Arcade Collecting > Restorations & repair
TheShanMan's Defender restoration - New repro wiring harnesses!!!
RetroACTIVE:
Ok... I still have TheShanMan's Defender boards... but they will be returning to him tomorrow...
His boards were plagued with problems... so this took a while
Initial Symptom: White screen, board was held in reset and all 4 leds on the ROM board stay on.
#1 Tested the ROM board with known good defender CPU... no dice. Beyond physical corrosion, many of the ROM chips were bad. A new set was installed... ROM board tested ok...(as it seemed...ribbon cable bites us later)
#2 The Watchdog circuit was faulty, holding the board in reset. This turned out to bad IC 5O (LS393).
#3 After fixing watchdog, no change in behavior... Observed IC 3G (LS153)... outputs appeared to be not quite at 5 v... so I replaced all of the 153s. Now the bars are no longer pure white... there are multicolored rug artifacts but still distinct bars.
#4 Video RAM data bus is corrupted, IC 1M (LS374). I replaced all of them (1M,3M,4M)... and BINGO! Now all of the leds go out and the game behaves like its going into attract mode... but the attract mode is screwed up.
#5 Bad IC 4K (LS139) (2 to 4 Line Decoder), causes this weird twinkling effect on the rug pattern and the attract screen to be missing nearly all of the graphics... except the bottom of the word DEFENDER... and I mean the bottom, I only know thats what it is by its blinking effect.
#6 Long term test proved system to be unreliable, the board locked up and after cycling power, I could not get it to come up reliably each time... I replaced the ribbon header on the ROM board and this solved the issue.
#7 I was also concerned about the CPU and Decoder ROM sockets, so I went ahead and replaced them for good measure.
Other things done:
Installed lithium kit, replaced all electrolytic caps, replaced 20 pin I/O header and cleaned up the boards in general.
This was fun... a bit wicked... but fun none the less. A big thanks to TheShanMan for being patient and understanding, its hard fitting this stuff into day to day life. Another good thing is I know have enough parts to help save plenty more Defenders!
:cheers:
Jim
TheShanMan:
Is this guy awesome or what? No need to thank me for being "patient and understanding" - how can someone complain with you being so generous with your time and ability? I'm just thankful that you enjoyed it, because I feel bad enough about how this project became much more difficult than we figured it would.
Hey, at least I correctly guessed that my board was stuck in reset! I would have been WAY over my head trying to repair this myself, despite being an embedded systems engineer early in my career. But this process has helped me just about as much as you could possibly hope without being physically present, so whenever I do encounter a real non-working game I will at least feel more comfortable tackling it. And you have certainly inspired me in that respect, Jim!
Of course, this will also make me more discriminating when it comes to buying games with apparent moisture or corrosion issues!
Thanks so much Jim. Can't wait to play Defender! ;D
Restoration will continue after I get the boards back. Still plenty to do on this prized possession!
RetroACTIVE:
Well... I win the ---meecrob----bag-of-the-year award... I sent the boards back to TheShanMan and forgot to put his 4164 adapter back in the box! So here he is excited and ready to go... and then :banghead: dummy forgets to put everything back in the box!
...this guy.... not so awesome :'(
TheShanMan:
No, you're too hard on yourself! With all the stuff of mine that you had, it's no surprise that something so little got overlooked. Remember when I PM'ed you a checklist of items to help prevent this very situation? Well, I forgot to include the adapter in that checklist, so I'll take some of the fault too.
So don't anyone let this guy convince you that he's anything less than awesome, because I certainly think he's awesome for what he's done for me, and this minor glitch doesn't knock my opinion of him in the slightest. :notworthy:
SirPeale:
That's the one I made for you, right? Both you guys handled it, how does it feel? Still in one piece?
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