gd87 keypad problems

[thecult]

I have one Pana GD87, keypad dont works , but I can turn on phone. Phone seems to work fine, but keypad don't works, can't turn off... there isn't messages of locked keypad, I have tried "erase memory" with cb2000 but still same problem

somebody knows a solution or what is the problem?

thanks in advance

best regards

[thecult]

tested with cb2000: when I send key commands vía cb2000, phone reply (printing keys on screen)... but keypad don't works

I think is not keypad problem because phone can't receive 50% of calls... it seems other kind of problem... processor?

b.r.

[jvc]

If communication with cb2000 is ok and no lock is showed on display, then your problem is hardware related. I have solved it twice: often some diodes located neer power button short and cause this problem. Check all diodes located on keypad side with tester!

[thecult]

hi jvc, thanks for reply

I was checked all diodes of front pcb, all seems to be ok... after reading your post I have re-checked, all ok

any idea? I can't change processor (I don't have processors for gd87, I can't buy, I can't do reballing because I don't have stencils for this ultra-small balls)

thecult

[jvc]

Please check if any keypad lines are shorted to GND (only power button has one line to GND) and if flip switch is working (when you open and close the flip LCD light on and off ecc.), it is located on LCD board. If you have another GD87 you should try with another flip assembly, in order to isolate the problem, as it may also be on LCD board, external key or flex. Eventually check 13 MHz and 32 Khz clock (or change xtals, but if no change put originals back). Also try cleaning board for water damage. Let me know!

[thecult]

thx again jvc. I will try

[qaasad]

i have a litel problem whith panasonic gd87 the telefon is workin normal but the keybad isnot workin i can torn it on and of ther is 2 locks on the display i can reciv a cals but i cant call sam one i can only call and if i take the card aut then the keys are working normaly ca

can samme one help

[thecult]

2qaasad: you need to unlock keypad by entering security code, if u don't know this code ... use cb2000 and reset eep values

b.r.

[thecult]

@jvc: at end I have changed processor (it was more easy than I was thinked), tested and changed xtal .... no solution!! I'm only waiting for other flip to test your last posibility

it's very hard

regards

thecult

[Platijet]

if you have another gd 87 change pcb's to find where is the problem(pcb or flexcable).check the "blue" key(on external lcd)

[jvc]

Changing CPU isn't too difficult but takes some good skills! Let me know!

[thecult]

cpu change in this phone is very easy, pcb pads are enormous and ball array is like other old ic's. First I thought that it will be more difficult because new processors have great arrays of small pads and there isn't stencils for make reballing.

Now I'm waiting, when other gd87 enter in my sat I will try the flip exchange. I can't do nothing meanwhile

thanks for your help

best regards

thecult

[thecult]

Originally Posted by platijet

if you have another gd 87 change pcb's to find where is the problem(pcb or flexcable).check the "blue" key(on external lcd)

Now I don't have other gd87, I have one last month but was returned to customer.

I have checked external blue key... it have 4 points soldered to pcb, with polymeter:

- When phone is off, polymeter gives continuity between two right or two left points (they are couples) but two points right don't give continuity with two points right

- But when phone is on ALL POINTS GIVE CONTINUITY WITH THE OTHERS, I think it could be the problem. I have desoldered button but still same situation


what do u think?

[Platijet]

measurment with multimeter(polymeter as you write) is not trustable all time because is using DC curent for this.some times if you have axid(from water damage) with multimeter maybe you wil measure many Kohm or Mohm resistance but the real resistance it will be a few ohm's(signal for keybord is palm's(AC) not DC).
i think problem is on flex.

[thecult]

ok thanks platijet, sorry for bad english very good explanation thx

Then it seems to be a problem on "flip" (flex,...) but not on main pcb. Well, I now only can wait for other "flip" to try with it.

Thanks again. Best Regards

TheCult