Ericsson T18s Trouble-Shooting Instruction page 52

• If the voltage is 0 V there's a foil damage and the phone has to be discarded.
If none of the LEDs are lit, measure the voltage at the marked side of them (~4.8 V,
Fig. 9.1).
• If the voltage is correct, replace V613 and R609 (class A, fig. 9.2).
• If it's incorrect there's a foil damage and the phone is to be discarded.
NOTE! Since the LEDs only are lit for ~10s you need to press a key before
measuring.
9.4 Keyboard illumination missing or faintly
glowing.
Open the phone and check for liquid damages.
Make sure all the LEDs (H655-H660, fig. 9.1) are mounted, correctly soldered and
mechanically intact.
Give the board power and start it up.
If one or a few of the LEDs aren't lit, measure the voltage of the LED from one side
to another.
• If the voltage is ~1.7V then the LED is faulty and is to be replaced.
• If the voltage is 0V then there's a foil damage and the phone has to be discarded.
If none of the LEDs are lit, measure the voltage at the marked side of them (~4.8V,
Fig 9.1).
• If the voltage is correct, replace V614 and R610 (class A, fig. 9.2).
• If it's incorrect there's a foil damage and the phone is to be discarded.
NOTE! Since the LEDs only are lit for ~10s you need to press a key before
measuring.
9.5 Both the keyboard and the display illumina-
tion doesn't work.
Open the phone and check for liquid damages.
Give the board power and start it up.
Measure the voltage at the marked side of one of the LEDs (~4.8 V, Fig. 9.1).
• If the voltage is correct, measure the voltage at the marked side of R607 (fig. 6.2,
~0.5V).
* If it's correct, replace R607 and R608 (class A, fig. 9.2).
* If the voltage is incorrect, check the soldering at pin 69 of D600.
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T18s, T18sc Standard Electrical Repairs
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