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Old 28th Oct 2018, 10:40 pm   #1
Jolly 7
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Default Trying to restore a Panasonic EB-G350 mobile phone

I was wondering if anyone might know how to test this mobile phone from 1996 without a charger or battery. The battery is dead and the charger is missing. I connected 4 AA batteries to the positive and negative terminals of the phone and only got a very faint response from the LCD. Is it essential to connect the terminal marked T and how might this be done? Thanks in advance.
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Old 28th Oct 2018, 11:34 pm   #2
KeithsTV
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Default Re: Trying to restore a Panasonic EB-G350 mobile phone

I believe the T terminal is connected to a thermistor embedded in the battery to allow fast charging to be used.

Do you know the voltage of the dead battery? It could be that the voltage from the 4AA cells is too low. It could be a 7.2v battery. You could try connecting it to a variable PSU and slowly raising the voltage while monitoring the current and see what comes up on the display.

Keith
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Old 28th Oct 2018, 11:43 pm   #3
Jolly 7
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Default Re: Trying to restore a Panasonic EB-G350 mobile phone

Hi Keith
The label on the dead NiCd battery reads 4.8V at 580 mAh. The voltage was reading 0.06 V, so I dismantled the battery and took the four flat-shaped cells out. I was a bit hesitant to go above 6V and on my simple variable PSU I can only adjust voltage from 1.5V to 12V, but not the current. If I can somehow verify that the phone is fine, I might try to reform the battery with NiMH or even a lithium cell.
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Old 29th Oct 2018, 6:54 pm   #4
duncanlowe
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Default Re: Trying to restore a Panasonic EB-G350 mobile phone

I think I might have one of those, with battery and charger somewhere. You might find the load is a bit high for AAs if they are dry cells, as the switch on demand of an old beast like that will be quite high. Even in standby they sucked a surprising amount of juice. If it is the one I think, then my wife ended up stranded in Munich trying to find me when the battery died very quickly!

EDIT: I've found it. Not the exact same model as it's a 400 series, but looks identical otherwise. The battery I have is a pattern one, 4.8v 600mAh. The charger provides 6.7v 550mA model EB-CA400UK. I can see one for sale (not me) for £8 ish on eBay.

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Old 29th Oct 2018, 7:19 pm   #5
G6Tanuki
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Default Re: Trying to restore a Panasonic EB-G350 mobile phone

When you say "only a faint response from the LCD" could this be because the backlight has failed?


Most phones of that era also illuminated the keypad and beeped when you pressed any keys. Does that happen on yours?
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Old 29th Oct 2018, 8:05 pm   #6
Jolly 7
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Default Re: Trying to restore a Panasonic EB-G350 mobile phone

The keypad does not illuminate or beep and the LCD display shows very faint blocks of dots which would have been digits of alphabets if working properly. It seems like it could be the backlight.
I guess I will need to open the phone up. I've never repaired a mobile before but this model was actually my first mobile, so am keen to give it a go. My original phone from 1997 got lost so snapped this one up when I saw it for sale recently.
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Old 4th Nov 2018, 12:11 pm   #7
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Default Re: Trying to restore a Panasonic EB-G350 mobile phone

To be honest that might be better kept as a shelf queen.
Old mobiles like that are something of a nightmare to the networks who will not support the old modulation format forever.

They are busy converting the spectrum for more efficient usage. I haven't heard any announcements about discontinuing GSM but
I wouldn't be surprised if that day is not too far off.
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Old 4th Nov 2018, 12:22 pm   #8
Lloyd 1985
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Default Re: Trying to restore a Panasonic EB-G350 mobile phone

I’ve often found with mobile phones that they refuse to power up unless the correct battery is fitted, the old Nokia’s I used to repair did nothing without the battery or a special jig for connecting it to a bench power supply. I have made such a jig from an old battery with the cells removed, and the PSU connected where the positive and negative from the cells were. Best bet is to get hold of a working battery, before you pull it to bits!

Regards
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Old 4th Nov 2018, 1:09 pm   #9
duncanlowe
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Default Re: Trying to restore a Panasonic EB-G350 mobile phone

The other issue might be a compatible SIM card. I have a Nokia that is slightly later than this. It's single band GSM so for a while would only be working on O2 or Vodafone. Vodafone SIM cards wouldn't work in it, but O2 ones did though I haven't tried any recent SIMs. And that's not because it's network locked, there was something different about the SIM. I know there was a change from 5v to 3.3v at some stage but expected they were backwards compatible.
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