Following DarrenF's lead....I always say (to myself)I'm gonna post my repair logs, but I never do. I never seem to find the time....I'm going to start trying to FIND the time. We'll see how it goes.
Anyways.....my repair jobs from this past Thursday and Friday....
BATTLEZONE
This one would boot up and immediately start playing, by itself! The players tank would start firing....over, and over, and over, etc. After a minute or two of non-stop firing, the firing would stop, the enemy tank would move into position, and kill me. My screen would give me the "broken window" display.....and hand there. The game would hand here for maybe 30 seconds, then the watchdog would kick in....and reboot the motherbboard.....and then repeat. The game woould not go into test mode....just crash and lock up. Maybe 1 out of every 20 power ups, the game would boot up normally. When this would happen, it would go into test mode. In test mode, I got 6 tones....indicating a bad B1 2114 RAM. Replacing the RAM didn't change the issue, except for making the RAM error tone go away. On a hunch (and before doing major troubleshoooting), I decided to swap in a good Atari POKEY at location B/C2. The POKEY handles the inputs/outputs (among other things). New POKEY, issues gone. Since the problem was (somewhat) intermittent, I didnt want to throw away a (possibly) good Atari custom chip......so I threw a new IC socket into the location, and the issue remained with the original chip.....so the POKEY was bad.
MILLIPEDE
On power up, this was giving me RAM error tones.....sometimes three tones (RAM at 2M), sometimes four tones(RAM at 4N). I replaced both 2101 RAM. Now I get five tones (RAM at 2L). I replace, and now I get nine tones(RAM at 2J) and sometimes 10 tones(RAM at 4K). I replace the RAM at 2J.....now I get 10 tones, so I replace the RAM at 4K. Now I get 6 tones (RAM at 4M), and I replace. Now I get 7 tones (RAM at 2K). I replace.....and what do you know....No more RAM errors. I should note, all these RAM are soldered in.....if they were originally socketed, I would have replaced them all from the get-go. Now that the errors are gone...I can see an image on the monitor, but it's dim/blurry/out of sync. I pull it and see it's a lovely Matsushita. The chassis' never been capped and there's visibly leaking caps. I throw a cap kit on it and stick the tube on my rejuvenator. The tube is showing nothing on the red and blue guns. They're so gone, they won't even rejuvenate.....the green gun restored nicely. I fire it back up.....and the sync is now good, but I obviously only have green. I grab a spare Matsushita tube from my parts shelf that I'd previously tested as good. Pulled the old tube from the chassis/frame and installed my replacement tube. Fired it up....looks good.....and realize I suck at Millipede.
GAUNTLET LEGENDS
This beast fired up, everything sounded good, but the monitor was dead. I pulled the monitor. It was a Neotec, though, I'm unsure of what model. The neckboard protector was labeled NT-2701, while the chassis was stickered NT-27E. This wasn't exactly surprising knowing Neotec. One has to wonder what was going on at their factory. The chassis didn't match my cap list for the NT-2701.....so I'll assume this was a NT-27E. I've never worked on one of those, so I didn''t have a cap list to compare. This chassis had never been capped, so I started with a cap kit. Fired it up, still dead.....no ticking, nothing. I measured the 3 output voltages from the switching power supplies transformer.....all were dead. I started digging through the power supply circuit.....looking for something "open". The bridge looked good, all diodes looked good, all power resistors looked good. This (realisticlly) only left a couple of componets.....the MOSFET and the controling IC. MOSFETs (almost) always short....it wasn't. That left IC101 (TDA4605). I replaced it and the monitor fired up.....B+ was pretty low....after a few adjustments, all was good.
We'll see how long I can keep this up!
Edward
Anyways.....my repair jobs from this past Thursday and Friday....
BATTLEZONE
This one would boot up and immediately start playing, by itself! The players tank would start firing....over, and over, and over, etc. After a minute or two of non-stop firing, the firing would stop, the enemy tank would move into position, and kill me. My screen would give me the "broken window" display.....and hand there. The game would hand here for maybe 30 seconds, then the watchdog would kick in....and reboot the motherbboard.....and then repeat. The game woould not go into test mode....just crash and lock up. Maybe 1 out of every 20 power ups, the game would boot up normally. When this would happen, it would go into test mode. In test mode, I got 6 tones....indicating a bad B1 2114 RAM. Replacing the RAM didn't change the issue, except for making the RAM error tone go away. On a hunch (and before doing major troubleshoooting), I decided to swap in a good Atari POKEY at location B/C2. The POKEY handles the inputs/outputs (among other things). New POKEY, issues gone. Since the problem was (somewhat) intermittent, I didnt want to throw away a (possibly) good Atari custom chip......so I threw a new IC socket into the location, and the issue remained with the original chip.....so the POKEY was bad.
MILLIPEDE
On power up, this was giving me RAM error tones.....sometimes three tones (RAM at 2M), sometimes four tones(RAM at 4N). I replaced both 2101 RAM. Now I get five tones (RAM at 2L). I replace, and now I get nine tones(RAM at 2J) and sometimes 10 tones(RAM at 4K). I replace the RAM at 2J.....now I get 10 tones, so I replace the RAM at 4K. Now I get 6 tones (RAM at 4M), and I replace. Now I get 7 tones (RAM at 2K). I replace.....and what do you know....No more RAM errors. I should note, all these RAM are soldered in.....if they were originally socketed, I would have replaced them all from the get-go. Now that the errors are gone...I can see an image on the monitor, but it's dim/blurry/out of sync. I pull it and see it's a lovely Matsushita. The chassis' never been capped and there's visibly leaking caps. I throw a cap kit on it and stick the tube on my rejuvenator. The tube is showing nothing on the red and blue guns. They're so gone, they won't even rejuvenate.....the green gun restored nicely. I fire it back up.....and the sync is now good, but I obviously only have green. I grab a spare Matsushita tube from my parts shelf that I'd previously tested as good. Pulled the old tube from the chassis/frame and installed my replacement tube. Fired it up....looks good.....and realize I suck at Millipede.
GAUNTLET LEGENDS
This beast fired up, everything sounded good, but the monitor was dead. I pulled the monitor. It was a Neotec, though, I'm unsure of what model. The neckboard protector was labeled NT-2701, while the chassis was stickered NT-27E. This wasn't exactly surprising knowing Neotec. One has to wonder what was going on at their factory. The chassis didn't match my cap list for the NT-2701.....so I'll assume this was a NT-27E. I've never worked on one of those, so I didn''t have a cap list to compare. This chassis had never been capped, so I started with a cap kit. Fired it up, still dead.....no ticking, nothing. I measured the 3 output voltages from the switching power supplies transformer.....all were dead. I started digging through the power supply circuit.....looking for something "open". The bridge looked good, all diodes looked good, all power resistors looked good. This (realisticlly) only left a couple of componets.....the MOSFET and the controling IC. MOSFETs (almost) always short....it wasn't. That left IC101 (TDA4605). I replaced it and the monitor fired up.....B+ was pretty low....after a few adjustments, all was good.
We'll see how long I can keep this up!
Edward

