Diagnostic help for Lenovo Ideapad S340-15IIL - Page 1
Forum section: electronics / repair

author: Hogwild
author_rank: Regular Contributor
timestamp: August 18, 2025, 05:28:33 pm
content: Hi:Please assume I know next to zero about diagnostics/repair.I have an Ideapad S340-15IIL that turns on, (at least the power switch lights up), then turns off after 3-4 seconds. I watched some repair videos, and did some minimal testing, but don't want to take the unit completely apart. I watched some videos, and learned that many things can cause this symptom.Tried so far:- The AC adapter tests good @ 19.5V.- The power input terminal inside measures roughly the same.- CMOS battery tests fine.- Pressing the hardware reset button yielded no change.Another possible cause is a bad or oxidized power button. Attached is a photo of the I/O board with the power button. Is there some way to test that without desoldering it? If those are terminals on the sides, they're so tiny I don't think I'll be able to get multimeter probes on them.

author: Swake
author_rank: Frequent Contributor
timestamp: August 20, 2025, 06:29:29 am
content: You'll need smaller probes... If you don't want to buy small SMD probes you might want to make probes using needles as tips.

author: Swake
author_rank: Frequent Contributor
timestamp: August 20, 2025, 06:33:54 am
content: An example of good enough probes for 8 bucks:https://nl.aliexpress.com/item/1005009630714941.htmlNot the best, but good enough by far

author: Hogwild
author_rank: Regular Contributor
timestamp: August 20, 2025, 03:52:04 pm
content: Thanks. Even with my magnifying lamp, I can't tell exactly where the terminals are, or even if they're underneath or something. I'm leaning towards buying another set of probes, for other work, but I'm not sure they're going to help with this. If only I had a heat gun/hot air station.Is it safe/helpful for me to try to spray some contact cleaner inside that button? It looks like there's not enough room and it's not designed for that.

author: CharlotteSwiss
author_rank: Frequent Contributor
timestamp: August 20, 2025, 04:14:32 pm
content: I repaired a PC years ago, where the power supply's no-load voltage was fine, but it dropped sharply during operation, preventing the device from booting. Are you sure the 19.5 volts is present even during those few seconds when the startup components require power?

author: Swake
author_rank: Frequent Contributor
timestamp: August 20, 2025, 05:48:28 pm
content: For most of this types of switch you can probe the connections from the side.If you think that switch is small look for that tiny capacitor just above the transistor in the middle of the picture in between the 2 USB connectors

author: Hogwild
author_rank: Regular Contributor
timestamp: August 20, 2025, 06:28:53 pm
content: How would I test that? Do I just need to test voltage across the input terminals during power on?

author: CharlotteSwiss
author_rank: Frequent Contributor
timestamp: August 20, 2025, 09:28:27 pm
content: Don't you have a power supply (one that can handle the amps the PC draws) to rule out the problem with the original power supply? Or, during startup, use a multimeter to see if the voltage drops before everything shuts down. Did you also reset the BIOS just to be safe? (I don't know the model, but you'll have to at least remove the back cover).

author: Hogwild
author_rank: Regular Contributor
timestamp: August 20, 2025, 09:33:02 pm
content: Isn't it rare for an AC adapter/PSU to provide proper voltage but insufficient current? Maybe I'm wrong. I'm certainly a beginner. As for the hardware reset, I already mentioned in my OP that I tried that. Multiple times.

author: CharlotteSwiss
author_rank: Frequent Contributor
timestamp: August 20, 2025, 09:46:50 pm
content: It happens with power supplies, but also with batteries, for example: the open-circuit voltage is fine, but under load they can't supply the required current. No beep sequence before turning off? Maybe you need to enable the buzzer in the BIOS...Have you tried unplugging anything unnecessary from the motherboard? (Battery, DVD, etc.)

author: Hogwild
author_rank: Regular Contributor
timestamp: August 20, 2025, 09:48:33 pm
content: Apparently, this is a common problem with this, and many other models of laptop. In all the diagnostics videos I watched for laptops, no one ever mentioned insufficient current. I wonder.

author: CharlotteSwiss
author_rank: Frequent Contributor
timestamp: August 20, 2025, 10:05:11 pm
content: I'm no technician, but in a case like this, I start by determining whether the power supply is capable of booting the device. Again, a PC I fixed would boot, but after a few seconds, it would die: the power supply needed replacing. This is just one of many attempts to rule out a possible problem.

author: Hogwild
author_rank: Regular Contributor
timestamp: August 20, 2025, 10:06:56 pm
content: It's a good point. I did manage to use it to boot a similar Lenovo laptop, with similar requirements. Since I have no other with which to test, I'm going to assume that's okay, at least for now.EDIT: I should have added earlier that the repair shop (mentioned below) is using a different, known good power supply.

author: Hogwild
author_rank: Regular Contributor
timestamp: August 29, 2025, 08:08:04 pm
content: I took the Ideapad to a well-reviewed local repair shop. They seem to be unsure what's causing the problem. They talked about some area looking like it had been scrubbed with a toothbrush after possible liquid spill. I'm just not seeing it from their photos. They also talk about reflashing the BIOS. They talk about one chip looking like it's been "tampered with". I'm not seeing that either. Does anyone see evidence of that from these photos?I remember when I first removed the base screws that they were slightly locked in with the usual chemical. The repair shop said there were signs of someone attempting repairs on this. I'm not seeing that from these photos. When I first removed the base, the screws were tight and and I found a blue substance on the threads. Maybe something like loctite blue?

author: Swake
author_rank: Frequent Contributor
timestamp: August 30, 2025, 06:53:01 am
content: First picture, very blurry:- Something is clearly going on with those stickers, not sticking well and bar code half gone.- In the area of the green circle it seems there is a white haze, which is an indicator of liquid ingress or at least the residue of something.Second picture- Very dirty. Might be that this is the area they refer to as toothbrush cleaned. Difficult to identify as the pictures are low quality.- If they want to indicate that the square 'ENE' chip is re-soldered then based on the looks of the pins all the other stuff is too. Unlikely.The use of a very small drop of Loctite on screws in a laptop and tablets is fairly common.

author: Hogwild
author_rank: Regular Contributor
timestamp: August 30, 2025, 02:52:05 pm
content: Here are a couple of my photos of the board before it was taken to the repair shop.