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**truclacicr** · 03-22-2024, 06:13 PM

S87 = STI9287

https://datasheet.lcsc.com/lcsc/2009...87_C842664.pdf (datasheet)

https://www.taobao.com/list/item/744174915443.htm (photo)

**harp** · 03-22-2024, 06:17 PM

Maybe this, check pinout against datasheet

Attached Files

**truclacicr** · 03-22-2024, 07:48 PM

Is B2F the Vdd supply for the SoC (CMS8S6990)?

https://www.semiee.com/file2/b200ba7...9xx_V1.0.6.pdf

**stj** · 03-23-2024, 03:21 AM

why 2 blown? do they feed each other?
reverse polarity mistake?
shorted ceramic caps?

**seb68** · 03-23-2024, 05:40 AM

For Member Harp and Trucglacier : it's the good component.
The B2F: Not the VDD supply for the SoC CMS8S6990.
For Member stj : The guy who brought me this GPS had wired it wrong. No shorted ceramic caps.

**truclacicr** · 03-23-2024, 11:29 AM

I would be concerned as to whether Vin has punched through the ICs and clobbered the loads. To this end I would measure the resistance between Vout and ground, and between Vin and Vout.

**seb68** · 03-23-2024, 03:17 PM

I removed the component B2F53S and the values are good between Vin and Vout and GND.
As this component is not identified I cannot go any further with the repair.

**truclacicr** · 03-23-2024, 05:16 PM

Can you determine the pinout?

It might also help to measure the feedback resistors, as this could tell us the FB reference voltage. Common examples are 0.6V and 0.8V.

It would also help to know which chips are powered by this IC, as that might tell us the output voltage.

Lastly, it might be worth identifying the manufacturers of other ICs, in case the designer used the same IC maker.