Motherboard Fusing Locations

[robstemmer]

I have a HP ENVY All-in-One 34-c1070xtBundle PC (33P27AA) and it was working fine until one day I saw a warning message pop up in the lower right corner of the screen and before I could make sense of what it said, everything shut off. Since then I have not been able to power up the computer no mater what I try. No standby lights, no fan noise, nothing.

I've tested the power supply and believe the voltages are good, at least when you measure the black and yellow I get around 19V on all of those. There is a green and a blue and I'm not sure what those are for or what they should be. The power supply has a 10 pin connector on it and the label says it should be outputting 20V. I ordered a new one but have yet tried it out.

My guess is it shorted somewhere. I cant seem to locate any discolored components or burn marks. The only fuse I can locate (i think this is a fuse) is a green colored SMD with the number 6 (or maybe its a 9 I don't know) on the top. Next to it on the board it says PW and there's a connector that goes to the cable for the power button.

Can I get a schematic for this board or can someone tell me where the fuses are so I can test them?

[Max3Aj]

Hi @robstemmer, Welcome to HP Support Community. 

Thank you for posting your query, I will be glad to help you. 

It sounds like your HP ENVY 34-c100xt suffered a sudden power failure, potentially due to a short circuit, motherboard failure, or power delivery issue. Since you already tested the power supply and found 19V on black and yellow wires, let's go through some steps to narrow down the issue.

Test the New Power Supply

• Since your current power supply outputs 19V instead of the 20V specified on the label, it's worth testing the new power adapter you ordered. A weak or failing power supply might still show voltage under no load but fail under load.

Identify Power-on Signal (Green/Blue Wires)

• On HP AIO desktops, power supplies often have an additional Power_ON or Power_Good signal wire (likely green or blue).
• Use a multimeter to check if either wire changes voltage when pressing the power button.
• If there’s no voltage change, the motherboard might not be receiving or processing the power-on signal.

Check the Suspected Fuse ("6" or "9" SMD component)

• Continuity Test: Use a multimeter in continuity mode (or resistance mode) and check if there is a connection across the fuse.
• Good fuse: Should show near 0Ω resistance or continuity.
• Blown fuse: Will show as an open circuit (infinite resistance, no beep).

If the fuse is blown, replacing it might restore power—though it could also indicate an underlying short.

Inspect for Short Circuits

• Check Resistance: With the power disconnected, use a multimeter to check for shorts between the power rails (yellow wires) and ground (black wires). A reading close to 0Ω suggests a short.
• If there’s a short, suspect voltage regulators, MOSFETs, or capacitors near the power input area.

Inspect the Power Button & Its Cable

• Some HP AIO desktops won’t power on if the power button cable is loose or damaged.
• Try jumping the power-on pins manually on the motherboard (using a metal tool or jumper) to see if the system reacts.

Check Standby Power & Mainboard Indicators

• Some HP boards have an LED that indicates standby power. If no LEDs light up at all, the board might not be receiving power.
• If your model has a CMOS battery, try removing and reinserting it to reset the system.

Next Steps:

• Test the new power adapter first.
• Measure the green/blue wire voltages to confirm if the power-on signal is being received.
• Test the fuse and check for shorts.
• Try jumping the power button pins to rule out a faulty switch.

If the motherboard still shows no signs of life, it likely has a failed power circuit or a dead motherboard.

I hope this helps. 

Take care and have a good day. 

Please click “Accepted Solution” if you feel my post solved your issue, it will help others find the solution. Click the “Kudos/Thumbs Up" on the bottom right to say “Thanks” for helping! 

Max3Aj

HP Support