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Showing results for tags 'checkerboard'.
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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.
Hey guys! Recently I managed to pick up a Macintosh Classic in very good nick, however, it wasn't working. The previous owner told be that he was using it one day, and the Mac made a bang and stopped working. He said that the fuse had gone, and that I would simply have to plug in a new fuse. I took it home and tried to power it up again just to see if I was lucky, but sure enough, it was broken. I didn't hear a hard drive spin, no beep, no CRT noises, nothing. I cracked it open and sure enough, the fuse was missing. I bought an equivalent fuse and plugged it in, I powered it up, but still, nothing happened. Just silence. There had to be a deeper issue. I completely disassembled the Mac, and took a look at the analogue board and found the true culprit. It seemed a track had completely blown off the board. I tested some of the components, mainly the MOSFET and the capacitors to see if they were failing. I noticed some leaky residue underneath the capacitors, so I began re-capping the board. I also noticed a dead-short across the MOSFET, so I scoured digi-key for a replacement. Here's a list of what I replaced: ALL capacitors on the board (I had to buy from two separate brands, Nichon and Saturn) TDA4605 - replaced with TDA4605-3 IRFBC40 - replaced with IRFBC40L CNY75GB - replaced with CNY75B I didn't have any wire, so I bridged that broken track with a lead I had snipped off a capacitor. When I plugged it all back in and tried it again, I was greeted with some jittery checkerboarding. At least it was actually turning on now. But, the CRT was the only thing working at this point, still no beep, still no hard drive noises. I washed all the sticky capacitor residue off with some isopropyl alcohol and a toothbrush, replaced that battery in the motherboard (I replaced the 3.5v battery with a 3.6v of the same type, does this matter?), and replaced all the capacitors. As my local electronics store didn't stock SMD capacitors, I used through-hole ones that I just soldered to the board. However, when I started the Mac, I still had checkerboarding. I noticed that when the RAM module was removed, the checkerboarding turned to straight vertical stripes. Does anyone know what the problem might be?
Hello Recently I got a macintosh classic that have the checkerboard screen issue. When I opened the machine, I saw a huge corrosion mark under the analog board. I thought it would be some leaking capacitors like many macintosh of this model have, I was ready to recap boards. But it's not. Actually no capacitors have leaked, it's the PRAM battery that opened up completely (litteraly). The analog board seems to be fine but the mainboard has been corroded so much that the battery holder has desoldered. I've tried to clean up some of the corrosion with isopropyl alcohol but there's still a lot of this brown heap. I'm now looking for help on how bring that board back to normal running; like get rid of the corrosion and maybe rewire some pcb tracks and put an PRAM equivalent battery. The machine powers up fine to the checkerboard screen, I tested it before opened it. Here's pictures of the disaster: The leak corroded the chassis. Where the leak occured, the battery holder was where the corrosion heap is. It affected some of chips legs and resistors on the other side. The dead battery. The top is slightly open. The battery and its holder. The holder is completly ruined and was desoldered by the corrosion. Hoping that you can get me some help