Dell Inspirion 1545 - Power problem - Page 1
Forum section: electronics / general

author: bogdan2013
author_rank: Regular Contributor
timestamp: November 14, 2013, 09:50:31 pm
content: Hello to all !I have a problem with a Dell Inspirion 1545 notebook . Won't turn on anyway . I checked the voltages ; the 3.3V rail and 5V rail are OK , but nothing on 1.8 V rail . After a lot of attemps it starts-up . I checked again the voltages . This time on the 1.8V rail I have voltage . Not a problem , I think , but I don't know why won't start , just sometime .P.S. : I checked the voltages with oscilloscope : linear without ripples or any noises .

author: SLJ
author_rank: Frequent Contributor
timestamp: November 15, 2013, 12:34:23 am
content: Could be a poor connection/bad solder joint somewhere or maybe right in the power supply section. Has it gotten really hot recently?

author: Stonent
author_rank: Super Contributor
timestamp: November 15, 2013, 02:31:13 am
content: I once had a Colonel (couldn't remember Air Force or Army) ask me to take a look at her Dell laptop that wouldn't power on.She said that she paid Dell to look at it and they quoted her $600 for a new board and $100 for the diagnostic which she declined because the laptop was around that price when she bought it.A strange problem I had seen on some Dell desktops before is they appeared to be 100% completely dead but if you unplugged them, removed the CMOS battery and let it sit 5 minutes and put it back together, they worked again.Sure enough, that fixed her laptop and I made $75. I thought the check she wrote to me was cool because it said "Pentagon Federal Credit Union" on it. She asked if I could make some official looking invoice because she was going to get her money back from Dell for saying it couldn't be fixed.So, try pulling the main battery, AC power and the CMOS battery and let it sit for about 5 minutes. Hit the power button a few times to bleed out any residual power.Also check the flat flex that goes to the power button on both ends, they sometimes work their way out.Also yeah if it has an Nvidia graphics chip, the solder might have cracked or a bga ball lifted. There are techniques to bake the motherboard in an oven for a short period of time to reflow the BGA. The HP DV6000 and DV9000 series had this pretty bad. Dell D630, and E6400's also had the problem but most could be prevented with a bios fix that ran the fans more often.https://www.google.com/#q=dv6000+reflow

author: GreyWoolfe
author_rank: Unknown
timestamp: November 15, 2013, 04:12:38 am
content: Stonent has it pretty close. Remove everything, but hold the power button in anywhere between 15-30 seconds. That does the bleed out. We did this back in the early 2000s before doing any work. (former Dell Certified System Specialist-laptops, desktops, workstations and servers).Tom, NW0LF

author: Stonent
author_rank: Super Contributor
timestamp: November 15, 2013, 04:54:04 am
content: Quote from: GreyWoolfe on November 15, 2013, 04:12:38 amI had my certification back in 1999 or 2000 I think. When it expired, I asked my employer if I could get it renewed and they said SURE! Just this time, you pay, and if you pass we'll reimburse you.

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: November 15, 2013, 05:15:31 am
content: Check the power jack,is it loose.Take the memory out and clean/rub the contacts with a pencil rubber/eraser.Try another charger, it could be a faulty sense pin and check charger voltage . Good luck with it .

author: G7PSK
author_rank: Super Contributor
timestamp: November 15, 2013, 09:13:54 am
content: Also check the power brick try swapping that for another one if you can as they have a handshake on some of the dell ones that have a habit of going dodgy. as Stonent said try the cmos battery for what they cost I always just change them for a new one often thats all thats needed but sometimes the tact switch goes wrong and several time I have come across start up problems which were due to the plastic button on the case getting worn inside where it makes contact with the tact button and no longer able to push the button far enough.

author: amyk
author_rank: Super Contributor
timestamp: November 15, 2013, 12:04:44 pm
content: Quote from: Stonent on November 15, 2013, 02:31:13 amThat sounds like it's EC-related, either bad firmware, the EC chip itself or its surrounding circuitry (causing the EC to lock up). The fact that it works again after a reset means the issue will likely recur (unless it was due to something random like a cosmic ray strike.)

author: Stonent
author_rank: Super Contributor
timestamp: November 15, 2013, 12:06:51 pm
content: I haven't seen it recently but it was common for a while.

