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    #21
    Re: gateway desktop no post

    Thanks again everell here are the measurements as suggested
    Bestec
    vsb 4.8v, Red 5.08v, yellow 12.16 volts and orange 3.32v
    delta
    vsb 5v, red 5.16v, yellow 12v orange 3.37v
    Pic attached show 001 delta psu and 002 bestec
    hope this can helps
    Attached Files

    Comment


      #22
      Re: gateway desktop no post

      Originally posted by everell
      My comment on testing the northbridge was only intended in humor.

      What????

      I just unsoldered the NB chip and was going to ask you what tester to use. Now I don't know which way I should solder it back on....

      Comment


        #23
        Re: gateway desktop no post

        Voltages on both power supplies look OK, and the photos look good. I did not see any bulged capacitors, nor did I see any burn areas on the pc boards indicating a problem. Usually the Bestec will have a burned area near the small transformer if it is giving a problem.

        Next step - make a list of the capacitors in the power supplies and on the motherboards. The capacitors need to be listed by brand, capacitance ( a number followed by uF), and voltage. The members on this site will be happy to tell you which capacitors are the potential problems and need to be replaced. I would go for cap replacements next, then consider reflashing the bios chip if it still doesn't work. There is a guy on ebay that will reflash you eprom for about five bucks. I have had him do it for me on two motherboards that were dead. Worked on both of them.

        Both power supplies working is good news. The mother board that spins the fan and can be stopped shows that the southbridge chip is not blasted. If this board had a catastropic surge, I would have expected the southbridge chip to be shot. So I think there is hope for this board. As we continue, you might get the other board to work also. One of the boards that I did the reflash on the bios chip was totally dead, and would not spin the fan. So you never know till you experiment, and learn lots of new things about computer boards.

        If the southbridge is working, I would think the northbridge is PROBABLY working also. No need to unsolder it and take it off the board. Do both of these mother boards have on board video? If they do, the mother boards will have a video connector soldered directly to the mother board.
        Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

        Comment


          #24
          Re: gateway desktop no post

          Originally posted by everell
          Voltages on both power supplies look OK, and the photos look good. I did not see any bulged capacitors, nor did I see any burn areas on the pc boards indicating a problem. Usually the Bestec will have a burned area near the small transformer if it is giving a problem.

          Next step - make a list of the capacitors in the power supplies and on the motherboards. The capacitors need to be listed by brand, capacitance ( a number followed by uF), and voltage. The members on this site will be happy to tell you which capacitors are the potential problems and need to be replaced. I would go for cap replacements next, then consider reflashing the bios chip if it still doesn't work. There is a guy on ebay that will reflash you eprom for about five bucks. I have had him do it for me on two motherboards that were dead. Worked on both of them.

          Both power supplies working is good news. The mother board that spins the fan and can be stopped shows that the southbridge chip is not blasted. If this board had a catastropic surge, I would have expected the southbridge chip to be shot. So I think there is hope for this board. As we continue, you might get the other board to work also. One of the boards that I did the reflash on the bios chip was totally dead, and would not spin the fan. So you never know till you experiment, and learn lots of new things about computer boards.

          If the southbridge is working, I would think the northbridge is PROBABLY working also. No need to unsolder it and take it off the board. Do both of these mother boards have on board video? If they do, the mother boards will have a video connector soldered directly to the mother board.
          Thanks again appreciate all your help and I am indeed learning a lot about computer boards thanks to the help of fine people like yourself. Just learning how to trouble shoot power supplies was gratifying very much appreciated. Yes the two boards do have on board video. Should I be looking for a new eprom? What is involved in having it re-flashed? Do I have to ship out the board or is the eprom removable? How do I find this guy on ebay?

          Comment


            #25
            Re: gateway desktop no post

            Looking at the photo of the board that spins the fan, the bios chip is the small square chip in a socket at the upper left hand corner in the photo. Insert a very small screwdriver in one of the two corner slots and gently pry upward. You might need to alternate sides as you pry it upward. Just don't get in a hurry and force it or you will break the socket. Once the bios chip is out, the only thing you need to send out for reflash is that little square chip.

            The seller on ebay that I used is gilabite. He charges $5.50 and a little postage. Did a great job for me. Look around and you might find others. On ebay you can do a search by seller and look for gilabite, or you can do a general search for bios chip.

