Dell D800 AC adapter turns off when plug in

By wrapmyride
Jun 15, 2008
Topic Status:
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  1. My Dell D800 laptop stop working.

    When I plug the ac-adapter the power light goes off on the adapter. It is obvious short on the motherboard. I did took it apart and look for some problem around DC-jack, but I don't think the problem is there. All the accessories are off . It is only mobo now by it self and does same thing. Anybody knows where I should look for the short. Which chip or diode it could be? I heard it is very common problem with D800 and D600 models. Since I am pretty good with soldering I think, and it is my hobby as well I would like to repair the mobo my self instead replace. Definitely would be much cheaper as well.

    Thanks in advance for any input on this matter.
  2. Tmagic650

    Tmagic650 TS Ambassador Posts: 20,748   +156

    Some laptops have a separate internal DC converter, and some DC converters are part of the motherboard. If you haven't tried another AC adapter, I would do that first. After replacing the AC adapter, check the DC jack for a high resistance using a good multimeter... A normal resistance would be around a half Meg ohm. If the internals are shorted, the resistance would be much lower. Unless you have the skill and tools to do surface mount soldering, I wouldn't attempt a repair
  3. wrapmyride

    wrapmyride Newcomer, in training Topic Starter Posts: 32

    Thanks for a quick replay. I did try another ac-adapter with same result. With the male plug in and light went out on the ac adapter checking resistance between positive and negative it starts let say with half Meg ohm and it claims and claim higher and higher very fast. So like you sad it points to DC converters. I do have a skill to replace a surface chip I have done it before like a mosfats and diodes with some success. I know this is a hobby of mine and if you know which chip to replace I would really appreciate it. I would like to extend my knowledge and do more serious stuff like this. Thanks again
  4. Tmagic650

    Tmagic650 TS Ambassador Posts: 20,748   +156

    I haven't had too much luck finding Dell service manuals. If the DC jack is on a removable assembly, and not soldered directly to the motherboard, you will find a separate converter board piggybacked to the motherboard. This symptom you have is not common at all. The first thing to determin is if the conversion circuits are part of the motherboard or on a separate assembly...
  5. wrapmyride

    wrapmyride Newcomer, in training Topic Starter Posts: 32

    Thanks for your help it helped me to look in a right direction and I think I got it.There are three same looking capacitors beside each other and one of them was faulty. Remove the one bad then solder a similar to it place and the AC adapter lite stays on and I can read voltage already on the motherboard. Now I will put it together and keep you updated if I did actually win this time. Oh one more thing you sad it is not very common I have seen already two Dell D600 with the same symptoms and this one.
    Thanks again Tmagic650
  6. Tmagic650

    Tmagic650 TS Ambassador Posts: 20,748   +156

    That's great wrapmyride,
    I haven't worked on many Dell laptops... It might be something common with Dell. Good luck
  7. wrapmyride

    wrapmyride Newcomer, in training Topic Starter Posts: 32

    I don't know if it is common on Dells, but I have seen this problem twice before this one. It could had been something else twice before, but now I know what to look for next time. This one is together and working.

    Thanks again Tmagic650
  8. Tmagic650

    Tmagic650 TS Ambassador Posts: 20,748   +156

    Ok wrapmyride,
    glad I could help and I will keep this in mind if I run across one in the future...
  9. mscrx

    mscrx Newcomer, in training Posts: 829

    hi guys,

    great to see problems being solved. I wanted to add that this problem was a common problem with the d*00 series. I had alot of d600 and d400 with this problem on my desk.
  10. lamo

    lamo Newcomer, in training Posts: 570

    mscrx, 19v short circuit problems are common problems for all laptops. they are connected with bad ceramic capacitors. but this case is lucky case of the problem solving. 19v bus located on all mb surface(this is due to that many PWM controllers eats 19v as their main input voltage), so when some capacitor is bad, the laptop completely dead. as for me, i solving such problems with "burning method". :)
  11. mscrx

    mscrx Newcomer, in training Posts: 829

    donno if it is a common problem. I can only tell from my experience with dell laptops and I support 1500 of them (from c400 to m6300 including all d-series models) and only the d400 and d600 I found had this problem. the others work(ed) pretty fine and no problems liek that. just my experience...
     
  12. wrapmyride

    wrapmyride Newcomer, in training Topic Starter Posts: 32

    .Thanks a lot for input on this problem guys, but can you Lamo be more specific on your "burning method". I know I got lucky to find that capacitor. In my case I did remove the black plastic from mobo where I was experting the problem and them I noticed one of the capacitor looked like had a left over glue from plastic on top of it. I did check the resistance on the bottom of the mobo and it was same resistance as other two, but on top of the capacitor was 0. Well soon I touch the top with tester the top kind fell apart. I think I got lucky there to locate it that way. That is why I would like to know Lamo method to locate them next time. Thanks again
  13. lamo

    lamo Newcomer, in training Posts: 570

    wrapmyride, i can describe this method, but i warning you, that this method is dangerous if you don't know or don't sure where to connect + cable.
    if you see, that resictance on the capacitor is 0 between + and gnd, do the following. you need good Power supply with voltage and current regulation. connect + of PS cable to positive field of capacitor(or to positive input of AC connector) and gnd to gnd field of MB. set the current of your PS to maximum, set the voltage regulator to minimum. turn on your power supply and start SLOWLY to increase the voltage of PS. don't forget to constantly check the current inceasing. when you reach current consumption near 1.5A stop to increase the voltage and begin to check capacitors(mosfets, resisotrs etc) for heating. i do it using my fingers :)
    usually this method usable when you have some dead capacitors on 19v bus.

