Jump to content

Ferrix97

6502
  • Content count

    253
  • Joined

  • Last visited

About Ferrix97

  • Birthday 09/20/1997

Profile Information

  • Gender
    Male
  • Location
    Mozzanica, Bergamo, Italy
  • Interests
    Love electronics and retrocomputing!

Recent Profile Visitors

320 profile views
  1. Ferrix97

    Macintosh Plus Analog Board Q12 replacement

    Have you also checked the diodes and the feedback circuit close to the optocoupler? You should check the main switching transistor off-circuit, as it's connected to primary of the transformer (which is a very low "DC resistance") but that rarely fails since it's beefier on 240V boards. As for Q12, I've had luck in the past with old BRX49 and BRX46. The older the better, the ones I've got don't require any resistor mod, they just have a different pinout.
  2. Ferrix97

    Macintosh Plus Analog Board Q12 replacement

    5.2V and 12.35V are on the limit of acceptable, I'd usually stay a tiny bit lower (like 5.1V), either way that shouldn't cause any damage
  3. Ferrix97

    Macintosh Plus Analog Board Q12 replacement

    The best thing to do is to try a bunch of BRX4x, It took me ages to find a working replacement. Best thing is to order an old part manufactured in the late 80s-90s and try that. Newer ones will not work.
  4. Your friend is not the only one who made that mistake... in this case the entire primary side of the power supply needs to be redone, probably a couple of resistors and diodes are still good, but if easier to redo the entire thing in one go. Pay special attention to the SCR, the board is very picky.
  5. Ferrix97

    Mac classic blows MOSFET

    If you replace the main switching mosfet you might also need to replace the blue capacitor next to it, forget the value or it's name, also check for shorts on the secondary, mainly the big rectifiers
  6. Ferrix97

    Hard to find G5 items

    There are about 3 to 5 cards compatible with the PCIe G5 (all of them better than the 6600). Personally I opted for the FX4500 but that might not be the best for every application. You can find cheap (paid about 25€ shipped for mine) PC cards and flash them with the Mac ROM later. Just make sure the card has VRAM on both sides.
  7. Ferrix97

    Powerbook 140 Issues

    That ticking coming from the speaker might be the power supply that turns on and off (with the old caps it's pretty unstable). But in this case the hard drive should stay off or follow the ticking. I also have a (quite old) video on my channel where I open the power supply by applying pressure on the lower side to crack the two halves clean. https://youtu.be/LxG3NO0jy9U If the board is cleaned properly and all the capacitor are replaced with good quality ones, it'll probably last forever. If you don't wan't to deal with all of this, you can also pick up a Playstation One power supply and change the connector at the end. They are more reliable and easier to obtain. Unlike the Macintosh Portable, PowerBooks have a moderately robust power supply circuit. I've seen them run with 12V power supplies without issues (as they have the same plug and most eBay sellers and such don't check the specs), they also have minot reverse polarity protection in form of a diode (that might short).
  8. Ferrix97

    Powerbook 140 Issues

    If you have a dark screen with no (or very little) contrast control it's almost always the caps. As for the ticking noise, it's possibile that the head inside the hard drive is stuck. I have videos that show how to solve both problems on my Youtube channel https://youtu.be/9YhiiOUWu64?t=4m7s https://youtu.be/XP-fWaDbv5s The power supply will need new caps soon, but I don't think it's the problem this time.
  9. Yes, there's a slight dip at around 9V when the IC starts working (if you measure while connected to a variac). But before staring to measure the IC, I'll change the poly cap and the fusible resistor first
  10. usually a bad TDA won't drive the mosfet, so it would show no life. You can compare it with a good working board my monitoring the supply voltage (pin 6) when slowly ramping up the mains voltage with a variac. but if yours blows the mosfet, that shouldn't help. Check the board for shorts or burnt resistors, but there's a high chance that the capacitor I mentioned earlier (even if it measures ok) is bad, I've seen that kill mosfets before.
  11. I'm away from home, so don't have a classic AB in front of me. Looking at my notes, the capacitor is CP23 (270pf 2000V) and the resistor is RP40 (220 Ohms Fusible). Both of them are very close to the mosfet. You should also check for shorted diodes (mainly the two big rectifiers, but doesn't hurt to check all of them)
  12. Usually when the mosfet blows, there are a few more components that fail with it, sometimes it's the regulator IC (but quite rare), and most of the times is a fusible resistor (can't recall value or location, possibly between the IC an the gate of the mosfet) and a polyester (blue or yellow) capacitor that's also close to the mosfet. Will try and dig up more information later if needed.
  13. Ferrix97

    Macintosh Portable power regulation

    You can tweak the PowerBook bricks to limit them at 1.5A, but it seems that rather than current limiting, they just go into protection. As for the capacitors, they are very simple to fix, I have a video showing how to do it on my YT channel
  14. I've made a video showing my last attempt. Unfortunately it was even harder to do with the iPhone in the way... This is just another attempt, not a repair guide. I still need to figure out the best airflow and temperature setting. But so far I can confirm that both my powerbooks are holding nicely and seem more robust than plastic or 2-part glue. https://youtu.be/X_tqtJlVk2g
  15. Ferrix97

    Macintosh Portable power regulation

    The Power Supply for the portable needs to be limited at 1.5A, only the white brick is recommended. The gray PowerBook ones deliver 2A or more and can damage the Portable
×