Hi. I have a hp 530 that suddenly refuse to charge and power even with battery. I think the two lead of the charger suddenly brigded and result in short circuit of the motherboard. Please help me. What component will test and how. I also need site where i could download schematics of laptop board. Thanks. PQ3 has 18.5v i/p and also 18.5v o/p. PQ4 has 18.5v i/p and 0.3v o/p.
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Hi friends of electronics
What you see in the video and pictures attached is the circuit for charging the batteries of a DC motor.
The problem is that this circuit cannot charge the batteries (3 1800mAH NiMH batteries) any more. When the circuit was OK, its green LEDs lit up one at a time to show that the batteries have charged more. But now that the circuit is flawed, LEDs light up as you see in the video and at the same time successive beeps are heard.
Please help me fix this circuit.
(the datasheet of the IC: https://pdf.datasheet.live/28... -
Hi all,
As the title suggests, how can I be sure that my EC chip is really dead?
I've recently gotten into this hobby of laptop repairs, and have successfully brought back to life a couple with some easy fixes, mostly shorted caps.
Now I'm working on HP Probook 455 G8, that had some "devil" run around on 3V line, burning a bunch of stuff. Luckily I have a dead 455G7 (for spare parts) so I managed to fix it (swapped burned parts) to a point that it will charge (both on barrel jack and usb-c), but it doesn't want to turn on. There is a 3V3 on a keyboard... -
Hello.
I have seen a short circuit tester made with 3 * 9V batteries, a voltage limiter component and a resistor connected to the probes of a multimeter.
The theory is that the meter becomes sensitive enough to read very low resistances and the lowest resistance to ground on a circuit is likely to be a short circuit in that area.
Link
The Amazing $1 Short Finder Upgraded! Convert ... - YouTube
https://www.youtube.com/watch?v=0eixDdCpiO4
My multimeter isn't normally sensitive to very small resistance, but when I put a 1 mega ohm resistor... -
Hello. My personal laptop just died on me, and to my luck, it does not seem like it can be fixed, but wanted an opinion. It is a Star Wars edition hp 15 laptop, with a dax1bdmb6f0 motherboard (without dedicated graphics). I was watching a video, moved the laptop, it shut off and thinking it was just a semi unplugged charging cable I pressed it back in, pressed the power button, saw it light up and left to another room. When I got back it was off again, but this time it did not turn back on.
The 3.3v line has a really low resistance, and if I plug in the charger, I do get 3.3v on...01-20-2023, 03:08 PM -
Hi,
I am repairing a ups which doesn't turn on ,it has the following ICs:
SG3525 used to drive inverter mosfets.
couple of uc3483, one for the power supply and another to drive a big mosfet at the output stage(i think the technique is called boost)
A LM358 and TL074 for control mechanism and of course the uController.
The SG3525 is shutting down every time the ups is turned on.
I want your help to know the function of LM358 and TL074 in the system.
I reverse engineered the LM358 circuit and i think that one of the block(A) is used for battery level...
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