Tales of a bombed Quadra 700: the "short" lived victory

[Big Ben]

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…

 

[dramirez]

You almost caught it time!

 

[chiptripper]

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.

 

[Big Ben]

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.

 

[naruse]

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:/