No display, only two lan leds issues

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