How to use thermo camera for laptop repairing

[Jane]

I have Acer 7745G laptop that does not start. When I connect power supply I can see a big short. I would like to use a thermo camera to detect that short . I use a laboratory power supply and set about 19V but not sure how many amps is still safe to use and at the same time there is enough heat so that camera can see the culprit of the short?
Can you please advise?
Thank you

[RethoricalCheese]

Re: How to use thermo camera for laptop repairing

You need to find shorted rail using a multimeter and then inject maybe 1V and 3-5A there. Then look at it using a camera.

If you just inject voltage to charging connector, wrong things warm up.

[piernov]

Re: How to use thermo camera for laptop repairing

https://www.badcaps.net/forum/showpo...02&postcount=2

2.2. Don't suspect that something is shorted with no reason
Shorted components are not the only failure mode of a laptop. Additionally, some places will measure low resistance to ground under normal operation. In general, high power low voltage (<2V) power rails will measure less than a few hundred ohms to ground. CPU VCore will measure a few ohms only. GPU VCore with newer NVidia GPU can even measure less than 1 ohm. It's normal. If you suspect a short to ground, always report your exact resistance to ground measurements.

2.3. Never randomly inject voltage
Voltage injection is used to find a short to ground. Only consider it after you found that there is a short to ground and after doing a visual inspection trying to find a broken component.

2.4. Never inject 19V
If the 19V main power rail is missing, there's a reason, often because a protection kicked in to avoid more damage. For example, the 19V power rail could be shorted to the CPU through a bad high-side MOSFET. In that case, the charging circuit protection kicks in and turns off the DC-in MOSFET. With enough luck, the CPU didn't take too much of a hit yet. If you inject 19V, you are sure to destroy it.
Always measure exact resistance to ground to see if there is a possibility of high-side MOSFET short. Always start at 1V and check if any of the large BGA (CPU/GPU/PCH) is warming up. Monitor the power consumption.