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presario 4764 power supply start up ?
I was just given a presario 4764 that had been working but then just quit..
no fan, no boot up, nothing. I installed a new power supply and still nothing. I'm told the power supply will not come on without a signal from the MB. Anyone know if perhaps a dead battery supply on the MB would prevent the main power supply from coming on ? I have a hard time believing I got a bad power supply. I dont want to dump the computer if perhaps a new battery on the MB will fire up the power supply, thanks in advance for any comments. Kevin Falconer Fort Myers, FL |
Was this computer working while you had it? It sounds like the
motherboard or CPU has problems. There is a very remote possibility that it is the battery. However, this signal the SMPS (switch mode power supply) receives from the MB is really from the SMPS. When you press the power button on a ATX computer, it requires a working CPU to tell the SMPS to turn on. Steps to check: 1. Swap out CPU if possible. 2. Unplug switch from MB and try shorting out the 2 pins on the MB 3. Go get a new computer Kevin Falconer wrote: I was just given a presario 4764 that had been working but then just quit.. no fan, no boot up, nothing. I installed a new power supply and still nothing. I'm told the power supply will not come on without a signal from the MB. Anyone know if perhaps a dead battery supply on the MB would prevent the main power supply from coming on ? I have a hard time believing I got a bad power supply. I dont want to dump the computer if perhaps a new battery on the MB will fire up the power supply, thanks in advance for any comments. Kevin Falconer Fort Myers, FL |
On Tue, 25 Nov 2003 23:52:21 -0700, Brian Friedl
wrote: Kevin Falconer wrote: I was just given a presario 4764 that had been working but then just quit.. no fan, no boot up, nothing. I installed a new power supply and still nothing. I'm told the power supply will not come on without a signal from the MB. Anyone know if perhaps a dead battery supply on the MB would prevent the main power supply from coming on ? I have a hard time believing I got a bad power supply. I dont want to dump the computer if perhaps a new battery on the MB will fire up the power supply, thanks in advance for any comments. Was this computer working while you had it? It sounds like the motherboard or CPU has problems. There is a very remote possibility that it is the battery. However, this signal the SMPS (switch mode power supply) receives from the MB is really from the SMPS. When you press the power button on a ATX computer, it requires a working CPU to tell the SMPS to turn on. Steps to check: 1. Swap out CPU if possible. 2. Unplug switch from MB and try shorting out the 2 pins on the MB 3. Go get a new computer It does not require a working CPU tturn on a power supply, in general, nor memory, battery or other parts installed unless Compaq did something unusal to the motherboard, which isn't all that unusal for Compaq. On the other hand, a CPU or other component that's shorting out could cause a problem, so any and all questionable parts can be removed from the motherboard. Considering that this may not even be an ATX power supply, if it's an AT it can be unplugged from the motherboard altogether and just plugged into one drive for a power-on attempt, or if an ATX just ground the PS-On pin in addition to above. The power supply might be checked to confirm that it's input voltage switch is set appropriate to the location, but otherwise that system is better retired for something more modern, standard, and of course, working. We might (or might not) be able to help more with a better description of the system, the motherboard and power supply type, as much detail about them as possible including the connector type and existance of external switches. Compaq also sold some systems (don't recall model numbers) with AT power supplies, having a rocker switch on the back for the AC input and a switch on the front bezel but the switch on the front wasn't actually a power switch, was a sleep switch. Those systems never turned off except by the back switch and I don't think the user was supposed to turn them off in back, just leave them running in sleep mode... leave it to Compaq to take perfectly working standard designs and create a problem. Dave |
A corrupted CMOS may inhibit power on.