            Another suggestion, since the board does have an unknown problem, I would remove the cmos battery. A flakey battery can cause all sorts of problems. You don't need to have a battery installed when troubleshooting just to get the computer to post. Without a battery, the computer will simply default to original cmos parameters. Your first job is to fix it so that it will post something. Then install a NEW battery. This will save a few more headaches down the road. The cmos battery is the little watch battery about the size of a quarter in a socket. It is usually a 2032 type battery.
            Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

            Comment


              #26
              Re: gateway desktop no post

              Thanks everell here are the Caps on the board that spins the fan are as fellows:
              KZG 16v@1800uf (4)
              KZG 6v@1500uf (2)
              TWF 4v@680uf (6)
              KZE 10v@680uf (4)
              KZG 6v@470uf (1)
              TEAPO 10v@470uf (3)
              TEAPO 6.3v@470uf (4)
              KZJ 6.3@1800uf (2)
              Sanyo 25v@470uf (1)
              TEAPO 10v@100uf (14)
              TEAPO 6.3v@1000uf (1)
              TEAPO 16v@22uf (1)
              TEAPO 6.3@220uf (1)
              PET ????(1)

              Comment


                #27
                Re: gateway desktop no post

                While you have the mother board out of the case, before you mess with the bios chip, another test you can do .... make sure cpu and heat sink are installed on motherboard, plug power supply connector into mother board. Plug monitor into mother board video connector. Go ahead and take out cmos battery. No floppy, hard drive, or CDROM plugged in. You will have to plug in the connector from the power-on switch to the mother board. Now turn it on and see if it will post.

                Sometimes when the mother board is installed in a case, the board is slightly misaligned just enough that it shorts something out. If it will post when not installed in the case, just install it back in the case and see if it will post. If not, turn off power and realign the mother board, then turn on power again. Repeat this until you can determine what is shorting the mother board. Surprising how many times you will run into this problem.
                Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

                Comment


                  #28
                  Re: gateway desktop no post

                  Originally posted by everell
                  While you have the mother board out of the case, before you mess with the bios chip, another test you can do .... make sure cpu and heat sink are installed on motherboard, plug power supply connector into mother board. Plug monitor into mother board video connector. Go ahead and take out cmos battery. No floppy, hard drive, or CDROM plugged in. You will have to plug in the connector from the power-on switch to the mother board. Now turn it on and see if it will post.

                  Sometimes when the mother board is installed in a case, the board is slightly misaligned just enough that it shorts something out. If it will post when not installed in the case, just install it back in the case and see if it will post. If not, turn off power and realign the mother board, then turn on power again. Repeat this until you can determine what is shorting the mother board. Surprising how many times you will run into this problem.
                  I am surprised!!!! With the board out and following your instructions it do post??? If i turn it of and on though sometimes it will post and sometimes it wouldn't. I have not put it back into the case yet i am too excited, but I did try it with the cmos battery installed and it will post.

                  Comment


                    #29
                    Re: gateway desktop no post

                    I have now put the board back into the case and all is working fine many many thangs to everell. Since this is a hobby I would like to trouble shoot the other board and I have tried the same process but still nothing. I can turn it on and off with the main switch put it will not post and it will not start the fan., as requested here is a list of caps on that board;
                    KZG 16v@1500uf (4)
                    RLX 6.3v@1500 uf (2)
                    TEAPO 6.3v@1000uf (10)
                    Rubycon 6.3v@2200 (6)
                    TEAPO 16v@470uf (4)
                    TEAPO 25v@100uf (1)
                    TEAPO 16v@100uf (5)
                    OST 6.3v@1500uf (1)
                    Shouls I be concerned about any of these?

                    Comment


                      #30
                      Re: gateway desktop no post

                      could also be broken bga soldering.

                      Comment


                        #31
                        Re: gateway desktop no post

                        That's really great that you got one to post. Now lets take it a step further. Pull that cmos battery out and measure its voltage. You may be suffering from a marginal battery. It has probably been there quite a while, and it wouldn't hurt to simply toss the old battery and put in a new one. The computer will post without a battery, or with a new (good) battery. But a marginal battery can cause all sorts of problems.

                        Next, when you turn on the computer and it does post properly, measure the +5volts, +12volts, and +3.3 volts. We can compare these results with your previous measurements. The two readings should be close, or you may have a problem still.

                        Since the computer does post, the bios chip is functioning properly. No need to reflash it. Perhaps that will be the issue on the other computer.

                        You still should consider recapping the board. I am not fond of the Teapo caps, and don't think many of the other members are either. Hopefully, some of the others on this website can steer you in the right direction on that. I usually just go for it and recap, using Nichicon PW series capacitors which I buy from Digikey. Ohe trick I have found is to always buy at least ten of any value I buy. Digikey gives a good price break when buying quantities of ten, and they always come in handy later.

