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  1. Thank you very much @LaPorta now I can confirm this. I was looking at the sorrounding BV4 transistors and they were connected exactly the same way as the one I burnt. Then I started looking on some high resolution photos I found on the internet and with some Photoshop I was able to make the photo more clear and got to see the BV4 on top of the transistor. Thanks a lot, now I can confirm my suspicions.
  2. Thanks a lot @LaPorta I have another floppy drive from a Performa (not compatible with the Classic) I may take the part from its PCB.
  3. You are right. When I was trying to troubleshoot my floppy drive, I left it on top of its bracket without noting it was touching the PCB producing a short. Some electronic component broke and smoke escaped from it. I don't know the specification of the part that broke so I can't change it. If someone has a clue, anything is welcome. The part is located in Q3.
  4. I have the exactly same problem with my floppy drive (Sony 1.44 Macintosh Classic) under System 6.0.8.
  5. Hi @PB145B you are right. It's the same exactly one. So basically that is my main and huge problem. Thank you all of you for give me this very important clue.
  6. BTW, the floppy drive has been serviced, the heads cleaned with isopropyl alcohol and lubricated according to the tutorials I've seen in YouTube. As I said before, as long it's not installed in its bracket, everything works fine.
  7. Hello, Does anyone know why the 1.44 floppy drive from my Macintosh Classic only reads floppy disks when it's not installed on the brackets? While it's connected without the brackets it reads very reliably. As soon as I install the floppy drive in its bracket, the drive reads the system software disk, the Macintosh icon appears, and then it will eject the floppy. That never happens when the drive its outside its bracket. I checked if everything was well installed, if the floppy gets stuck in the opening of the drive, but nothing. Everything looks normal. Thanks.
  8. Finally in some way, I found the solution to the problem. Is not quite elegant but at least it allows me to play with my computer. For some reason when I use an adapter to plug the computer to the power outlet without connecting the ground pin, the voltages remain stable, both the 5V and 12V rails. If I plug the Mac without the adapter the voltages go down. It looks like a lot of energy is escaping through the grounded cable.
  9. The first thing you should do to start diagnosing your Mac is replacing all the capacitors from the logic board and the analog board. Even if they look fine they don't bulge on the top part but they leak from the bottom. Those different patterns you see that change every time you insert a RAM module is normal, those patterns are the ram filling the screen. The more you RAM you install, more patterns you will see.
  10. I'm posting an image of my analog board just in case someone notice something.
  11. I think that big heatsink is attached to a power transistor. I didn't check the little board on the back of the CRT. I'm taking note to check it next time.
  12. Another video, this time booting the Classic using a heater.
  13. Thanks @Joe I already replaced the optocoupler with no luck. The other suspects need to be changed, still I don't know what the heat from the hair dryer has to do with the problem.
  14. Hello everyone! I don't want to quit from this project yet, I recapped each and every single capacitor on the logic board and the analog board. Replaced the two diodes (DP3, DP4) and the optocoupler as some suggested. Reflowed most of the solder joints on the back of the board and searched for broken or cold joints. No luck. The only way I'm able to increase the voltage to the minimum required to boot is using a hair dryer (shown on the video below). I tried to pinpoint the exactly location where the hot air flow is directed and it seems to be the top part where the MOSFET and some
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