    Attention! This method is VERY dangeous if you don't know WHAT EXACTLY you do! do it at your own risk.
  14. wrapmyride

    wrapmyride Newcomer, in training Topic Starter Posts: 32

    Hi Lamo.
    I am sure lot off guys will be happy to know this method. I know I am very happy and next time I will try it for sure. I do understand the risk involved, but you start with a dead mobo and you may end up with success or it will be still dead mobo. Again it is a hobby of mine and I like to learn new things all the time. This is a very good info for laptop repairs.
    Thanks a lot again.
  15. airation

    airation Newcomer, in training

    D800 shorting ac adapter

    I have 6-7 Dell D800 motherboards with similar problems. Think you could fix them wrapmyride?
  16. deux35

    deux35 Newcomer, in training

    Hey wrapmyride, I found the faulty capacitor but how can you find the right replacement.

    thanks
  17. wrapmyride

    wrapmyride Newcomer, in training Topic Starter Posts: 32

    I believe Lamo would answer that question better. I would try to match it with a same looking one from a used mobo. I have few laying around just for that reason. But first if you can open a working D800 that would by the best to get the reading from that one to make sure what you looking for. Then check the one you want to use with the meter from used board so you know it is good and replace it. You can also try to find then in special electrical stores if you have any in your area, but I find it more harder find it there, because there is very few stores like that and they usually have small inventory.
  18. wrapmyride

    wrapmyride Newcomer, in training Topic Starter Posts: 32

    My apology I was a way sorry for late reply. I would probably could, but Lamo would be better because he show me the way how to do it. I am still learning myself. It is still only a hobby for me. My record is from tree tries two wins one loss. But I have to admit those two wins felt good. You should try it your self I think its fun. I have to admit you have to understand the electronics little and keep learning and then practice soldering a lot.
  19. justamailman

    justamailman Newcomer, in training

    d800 vga connector problem

    Hi wrapwmyride

    Have you heard about vga connector problem on dell d800. I have such problem . It is working ok if I push the vga cable upward when connected to my vga connector. I figure it is a loose solder probably. I have open the laptop down to the motherboard but found nothing obvious. I would like to fix it myself but am not sure where the connection pins are located on the motherbord itself in order to resolder them . Is there a way to find out . Do they publish schematic or something to follow somewhere
    Thanks in Advance
    from Ontario, Canada
  20. lamo

    lamo Newcomer, in training Posts: 570

    usually ,you have 30-40 capacitors in MB at 19v bus. if one of them makes short circuit, you'll have to unsolder all of them. and this is useless. with the burning method you can find one faulty capacitor without unsoldering 30-40 small planar elements. and of course, you can find any faulty chips/mosfets/etc with this method. let's take some example: asus w3j. laptops wasn't react to power button pressing. there's short circuit in 3.3v bus. with this method, i found the dead ricoh r5c832 cardbus controller(a lot of heat). this took to me about 5 minutes.
  21. wrapmyride

    wrapmyride Newcomer, in training Topic Starter Posts: 32

    I think you should read the whole thing, because Lamo already explained how it is done. I have tried the burn in technic what Lamo suggested and I it worked. The subject here is when you can not use a regular adapter, because it will shut itself of to protect the components and itself I think. You have to find where is the short and that is the fastest way. I recommend to read Lamo's post #13 again and like he says be very careful.
  22. airation

    airation Newcomer, in training

    D800 with short in mobo

    lamo, I have several D800 mobo's with a short. Do you think you could repair them?
  23. toddbailey

    toddbailey Newcomer, in training

    D800 Schematic

    Did anyone ever find a m/b scemtic for the dell d800 laptop?

    I need to t/s a non working fan and not recogiz. the psu connected issue.
  24. master99

    master99 Newcomer, in training

    DELL D800-Dell D800 AC adapter turns off when plug in


    Hello i am having the same problem, what i would like to know is what part of the board did you come across these capacitors ? underside of motherboard? or the top of the board? where are they near? which compacitors are they are they the small brown ones? or the black ones with the writing on? or the tanned ones which are kind of bigger? please can you tell me what part of the board please, and which one you removed i most have the same problem. but i wouldblike to know where they are on the board so i can test to see if it is them. thank you for your time
  25. wrapmyride

    wrapmyride Newcomer, in training Topic Starter Posts: 32

    I have to say the same thing what I sad before. Read all the replays in this two pages especially the ones from Lamo. He is the one who showed and explained us the "burning method". I have done that method numerous times with success on different motherboard as well. At the beginning I strangled a little, but that is the fun. I can't tell you which capacitor it is, because it could be any and there is a lot of them. It could be on top or bottom just follow Lamos guide of burning method and it will show you which one is it.
    Thanks a lot again to Lamo.
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