Arcade Collecting > Restorations & repair
TheShanMan's Defender restoration - New repro wiring harnesses!!!
RetroACTIVE:
Just a quick update...
Got the replacement IC installed... but that wasn't the only thing wrong... Also found a bad 74153 so I replaced them all (4) since they were of the same date code. Now when the unit comes up I get the distinct color bars with some rug artifacts... its no longer a white screen of bars... I'm actually seeing color... this is a good thing... not working yet... but a definite improvement.
- Watchdog circuit fixed.
- Reset circuitry checked out ok...
- The 12MHz, 6 MHz and 4 MHz clocks are working as they should.
- Not sure about the color RAM but I think its fine... (besides that would not cause this latest behavior)
- Appears as if the Data bus is corrupted (video RAM side), I've yet to check out the LS374 latches on the RAM address bus to prove this... but this seems highly probable
:cheers:
TheShanMan:
Man, there's a lot going on with this board! I'm glad I sent it in as I probably wouldn't have had much hope figuring out all of these issues.
At least my suspicion that there was a watchdog problem was right. :)
Excited to see the progress, and as always, I appreciate what you're doing! :notworthy:
RetroACTIVE:
I believe I confirmed my suspicions with the 374's this evening... I ordered a couple of tubes of them earlier this week and they should be here by now :angry: .... anyway when they come in... I'll let you know the prognosis ... I'm hoping this is it. The last thing to worry is the CMOS RAM... I don't want to remove it until I'm sure it needs to be fixed... that will come after the board is actually running of course.
Also got replacement ROMs yesterday... left the ROM board at the office DOH!... so I didn't get to test them until this evening.
Sorry this has taken so long... had a couple of project deadlines at work and I was quite low on parts as I've fixed a few of these things and have not restocked in a while... I also decided to replace a few questionable IC's (rusty,crusty,...etc)... this board sat in a barn for 8 years and I believe moisture got the best of it... so I tried to clean things up as best as possible.
However... I'm thinking just about done with this old fellow....
:cheers:
TheShanMan:
Retro reported to me that 2 of the new ROM's were bad, so we gotta wait for those 2 to get resent.
Even though I'm overloaded with other projects right now, I felt a compulsion to get a little work done on the defender today. Installed my new t-molding and vacuumed it out really good. I still need to replace the front lower particle board panel that has moisture damage, and I need to clean up and touch up the artwork. It's in good condition for 28 years old so I don't think I'll be completely repainting, other than the top and back since they're straight black, and don't look nearly as good as the sides.
Bummed about the delay caused by the bad ROM's because Retro seems to be so close to done, and I'm itching to play. But a few more days won't kill me, especially when I have some stuff I need to do on my '66 mustang (my other time sink of a hobby).
Oh, one other bummer. I never looked closely at the coin mechs, but there is only one complete mech, and I wonder if it even works as is - I know the PO had it on free play and there's no coin box. It's taken a hit from moisture too, so at the very least I'm going to have to take it all apart and clean it up. Anyone know how hard it is to get a williams coin mech? I'd like to get 2 working. I understand the middle one was actually used for Susan B. Anthony dollars, and mine is blocked - I imagine it became fairly standard to have the middle one blocked as those dollars became less common?
SirPeale:
They're just regular coin mechs. I've got a bunch of quarter mechs for you. $5.00 each.
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