Guys ( especially you, [USER="328836"]Sephir0th[/USER] ), you won't believe.
I fixed it. The issue was short at [B]+3.3V[/B][B]_WWAN[/B] power rail, which is number 11 in power on sequence. I was stopped at number 7 = [B]PCH_RSMRST#[/B], because of its fluctuation. I stopped checking anything else later on. But then I realized, it is actually ON, but after then it shuts off from some reason. Firstly I though that its fluctuation is somehow an issue.
So I found shorted cap at +3.3V_WWAN​ and now the laptop runs fine. Thank you a lot for your time, I got a lecture...
YellowJacket
Senior Member
Last Activity: 05-10-2025, 08:59 AM
Joined: 12-27-2020
Location: Slovakia
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UPDATE:
I was able to charge a little the battery ( USB charger plugged in, then inject +17V directly to battery pin ). It took around 1.5A, but only for few seconds, maybe one minute max. Then it took no current at all. Vbat was 14V and main power rail 16.7! Although the board behaved exactly the same. The battery is not charged from the charger.
When I unplug the charger, the battery still connected, the LED on the power button is turned off ( in case of powering from the charger, LED is constantly flashing, like 0.5sec ON, 1sec off ). After pressing it, the LED turns on briefly...Last edited by YellowJacket; 05-08-2025, 09:52 AM.Leave a comment:
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CPU coils are all time low, VR_ON, I found only [B]I[/B][B]MVP_VR_ON [/B]( is it it? ), and it is at 0V. [B]RUN_ON[/B] is fluctuating at 3.4V, [B]SIO_SLP_S3#[/B] is also fluctuating at 3.5V. See the attachment.
I believe, I have to have [B]0.6V_DDR_VTT_ON_R[/B] (pin S3 of PU200) high in order to generate +0.6VSP ( which is 0V all the time ). That signal is although also fluctuating (attached. Also with S5 pin signal). The EC is the one, who deploys that signal.
PCH_RSMRST# is 3.5V fluctuating, PCH_PLTRST# is 0V.CPU coils are all time low, VR_ON, I found only [B]I[/B][B]MVP_VR_ON...Last edited by YellowJacket; 05-08-2025, 12:33 AM.Leave a comment:
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All selected power rails are fluctuating, see attachments. Only [B]+0.6V_DDR_VTT[/B] is 0V. Resistances seem fine to me. Actually all enabled signals are fluctuating, obviously ( RUN_ON for example 0-1.9V ).All selected power rails are fluctuating, see attachments. Only [B]+0.6V_DDR_VTT[/B] is 0V. Resistances seem fine to me. Actually all enabled signals are fluctuating, obviously ( RUN_ON for example 0-1.9V ).All selected power rails are fluctuating, see attachments. Only [B]+0.6V_DDR_VTT[/B] is 0V. Resistances seem fine to me. Actually all enabled signals are fluctuating, obviously ( RUN_ON...
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Sorry
Resistance of the 1.8VALW rail is [B]2k8[/B].
Not sure, what do you mean by S3 and S0. Like what signal. Do you mean [B]SIO_SLP_S3#[/B] and [B]SIO_SLP_S0#[/B]?Sorry
Resistance of the 1.8VALW rail is [B]2k8[/B].
Not sure, what do you mean by S3 and S0. Like what signal. Do you mean [B]SIO_SLP_S3#[/B] and [B]SIO_SLP_S0#[/B]?Sorry
Resistance of the 1.8VALW rail is [B]2k8[/B].
Not sure, what do you mean by S3 and S0. Like what signal. Do you mean [B]SIO_SLP_S3#[/B] and [B]SIO_SLP_S0#[/B]?Sorry
Resistance of theLeave a comment:
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Hi.
- I can't locate the PR725 resistor ( boardview unavailable ), but I will try to locate it, it just takes some time. Onboard, it has value 78k2, but yeah, its onboard, it was expected, that value will be lower.
- battery nominal voltage is 15.2V ( "limited charging voltage" = 17.6V )
[USER="149220"]mcplslg123[/USER] - I probably confused you, but the main power rail was stable whole time, there was unstable only voltage at the output of the coil PL701 ( which is probably fine in NVDC mode ). If you look at second picture from my #3 post, you will...Leave a comment:
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I got the new ISL IC, replaced it, but there is no change, the main power rail is 8.6V, not +17.8V, like it is shown in schematic. I got new measurements around ISL, with the USB charger, here are results ( value marked with [B]~ [/B]indicates fluctuation at this pin. Its AC waveform with peak-to-peak value is attached ):
DCIN = 19V ~
VDD = 5V
ACIN = 3.4V ~
ACOK = 2.9V
Looks like you were right, [USER="149220"]mcplslg123[/USER] , and the power management chip is not the culprit. But now I am really lost. What should I check now? Why is the main power...Leave a comment:
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Well, next time better do one picture ( or two, if there are coils also on the other side of the board ), and write measured values on the picture ( like for example [URL="https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/3623799-dell-latitude-5410-dead-pwrbtn-flashing"]here, in my thread[/URL] ). What is more important, don't use diode mode, but switch to resistance measurement. You also forgot to mention the board number.
