MacBook Pro 8,1 - replacement for r7020 (20mOhm? sensing resistor) - GSM-Forum

kiezbengel · 10-08-2016, 22:20

I have to replace R7020 (SMC_DCIN_ISENSE ) on logicboard 820-2936

it has 4 terminals and I am not successful in finding a replacement by searching with the values given in schematics. Can anyone more experienced help me ?

0.02 0.5% 1W MF 0612-1

rookieme · 10-29-2016, 09:05

Hi, in fact you neer a resistor with only 2 terminals.
Pins 1 & 3 are connected, so are pins 2 & 4.
The easy way to find one is to have it removed from a non working board.

kiezbengel · 11-01-2016, 00:41

yes,*thanks,*I found that out too. In fact my resistor is fine :-)
Wrong beginning after visual inspection only. ( I was just wondering about 4 terminals)

do you have some experience with this ?

I had a short to GND on PP3V42_G3H and after I attached 3.4 Volts manually to that rail the short on that rail is gone. (without anything ****ing)

I think I have more shorts but one step after another

I have a short to GND on SMC_BC_ACOK too. I removed Q5310 and U6901.

R5078 is a Resistor to PP3V42_G3H and as I have no short there anymore it shouldn't be the reason. My ISL ( U7000) was just freshly replaced and shouldn't be the cause.

As the SMC is the only thing left on that circuit. . . Do I assume right it is bad and has to be the cause ?

rookieme · 11-06-2016, 16:19

ok, did you had liquid damage with the board?
By injecting 3,4 V to PP3V42_G3H rail i guess you burned away the short [capacitor or something similar]
Now do you get any voltage at the output of U6690 by connecting magsafe power?
I guess you mean R5087, measure it to check its resistance.
You can try to remove U7000, clean the pads and do some measurments without it.

kiezbengel · 12-01-2016, 16:10

aha yes,*I am a little busy now and also i wait my donor board. Once I get back to it I will check and measure more and will remove the isl again just to go sure and sort it out . . . as like the resistor too so that before I approach to u7000 ( what is a pain with my experience level) I am sure that nothing else on that rail can be the short.

And yes for sure ! This is a hell of water damage !! A corroded peace of **** which,*with the right experience level,*you wouldn't waste your time on. But I have to experiment hahah

When you say "burned the short away" means that I finally destroyed the component that was the cause ?

I appreciate your help and fast answer man !! Will get back to it soon

bye

kiezbengel · 12-15-2016, 19:51

even though my donor board didn't arrive yet I was too curious and removed my ISL again. short to GND on SMC_BC_ACOK remained. I removed the SMC and the short is gone. Th chip looks perfect on both sides and the board BGA looks fine too. I assume it would be a waste of time to attempt recalling this one,*so I´ll wait for my donor board and reball the SMC of it

10-08-2016, 22:20	#1 (permalink)
kiezbengel Major Poster Join Date: Nov 2011 Posts: 48 Member: 1695219 Status: Offline Thanks Meter: 16	MacBook Pro 8,1 - replacement for r7020 (20mOhm? sensing resistor) I have to replace R7020 (SMC_DCIN_ISENSE ) on logicboard 820-2936 it has 4 terminals and I am not successful in finding a replacement by searching with the values given in schematics. Can anyone more experienced help me ? 0.02 0.5% 1W MF 0612-1

10-29-2016, 09:05	#2 (permalink)
rookieme Junior Member Join Date: Oct 2016 Posts: 2 Member: 2642557 Status: Offline Thanks Meter: 1	Hi, in fact you neer a resistor with only 2 terminals. Pins 1 & 3 are connected, so are pins 2 & 4. The easy way to find one is to have it removed from a non working board.

11-01-2016, 00:41	#3 (permalink)
kiezbengel Major Poster Join Date: Nov 2011 Posts: 48 Member: 1695219 Status: Offline Thanks Meter: 16	yes,thanks,I found that out too. In fact my resistor is fine :-) Wrong beginning after visual inspection only. ( I was just wondering about 4 terminals) do you have some experience with this ? I had a short to GND on PP3V42_G3H and after I attached 3.4 Volts manually to that rail the short on that rail is gone. (without anything ****ing) I think I have more shorts but one step after another I have a short to GND on SMC_BC_ACOK too. I removed Q5310 and U6901. R5078 is a Resistor to PP3V42_G3H and as I have no short there anymore it shouldn't be the reason. My ISL ( U7000) was just freshly replaced and shouldn't be the cause. As the SMC is the only thing left on that circuit. . . Do I assume right it is bad and has to be the cause ?

11-06-2016, 16:19	#4 (permalink)
rookieme Junior Member Join Date: Oct 2016 Posts: 2 Member: 2642557 Status: Offline Thanks Meter: 1	ok, did you had liquid damage with the board? By injecting 3,4 V to PP3V42_G3H rail i guess you burned away the short [capacitor or something similar] Now do you get any voltage at the output of U6690 by connecting magsafe power? I guess you mean R5087, measure it to check its resistance. You can try to remove U7000, clean the pads and do some measurments without it.

12-01-2016, 16:10	#5 (permalink)
kiezbengel Major Poster Join Date: Nov 2011 Posts: 48 Member: 1695219 Status: Offline Thanks Meter: 16	aha yes,I am a little busy now and also i wait my donor board. Once I get back to it I will check and measure more and will remove the isl again just to go sure and sort it out . . . as like the resistor too so that before I approach to u7000 ( what is a pain with my experience level) I am sure that nothing else on that rail can be the short. And yes for sure ! This is a hell of water damage !! A corroded peace of *** which,with the right experience level,you wouldn't waste your time on. But I have to experiment hahah When you say "burned the short away" means that I finally destroyed the component that was the cause ? I appreciate your help and fast answer man !! Will get back to it soon bye

12-15-2016, 19:51	#6 (permalink)
kiezbengel Major Poster Join Date: Nov 2011 Posts: 48 Member: 1695219 Status: Offline Thanks Meter: 16	even though my donor board didn't arrive yet I was too curious and removed my ISL again. short to GND on SMC_BC_ACOK remained. I removed the SMC and the short is gone. Th chip looks perfect on both sides and the board BGA looks fine too. I assume it would be a waste of time to attempt recalling this one,*so I´ll wait for my donor board and reball the SMC of it