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I am trying to repair a GPS unit. There was a zener diode (to56 PolyZen protection diode) which had blown off and I had replaced. This is part of the battery charging circuit I believe, as once I replaced it, the unit would power on and charged the battery for some time. Few weeks later the zener seemes like it has died again.

I found once I replace the zener again there is voltage at the battery terminal which slowly drops down but never comes back up so it seems something is killing it. The voltage drops gradually over 5 minuites

I’ve traced the output of the battery terminal to an IC like component that is next to this zener so have reason to believe it is faulty; but can’t figure out what it is.

The marking on the IC is D8 = 1K 70S

Would appreciate any insight as to what it could be.

Picture of board

It is the 10-Pin component in the middle, marked U750 on the board. The zener is slightly cut off the image next to C106.

Managed to find the component, it was RT9505GQW. Thanks to Remco Vink who pointed out the manufacturer was Ricktek. I emailed the company and got the correct part number. Many thanks to everyone for your help.

Hi I managed to replace the IC but didn't turn out to be the culprit. I keep getting 0.2v with the battery disconnected or battery voltage +0.2v when connected. I've found another component that is also connected directly to the battery and going to have a go at changing it. It is a 3 leg component with the marking "132V" situated next to the RT9505GQW I just replaced. Would really appreciate your help in finding this. Many thanks

Dave Tweed
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Bilal
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    Could you add some more information about the board?, is it a developer board, is it a commercial unit does it have a serial number or anything which might be traceable to schematics or other information – Remco Vink May 01 '18 at 12:50
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    So not a definitive answer but maybe it will help someone else, I found the following chips with similar markings, i quickly tried looking for the manufacturer and info about the product series. But don't have time atm to continue looking. It looks similar to markings on the RT9505, based on this: https://www.aliexpress.com/item/RICHTEK-RT9505GQW-RT9505-D8-EJ-D8-CF-D8-DE-Linear-Single-Cell-Li-Ion-Battery/1850179349.html and these https://detail.1688.com/offer/542979400459.html?spm=a261b.2187593.0.0.39ef32e3oI1ot5 resellers of the part – Remco Vink May 01 '18 at 13:16
  • It is a Snooper S8000 sat-nav which I've been trying to repair. I've been learning to repair for some time now and have always struggled with identifying and sourcing components like this. Usually I spend hours/days searching Google and electronic components sites to try find the component using the markings, it just seems to be pot luck if I do. How did you manage to find it so quickly? Is it possible to find schematics of everyday electronics? – Bilal May 01 '18 at 13:48
  • @Bilal Some people just know the google-fu. Us lesser mortals will never be able to match them. – Hearth May 01 '18 at 16:51
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    @Bilal https://electronics.stackexchange.com/questions/334128/how-do-i-identify-smd-components-or-how-do-i-identify-any-component/334129#334129 – Voltage Spike May 22 '18 at 04:35

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