Acer aspire es1-432 component missing

[String2016]

I need help on this i have here ACER aspire es1-432 rev:F ZQF motherboard, it just came here technician before told me that there is burnt components on the board , when i checked it something component is missing here at the pads is already broken.can someone please help me identify this component and where to connect this, since the pad already broken.i have upload a photo of the board

[BlueMidnight]

Re: Acer aspire es1-432 component missing

There appear to be 2 missing capacitors. (see attached photo)

PC207 (big one): 10uF 25V 0805 ceramic
PC206 (small one): 0.1uF 25V 0402 ceramic

There is supposed to be a big and small capacitor on the top side of the board, and another big and small on the bottom side (directly underneath). These seem to correspond to PC88, PC89, PC206, and PC207. The pad in the middle of each big and small capacitor is ground.

I see PR170 (with "2R2" written on it) next to PQ20. And PC202 next to it. So similar numbers ("PC2xx") must be on the top side of the board. Which means the missing small capacitor is PC206 and the big one is PC207.

Also, it's hard to see in the photo, but if any of those dark areas are burnt/carbonized PCB material, then they must be thoroughly scraped off. That stuff is conductive. That includes every bit of burnt material underneath PQ21 or anywhere else along the edges of the crater.

Hopefully nothing else important was fried during the incident.

[SMDFlea]

Re: Acer aspire es1-432 component missing

Check the schematic, there`s no boardview available . https://www.badcaps.net/forum/showthread.php?t=70848

[String2016]

Re: Acer aspire es1-432 component missing

thanks for the response now i know two missing caps in that burnt area but how do i replaced that when the pad is burnt and broken? where should i connect this caps?schematic right it show PC206 AND PC207 is missing.

[String2016]

Re: Acer aspire es1-432 component missing

I already clean the area there is a small soldered left on the side of burnt small capacitor and its connected to pin 5 of PQ20 and pin3 of PQ21

[BlueMidnight]

Re: Acer aspire es1-432 component missing

Hmm... that seems very suspicious. Because if it were supposed to be connected to the source of PQ21 (pin 3) and the drain of PQ20 (pin 5), then the pad should just be a fraction of a millimeter larger and actually be part of the pad between the 2 MOSFETs. Plus that would make the small capacitors be something that I can't find on the schematic.

For those reasons I believe you still have some conductive carbonized areas present in that area. Scrape the edges of the crater with a sharp instrument (like a dental pick). Often the lower layers burn before the top layer, so don't let a normal-looking green or copper top layer fool you. If it's not burned, it will scrape away pretty easily. If it's not burned, it won't. Everything left should be the same healthy light brown color. Remove PQ21 and examine underneath if you have to.

Assuming those capacitors are what I think they are... one way of replacing them would be to cut/etch the pad next to the drain of PQ21 to create a small disconnected area to act as a ground pad. Then scratch off the solder mask and attach both capacitors right there (and even make it large enough to hold the other 2 capacitors from the bottom of the board). Then, run a wire from the pad you created to a nearby ground. (Here's an example of something I've done before.. https://imgur.com/a/FJUz8)

Or... the capacitors could be placed right next to the other 2 capacitors on the opposite side of the board. But then the vias must be repaired.

You would have to poke/drill some wires through and connect them to the pad next to the drain of PQ21. The schematic doesn't show anything the vias would be connected to internally, so it should be safe. It is important that those capacitors have a small electrical distance between themselves and the drain of PQ21. You can't just run a wire completely around the outside of the board (that defeats the purpose of a bypass capacitor).

[String2016]

Re: Acer aspire es1-432 component missing

thanks for the response bluemidnight you mean the opposite side capacitor on the upper is this?shoud i put each side the small and big capacitor and connect eact side to those side of upper capacitor?or one side of two capacitor and the other side jump a wire to drain of pq21?

[BlueMidnight]

Re: Acer aspire es1-432 component missing

I mean there are 2 more capacitors on the opposite surface of the board. (see photo)

I can only find blurry photos of this board, so you will have to examine the area yourself. But, you might be able to put the missing capacitors right next to the existing ones.

Or you can find a way to mount them on the top side as I explained before. Or even cut a small piece of FR4 board to place on the cratered area, and then mount the capacitors to that (along with wires going to where they are needed).

Either way, you'll still need to fix the vias that connect the top side and the bottom side.

[String2016]

Re: Acer aspire es1-432 component missing

I put the capacitor near pc88 and pc89 connected to it now the laptop turns on and have display, but another problem when i plugged the battery at first, it will display then suddenly no image on the screen.cannot turn on also with battery only plugged in

[BlueMidnight]

Re: Acer aspire es1-432 component missing

I'd troubleshoot that just like any battery weirdness. First, try a different battery if possible.

If the battery is okay, or you don't have another one, then start measuring the DC input and battery charging circuits. On this model, I'd start with the MOSFETs (PQx) shown in the attached photos.

Ideally, measurements should be taken with AC connected, battery connected, and then both AC and battery connected.

[asrikerex]

Re: Acer aspire es1-432 component missing

I'd troubleshoot that just like any battery weirdness. First, try a different battery if possible.

If the battery is okay, or you don't have another one, then start measuring the DC input and battery charging circuits. On this model, I'd start with the MOSFETs (PQx) shown in the attached photos.

Ideally, measurements should be taken with AC connected, battery connected, and then both AC and battery connected.

Hi, sorry for bothering you. I have a question. What is the output voltage on pin 4 at ic PQ5?

[BlueMidnight]

Re: Acer aspire es1-432 component missing

Hi, sorry for bothering you. I have a question. What is the output voltage on pin 4 at ic PQ5?

PQ5 is a MOSFET and is part of a step-down regulator (also called a buck converter) in the battery charging circuit. Power comes in pins 5-8 and out pins 1-3. Pin 4 is the gate and is pulsed very fast (kilohertz) to control the MOSFET.

The voltage you see on pin 4 depends on your multimeter. It also depends on if the battery is connected and charging, etc. You can only see it properly with an oscilloscope. And you probably don't have to.

This thread was for answering String2016's question. I recommend starting your own thread if you have more questions of your own.