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Need help repairing HP prime - Printable Version

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Need help repairing HP prime - Marcovecchio - 06-26-2020 05:33 PM

I just got a non working HP prime, to try to fix and use it. It's completely dead, no screen or leds light up.

It's in very good condition, externally and internally, except in the region shown in the photo: there's a power inductor partially broken. I can hardly read it's markings, seems to be 4R7, and I'm afraid some other components in the surroundings have been tinkered with too.

Well, I want to replace the inductor and check if other components in the region need replacement, but I have no hires pictures of the region or a schematic. Could someone help me identifying this inductor, and if there are other components missing in the surroundings?

Any info on the function of this region would be great too, it looks like a power converter / regulator circuitry to drive something with a specific voltage.

Thanks a lot!


RE: Need help repairing HP prime - ramon_ea1gth - 06-26-2020 08:16 PM

If the inductor is blown (you need a high current to achieve this), be prepared for damages in more sensitive components. With no schematic and only from the photo, I would be worried about Q304, Q305, Q306 or D308.

RE: Need help repairing HP prime - John Keith - 06-26-2020 10:35 PM

It is unlikely that the inductor is blown electrically, there would be burn marks and other obviously burned out components if it was. If you want to try replacing the inductor, 4R7 means a 4.7 microhenry inductor. You can search DigiKey and similar sites for a part of the same size and case type.

RE: Need help repairing HP prime - ramon_ea1gth - 06-27-2020 09:11 AM

NXP has an evaluation kit for the i.MX 6ULL processor and there is technical information and schematics that can be available upon registration. Maybe you can get some clues, as the kit could be closely related to the HP Prime G2 board.

RE: Need help repairing HP prime - Marcovecchio - 06-27-2020 04:15 PM

Thanks for the help, Ramon and John. The inductor is physically damaged, it has no signs of electrical failure. I suspect someone damaged it when prying the housing open, since the inductor is near the PCB edge. But I have no idea if this guy opened the calculator to try fixing it (and damaged the inductor in the process), or if the calculator was working fine when opened and suffered this damage.

Anyway, I thank you for confirming it's a 4R7, I will replace it and see if it helps.

And thanks for the NXP evaluation kit advice, I'll look into it! However, this Prime seems to be the older model, not a G2.

Thanks again!