Jump to content

BlaBla1985

6502
  • Content Count

    9
  • Joined

  • Last visited

  1. BlaBla1985

    Macintosh Portable audio issue

    I think my bench supply lacked the power needed to run everything at once thus causing the instability. As the bench supply was connected to the battery contacts. But i'll use it like this from now on, it means i can no do some stuff with it. i have a few large clamps and a heatgun, i'll see if i can crack it open and fix up the original PSU. Thanks for the tips.
  2. BlaBla1985

    Macintosh Portable audio issue

    I charged the battery overnight on a 6V car battery charger and tried it out in the portable and that fixes the audio chirping and the instability. I don't think the original PSU is in good shape as the output goes up and down between 7V and 7,5V.
  3. BlaBla1985

    Macintosh Portable audio issue

    i don't use the original charger or the battery. i use a bench power supply set to 6.5V, 2.2A on the battery terminals. although that could mean that the output of that supply isn't as clean as i thought. i have a battery that should work, and some aftermarket 7.5V PSU that came with this Portable and an original one that came with a dead model that i never got working. I could give that a shot. how should i open that original PSU if i need to recap it? it's not screwed together i believe.
  4. BlaBla1985

    Macintosh Portable audio issue

    I'm having a weird issue with the audio in my portable, it often starts to "chirp" for lack of a better term. sometimes it's a continous chirping sound, sometimes it's random chirping and buzzing. And sometimes it's completly quiet unless it's supposed to make a sound. The chirping will usualy mean the system is not running stable, so it will randomly crash if a sound should be played or a floppy it accessed. I've tried to use the system without the harddrive, but the problem remains, no floppy drive, the problem remains. Disconnecting the speaker didn't help alwell (although the noise was gone offcourse). I was wondering if the mosfet that provides the 12V to the soundsystem can be taken out of circuit to test it without any audio stuff connected... but i don't know it the computer will like that. Will it then just burb out random errors or boot with no sound?
  5. BlaBla1985

    Macintosh Portable Display Interchangability

    so, i have a non backlit mainboard with a backlit screen. it has a card in the ROM slot with i guess the backlight driver and a strange cable. Was this some aftermarket solution or an upgrade to the older models? i sadly don't have a better picture of the display cable, but the wires from the card and the connector that goes to the mainboard are soldered onto the flatflex that is connected to the screen
  6. BlaBla1985

    Macintosh Portable Troubleshooting

    i guess the hardest thing in reverse enginering it are those resistor values. i tried to probe around on the hybrid during my troubleshooting, but that really didn't help much without any knowlegde of the actual components. it was more of an accident that i found that short while looking at the chips datasheet to see what it does.
  7. BlaBla1985

    Macintosh Portable Troubleshooting

    on my logicboard, 2 traces on the right end of the hybrid were heavily corroded and made an almost short on 2 pins. There is only a Cap on the other end of those (C18 on the logicboard i believe) and it should be high resistense. it also booted sometimes from disk but it mostly failed halfway. i ended up cutting the 2 traces completly and bodging them with some wire. it's been working fairly good ever since. the 1 meg ohm resistor is no longer there btw
  8. BlaBla1985

    My Macintosh Portable adventure

    i'm not really an Apple or Mac user at all, i mostly have MS DOS portables, and a few other systems like an Osborne 1 and a Commodore SX-64. The fact that Apple made a luggable Mac was the reason i had to have a working one in the collection. If the previous recapper of this one had paid a little more attention to what he or she was doing it would have worked great. The fact that all the cap goo was left on the board was a large part of the work I had to do now. i have another portable, i bought it 2 or 3 years ago. i recapped that and cleaned it but it has never done anything. When i hook that board up to the bench power supply the draws 0.018A and that's all, even at the battery terminals.
  9. BlaBla1985

    My Macintosh Portable adventure

    Hello all, The last few weeks i've been studying the various repair threads of the forum in order to get my own portable running. I'd like to thank everyone here on this forum for providing such a treasure trove of knowledge. Thanks to all that, i now have a working portable. So this is more of a show and tell and thanks post then a help wanted one. I found this post my mc128k: power regulation to be very usefull in diagnosing what was wrong. Also Techknights replies to various posts were a great help. I got the Mac Portable M5120 with a backlit display, ram board and modem from ebay early januari. It was a non starter to begin with, although it still tried to do something when power was applied to the barrel plug. It turned out that the fuse on the mainboard was dead. One of it's previous owners had done a full recap of the system but i think it wasn't cleaned at all and maybe even the old solder was left in place because some of the caps weren't attached to the board at all or by very dull looking solder points. I cleaned a recapped it again. The mosfet that drives the harddisks 12V was looking a bit green and there was a whole load of cap goo underneath it, on of the traces that controls the gate of the fet was also gone. The final point was a short and a bad trace on the Hybrid board. The LT1054's "cap+" and "cap-" pins had less then 50 ohms between them, and one of the traces from the chip to the cap on the mainboard measured about 20 ohms. I removed the corrosion between the 2 traces and added 2 wires to repair the connections. and after this, the portable booted from floppy and from the harddisk. Even the backlit display works. So, thanks to everybody on this forum for sharing your knowledge. one of the things i do need some help with is getting software from windows onto the mac. Most disk images i find are for 8ook drives and nothing seems to be able to write those. The only other apple computer i have is an Apple 2c. Is the SD card floppy emulator a good way to do that? I guess the the floppy emulator would be usefull for the 2c aswell.
×