68kMLA Classic Interface
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| Tales of a bombed Quadra 700: the "short" lived victory | |
| Posted by: Big Ben on 2024-02-18 22:58:22 Hello, Let me tell you the terrible tale of the bombed Quadra 700. Do you feel that sensation traveling your spline? Fear! You name it! That’s the feeling I had when I took off the shelf this freshly bought Q700 and I heard something moving… Removing the top revealed what everyone fear the most… an 1/2AA battery socket loaded with a bombed Maxell floating around. Damn it! Let’s remove the PSU and the drive holder to get a sneak peak of the carnage…  Well this isn’t that bad! Is this Quadra 700 the first Mac I’ll actually save from a lithium bomb? Some cleaning after it looks quite nice! Almost everything fall off and a bit of work with a spludger and the iron did the rest.  I won’t say it looks like new, but it is quite nice! With a bit more solder iron work I managed to clean the battery support viad and holes. Except I ripped off the ground pad on both sides, it was too damaged. But does the inner still work? Does it need a wire patch? Let’s find out! Taking the multimeter in continuity mode I connected both probes and it ringed! Hourra! Another ground test, it still ring hourraaa….. ay? Wait. I messed up, this pin on the molex is not the ground. I moved both probe to the two molex on the board, both have 5V and GND shorted. Damned. Slowly I removed each tatalium capacitor I found on the 5V rail, hoping it was just an old cap failure… Except it’s still shorted and caps where fine. A "short" lived victory against the bomb, a long battle now begins to find the short… | |
| Posted by: dramirez on 2024-02-21 17:03:54 You almost caught it time! | |
| Posted by: chiptripper on 2024-03-08 12:51:59 Are you certain it’s a proper short? Have you tested for resistance as well as just using the continuity setting? What reading do you get? My probe will sometimes buzz like a short when there’s simply very low resistance. Mac II / IIfx have some circuits like this. | |
| Posted by: Big Ben on 2024-03-09 13:46:30 I wasn't, but the resistance is pretty low, around few ohms, I took some time to check against a working Quadra 700. Good to know, Quadra 700 have a very low resistance between the 5V rail and the ground, no need to freak out like I did. I started to continue cleaning up the bombed Quadra 700 case, I'll give it a try tomorrow I guess after I re-soldered the caps. Can't wait to try the PowerPC card that came with. | |
| Posted by: naruse on 2024-12-25 20:01:54 Thanks for posting this!, indeed the resistance between 5v and gme is ~13ohm I thought I had a short as well, turns out there is none. I also have a bombed Q700 and managed to get it to a point where it chimes correctly but I don’t get any video unfortunately:/ | |
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