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Hi there, I have got a macintosh classic with a broken motherboard. It gives horizon lines and doesn't boot. I have tried a lot. I have cleaned the motherboard with alcohol, I have cleaned it in soapy water, I have replaced all capacitors, I have checked the traces and contacts, all with no succes. When I got this mac it had a bad battery leak but thankfully no traces were erased but I think (having tried almost everything) some chips got effected by the battery acid. What else can I try other than replacing the motherboard? All sugestions are more than welcome! 

 

Thanks, Luuk. 

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If you have a picture of the screen and/or logic board it might assist in identifying the problem. At any rate, I was recently helping a friend with his Classic II, which had problems similar to what you described, and it turned out that there were a few traces that had been messed up by the nearby capacitors. Patching them up fixed it.

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Browsing the big world of Google makes it seem like there could be damage to the board from the battery or capacitors. Open it up and take a look. And like AwkwardPotato said, send us some pictures to narrow down the issue.

 

If the battery didn't explode (which is common), first remove that thing... It's a ticking time bomb. Then disconnect everything and scrub it down (especially on places that appear to be corroded). If there are lifted traces (which hopefully there aren't) just send pictures and someone more educated than I am can give you help.

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Just at first glance, the trace going to D1 definitely looks rough. C1 looks kinda rough too.

 

I also put a few arrows on questionable spots:

oie_zdKQLp8sE9LM.jpg.6f414d64efc548854e92dc2013d0b4a5.jpg

 

Those two ICs near the bottom center look like they have corrosion on them.

Edited by TechEdison

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I see alot of potential trace/via damage. especially in the battery area. And even some trace to pad interconnects on the VIA IC itself are questionable. 

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Man every time I hear a "horror story" about these computers it makes me wonder how in the world mine had none of that...

 

On the bright side, trace damage can be repaired. At least it wasn't a battery bomb that results in un-savable board + case.

 

The 8-Bit Guy just did a video about repairing trace damage (where the board itself cracked) on a PCJr display.

Edited by TechEdison

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I measured the traces going tot the arrow of technight but they still work. The only real damaged trace are the one going to the battery, but the computer should be able to boot without it right? There is corrosion on some chips so I think they might be damaged internaly, is that posible? 

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Some chips got corroded so bad i think some chips are dead so Im gonna ritire this motherboard andere look for an new one so I can get this machine working again. Thanks for all te help tho! 

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15 hours ago, TechEdison said:

 

 

The 8-Bit Guy just did a video about repairing trace damage (where the board itself cracked) on a PCJr display.

 

My very first repair I ever did in my life, I was 9 years old at the time was a cracked PCB repair. it was an old, well, new for the time, PH-D8000 fisher CD boombox (which I still have) that had a broken PCB for the Cd player and I had to solder wires across the crack. Didn't work first try but kept at it until eventually I got it. Its in horrible condition today as I was a kid and didn't take care of my things that well. So I ended up picking up another one just for nostalgia reasons. 

 

I have repaired tons of PCB cracks, but I don't go around holding a video camera every time I do it like he does. Maybe I should? I think the last PCB crack I had to fix, was one of the worst ones. It was a Toshiba CRT projection TV that one of the modules went bad with leaking caps and the last technician cracked the PCB trying to get it out. So I had to wire back about 20 or so traces. Not fun. At the same time fixing the module that he pulled. I cant remember the exact name of the module but its function was comb filtering analog signals, and formatting all the different signal types, resolutions, and frequencies to the native frequency of the deflection board, as it only ran at 1 resolution and 1 frequency so it needed a formatter to adjust everything else. It was a known issue at the time and would cause a horizontal sync loss/scrambled picture when the caps leaked. And this was not even 5 years out of the DOM. 

Edited by techknight

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13 minutes ago, techknight said:

as I was a kid and didn't take care of my things that well.

Man even though I'm still technically "a kid" this totally brings memories to me. I took apart everything I could get my hands on, and most things didn't make it back alive. The most notable for me was an old (yet fully functional still) CTX EZBook... Those things seem increasingly rare, and I guess I'll never own a functional one again.

 

Edit:

Actually this I believe is the one I had: https://www.ebay.com/itm/CTX-EzBook-700E-Series-Laptop-AS-IS-FOR-PARTS/112020523583?epid=1672998210&hash=item1a14f18a3f:g:VuIAAOSwnFZXVv2b
 

And it appears to be the only complete one on ebay.... I might just have to grab that.

Edited by TechEdison

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Yea I had one of those 2nd hand from a laptop place, but the hinges were destroyed, its a known problem with that model. 

 

My dad bought a new family computer in the summer of 97 and it so happened to be a CTX. Everything failed on that thing except the motherboard and video card. Ive had to change the RAM, had to change the CD drive, had to change the floppy drive, and I had to change and send back the Maxtor hard drive under warranty 3 times until we said screw it and got a Fujitsu. Even had to change the CPU! it had a K6-200 which got crash happy and eventually stopped POSTing. Replaced it with an intel MMX 233 and it worked again. Had to set the jumpers to match the CPU of course, I was 12 at the time dad got the machine. 

 

I still have that frankenstein of a machine, Actually got it back Christmas of 2015. When I got rid of years ago to a friend of mine, his parents died and somehow it ended back up in the basement of my families house I moved out of, along with all of the other stuff that was cleared out of the house at the time. So I saw it and grabbed it back. Ended up finding another one just like it so I could make a really nice machine between the two but never got around to it. I learned alot with that machine, even participated in the Microsoft beta program for Millennium and 2000 with it. Still have the beta discs kicking around somewhere. 

Edited by techknight

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