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JNizzle

6502
  • Content Count

    14
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About JNizzle

  • Birthday 01/04/1997

Profile Information

  • Gender
    Male
  • Location
    Australia
  • Interests
    Engineering, retro electronics and video games!
  1. JNizzle

    Classic Analog Board repair

    Awesome! This may come in very handy with my Classic, which I've hit a bit of a wall with. Thanks!
  2. JNizzle

    Bringing a Mac Plus back from the dead!

    We're talking about C33 and 36. I'll take a photo of what I replaced, and what I replaced these caps with. I'll post the links to imgur, as all my pictures are coming out huge for some reason. Caps I replaced: https://i.imgur.com/VOwJRCY.jpg What I replaced them with: https://i.imgur.com/PaH0Iga.jpg I tested all the diodes in the rectifier, I'm getting about 2.1mV in one direction and about 4.6mV in the other.
  3. JNizzle

    Bringing a Mac Plus back from the dead!

    I was poking around in the power supply with my multimeter, and those two caps that I replaced have contact with ground. I'm at least 90% sure that's where my problem lies, as I was at least getting a PICTURE before I replaced them. What actual purpose do they serve? Also I've yet to find any continuity between any component and the live and neutral prongs of the AC input.
  4. JNizzle

    Bringing a Mac Plus back from the dead!

    Alright people, I'm still having issues with the mac. I replaced the two film capacitors with two caps of the same rating and voltage, the dude at Radio Parts (aussie electro store) said they should do the trick. I soldered them in and replaced the fuse with an identical one. However, I didn't even get to turn the mac on before it tripped my house. I plugged the cable into the wall, plugged the other end in my mac, switched it on at the power point, and everything went dark! I think I may have a short somewhere, but I'm unsure.
  5. JNizzle

    Bringing a Mac Plus back from the dead!

    Alright, thanks for the help everyone. I bought some more caps to replace the two film ones on the AB, they're not identical, but they're electrically the same. I bought some fuses as well. When I get home I'll fix it all up, and I'll try re-seating the cables to the logic board. I'll also try re-seating the RAM.
  6. JNizzle

    Bringing a Mac Plus back from the dead!

    Yeah I think I've chosen caps that are a little too high for what was originally on the AB, but I'll swap them out later. I swapped the purple 100uF 200v capacitors out for 100uF 400v ones. Also, you mentioned that the caps might have trouble staying "formed". What exactly does this mean? I tried googling it but I'm not getting clear stuff or I'm just getting walls of text.
  7. JNizzle

    Bringing a Mac Plus back from the dead!

    Okay, noted. I will replace those caps as I just checked, and they do look a little old and cracked. Also, I was under the impression that any capacitor could be replaced by one with the same capacitance, but any HIGHER voltage, as the voltage on a capacitor is only it's minimum voltage. Correct me if I'm wrong.
  8. JNizzle

    Bringing a Mac Plus back from the dead!

    Okay, now some deep dark stuff is going on. I plugged it in, and it's fuse blew in half. It tripped the whole house, everything went dark. I can't do any more testing until I find a new fuse, but this has me thinking, is there just some potentiometer I just need to adjust?
  9. JNizzle

    Bringing a Mac Plus back from the dead!

    Alright, so I resoldered all the contacts around the flyback transformer, and I resoldered the area around that burned-out CRT power plug that I mentioned, because it was covered in a dusty black residue. I'm not sure if this fixed my problem though. I seem to be getting a more solid distribution of horizontal white lines, but my computer hasn't booted since I resoldered. Any ideas? I also haven't heard that whistling in a while, so that may have fixed itself.
  10. JNizzle

    Bringing a Mac Plus back from the dead!

    As I've been turning this Mac off and on throughout the day to test how my repairs have been holding up, I've noticed another weird thing. There is no startup bong and the screen does this stripy half-on kinda thing, where the top of the screen just isn't working and the other half is showing horizontal stripes. Tapping on the side of the Mac restores the picture and I hear the healthy startup bong. I've opened the Mac up again to see if anything is screwing up. This is an odd case!
  11. Hello people! I recently acquired a Mac Plus while doing a clean out of my grandfather's old factory. The keyboard and mouse were FUBAR, as they had been left under an old can of paint which leaked all over them. He said that there was also a hard drive somewhere, but we couldn't find it. I scrubbed as much old paint of this Mac as I could, and besides from a rather even coat of yellowing, it seems to be in pretty good nick. I took it home and plugged it in, and it made the start up bong and the floppy drive made noises, but the screen never fired up. I cracked open the case and besides some dust, everything seemed to be in relatively good shape. No caps were leaking, and nothing looked corroded. I also discovered that this Mac had 4Mb of RAM. Nice! I came to the realisation that this Mac had deeper problems. I noticed when I found the Mac, that it had LOTS of screen burning, which indicated to me that the CRT as a whole could have just bit the dust, or that the flyback transformer was completely screwed. Further poking around inside the machine also revealed that the CRT power connector looked like it was burned or melted. I thought while I had it open, I'd perform the cap change just in case, for longevity if I ever got this thing working. I couldn't find all the correct caps, so I used some higher volt ones, and there was one blue non-polar one that I didn't change at all. Upon firing this up after the change, it worked! I have no idea why the cap change fixed it, non of the caps seemed damaged in the slightest, I verified this when I removed them. No residue or anything! So now I have a semi working Mac, but I have 2 issues which I'm unsure of how to fix. The computer makes a REALLY REALLY high pitched squealing noise. I think this may be the flyback transformer, but I'm not sure. UPDATE: When I fired up the machine to take the photos in this post, the noise was gone! I'm unsure if it will come back, has anyone else had this problem? It's also VERY hard to insert floppies into the drive. The seem to be stuck on something, I'm not sure what though (I've made sure it's aligned correctly). Also, sometimes when I put them in, the jitter around in my hand like crazy until whatever mechanism in there stops, and I can finally insert the disk! And on top of that, the auto eject doesn't seem to be working, but I'm not that familiar with macs that boot directly from disk, as my other mac (a mac classic) is currently not working AND it has a hard drive. I also have no boot disk to test this machine further. Let me know what you guys think!
  12. JNizzle

    Repairing a very damaged Mac Classic

    Thank you so much for your help, I'll definitely try this when my exams are over! I met someone who will lend me a Mac Classic in perfect working order, so I'll be able to test most of my components in there and hopefully rule out some issues.
  13. JNizzle

    Repairing a very damaged Mac Classic

    I tested the voltages, I discovered I'm getting about 4.4v and 11.4v. I adjusted the potentiometer, and I can nail 12v, but I can't get 5v. It just seems to top out at 4.6v and I can't get it any higher. Thoughts?
  14. 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?
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