Search results

Had to rebuild a PSU too, the one that Cisco used in it's routers (1800 iirc) fits inside the casing perfectly along with two DC-DC step-up converters for the display. It's slightly less powerful than the original one, but seems to work fine.

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...

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

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.

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.

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

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...

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...

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...

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

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...

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...

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)...

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

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...

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

How hot did you get it? I had my hot air station set to 380°C IIRC If it's ABS it should melt at about 250

I think it was the first thing I tried, didn't work all that well either

Try booting from something like the NAD or Utility disk, they usually don't have PowerBook support therefore they won't software control the backlight. 

Have you tried cleaning the slider control? IIRC on some models is software controller so if it's defective it will start misbehaving only in the boot process