T20 nothing on the screen (LCD is ok!) - GSM-Forum

MaRiN · 03-31-2003, 19:34

I have Ericsson T20 wich works ok but have nothing on the screen. I test LCD in good phone, and LCD and rubber are ok. I checked all lines to LCD, and everything is ok. I changed LCD diodes V608, V611, and rehot all pcb, but still have nothing on the screen.

Does anybody have any idea how to solve this problem?

OLUJA · 04-01-2003, 15:56

You must to measure voltage on the PCB-display contacts,and one of them must be about 6.00 V,and if you don't have it,or that pin is 2.8 to 3.2 V ,wrong is "multi mode chip" or AD/DA conv. (it is the same chip,the name are diferent),or that line is broken(V=0).
But if you have good voltage,and display not working,it is software problem (diferents between display and motherboard...,or only software problem) .

johny3310 · 04-02-2003, 15:06

OLUJA is right: reflow multimode adapter chip with good flux. I have repaired more than 10 T20/T29 with this problem

doctorvatson · 04-02-2003, 15:37

write good eeprom and reflash

PROFESOR · 04-03-2003, 16:11

change n800 evrey thing will be ok

MaRiN · 04-03-2003, 22:16

I just measure voltage on lcd pins, and I have 2.5V on pin on wich working phone have 5.8V

Is this multimode or CPU problem?

xmobile · 04-03-2003, 23:45

replace 4cr IC with newone

johny3310 · 04-04-2003, 10:04

Quote:

Originally posted by MaRiN
I just measure voltage on lcd pins, and I have 2.5V on pin on wich working phone have 5.8V
Is this multimode or CPU problem?

15 minutes ago, i repaired one T20 by reflowing multimode
chip with flux. Why you don't believe me? Just try it! (be sure to remove keypad & luminescence foil first)

BTW; where are you from? I am from Karlovac.

MaRiN · 04-04-2003, 13:58

Quote:

Originally posted by johny3310
15 minutes ago, i repaired one T20 by reflowing multimode
chip with flux. Why you don't believe me? Just try it! (be sure to remove keypad & luminescence foil first)

BTW; where are you from? I am from Karlovac.

In my first post I wrote:

I checked all lines to LCD, and everything is ok. I changed LCD diodes V608, V611, and REHOT ALL PCB, but still have nothing on the screen.

And thats mean that rehoting multimode, and all pcb with good flux in my case don't give me result!

doctorvatson · 04-04-2003, 14:19

read my previous post

OLUJA · 04-04-2003, 19:38

Hello MARIN,and others !!!

How do you mean to repair something really complicate ,when you panic in that simple problem like your"NO display T-2x"!?
If you want to be prof.you must to mesure not only heating,and cleaning (sometimes that help).First, did you mesure voltage on cont.pin of L.C.D. on the P.C.B,and if you have, is the last one (on the right side) VLCD is 5.8 voltage?
That VLCD,come from N800 (he is the master...),from pin B6,but between them we have some resistor !
---That mean's if your voltage VLCD=2.5 V,then is broken lines from that pin to N800,or bad solder-ball under N800,or bad solder-ball point under N800,or BAD N800 !
---But if your voltage 5.8 V on that pin VLCD,than your problem is SOFTWARE,"peace of cake" !

doctorvatson · 04-07-2003, 13:23

@ OLUJA:
just notice:I repaired some phones with 1-pin 2,5v only by writing good eeprom.

mobileland · 04-17-2003, 02:35

I¨ve repaired a hundred of T28,20,29 ericssons with changing 4cr chips.No network,no display,black display,powering off,earring problems ...

03-31-2003, 19:34	#1 (permalink)
MaRiN Freak Poster Join Date: Nov 2000 Location: Croatia Age: 47 Posts: 353 Member: 2466 Status: Offline Thanks Meter: 10	T20 nothing on the screen (LCD is ok!) I have Ericsson T20 wich works ok but have nothing on the screen. I test LCD in good phone, and LCD and rubber are ok. I checked all lines to LCD, and everything is ok. I changed LCD diodes V608, V611, and rehot all pcb, but still have nothing on the screen. Does anybody have any idea how to solve this problem?

