Sega Genesis systems and its usually due to a RF shield becoming disloged, but there is no such issue here. I am going to try another AV cable when I can get one from my house (at work now). but until then are there any suggestions?

Thanks in advance.
Geo

 

[Xian Xi]

I just bought a bulk lot of broken consoles for a pittance and included was a AES that was supposedly not working at all, but I tried with another power supply and it fires up and works for the most part, but whenever the screen turns white or flashes white the screen scrolls until the white goes away like the vertical sync is all off. I have encountered this problem before with Sega Genesis systems and its usually due to a RF shield becoming disloged, but there is no such issue here. I am going to try another AV cable when I can get one from my house (at work now). but until then are there any suggestions?

Thanks in advance.
Geo

You need to update the caps on the AV output. It's most likely a revision that has 100uf caps, change them to 470uf@6.3-10v(for best fit).

 

[Retrogamer]

These guys?

 

[Xian Xi]

Yes, correct. There are 5 of them. The resistors you can update to 75ohm as well.

 

[Atro]

14Mhz OC ?

 

[Retrogamer]

14Mhz OC ?

Eh?

 

[GadgetUK]

He means - looking at that photo, theres a crystal oscillator package on its back there with wires leading off. It looks like it replacing the onboard crystal with a 14Mhz one to overclock it. I would start by reverting that mod and putting it back to a stock 12Mhz. I am not sure if that's the master clock or someone has converted the video encoder from one region to another.

 

[Atro]

I am not sure if that's the master clock or someone has converted the video encoder from one region to another.

That red wire is connected to PIN12 ( Vcc ).
I hardly see any mod on the CXA1145.
Color sub-carrier mod would be PIN7 iirc.

Seems like the modder wanted a safe & easy +5v to tap, so the encoder leg was
kinda a safe bet.

 

[Xian Xi]

I don't think it's an overclock, most likely a crystal that is slightly higher than 24mhz to help make it closer to 60hz.