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MBA A1466 820-00165 no green light, no boot

jurgenkoppen

jurgenkoppen

Member
Thank you for all your help, it is so much appreciated. And yes, the tinyness of the components are a real challenge for me, but I am determined to learn how to do it, if it is the last thing I do. Largely my shakiness is from excitement, it is all so new and mysterious...but I am learning quickly. I did not realize for instance that you would prep the tiny components with a bit of leaded solder until you just now mentioned it. Makes perfect sense!! I have a few of 2009/2010 Mbps I got on Ebay to be my learning aids, ( I was hoping to restore them by replacing the Tantallon cap) Working with this forum is the most exciting way to go about learning..However the components on the Mbas, which my friends give me to fix, are even smaller...One question on diodes: I suppose I can find some on my donor boards, but I am not sure what designation is important...
 
jurgenkoppen

jurgenkoppen

Member
I looked on some of my donor boards for a diode, and found plenty with the 6.8V designation on the A1268 board. However, the symbol is different. The one on the 00165 board has one triangle pointing away from ground towards the horizontal bar. All donor board diodes I have seen have 2 triangles pointing towards each other. Is this just a slightly different symbol still meaning the same? Can I still use those on the donor boards? I also ordered some monsters, as you put it , but perfect for my currently still limited skill level: https://www.ebay.ca/itm/291528748673. In case the donor board double triangle diodes are not useful...
 
2informaticos

2informaticos

Administrator
Staff member
Original is 6.8V zener diode; pretty sure will work any from 5V6 to 8V2 range.
Using fake charger, machine will work even shorting D7012 to ground.

Te zener voltage is marked on the schematics; doesn't matter package symbol.
 
jurgenkoppen

jurgenkoppen

Member
I finally have some time and I am setting out this morning to transplant the 6.8V diode from my A1286 donor to the MBA. Just wondering if you would help me clear up a bit of foggy understanding as far as orientation goes? I suppose I can determine the orientation of the diode I will harvest by measuring resistance and that way determine which way the one way valve for current is oriented, right? And then install it accordingly with the non conducting side to ground. Is that right? Here is where the diode will be coming from...Screen shot 2019-03-08 at 11.13.40 AM.png
 
2informaticos

2informaticos

Administrator
Staff member
You talk about bidirectional TVS diode.
I'm not sure if it works as you need, for very small current; but you can try.
No matters how you solder it, is bidirectional.

TVS diode are used to protect against overvoltage, sinking high currents...
 
jurgenkoppen

jurgenkoppen

Member
I tried and tried,but could not get any of them to stick. I think I will have to wait for the monster zener diode with legs aka pins to arrive from China. I really suck at tiny soldering still. Must watch more videos on it, I suppose....
 
jurgenkoppen

jurgenkoppen

Member
Yes, I was quite frustrated and had to call repeatedly on my infinite patience.Thank you for letting me know that I am not alone in finding this super tricky. The tiny bits either flick away or get stuck to the iron. I will educate myself , there must be some youtube channel that discusses how to go about this. I shall never surrender....if anyone else can do it, then so can I. Cheers, you are an awesome teacher
 
2informaticos

2informaticos

Administrator
Staff member
You can't solder it with iron tip.
Use it only to place it on the flux, in it's place.
Then use hot air to solder it.
Microscope should help you a lot.
Put more flux there, so hot air do not move it away...
 
jurgenkoppen

jurgenkoppen

Member
It turns out that the 6.8V multidirectional diodes are not a replacement for the 6.8V Zener diode. Well, if nothing else it was good exercise in removing diodes from the donor boards. I added leaded solder as I removed them from the donor board, at least they cannot get away that easy, and I have them primed with leaded solder ready to reinstall. After a lot of tries I did get it into place. Would have been so cool if that would have done the trick, since there are lots of them on the old board in the audio circuits, but alas, no cigar. So I am back to zener diode shopping...Being in Canada makes buying stuff from Louis' website pretty expensive, shipping is over the top, for reasons beyond my comprehension.
 
2informaticos

2informaticos

Administrator
Staff member
D7012 has a very low current for its zener voltage
Bigger diodes could require higher current to enter in zener zone.
Check datasheet specifications of the one you want to buy.
0.25-0.5W will work for sure; probably 1W too, just try.

You can short D7012 to ground and use fake charger, it should work...
 
jurgenkoppen

jurgenkoppen

Member
OK so have to admit defeat. I gave up on the board and the zener diodes, just purchased another logic board and just installed it. Still no light on the charger, no boot. Could it be the DC in board which is causing my problem? I also disconnected the keyboard when trying to boot, in order to make sure that no short in the keyboard would interfere. But nada.
 
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jurgenkoppen

jurgenkoppen

Member
Nevermind, she did boot up after all with my new logic board. Appears that the battery is fried and the machine will shut down immediately when I plug it in. The LCD screen was shaky, but stabilized and now is going without flicker....I am getting a new battery and call is a day.
 
jurgenkoppen

jurgenkoppen

Member
OK, I did throw the towel on the old logic board we discussed above, and bought a working one on Ebay. I know it is cheating, but wtf, I am a newbie and got tired of messing with it. Put in the new logic board,: it booted up fine for about 10 min, until I removed some fingerprints smudges on the LCD screen, upon which I lost my backlight. So I did the reseating of the connector, checked the fuse ,which is fine, and then assumed that the screen (which was the original screen in a water damaged machine), might have been compromised when it shorted, and bought another screen. But alas, I still have no backlight. The machine boots, runs well on an external monitor. Now if I could please have some help on finding what else might be the issue...So now I have a new used logic board, a new used screen, and a brand new battery...
 
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2informaticos

2informaticos

Administrator
Staff member
Do you get image on internal screen, only missing backlight?
The forum is full with information about backlight issues, especially for 00165 boards...
 
jurgenkoppen

jurgenkoppen

Member
Yes, I do have the image, only it is very dark. I can run an external screen, so the machine is fine otherwise.
I looked at some of the forum backlight info, and did some measurements. I have nothing on PPVIN_S0SW_LCDBKLT, 0V. So it must be what generates PPVIN_S0SW_LCDBKLT. I 'll keep digging...
 
jurgenkoppen

jurgenkoppen

Member
OK, I tested Q7706 which has voltage only on p2 ands p5, 3.3V each. Then I looked at C7782 which was corroded enough to nearly fall off....
 
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