--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html Important: The email address in this message header may no longer work. To contact me, please use the Feedback Form at repairfaq.org. Thanks. kony writes: On Tue, 25 Nov 2003 23:52:21 -0700, Brian Friedl wrote: Kevin Falconer wrote: I was just given a presario 4764 that had been working but then just quit.. no fan, no boot up, nothing. I installed a new power supply and still nothing. I'm told the power supply will not come on without a signal from the MB. Anyone know if perhaps a dead battery supply on the MB would prevent the main power supply from coming on ? I have a hard time believing I got a bad power supply. I dont want to dump the computer if perhaps a new battery on the MB will fire up the power supply, thanks in advance for any comments. Was this computer working while you had it? It sounds like the motherboard or CPU has problems. There is a very remote possibility that it is the battery. However, this signal the SMPS (switch mode power supply) receives from the MB is really from the SMPS. When you press the power button on a ATX computer, it requires a working CPU to tell the SMPS to turn on. Steps to check: 1. Swap out CPU if possible. 2. Unplug switch from MB and try shorting out the 2 pins on the MB 3. Go get a new computer It does not require a working CPU tturn on a power supply, in general, nor memory, battery or other parts installed unless Compaq did something unusal to the motherboard, which isn't all that unusal for Compaq. On the other hand, a CPU or other component that's shorting out could cause a problem, so any and all questionable parts can be removed from the motherboard. Considering that this may not even be an ATX power supply, if it's an AT it can be unplugged from the motherboard altogether and just plugged into one drive for a power-on attempt, or if an ATX just ground the PS-On pin in addition to above. The power supply might be checked to confirm that it's input voltage switch is set appropriate to the location, but otherwise that system is better retired for something more modern, standard, and of course, working. We might (or might not) be able to help more with a better description of the system, the motherboard and power supply type, as much detail about them as possible including the connector type and existance of external switches. Compaq also sold some systems (don't recall model numbers) with AT power supplies, having a rocker switch on the back for the AC input and a switch on the front bezel but the switch on the front wasn't actually a power switch, was a sleep switch. Those systems never turned off except by the back switch and I don't think the user was supposed to turn them off in back, just leave them running in sleep mode... leave it to Compaq to take perfectly working standard designs and create a problem. Dave |
On 26 Nov 2003 08:30:12 -0500, Sam Goldwasser
wrote: A corrupted CMOS may inhibit power on. It can prevent the system from POSTing, but without a viable BIOS, even without the EEPROM in the board it should still be able to pull the PSU power-on pin low, turn on the power supply so at least it's fan would be spinning and voltage levels obtainable. The question at this point might be, "Which fan isn't turning?". Apparently some Compaq systems do use logic for the CPU fan control, it may not spin but the power supply fan should still be on. Dave |
kony writes:
On 26 Nov 2003 08:30:12 -0500, Sam Goldwasser wrote: A corrupted CMOS may inhibit power on. It can prevent the system from POSTing, but without a viable BIOS, even without the EEPROM in the board it should still be able to pull the PSU power-on pin low, turn on the power supply so at least it's fan would be spinning and voltage levels obtainable. Apparently not. I had a Compaq system which played totally dead and resetting the CMOS fixed it. The question at this point might be, "Which fan isn't turning?". Apparently some Compaq systems do use logic for the CPU fan control, it may not spin but the power supply fan should still be on. Nothing, dead as a door stop. :) --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html Important: The email address in this message header may no longer work. To contact me, please use the Feedback Form at repairfaq.org. Thanks. |
On 26 Nov 2003 12:10:23 -0500, Sam Goldwasser
wrote: kony writes: On 26 Nov 2003 08:30:12 -0500, Sam Goldwasser wrote: A corrupted CMOS may inhibit power on. It can prevent the system from POSTing, but without a viable BIOS, even without the EEPROM in the board it should still be able to pull the PSU power-on pin low, turn on the power supply so at least it's fan would be spinning and voltage levels obtainable. Apparently not. I had a Compaq system which played totally dead and resetting the CMOS fixed it. Hmmm. Leave it to Compaq to "fix" something that isn't broken... every motherboard I've ever tried will turn on a power supply without anything, even the EEPROM, plugged into it. Makes sense though, since they often solder the EEPROM to the PCB. The question at this point might be, "Which fan isn't turning?". Apparently some Compaq systems do use logic for the CPU fan control, it may not spin but the power supply fan should still be on. Nothing, dead as a door stop. :) I'm not entirely clear on which board the original poster had, perhaps that info would help... possibly I have one here but once it's pulled from the original case it's hard to tell Dave |
Yes, but from the sound of it the original poster is referring to a AT,
not ATX board. On those, the fan is wired to the main power circuit and comes on when the power is turned on at the front of the machine. Later ATX models had the power managed through the board. KC "Sam Goldwasser" wrote in message ... kony writes: On 26 Nov 2003 08:30:12 -0500, Sam Goldwasser wrote: A corrupted CMOS may inhibit power on. It can prevent the system from POSTing, but without a viable BIOS, even without the EEPROM in the board it should still be able to pull the PSU power-on pin low, turn on the power supply so at least it's fan would be spinning and voltage levels obtainable. Apparently not. I had a Compaq system which played totally dead and resetting the CMOS fixed it. The question at this point might be, "Which fan isn't turning?". Apparently some Compaq systems do use logic for the CPU fan control, it may not spin but the power supply fan should still be on. Nothing, dead as a door stop. :) --- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html Important: The email address in this message header may no longer work. To contact me, please use the Feedback Form at repairfaq.org. Thanks. |
1. Swap out CPU if possible.
not possible, soldered in 2. Unplug switch from MB and try shorting out the 2 pins on the MB which two pins ? 3. Go get a new computer got one, just trying to get this one going for company to use, games and such thanks for the comments.... Kevin |
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