                        On the other board that won't post, measure the +5 volts, +12 volts, and +3.3 volts with the mother board powered up. That should tell you if one of those lines is loading from a problem, and where your trouble lies. Don't be scared to put that voltmeter to use.
                        Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

                        Comment


                          #32
                          Re: gateway desktop no post

                          I would like to comment further on your Bestec power supply. I have a Bestec ATX-300 12E Rev. D which looks different from yours. Mine has two 8 pin integrated circuits between the two heat sinks. One is a UC3842 which is the main PWM chip. The other is A6351A which is a PWM chip for the 5vsb circuit. In the picture you posted, I saw only one chip. Check and see if your power supply has one or two chips, and what number is on the chip. If you only have one chip, look at the heat sink nearest the two big capacitors. Does it have one or two transistors screwed to it? One transistor would be much larger than the other. A few more pictures would really be appreciated, especially close up between the heat sinks.

                          What concerns me is that you may have an early model of the Bestec ATX-300 12E, and it may have the mother board killer circuit in it. If so, you will need to replace it.

                          Tom
                          Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

                          Comment


                            #33
                            Re: gateway desktop no post

                            Originally posted by everell
                            That's really great that you got one to post. Now lets take it a step further. Pull that cmos battery out and measure its voltage. You may be suffering from a marginal battery. It has probably been there quite a while, and it wouldn't hurt to simply toss the old battery and put in a new one. The computer will post without a battery, or with a new (good) battery. But a marginal battery can cause all sorts of problems.

                            Next, when you turn on the computer and it does post properly, measure the +5volts, +12volts, and +3.3 volts. We can compare these results with your previous measurements. The two readings should be close, or you may have a problem still.

                            Since the computer does post, the bios chip is functioning properly. No need to reflash it. Perhaps that will be the issue on the other computer.

                            You still should consider recapping the board. I am not fond of the Teapo caps, and don't think many of the other members are either. Hopefully, some of the others on this website can steer you in the right direction on that. I usually just go for it and recap, using Nichicon PW series capacitors which I buy from Digikey. Ohe trick I have found is to always buy at least ten of any value I buy. Digikey gives a good price break when buying quantities of ten, and they always come in handy later.

                            On the other board that won't post, measure the +5 volts, +12 volts, and +3.3 volts with the mother board powered up. That should tell you if one of those lines is loading from a problem, and where your trouble lies. Don't be scared to put that voltmeter to use.
                            Thanks everell I will let the first computer run for a couple of days before I take any further action and will probely try re-capping it? In the mean time I will spend some time on the one that will not post or spin the fan just to try my luck of getting it up and running? so i hope you don't mind my asking foolish questions as I go like what is a bga and how can one check the solder for being broken as suggested by kc8adu

                            Comment


                              #34
                              Re: gateway desktop no post

                              I don't mind your foolish questions as I don't consider them to be foolish at all. We all have to learn, and too many of your questions sound like "been there done that". So I feel just as foolish at times.

                              I do think you should run your good computer on the Delta power supply. I still have reservations about that Bestec until we can determine if it has the mother board killer circuit in it. If so, it can be characterized as being something like a time bomb. At a moment you least expect, it goes boom and then your mother board is finished!

                              I have no idea what a bga is. I think it was probably a typo error and he meant to say vga. So do a careful visual check of the solder connections on the "vga" connector soldered to the mother board. A magnifying glass will be helpful. What you are looking for is fractured solder joints. The "vga" connector is the one the monitor plugs into.

                              Did you check the voltages while the computer is running? How did they look?

                              Have you tried hooking up hard drive and cdrom to the computer yet? Hook them up one at a time and then test for proper operation. One of them may have been the cause of the original problem.
                              Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

                              Comment


                                #35
                                Re: gateway desktop no post

                                No, it wasn't a typo.
                                .
                                BGA = Ball Grid Array.
                                That's usually how IC chips [like the main chipset on a mobo] are attached to PCB's when you don't see any pins or legs on the chip.
                                .
                                Sometimes the solder separates and you get a bad [or no] connection between the chip and the PCB. Some parts are famous for it. [The main cause of the famous Xbox LED circle of death is BGA soldering issues.]
                                .
                                http://en.wikipedia.org/wiki/Ball_grid_array
                                .
                                Last edited by PCBONEZ; 06-19-2009, 08:11 PM.
                                Mann-Made Global Warming.
                                - We should be more concerned about the Intellectual Climate.

                                -
                                Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

                                - Dr Seuss
                                -
                                You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                                -

                                Comment


                                  #36
                                  Re: gateway desktop no post

                                  Originally posted by everell
                                  I don't mind your foolish questions as I don't consider them to be foolish at all. We all have to learn, and too many of your questions sound like "been there done that". So I feel just as foolish at times.

