----------------------------------------------------------------- | Q*BERT BOOTLEG SYNC ADAPTION | ----------------------------------------------------------------- COPYRIGHT 2002 (www.andys-arcade.com) REVISION NUMBER: 1.0 REVISION DATE: 06 April 2002 CREATED BY: Andy Welburn STANDARD DISCLAIMER: -------------------- REMEMBER, NO WARRANTEES, EXPRESS OR IMPLIED, ARE GIVEN. USE THIS INFORMATION AT YOUR OWN RISK. I AM NOT RESPONSIBLE FOR ANY DAMAGES THAT MAY OCCUR TO YOUR PERSON OR PROPERTY. ----------------------------------------------------------- GENERAL OVERVIEW: ----------------- I had a number of qbert bootlegs most of which worked or partially worked but only one of them would sync up properly on my monitor. That one would only sync up properly when i smacked it a few times. Very odd. I noticed there was a few hacks on the pcb, one of these hacks had a loose ground pin on one of the piggybacked IC's, i re-flowed it, and the board synced every time... bingo, this little hack must have had something to do with the sync i thought... Time to document it methinks.. INGREDIENTS: ------------ 1 - Working bootleg Q*Bert Board 1 - 74LS02 (14 pin Quad 2-input NOR gate) 1 - 74LS221 (16 pin Dual monostable multivibrators with Schmitt-trigger inputs.) 1 - 50k cermet pot 1 - 1uf ceramic disc capacitor 1 - spool of jumper wire OBSERVATIONS: ------------- You can get away with a 100uf ceramic cap if that's all you have to hand ;) INSTRUCTIONS: ------------- 1: get the booty qbert in front of you, take the 74ls02 and cut off all legs on it apart from pins 1,2,3,7,14. bend out legs 1 and 3, trim off excess, leave enough to solder onto. 2: place the ls02 over the IC at location M10 (also a 74ls02) on the pcb, solder the legs of 2,7,14 onto that IC. 3: Locate the 7407 at P10, snip leg 11 as close to to the pcb as possible, and bend the remainder of the leg up. Solder a wire link from pin 1 of the piggybacked ls02 to the now lifted pin 11 of P10. 4: get the 74ls221 and cut off legs 4,5,6,7,9,10,11,12 5: bend out legs 1,2,3,13,14,15 and trim, but leave enough to solder onto. 6: piggyback the ls221 on top of the IC at location N9 (an ls157). You are only using this location to grab the power rails, so solder down legs 8 and 16 onto the chip below. 7: solder a wire link from pin 1 of the 221 to GND. 8: solder a wire link from pin 3 of the 221 to +5v. 9: solder a wire link fron pin 2 of the 221 to pin 3 of M10 (THE CHIP BELOW, NOT THE PIGGYBACKED IC) 10: solder a wire link from pin 13 of the 221 to pin 3 of M10 (THE PIGGYBACKED CHIP, NOT THE CHIP BELOW) 11: solder the 1uf capacitor between pins 14 and 15 of the 221. 12: solder one side of the horseshoe of the 50k pot to +5v 13: solder the wiper and other side of the horseshoe of the pot together, and then sodler to pin 15. DONE! You will now be able to adjust the sync using the pot! enjoy! Andy ----------------------------------------------------------------- | END | -----------------------------------------------------------------