Member Avatar for robla64

have an Inspiron 8100 that was not working for quite a while.

I decided to try and start it with a charged battery from
another machine.
It started, and would work on battery power...the AC power would work
ONLY after starting it from the battery. It still would not start with
AC power plugged in so I resorted to starting via battery then plugging
in.
If it does happen to get turned off, it will only start from battery again, if I pull out the battery for a few hours

Most of the time I use it in standby.

I replaced the DC power board and the power supply and it still behaves the same way.

There has to be a solution to this. Any ideas.
Rob

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  • Latest Post Latest Post by cguan_77

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Short primer and practical tests for the Inspiron 8100 symptom described by (won't power on from AC unless first started from battery; battery removal for hours temporarily clears it). 's BIOS-reset suggestion is reasonable to try, but when firmware and the DC board/adapter have already been handled the problem is usually at the board-level power circuitry or the embedded controller (the chip that manages power sequencing).

Suggested diagnostic steps (in order):

  1. Confirm the adapter actually delivers the labeled DC voltage at the barrel and at the laptop DC-in pad with no load. A bad adapter or broken jack wiring can look OK unloaded but fail under load.
  2. Do a full power-drain/EC reset: remove main battery, unplug AC, remove the coin-cell CMOS battery if accessible, then press-and-hold the power button for 30-60 seconds. Reconnect AC only and try to power on. This clears latched faults in the power controller without replacing parts.
  3. Check for the standby rail (5Vsb/standby voltage) on the motherboard when AC is attached and the battery is removed. If the standby rail is missing the system will not start on AC alone; if present but the system still refuses to turn on, the EC or power MOSFETs that switch the main rails are suspect. Use a multimeter and basic board schematics if available; take ESD and safety precautions.
  4. Visually inspect the area around the DC jack, capacitor group near the power input, and any MOSFETs or diode pack for bulging, leakage, soot, or cracked solder joints. Electrolytic capacitor failure is very common on older Dells and often creates intermittent or latching power faults.

If tests show no standby rail or shorted power devices, the usual fixes are replacing/regluing caps and power-MOSFETs or replacing the motherboard/charging board. If not comfortable with board-level work, a repair shop or sourcing a used Inspiron 8100 motherboard are practical next steps. Keep notes of LED patterns and voltages measured — they help a technician isolate the failed stage quickly.

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Member Avatar for cguan_77

hi rob,

if ever you get the chance to power on your computer go to BIOS set-up and try to Load All Default Settings or Try to reset the BIOS..Don't know if it will work..but just TRY..

Member Avatar for robla64

Thanks but the Dell bios has no reset to default... and I have installed the latest bios to it more than once.
Any other ideas?

Member Avatar for cguan_77

thanks for the reply, if your bios is already updated then most probably some of the IC that controls the power circuit is not functioning properly

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