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techknight

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  1. Classic ii monitor flicker

    That is the power supply cycling over and over again. Probably caps. Both the analog board and logic board needs cleaned and fully recapped before you can even begin troubleshooting.
  2. 0F0004 error on 128k

    RAM possibly. known for it.
  3. Advice needed! Macintosh Portable Non backlit

    Only spare display I have is junk. it works perfectly except it has tunnelvision like the other powerbooks get. So I keep it around as a "test unit" for fixing boards. Havent used it or fixed boards in a long long time as I have been so busy at work. I cannot wait until we can get financially stable enough so I can hire some code monkeys. Right now I gotta do everything myself. that includes engineering all the electronics in our product line, up to designing the SQL back-end for our infrastructure to administration/support webapps, video LED display content management systems with hotkeys/headshots, etc etc etc. Getting old, fast. I am getting burned out. My current project is getting my crypto library/exe running on the Debian server I just got finished setting up, transferring from the old CentOS environment I was running on. But it wont get past a Segmentation fault, even recompiling didn't help. lol. Enough rubbish to pull my hair out. Funny though, ran fine in the CentOS system. But I digress...
  4. Macintosh Plus Analog Board Q12 replacement

    So I figured it out. macalle69 you in fact did unlock the secret. I have been comparing datasheets from old SCRs to modern SCRs, the threashold voltage and current for triggering is the same. Except for one thing. the load impedence is an order of magnitude more on the old SCRs than on the new SCRs. So when you do the math, to match impedence, that means the old SCR requires 2mA of threshold at 10Ohms, whereas the newer replacements are 200uA at 10ohms. old SCRs are 200uA at 100Ohms. an order of magnitude off. So what this actually means is the circuit is latching the SCR too early as the current across the 2N3906 transistor is ramping up. So by increasing the gate impedance, you require more voltage to trigger the gate. The more resistance you add, the more voltage/current its going to take to trigger the SCR. Precisely what we want. Thats my view at this point. Yall will have to experiment more to see if my theory is correct or way off base here.
  5. Macintosh Plus Analog Board Q12 replacement

    oops double post.
  6. Macintosh Plus Analog Board Q12 replacement

    Well you may have unlocked the secret. Nothing wrong with that! Gotta see which pin that center pin is in the datasheet so I can figure out what part of the circuit this resistance was added to so I can better understand its now added purpose/change.
  7. Macintosh Plus Analog Board Q12 replacement

    Ah ok, so you added some resistance to the circuit.
  8. Advice needed! Macintosh Portable Non backlit

    Half lines are definitely the display, you need another panel.
  9. Macintosh Plus Analog Board Q12 replacement

    With absolutely no details of what you meant by "fixed". Please elaborate for the others in this forum that could use this information. (like me
  10. PowerBook 520, lines on screen, pram batteries

    In the screen itself. There are others on this site that may have documentation to exactly where, but I know it needs caps because I have a monochrome display myself for the 520, and they are leaking. I dont need the display so its sitting in pieces disassembled, rotting away. lol.
  11. PowerBook 520, lines on screen, pram batteries

    That is normal with that type of display. you may need to play with the brightness/contrast a bit to reduce the effect. But chances are, there are capacitors in the display itself that will need checked/replaced.
  12. SE/30 Stripes on Display?

    Slow death chimes? Machine is unable to read the RAM properly. So you have a broken RAM trace, or bad muxes.
  13. Is there any documentation or software out there for writing GUI apps for GS/OS? And did they ever have a GUI BASIC for GS/OS? Just Curious.
  14. PowerBook 170 Dark Corners

    Also, read THIS: https://www.eham.net/ehamforum/smf/index.php?topic=40151.5;wap2
  15. PowerBook 170 Dark Corners

    Well then it appears whatever adhesive/sealant you did use was solvent based, and that will eat up the ribbon cables and its bonding to the LCD glass itself. Hence why you have this failure. Your only other option (with a new display) is silicone maybe? Edit: Nevermind. these displays have the zebra stripes that bond the glass to the base PCB. You have to clean the crap out of the glass connections, the PCB, and the zebra strips(elastometric connector) themselves, and then you have to turn the metal taps that hold everything together super super tight. they cannot be loose. Also the alignment has to be dead-on.
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