iPhone 6S PP1v8 partial short 500ohm - GSM-Forum

czesk20 · 11-05-2017, 22:00

Phone had a little water damage around WiFi ic near C5283_RF and C5284_RF.
There was short on VCC_MAIN after removing C5283_RF short was gone.
I replaced C5284_RF as well.

I checked other lines before tried to power it on and found out that
PP1V8 line has good reading in diode mode about 270 (same as in good phone)
but resistance on that line is too low ( 505ohm ) with comparison to good motherboard (> 37kohm).

Anyway phone powered up ( there was 1.8V on PP1v8 ) and was working fine but time to time turned off
- LCD went black no image no backlight - so checked backlight and LCD chestnut circuit but all
readings are the same as in good motherboard.

So my assumption is that there is something wrong with PP1V8 line (it is connected to LCD as well).
I removed FL3104, FL3220, FL4205 and by doing that disconnected some capacitors on PP1V8 around LCD,
back and front camera connectors. No change still low resistance on PP1v8 line.

I removed some capacitors on PP1v8 line: C0900, C1322, C1323 no change still low resistance

I realized that sometimes if LCD was not connected I had about 3.8V on PP1V8 line
so after checking schematics again realized that maybe power IC is damaged in some way
(partially shorted PP1v8 line) and decided to remove power IC U2000.
Unfortunately no change still low resistance on PP1v8 line (500ohm)

Did someone had similar issue and can help?

czesk20 · 11-05-2017, 23:16

Image below:

ninos22 · 11-06-2017, 18:59

PP1V8 is produced from u2000, and goes to NAND & CPU

So you have to check one by one.

Unfortunately i did not have this problem yet to help you more.

Joe025 · 03-01-2019, 10:46

Hallo do you fixed your PP1V8 problem. I got the same!
In my case the Voltage at PP1V8 is up to 3.5V

I can not finde any shorts.

Burebista · 03-03-2019, 01:57

Quote:

Originally Posted by Joe025

Hallo do you fixed your PP1V8 problem. I got the same!
In my case the Voltage at PP1V8 is up to 3.5V

I can not finde any shorts.

3.5V instead of 1.8V? Well that's interesting. What voltage drops in both
ways you have when you take measurements in diode mode?
Also did you tried to power supply that line with external 1.8V?

ikarofox · 03-26-2019, 04:51

98/5000
I know that your post is old, but now you have a greater hope, have you ever helped us?

11-05-2017, 22:00	#1 (permalink)
czesk20 Insane Poster Join Date: Nov 2012 Posts: 78 Member: 1836029 Status: Offline Thanks Meter: 9	iPhone 6S PP1v8 partial short 500ohm Phone had a little water damage around WiFi ic near C5283_RF and C5284_RF. There was short on VCC_MAIN after removing C5283_RF short was gone. I replaced C5284_RF as well. I checked other lines before tried to power it on and found out that PP1V8 line has good reading in diode mode about 270 (same as in good phone) but resistance on that line is too low ( 505ohm ) with comparison to good motherboard (> 37kohm). Anyway phone powered up ( there was 1.8V on PP1v8 ) and was working fine but time to time turned off - LCD went black no image no backlight - so checked backlight and LCD chestnut circuit but all readings are the same as in good motherboard. So my assumption is that there is something wrong with PP1V8 line (it is connected to LCD as well). I removed FL3104, FL3220, FL4205 and by doing that disconnected some capacitors on PP1V8 around LCD, back and front camera connectors. No change still low resistance on PP1v8 line. I removed some capacitors on PP1v8 line: C0900, C1322, C1323 no change still low resistance I realized that sometimes if LCD was not connected I had about 3.8V on PP1V8 line so after checking schematics again realized that maybe power IC is damaged in some way (partially shorted PP1v8 line) and decided to remove power IC U2000. Unfortunately no change still low resistance on PP1v8 line (500ohm) Did someone had similar issue and can help? Last edited by czesk20; 11-05-2017 at 22:09.

11-05-2017, 23:16	#2 (permalink)
czesk20 Insane Poster Join Date: Nov 2012 Posts: 78 Member: 1836029 Status: Offline Thanks Meter: 9	Image below:

11-06-2017, 18:59	#3 (permalink)
ninos22 Freak Poster Join Date: Mar 2013 Location: Greece Age: 35 Posts: 425 Member: 1903358 Status: Offline Thanks Meter: 146	PP1V8 is produced from u2000, and goes to NAND & CPU So you have to check one by one. Unfortunately i did not have this problem yet to help you more.

03-01-2019, 10:46	#4 (permalink)
Joe025 Insane Poster Join Date: Jun 2013 Location: Germany Posts: 74 Member: 1959885 Status: Offline Thanks Meter: 6	Hallo do you fixed your PP1V8 problem. I got the same! In my case the Voltage at PP1V8 is up to 3.5V I can not finde any shorts.

03-26-2019, 04:51	#6 (permalink)
ikarofox Junior Member Join Date: Aug 2007 Age: 35 Posts: 20 Member: 569081 Status: Offline Thanks Meter: 0	98/5000 I know that your post is old, but now you have a greater hope, have you ever helped us?