nokia with many problem

[SE-THAILAND]

i have 3310 many phone waiting for solve no network problem.this main problem


3310 phone A.RSSI 112 db Tx with wintesla ok.test with SIM card. (look in net monitor) get 637 -93 but when get * symbol ANT not lightup.and 0 voltage on TX-BUF,PAC-DCS line


3310 phone B.RSSI 116 db Tx with wintesla ok.test with SIM card get random (look in net monitor) 635,637,662,701,703,705752,763 allway


3310 phone C.RSSI 93 db(with one phone 116) Tx with wintesla not work not current consume.in Tx level 5 voltage on TX-BUF line is 0.2V and PAC-gsm line is 0.15V.testwith SIM card get 0 allway


8850 .RSSI 144 db Tx with wintesla not work.i try change 26 Mhz but not help


all phone cobba, haggar, ccont, ok .cause i change to new chip


i'll wating for help.

[willy]

Srtech,
measure some 1800 saw filter and antenna switch !

measure that Vtx is supply
check TXP is enabe ( high)
checkTXC on each TX level !

that you wrote here , it is in 1800 Mhz,, try to see how is GSM 900 working !

Willy

[SE-THAILAND]

hi willy

for phone A,B i try change antenna switch but not help

Vtx is ok (2.8 v)
where test piont for TXP,TXC line

i try on 900 band but still not work

thank for reply

[willy]

Srtech,

use oscilloscope to measure TXC at R518 and TXP at J503 and VCO loop at C558 !

Willy

[SE-THAILAND]

willy

i compare with good phone waveform @ TXC,TXP,C558 ok (all Rx Tx)

yesterday i buy secondhand osciloscope HAMMEG HM303-3 maximun 30Mhz.then i check pin 3 of 26 Mhz(G502) get about 200-250 mV and L511 get about 100-150 mV only (test with good phone)posible osciloscope fault ?.but test CAL. piont of osciloscope is ok

[gsmsalers]

Willy.
Hi. Before you told me you use 250 Mhz OSCILLOSCOPE with 1/10 impadence. So it is okey all Nokia repairing without any trouble? Can it diagnose gsm 900 and 1800 networks? If yes how much does it cost in your country? Also is there anyone who can sell me cheap good RF COUNTER and OSCILLOSCOPE ?
Thanks for attentions.

[Scaramouche]

Hi
I only have a 100mhz scope, and i do basic RF repairs. Instead of seeing a good 900mhz RF waveform, i see either some fuzzy **** or a tiny part of the waveform. It doesnt really matter, since when I test the TX part, all iam watching is the amplitude of the waveform increase as I crank up the PA using wintesla. As for a frequency counter, Sunkko in china are selling one dont know the price though

[willy]

Gsmsalers,

I used Hitachi V1565 , 100Mhz with readout !
and it good test logic side , but not for high frequency !
like Hager IP/QP to COBBA ,100 Mhz is more then enough !


Willy

Originally posted by gsmsalers
Willy.
Hi. Before you told me you use 250 Mhz OSCILLOSCOPE with 1/10 impadence. So it is okey all Nokia repairing without any trouble? Can it diagnose gsm 900 and 1800 networks? If yes how much does it cost in your country? Also is there anyone who can sell me cheap good RF COUNTER and OSCILLOSCOPE ?
Thanks for attentions.

[willy]

Srtech,

let we say in 3310 :

Vp-p of 13Mhz at C303 , it need 600~750 mv !
C558 is for 3310 PLL VCO loop from Hager , you have to set CH in wintesla for RF RX control !

you have to measure RX IP/QP at R504 , and TX from COBBA at R541 and R548 !
then go to measure at T504 TX out from Hager !

Willy

Originally posted by srtech
willy

i compare with good phone waveform @ TXC,TXP,C558 ok (all Rx Tx)

yesterday i buy secondhand osciloscope HAMMEG HM303-3 maximun 30Mhz.then i check pin 3 of 26 Mhz(G502) get about 200-250 mV and L511 get about 100-150 mV only (test with good phone)posible osciloscope fault ?.but test CAL. piont of osciloscope is ok

[SE-THAILAND]

willy

i try measure RX IP, RX QP, TX IN, TX IP, TX QP, TX QN .TXC .TXP line it good work.but no voltage on Vapc line.line not cut or short .i try swap HAGAR chip with good phone but still not work

u have idea for other phone ?

regard

[willy]

Srtech,

i think, you said: Vapc = Vchp ?

if yes, then measure at c560 R781 and N600 , and VCP from CCONT!

Willy

[SE-THAILAND]

willy

i said Vapc =voltage automatic power control .at PA

to day i get new problem with 3310.it show network few minute then insert sim card on GSM but test TX with wintesla no problem .for DCS work fine .i try change ANT switsh but not help

regard

[willy]

Srtech ,

try to remove COBBA, and clean all tin ball in PCB pad !

Willy

Originally posted by srtech
willy

i said Vapc =voltage automatic power control .at PA

to day i get new problem with 3310.it show network few minute then insert sim card on GSM but test TX with wintesla no problem .for DCS work fine .i try change ANT switsh but not help

regard

[KKK]

just reheat haggar and cobba and your phone will be ok

[Scaramouche]

I found that reheating rarely works. It works for a few hours and then its back to its old tricks. Re-balling is the best way