OK. I purchased a non-working Joust along with some other games a couple months ago. I finally had some time, so I decided to start with the Joust as it was the one supposedly working most recently though having some lock-up issues, which progressed to non-working altogether. Plus... I just love Joust. 
Plugged it in: no 12v. Found missing fuses for the 12v. Replaced the fuses and 12v now present. Board getting all necessary voltages... but no activity from the 7 segment.
The boardset was rocking red ROMs but had 2 replacement ROMs... #10 with a green dot sticker, and #7 with a red dot sticker. Checking with the ROM files, #10 for a red set should be red, not green... and a checksum showed it was truly a green rom. Ok, on to #7... also should be red, it ALSO matched green rom. Programmed a proper red pair and installed. Still no activity.
Decided to make a ROM dump and check all the ROMs. Every ROM but 1,2, and 4 had bad checksum! Programmed new for the defective ones.... still no activity. Checked the ribbon cable for continuity... all good. Ribbon had been replaced, but gave a crimp anyway just in case. Still no activity. Reflowed all the connector pins while I had it on the bench.
WELL, back to the KLOV for more reading up. Consulted Lon's Joust Repair Log thread [located right here ---> https://forums.arcade-museum.com/showthread.php?t=398434&] Thanks Lon! It's already proving useful.
Lon's Log pointed me to a 2011 thread from YellowDog who had also had a dead Joust behaving like mine. (Probed my ROM board and found lots of inactivity.) He found the CPU installed backwards. Well, whaddya know... so was mine. And in addition, a broken leg! Swapped in another 68B09 and whoa! was that noise? (It actually startled me
) Monitor showing lots of activity.. but not right... but it seemed to light garbled blocks sequentially like the J-O-U-S-T coming up on screen.
Getting a really weird code. (Left my note at the house but it was if I remember right it was: [blank]-[backwards lowercase c]-7. Seemed like the left vertical segments were not responding... though they do all simultaneously blink at shutdown. Getting some fuzzy outputs on the BCD. Then the 7 segment stopped altogether. Probing also found a few other bad chips on the CPU as well. Had to order some parts, will be back at it when they come in!
Plugged it in: no 12v. Found missing fuses for the 12v. Replaced the fuses and 12v now present. Board getting all necessary voltages... but no activity from the 7 segment.
The boardset was rocking red ROMs but had 2 replacement ROMs... #10 with a green dot sticker, and #7 with a red dot sticker. Checking with the ROM files, #10 for a red set should be red, not green... and a checksum showed it was truly a green rom. Ok, on to #7... also should be red, it ALSO matched green rom. Programmed a proper red pair and installed. Still no activity.
Decided to make a ROM dump and check all the ROMs. Every ROM but 1,2, and 4 had bad checksum! Programmed new for the defective ones.... still no activity. Checked the ribbon cable for continuity... all good. Ribbon had been replaced, but gave a crimp anyway just in case. Still no activity. Reflowed all the connector pins while I had it on the bench.
WELL, back to the KLOV for more reading up. Consulted Lon's Joust Repair Log thread [located right here ---> https://forums.arcade-museum.com/showthread.php?t=398434&] Thanks Lon! It's already proving useful.
Lon's Log pointed me to a 2011 thread from YellowDog who had also had a dead Joust behaving like mine. (Probed my ROM board and found lots of inactivity.) He found the CPU installed backwards. Well, whaddya know... so was mine. And in addition, a broken leg! Swapped in another 68B09 and whoa! was that noise? (It actually startled me
) Monitor showing lots of activity.. but not right... but it seemed to light garbled blocks sequentially like the J-O-U-S-T coming up on screen. Getting a really weird code. (Left my note at the house but it was if I remember right it was: [blank]-[backwards lowercase c]-7. Seemed like the left vertical segments were not responding... though they do all simultaneously blink at shutdown. Getting some fuzzy outputs on the BCD. Then the 7 segment stopped altogether. Probing also found a few other bad chips on the CPU as well. Had to order some parts, will be back at it when they come in!