                                  I do think you should run your good computer on the Delta power supply. I still have reservations about that Bestec until we can determine if it has the mother board killer circuit in it. If so, it can be characterized as being something like a time bomb. At a moment you least expect, it goes boom and then your mother board is finished!

                                  I have no idea what a bga is. I think it was probably a typo error and he meant to say vga. So do a careful visual check of the solder connections on the "vga" connector soldered to the mother board. A magnifying glass will be helpful. What you are looking for is fractured solder joints. The "vga" connector is the one the monitor plugs into.

                                  Did you check the voltages while the computer is running? How did they look?

                                  Have you tried hooking up hard drive and cdrom to the computer yet? Hook them up one at a time and then test for proper operation. One of them may have been the cause of the original problem.
                                  Thanks again I have the first computer up and running fully HD and all and it do seem to be doing well. I did notice that it did hang on shut down a few times and I had to manually shut it down. I will change out the power supply just to be sure. I have not taken the measurements yet will post pictures and voltage readings

                                  Comment


                                    #37
                                    Re: gateway desktop no post

                                    bga=ball grid array, sounds good to me. But how would you be able to check for bad solder joints on the bga? The bga pins on the north bridge and south bridge are under the chips - you can't get to it using an ordinary soldering iron. I can't imagine how anyone could remove a north bridge or south bridge chip without doing a lot of damage to the chip.
                                    Old proverb say.........If you shoot at nothing, you will hit nothing (George Henry 10-14-11)

                                    Comment


                                      #38
                                      Re: gateway desktop no post

                                      Originally posted by everell
                                      But how would you be able to check for bad solder joints on the bga?
                                      You can't short of it just not working.

                                      Working with BGA takes special equipment.
                                      Basically they use temp controlled equipment to heat the PCB and the chip to melt the solder balls in between them.
                                      Mann-Made Global Warming.
                                      - We should be more concerned about the Intellectual Climate.

                                      -
                                      Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind.

                                      - Dr Seuss
                                      -
                                      You can teach a man to fish and feed him for life, but if he can't handle sushi you must also teach him to cook.
                                      -

                                      Comment


                                        #39
                                        Re: gateway desktop no post

                                        Originally posted by everell
                                        I don't mind your foolish questions as I don't consider them to be foolish at all. We all have to learn, and too many of your questions sound like "been there done that". So I feel just as foolish at times.

                                        I do think you should run your good computer on the Delta power supply. I still have reservations about that Bestec until we can determine if it has the mother board killer circuit in it. If so, it can be characterized as being something like a time bomb. At a moment you least expect, it goes boom and then your mother board is finished!

                                        I have no idea what a bga is. I think it was probably a typo error and he meant to say vga. So do a careful visual check of the solder connections on the "vga" connector soldered to the mother board. A magnifying glass will be helpful. What you are looking for is fractured solder joints. The "vga" connector is the one the monitor plugs into.

                                        Did you check the voltages while the computer is running? How did they look?

                                        Have you tried hooking up hard drive and cdrom to the computer yet? Hook them up one at a time and then test for proper operation. One of them may have been the cause of the original problem.
                                        I have now changed out the power supply as suggested and the voltage readings are as follows Red 5.16v yellow 11.87v orange 3.36v violet 4.97 with all working fine. I did find a bad stick of ram (1 gig).The other board with power on it is not reading any voltage at all although the power light is on and I can turn it on and off with the switch?? another pic of that Bestac hope it will help
                                        Attached Files

                                        Comment


                                          #40
                                          Re: gateway desktop no post

                                          Originally posted by everell
                                          I would like to comment further on your Bestec power supply. I have a Bestec ATX-300 12E Rev. D which looks different from yours. Mine has two 8 pin integrated circuits between the two heat sinks. One is a UC3842 which is the main PWM chip. The other is A6351A which is a PWM chip for the 5vsb circuit. In the picture you posted, I saw only one chip. Check and see if your power supply has one or two chips, and what number is on the chip. If you only have one chip, look at the heat sink nearest the two big capacitors. Does it have one or two transistors screwed to it? One transistor would be much larger than the other. A few more pictures would really be appreciated, especially close up between the heat sinks.

                                          What concerns me is that you may have an early model of the Bestec ATX-300 12E, and it may have the mother board killer circuit in it. If so, you will need to replace it.

                                          Tom
                                          There ar two chips between the heat sink. The large one is T-105USWT1A and the smaller one is T-ATX250HPT2E. There is only one transister screwed to the heat sink closest to the two large cap
                                          Attached Files

                                          Comment

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