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(Nearly) dead Gateway laptop...
Appears (to my eye) to have a faulty voltage regulator on the motherboard,
but where? 19.5 VDC input from the AC adapter, but only 1VDC (slightly less actually) available at the Power On switch (which I would expect to have at least 5 VDC). Anybody have any idea how power is handled for these critters? Model 305CRV. Can get SN if necessary. I somehow expected to find something like a LM317, or at least a couple of 7805/7905 combinations. Shows what I know about laptops. Any help is appreciated... Thanks, Dave |
(Nearly) dead Gateway laptop...
On Thu, 28 Oct 2010 09:41:01 -0500, "Dave" wrote:
Appears (to my eye) to have a faulty voltage regulator on the motherboard, but where? 19.5 VDC input from the AC adapter, but only 1VDC (slightly less actually) available at the Power On switch (which I would expect to have at least 5 VDC). Anybody have any idea how power is handled for these critters? Model 305CRV. Can get SN if necessary. I somehow expected to find something like a LM317, or at least a couple of 7805/7905 combinations. Shows what I know about laptops. Any help is appreciated... Thanks, Dave I would expect some type ofswitch mode power supply - they're available as a single chip with minimal external components. Much more efficent than the 'room warmers' like the LM317/78xx devices. Check for questionable electrolytic capacitors - a dead one can kill the switch mode power supply. SMPS don't like caps with high ESR either - probably easier to replace than to test. John |
(Nearly) dead Gateway laptop...
wrote in message ... On Thu, 28 Oct 2010 09:41:01 -0500, "Dave" wrote: Appears (to my eye) to have a faulty voltage regulator on the motherboard, but where? 19.5 VDC input from the AC adapter, but only 1VDC (slightly less actually) available at the Power On switch (which I would expect to have at least 5 VDC). Anybody have any idea how power is handled for these critters? Model 305CRV. Can get SN if necessary. I somehow expected to find something like a LM317, or at least a couple of 7805/7905 combinations. Shows what I know about laptops. Any help is appreciated... Thanks, Dave I would expect some type ofswitch mode power supply - they're available as a single chip with minimal external components. Much more efficent than the 'room warmers' like the LM317/78xx devices. Check for questionable electrolytic capacitors - a dead one can kill the switch mode power supply. SMPS don't like caps with high ESR either - probably easier to replace than to test. John Hey, THANKS John. I will definetly check this out. Much appreciated. Dave |
(Nearly) dead Gateway laptop...
"Dave" wrote in message netamerica... wrote in message ... On Thu, 28 Oct 2010 09:41:01 -0500, "Dave" wrote: Appears (to my eye) to have a faulty voltage regulator on the motherboard, but where? 19.5 VDC input from the AC adapter, but only 1VDC (slightly less actually) available at the Power On switch (which I would expect to have at least 5 VDC). Anybody have any idea how power is handled for these critters? Model 305CRV. Can get SN if necessary. I somehow expected to find something like a LM317, or at least a couple of 7805/7905 combinations. Shows what I know about laptops. Any help is appreciated... Thanks, Dave I would expect some type ofswitch mode power supply - they're available as a single chip with minimal external components. Much more efficent than the 'room warmers' like the LM317/78xx devices. Check for questionable electrolytic capacitors - a dead one can kill the switch mode power supply. SMPS don't like caps with high ESR either - probably easier to replace than to test. John Hey, THANKS John. I will definetly check this out. Much appreciated. Dave Hey John, took a look at the motherboard again with no (obvious) luck. One question: would the there be a SMPS on the motherboard, in addition to whatever is in the AC adapter? I have the voltage from the AC adapter coming into the board, but it does not appear to be "processed" into anything like a 5V supply for the digital logic to operate with. It seems to simply drop to the 1VDC level I mentioned earlier. I feel like I ought to be able to locate the source of the trouble, but haven't been able to do so. Thanks, Dave |
(Nearly) dead Gateway laptop...
Dave Inscribed thus:
"Dave" wrote in message netamerica... wrote in message ... On Thu, 28 Oct 2010 09:41:01 -0500, "Dave" wrote: Appears (to my eye) to have a faulty voltage regulator on the motherboard, but where? 19.5 VDC input from the AC adapter, but only 1VDC (slightly less actually) available at the Power On switch (which I would expect to have at least 5 VDC). Anybody have any idea how power is handled for these critters? Model 305CRV. Can get SN if necessary. I somehow expected to find something like a LM317, or at least a couple of 7805/7905 combinations. Shows what I know about laptops. Any help is appreciated... Thanks, Dave I would expect some type ofswitch mode power supply - they're available as a single chip with minimal external components. Much more efficent than the 'room warmers' like the LM317/78xx devices. Check for questionable electrolytic capacitors - a dead one can kill the switch mode power supply. SMPS don't like caps with high ESR either - probably easier to replace than to test. John Hey, THANKS John. I will definetly check this out. Much appreciated. Dave Hey John, took a look at the motherboard again with no (obvious) luck. One question: would the there be a SMPS on the motherboard, in addition to whatever is in the AC adapter? I have the voltage from the AC adapter coming into the board, but it does not appear to be "processed" into anything like a 5V supply for the digital logic to operate with. It seems to simply drop to the 1VDC level I mentioned earlier. I feel like I ought to be able to locate the source of the trouble, but haven't been able to do so. Thanks, Dave There are maybe half a dozen SMPS in a laptop ! You need to trace the 19V to find out where it goes. Not at all easy, even if you have a circuit diagram ! -- Best Regards: Baron. |
(Nearly) dead Gateway laptop...
"Baron" wrote in message ... Dave Inscribed thus: "Dave" wrote in message netamerica... wrote in message ... On Thu, 28 Oct 2010 09:41:01 -0500, "Dave" wrote: Appears (to my eye) to have a faulty voltage regulator on the motherboard, but where? 19.5 VDC input from the AC adapter, but only 1VDC (slightly less actually) available at the Power On switch (which I would expect to have at least 5 VDC). Anybody have any idea how power is handled for these critters? Model 305CRV. Can get SN if necessary. I somehow expected to find something like a LM317, or at least a couple of 7805/7905 combinations. Shows what I know about laptops. Any help is appreciated... Thanks, Dave I would expect some type ofswitch mode power supply - they're available as a single chip with minimal external components. Much more efficent than the 'room warmers' like the LM317/78xx devices. Check for questionable electrolytic capacitors - a dead one can kill the switch mode power supply. SMPS don't like caps with high ESR either - probably easier to replace than to test. John Hey, THANKS John. I will definetly check this out. Much appreciated. Dave Hey John, took a look at the motherboard again with no (obvious) luck. One question: would the there be a SMPS on the motherboard, in addition to whatever is in the AC adapter? I have the voltage from the AC adapter coming into the board, but it does not appear to be "processed" into anything like a 5V supply for the digital logic to operate with. It seems to simply drop to the 1VDC level I mentioned earlier. I feel like I ought to be able to locate the source of the trouble, but haven't been able to do so. Thanks, Dave There are maybe half a dozen SMPS in a laptop ! You need to trace the 19V to find out where it goes. Not at all easy, even if you have a circuit diagram ! -- Best Regards: Baron. Wow. Give or take a half dozen potential sources of such trouble. Or other trouble. Okay. And, yeah, to the observation that tracing this path is not easy. Man. sigh Well, thanks for the reality check. :) Much appreciated. Take it easy... Dave |
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