Macbook pro 13 A1708 Low voltage on bios chip

[Marek011]

Hi, While trying to unsolder the BIOS chip, I accidentally blew out the R6130 capacitor and now I'm wondering what kind of capacitor it is because I don't know which one to buy. Getting to the point. The Mac draws 20v and 0.330A and does not turn on, it is dead. On pin 8 of the BIOS chip (U6100), the meter shows only 1v and then drops to 0v. After connecting the USB tester to the board itself (with all ribbons disconnected), the board consumes 5V and 0.024A

Where could the problem be?

[mon2]

Hello and welcome to the forum.

1) R6130 is a component that has the 'R' prefix and respectively, is a resistor (not a capacitor).

2) This R6130 is a 33 ohm, 0201 sized component. It is required to pass the signals of this bios onto the logic board. The faults you are observing may be linked to this missing resistor. This resistor is quite tiny being a SMD 0201 sized component. They are very inexpensive but do require tweezers & hot air tools to handle. Highly recommend to purchase spares as they are very easy to lose.

3) Suggest for you to post a clear picture of this area of the logic board.

[Marek011]

Thank you for the correction, I am sending a photo and ordering the missing resistor. Unfortunately, someone was there before me and I have to clean up the flux remnants

[mon2]

See attached. Unless you have hot air tools and experience with these tiny buggers, it may be best to locate a local cell phone or similar repair shop that is comfortable with this repair. Do ask them if they can handle repairing 0201 SMD sized parts for the 33R (33 ohm) missing resistor and the highlighted possible issues.

[Marek011]

See attached. Unless you have hot air tools and experience with these tiny buggers, it may be best to locate a local cell phone or similar repair shop that is comfortable with this repair. Do ask them if they can handle repairing 0201 SMD sized parts for the 33R (33 ohm) missing resistor and the highlighted possible issues.

I have the required equipment, I will try to repair it, I am sending more detailed photos. Thank you so much.

[mon2]

The missing 33R resistor is not technically required. If in a pinch and wish to test, you can apply a small solder blob to bridge the very tiny 0201 SMD pcb pads. Be sure to not short to other nearby traces. From the angle of the light, the broken traces may not be broken afterall. Just confirm the same with a meter in diode mode - should tone beep if the trace is not broken. Then be sure to solder back the bios to the proper pin #1 orientation.

That along with lots of flux, lots of patience and some TLC and you should be able to repair this flash bios.

[Marek011]

The missing 33R resistor is not technically required. If in a pinch and wish to test, you can apply a small solder blob to bridge the very tiny 0201 SMD pcb pads. Be sure to not short to other nearby traces. From the angle of the light, the broken traces may not be broken afterall. Just confirm the same with a meter in diode mode - should tone beep if the trace is not broken. Then be sure to solder back the bios to the proper pin #1 orientation.

That along with lots of flux, lots of patience and some TLC and you should be able to repair this flash bios.

Thank you, i will try to repair this Mac today,

Regards

[Marek011]

The missing 33R resistor is not technically required. If in a pinch and wish to test, you can apply a small solder blob to bridge the very tiny 0201 SMD pcb pads. Be sure to not short to other nearby traces. From the angle of the light, the broken traces may not be broken afterall. Just confirm the same with a meter in diode mode - should tone beep if the trace is not broken. Then be sure to solder back the bios to the proper pin #1 orientation.

That along with lots of flux, lots of patience and some TLC and you should be able to repair this flash bios.

I bridged the resistor, cleaned the flux residues and soldered the BIOS chip to test, now I get a constant voltage of 1.45V instead of 3.3V on pin 1.

[mon2]

Post pics of the reworked area again for a review.

Carefully measure the voltage to ground of each pin on this flash IC. Be sure that the chip was soldered in the correct orientation (ie Pin #1 is pin #1 on the PCB pads).

While the flash is being used, the IO pins will toggle high / low so a standard meter will rarely be able to capture this toggling effect. Instead, you will see a voltage that is neither the max nor the minimum. A logic analyzer or digital oscilloscope is recommended to view the true activity on this flash device. If using a logic analyzer, there are SPI bus decoder plugins that will then display in text, the traffic and SPI commands being issued by the bus master (host) controller.

[Marek011]

After making a blob on the legs for the resistor, as if the space under the resistor had burned, I scratched a piece of the PCB to get to the tracks. Is it still salvageable?