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The Latitude E7440 is an ultrabook by Dell released in November 2013, identified by model number 730-6964, with a fully usable touchscreen display. It is a high end business laptop built to be portable and sleek yet sturdy.

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What is the chip mounted in PD5 near the power plug.

Hello, it appears the chip mounted to PD5 (maybe a transistor, maybe a diode) on my board was damaged by a power surge. this is usually crammed under the display and power cable. I don’t want to have to toss out an otherwise working computer because a single easily replaceable component broke. The chip is damaged to the point i cannot read what it’s marked with; I just need someone to pop one of these computers open, and take a photo where the markings on the chip are clearly legible.

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SjitpostingTM just by the reference designator you know it is a diode. Let us the exact model of your motherboard. List all the numbers etc. that are silkscreened to the board. Post some good pictures of your board and where this didoe is located with your Question

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Hi you guys really seam to know your stuff so here is the question.

I have an e7450 with the same problem as the original poster. The diode in location PD5 has 502Oj on the top of it. All 3 pins have zero resistance between them so it is obviously faulty.

The single pin is connected to ground the other 2 have zero resistance to the signal pin on the charger jack.

I removed this diode to see what would happen and everything started work ok. Dose anyone know what this diode is for. Is is dangerous or damaging to leave it out of the board.

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Hi,

If the motherboard is a Compal LA-9591P here’s an image from the schematic showing what PD5 is.

It is a DA204U S02323-D, series switching diode.

Here’s a supplier for an equivalent diode. I couldn’t find a supplier for the nominated one. It looks like the minimum order is 100 pieces but I may be wrong. Maybe it means that they have 100 in stock.

Block Image

(click on image to enlarge)

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The i5 and i7 units are the same fundamental board, but the i7 boards can have more reliability issues with the motherboard - I went over this more in my answer. At this point, anything that still works (with the i7 CPU) is a good unit. My 7440 is one of these with a well built board, but I wouldn't be shocked if it's running a replacement board.

As far as an entry level "stripper" board, I've never seen an i3 E7440. That said, I don't put it past Dell to have made it for the education market nobody else can get since they stripped a good system to make the schools happy with cost with this series. My Lat 7490 is a machine that is a known victim of potentially having a crappy screen (768p=TN vomit, FHD=IPS). In recent years, Dell has properly quarantined these i3 machines to the EDU market now :-). If you bought one, then you're at fault when it's unbearable to use. I care about the screen since I sometimes have to work with photos, so I don't accept anything less then IPS when TN can be avoided.

That said, there isn't anything "wrong" with the stripped education systems and cheap garbage screens, but on the used market they're a hard sell because of what you can get by waiting. See my 8th gen i7 7490 with the LG IPS panel. Tell me why I should buy an EDU machine when I can get one with a really nice 14" LCD, and an i7? Yes, I was in the right place at the right time too but waiting pays off despite having to get a battery, and sort out the RAM (stripped to 4GB from the factory 16GB, which I had on hand).

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As far as buying the inductor, it may come down to finding a dead board, or one with a BIOS lock (especially with the infamous BIOS I didn't install to keep that feature out). They're cheap, since the cost of a board ends these machines lives hard stop since the board is as much as a whole no HD unit.

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Hi @Your Handyman Expert,

Did you check for continuity in both directions i.e. between 1 & 2 and 2 & 1, 1 & 3 and 3 &1 and 2 & 3 and 3 & 2?

Just asking as there are two diodes in the component so they will conduct in one direction but not the other depending on which way the meter leads were placed.

Also there may be no continuity from pin 1 back to the charge port as there is another diode in the path i.e. PQ2. Again it depends on which way the meter was connected and also if your motherboard is the same as linked above ;-)

I think that it is used to guard against voltage spikes from the port being passed through to the motherboard's chipset when the charger is plugged in but this is only a guess as I'm no expert.

If it is faulty it is best to replace it as it's put there for a purpose. Manufacturers don't spend more than they have to when designing/making electronic devices

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Hi Jayeff

Thanks for your fast answer. Yes continuity is in both directions between all pins so I am pretty sure it is a faulty component. I dont know that much about electronics other than youtube video. That's where I saw someone testing between the ground pin and components that's how I found this.

There could also be something else wrong I just know that with that component removed it all seams to work.

Now i just need to find a replacement diode which seams to be easier said than done.

Thanks for your help.

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@Your Handyman Expert

When you say in both directions between all pins, just to clarify, you will get continuity between 1 & 2 but not between 2 & 1 and between 3 & 1 but not 1 & 3 and between 2 & 3 but not 3 & 2 depending on the way the meter leads are connected. if they are reversed continuity will be in the other direction i.e. between 2 & 1 and not 1 & 2 etc

Also did you test the component removed from the motherboard? If not you may be seeing parallel circuit paths through the motherboard

What is the make and model number of the motherboard?

If you search online for "(insert make and model number) schematics" you may be lucky enough to find a free download.

The actual component used is shown on the schematics (see type in Chosen Solution above) however that was for that motherboard and yours may be a different yet similar component i.e. different specs. You just have to find it in the schematics.

If you click on the circuit image in the Chosen Solution you will see the component ID next to the component i.e. DA204U- SOT232-D. It will be shown the same in the schematics for your motherboard

The SO2 232-D is the type of smd (surface mount device) package the component comes in so that it is compatible with where it is situated on the board i.e. SO2 = Small Outline type 2 with number of pins, lead spacing, lead size etc. The DA204U is the specification for the device.

The info printed on the device can sometimes be just the manufacturer's product code and if you can't find it by searching for that number then the schematics is all you can go on.

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