author: bogdan2013
author_rank: Regular Contributor
timestamp: November 15, 2013, 04:28:38 pm
content: @SLJ maybe bad solders . I pressed a bit the board and after has started without problems .I found a 51117 from T.I. step-down driver . All pins have good continuity .But I'm not sure if I need to have 1.8V every time , indifferent if the notebook is turned on or off . The logic components permanently need to have 1.8V , or just when I start the notebook? To be clear for all .If I need to have 1.8V just when I press the power button , mean the problem is from those pins from power-button .Again to all : The problem is not from main power supply . I HAVE 5V and 3.3V .

author: SLJ
author_rank: Frequent Contributor
timestamp: November 15, 2013, 07:19:31 pm
content: Bad solder joints can be a pain to find. Still if you have a ESD safe iron with a small tip you might want to try hitting some of the suspected solder joints.

author: bogdan2013
author_rank: Regular Contributor
timestamp: November 15, 2013, 07:40:54 pm
content: I found a bad solder joint at connector for power button . Fixed it but still nothing . I hate those motherboards with more than 2 layers : you don't know where are go the traces .

author: fluxcapacitor
author_rank: Frequent Contributor
timestamp: November 15, 2013, 10:37:13 pm
content: Heres a Dell 1545 motherboard schematic .http://kythuatphancung.com/download/dell-inspiron-1545-wistron-roberts-discrete-laptop-schematics.html?dl

author: Stonent
author_rank: Super Contributor
timestamp: November 16, 2013, 12:33:47 am
content: Quote from: fluxcapacitor on November 15, 2013, 10:37:13 pm

author: bogdan2013
author_rank: Regular Contributor
timestamp: November 16, 2013, 10:26:49 am
content: Thank you very much , fluxcapacitor ! Now is more easy for me to find the problem . Thanks again !

author: bogdan2013
author_rank: Regular Contributor
timestamp: November 16, 2013, 11:28:24 pm
content: Ok : I think I found the problem . This winbond wpce775la0dg looks to be the main power controller . Each regulator (without main 5V and 3.3V) have an enable pin which go to this controller : the regulator for CPU , for GPU , the MOSFETs for USB power . Even the power LED is connected to this controller . I found the power button connector : is short a pin from controller for power triggering . I have 3.3V there , not a problem . I check the clock : 32 KHz not a problem . 3.3V for controller are every time there ...Is OK to try to reflow that controller ?

author: amyk
author_rank: Super Contributor
timestamp: November 17, 2013, 12:11:31 pm
content: That's the EC. I wouldn't just reflow it without checking if it's really due to some pins not soldered correctly.Page 58 of the schematic has the power diagram. (Not as complicated as some other laptops I've seen...) Make sure all the _ALW rails are up first, then check the TPS51116 - the S5 and S3 pins in particular, as they control the 0.9/1.8V rails (for the RAM). Those aren't on in soft off state. Check the powergood signals back to the EC, it could be that it turns on the regulators but doesn't see a powergood feedback after a certain time, so it turns them off again, or it just keeps waiting for a powergood that never appears, so it doesn't bring the CPU out of reset.As I mentioned before, if it's because the EC firmware is corrupted, then nothing you do with the hardware will fix it.

author: bogdan2013
author_rank: Regular Contributor
timestamp: November 17, 2013, 01:45:06 pm
content: I checked all power connections , enable pins for regulators .Something suspect for me are those TC5 & TC6 components (Sheet nr. 43) . Looks to be some caps , if I'm sure . Permanently I have 15 ohms impedance between these caps .

author: amyk
author_rank: Super Contributor
timestamp: November 18, 2013, 08:34:25 am
content: 15 ohms both ways?That's the 1.05V supply which is rated for > 9A, so a 15 ohm impedance on the rail doesn't look that abnormal; remember that these are low voltage, high current circuits so they may look shorted. The CPU is another one, a device powered by <1V that consumes >1W in the lowest clock-stopped power state will have a static impedance <1 ohm.

author: bogdan2013
author_rank: Regular Contributor
timestamp: November 18, 2013, 02:29:31 pm
content: What the hell ... I just took some measurements for see the 1.05V rail when I enable the regulator (here :http://imageshack.us/a/img18/1108/65y0.png) , I leave my probe down , I save the image to my stick and when i'm looking on the table the power led was turned on , CPU was a bit warmed , I plug-in the VGA cable : I have image , all goods .

author: amyk
author_rank: Super Contributor
timestamp: November 19, 2013, 01:07:50 pm
content: Maybe some loose connection somewhere...And if that reading is accurate, 1.15 is a bit on the high side (~+10%) for a 1.05V rail, might be OK but remember that the components running off it are a lot more fragile than typical "power electronics" like audio amps and the like.