Ericsson R250s PRO Troubleshooting Instructions page 7

If the fault still remains, send the unit on according to the local company directives.
2.1.2 The phone gets serv
Set the GSM test instrument at power level 5 and the signal strength -68,5dBm,
for GSM900.
To try GSM1800, set the power level 0 and the signal strength of -68,5dBm
Set up a call to a GSM test instrument.
If it works.
Go to the section 2.1.3,read the RX level from the GSM instrument while the call is connected.
If it does not work.
Probably the fault is located at the TX.
If calls cannot be connected at the lower channels only, then the fault is N570,
and the phone can not be repaired at this level, send the unit on according to the local company
directives.
Disassemble the phone and check for liquid damage.
No further action should be taken for a liquid damaged telephone.
Check visually the antenna connector X101, if it is damaged, bad soldered or dirty.
If necessary, replace X101.
Measure the resistance from the P401 test point, to ground >10 kohms.
If the resistance is too low, usually 200 ohms, then N401 is damaged, and the phone can not be
repaired at this level, send the unit on according to the local company directives.
Check that L403 not is burned.
Check the soldering at Z205, Z203, GSM900 and Z204 GSM1800.
Check the soldering at N560 and N570.
Measure the resistance at C853 >100 kohms, L560 and L223~0 ohm.
If the fault still remains send the unit on according to the local company directives.
4/00021-2/FEA 209 544/18 D
If pin4, the control voltage is too low or missing.
Measure the resistance of R312~22 kohms.
If R312 is ok, measure the control- voltage 1,7V at N301 pin5, at the start of
the board.
If the control voltage is too low or missing, replace N301 and C317.
If the control voltage is ok at N301pin5 and too low at N303 pin4,
replace C319 and C314.
Standard Trouble Shooting Instructions
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