No display, only two lan leds issues

P5 Fault Finder Pinout,

Or, with power sources

Often you can also find the faulty circuit by measuring the Ohms value,

(Thank you to Johnny_B for publishing it)

All the best about hardware/support from Johnny_B, link :
http://jb8a8f8.com
http://jb8a8f8.nl

Rev. M/G or ? mainvoltage information.
More info, see this topic,
Rev M/G voltage source information

Note: If the voltage are fine, but by Ohm values are the 1.2/2.6/3.3 values to low, others are fine then it is most likely a cpu issue.


TIP: One of my cases,
No front LED, but two LAN LEDs are On.
Other symptoms without simcard always 5v at Vcc / Rst / Clk / IO. when the print on / off and immediately on again it runs.
Voltage P5 values are correct, Display connector second row 3.3/5.0/3.3/3.3/2.7/0.0.. (normal = 3.3/5.0/3.3/3.3/3.3/3.3..).
4 large caps replaced / replaced Q8 did not help.
After replacing the U18 - TL7702A the problem was solved.

TIP: One of my cases,
Ohm value looks healthy, but ampere value too high.
volt measurement,
2.6v = 1.9v
1.3v = 0.890v

After removing the U7 R283 0 Ohm resistor,
U7 side = 2.6v, other side = 1.9v, 1.3v = 0.890v but the Amp consumtion is fine now.

In my case a bad connection U24 LG.
Check the connection U24 LG pin 2 to the U25 pin 4 / HG pin 14 to the U24 pin 4.

TIP: One of my cases,
Symptoms,
Ohm value u6/3.3v was 37 U7/2.6v ohm value was 800.
So both wrong, others were fine.

Removed U6 R118, U6 side okay.
Removed U7 R283, U7 side okay.

At the beginning I thought it was a problem on the 3.3v circuit, but in the end it was a diode problem U7.
Diode D6 leaked a little, after replacing the problem was solved.
By heating the U7 sector I saw that the Ohm value rises.

TIP: 5v circuit
If you have a problem with the 5v circuit, see this drawing.

Or read on the topic, DM_800_REV_L_Dead_only_eth

U23, 24 25..
Updated, More information added and changed some voltages.



U6..


U7..


U7/P5 pin 2 test for short circuit (Ohm measurement).

U7Tests