Btw, do you have any programmer for flashing bios?Well, next timeLeave a comment:
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I believe, you meant `inductor` ( conductor is basically every conductive part of the circuit board ), and then yes, measure voltages at all inductors. It is the best place, where you can measure voltage of a switch mode power supply, because you just can't miss it.Leave a comment:
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Hi. According to your description, I assume, it is bios related ( maybe there was windows update running in background? ). To be sure, measure voltages at all coils, and post here a picture with measured values. Also add the board number of your mother board.Leave a comment:
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Well, the replacement IC is already ordered, so I will just change it, and if it doesn't solve the fluctuation, will dig more. The linked video assured me, that even healthy looking waveform from the charging IC could be somehow defective IC.Leave a comment:
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Hi [USER="149220"]mcplslg123[/USER], you are indeed correct and I just figured it out yesterday, I didn't update the thread. I tried to measure both PQ700 and PQ701 dual channel mosfets out of the board, and they are good ( tested with diode mode both integrated transistors for each of G-S-D. They are opening and closing as they should ). Also tested the PQ702 mosfet for charging.
Measured values around the charging IC ( [B]ISL9538CH[/B] ):
DCIN = 19V
VDD = VDDP = 5.16V
ACIN = 3.5V
ACOK = 3.1V
There are few waveforms measured around PQ701 (...Leave a comment:
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DELL Latitude 5410 - dead; pwrbtn flashing
Hi folks,
DELL Latitude 5410, board number FDZ41 LA-J371P Rev: 1.0 (A00), schematic uploaded in different post, here is the link --> [url]https://www.badcaps.net/filedata/fetch?id=3484415[/url]
When I connect it to a power ( DELL round charger, or USB-C ), LED on the power button starts flashing white, and the laptop doesn't do anything ( flashing slows for a very brief time in time when I press it, but it continues again ). Battery is not charging. While the charger is connected, I have few voltages present, but some of them are fluctuating, see attached pictures.
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I got an advice, to try to flash firmware from #4 post:
[url]https://www.badcaps.net/forum/troubleshooting-hardware-devices-and-electronics-theory/troubleshooting-laptops-tablets-and-mobile-devices/bios-requests-only/83983-edp51-edb51-la-h331p-rev-1-0-a00-bios-needed[/url]
Problem fixed ( the model is XPS 15 7590 if someone is interested )https://I got an advice, to try to f...s-needed[/url]Leave a comment:
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// UPDATE: I found some info, I can figure out, which one of these it is by finding its GPU. This one has [B]N18P-G0-MP-A1[/B] on it ( GeForce GTX 1650 Mobile, right? ), so it should be XPS 15 7590, am I correct?
// UPDATE 2: during `BIOS flash Update` utility, there was actual bios version for XPS 15 7590, ver 1.5 . I put an most recent version 1.35 for XPS 15 7590 from DELL support, update was successfully done, but now I have no picture on the screen. Num lock key doesn't react. Why is that? I am sure, I have done everything correctly, and previous BIOS assured me, that this board...Leave a comment:
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XPS 15 7590 ( or Precission 5540 ? )
Hi friends,
firstly, I have to let you know, I am not working with DELL laptops often ( actually, I can't remember, if I was fixing some board issue on DELLs ). And now I got for repair one from my friend. He bought it as a not properly working one, and its history is almost unknown. The issue is, it can not boot. This is not important in this situation.
Now, let me clarify the confusion in the topic name - the friend claims, that the model is Precission 5540. And when I get into BIOS settings, I can see the service tag [B]CMR4533[/B], which indicates he is right. But... -
Well, I replaced it for N-channel mosfet from some donor board, with really high maximum drain current, and it works just fine. If this thread can be deleted, you can do it so. Sorry for useless thread.Leave a comment:
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Identifying a component
Hello friends,
I have difficulties with finding this component online: "312L", with 'L' letter underscored. Damaged component is from a drone, and It is connected to a motor ( with the upper leg ). Any ideas, what it is? Looks like some N-channel mosfet to me, even by measuring another, working one, it behaves exactly like N-channel mosfet. But I would like to find the exact component, to be sure, what parameters it has. For proper replacement.
Thank you in advance for any hint.... -
Hi. For now, I took it off, since I was unable to find the replacement diode array. I found some in my spares, but it was a bit bigger. Still have TV, so if I find sone replacement, I will solder it.
BTW, is there a big chance, that TV will be damaged without the diode array in a way, that it is unrepairable?Leave a comment:
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Update: yeah, maybe admin can delete this topic, since after reading some topics here, on TV section, related to samsung brand, I found out, that some models have common fault with diode arrays, located on that small board connected to panel. In my case, D001 was the culprit. But for future reference, the array is shown in attachment....
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