AES Black screen problem

just installed a socket + Unibios 2.3 on a AES model: neo-o. Trace looks okay and without the cart it reports a blue screen. With cart it just shows black screen no sound. Cleaned both cart and connector. Also tried using the old bios chip which posts a yellow screen ( VideoRAM error ?).
Any suggestions iam at a loss at the moment and kinda pissed.

Try a different cart.

Xian Xi said:

Try a different cart.

Click to expand...

Seconded...

Also, Look all over your PCB and make sure you didn't accidentally drip some solder and cause a short........

Also, make sure you put the Bios in the right direction....


More suggestions:
Check all the traces... With a Multimeter where possible (usually a good idea to do it before you put the socket on). Somebody once posted where all of the traces go tho.

Re flow the pins...

okay tried 3 carts Nam ,Sengoku, and Baseball pros same result
bios is pointed the right way and i checked connections with multimeter like this post shows http://www.neo-geo.com/forums/showpost.php?p=2501452&postcount=6

again trace looks okay

still stumped

Damn...

The repair would've been MUCH easier if I had seen this thread.

Address line A1, pin 22 on the BIOS chip had the platethru and upper pad pulled.

This line went to A2 (don't you love how some chips start numbering with A0 and others with A1?) of the LSPC2, which is pin 175. Without the address line giving the proper signals the LSPC2 would never access the address lines of the Video RAM.

(Read here if you want to learn more about how chips are accessed by a CPU)

RJ