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04-01-2003, 15:56	#2 (permalink)
OLUJA Insane Poster Join Date: Feb 2003 Location: Belgrade,Serbia Age: 55 Posts: 64 Member: 23157 Status: Offline Thanks Meter: 0	You must to measure voltage on the PCB-display contacts,and one of them must be about 6.00 V,and if you don't have it,or that pin is 2.8 to 3.2 V ,wrong is "multi mode chip" or AD/DA conv. (it is the same chip,the name are diferent),or that line is broken(V=0). But if you have good voltage,and display not working,it is software problem (diferents between display and motherboard...,or only software problem) .

04-02-2003, 15:06	#3 (permalink)
johny3310 Freak Poster Join Date: Jul 2002 Location: Croatia Age: 49 Posts: 499 Member: 14004 Status: Offline Thanks Meter: 6	OLUJA is right: reflow multimode adapter chip with good flux. I have repaired more than 10 T20/T29 with this problem

04-02-2003, 15:37	#4 (permalink)
doctorvatson No Life Poster Join Date: Aug 2001 Location: Russia Moscow Age: 46 Posts: 567 Member: 5889 Status: Offline Thanks Meter: 0	write good eeprom and reflash

04-03-2003, 16:11	#5 (permalink)
PROFESOR Freak Poster Join Date: Dec 2002 Location: UK Age: 44 Posts: 130 Member: 19294 Status: Offline Thanks Meter: 15	change n800 evrey thing will be ok

04-03-2003, 22:16	#6 (permalink)
MaRiN Freak Poster Join Date: Nov 2000 Location: Croatia Age: 47 Posts: 353 Member: 2466 Status: Offline Thanks Meter: 10	I just measure voltage on lcd pins, and I have 2.5V on pin on wich working phone have 5.8V Is this multimode or CPU problem?

04-03-2003, 23:45	#7 (permalink)
xmobile Major Poster Join Date: Sep 2002 Location: Novi Sad,YU Posts: 43 Member: 15650 Status: Offline Thanks Meter: 0	replace 4cr IC with newone

04-04-2003, 14:19	#10 (permalink)
doctorvatson No Life Poster Join Date: Aug 2001 Location: Russia Moscow Age: 46 Posts: 567 Member: 5889 Status: Offline Thanks Meter: 0	read my previous post

04-04-2003, 19:38	#11 (permalink)
OLUJA Insane Poster Join Date: Feb 2003 Location: Belgrade,Serbia Age: 55 Posts: 64 Member: 23157 Status: Offline Thanks Meter: 0	Hello MARIN,and others !!! How do you mean to repair something really complicate ,when you panic in that simple problem like your"NO display T-2x"!? If you want to be prof.you must to mesure not only heating,and cleaning (sometimes that help).First, did you mesure voltage on cont.pin of L.C.D. on the P.C.B,and if you have, is the last one (on the right side) VLCD is 5.8 voltage? That VLCD,come from N800 (he is the master...),from pin B6,but between them we have some resistor ! ---That mean's if your voltage VLCD=2.5 V,then is broken lines from that pin to N800,or bad solder-ball under N800,or bad solder-ball point under N800,or BAD N800 ! ---But if your voltage 5.8 V on that pin VLCD,than your problem is SOFTWARE,"peace of cake" !

04-07-2003, 13:23	#12 (permalink)
doctorvatson No Life Poster Join Date: Aug 2001 Location: Russia Moscow Age: 46 Posts: 567 Member: 5889 Status: Offline Thanks Meter: 0	@ OLUJA: just notice:I repaired some phones with 1-pin 2,5v only by writing good eeprom.

04-17-2003, 02:35	#13 (permalink)
mobileland No Life Poster Join Date: Feb 2003 Location: www.X-SIM.me Age: 45 Posts: 2,424 Member: 22955 Status: Offline Sonork: 67574 - Not use it Thanks Meter: 584	I¨ve repaired a hundred of T28,20,29 ericssons with changing 4cr chips.No network,no display,black display,powering off,earring problems ...