T28 backup battery
 

Please tell me if the faultly backup battery can be the reason why T28 can't switch on???
What kind and voltage is this battery...
I have 3,5V on my LiPol battery and 1,8V on my backup bat. ,but phone not working(can't switch on, can't charge)
Whitch IC distribute power to phone???
thank U

check for shortcircuit on battery terminals...if pressent, changa PA

I have two T28s
thirst have short circuit on Lipol contacts battery

second is working ok but when battery go under 3,5V phone go death and I have to charge battery by power sup. (this Lipol bat. is good mean new)

Where is PA located????

Thank a lot

PA = "Power Amplifier". Located besids antana switch, marked as RMxxx (xxx is a type of PA e.g. RM009) with Rockwell log on it. Desolder it and your phone should start and find network, but it will be unable to make calls. About second one I don't have any idea. Is your battary made in China? Try to use 100% working battary from working t28.

WBR B0BA

Thank you b0ba
my battery is good (tree peaces of working Nihm 500mAh maded in Sweden).

I was wrote on other my topic, that I discover T28 display contrast blinkink (If you look good on disp. you will see it,but it hard to see), maybe it couse by hi consumption of power is so hi, I don't know.... What you mean?

what about backup battery ?? is it Li acumulator? or? and what about voltage?


Thank you very very much..

about PA... If I remove it, (I can do that) I don't thing so that I can put it back, cause I still haven't any reball tools.... If you can advice me how or where buy or links to help me I will be very happy...
thank very much again

hi flashman,
blinking is from power suply, resoldering this ic
geo

Thank U,
please whitch IC is power suply and whitch IC is for charging???

many thanks for U

New things discovered:)

when phone normally working (on the netw.) everything ok.
battery is empty and phone tell me it (when I look at info in phone about time to work-it show me 0h in standby 0h0m to call)
after incomming call phone switch off (battery voltage was 3,5V)
I tryed to switch it on again-phone looks to work ok (info in phone tell me that I have 0h stand by and 0h4m for call)
After hour phone switch of and battery voltage was 3,25V - After this I can't switch on phone:(
Any idea?
thank U

hi again flashman,
power suply is in top side of the board, left to the batery contacts
geo

many thanks george gsm
I will check it