PowerBook G4 15" function key problems

[weckart]

I have a PBG4 1.25GHz, in which the function keys on top of the number row have never worked except for the eject button.

I have tried:
a] Resetting the SMC
b) Resetting the PRAM
c) Reinstalling the OS, trying both Tiger and Leopard.
d) Checking over all the keyboard/Assistive devices settings in System Prefs
e) Swapping the keyboard over for another of the same generation PBG4
f) Swapping the power supply
g) Googling for ideas

Nothing has worked. The brightness control slider in SysPrefs is still there but I can't control it from the keyboard. Does anyone have any ideas what the issue could be? The PB has 2 good batteries and one wonky one, which sometimes charges and sometimes doesn't but the DC-in looks fine to me.

 

[eyoungren]

What happens if you use the FN key with the function keys?

 

[weckart]

What happens if you use the FN key with the function keys?

Nothing. It is as if whatever signals the keyboard makes to the logic board are not being picked up somehow. I tried flipping the Fn function via SysPrefs but still no go.

 

[eyoungren]

I'd say then you have a bad keyboard.

The 17" Powerbooks have a ribbon cable that plugs into the logicboard. I have sometimes had a few keys stop working. Pulling out the ribbon cable, wiping the contacts clean and then putting it back has always fixed that.

If your PB has a ribbon cable for the keyboard you could try that. But otherwise it seems that row of keys has probably failed.

 

[drewsof07]

I'd say then you have a bad keyboard.

The 17" Powerbooks have a ribbon cable that plugs into the logicboard. I have sometimes had a few keys stop working. Pulling out the ribbon cable, wiping the contacts clean and then putting it back has always fixed that.

If your PB has a ribbon cable for the keyboard you could try that. But otherwise it seems that row of keys has probably failed.

Sounds like the OP swapped the keyboard, but I would recommend checking and/or cleaning the snap connector that connects the keyboard/trackpad ribbon cable to the logic board. Entirely possible one of them has a speck of dust or crumb preventing connection. Worst case would be a corroded contact.

 

[weckart]

Sounds like the OP swapped the keyboard, but I would recommend checking and/or cleaning the snap connector that connects the keyboard/trackpad ribbon cable to the logic board. Entirely possible one of them has a speck of dust or crumb preventing connection. Worst case would be a corroded contact.

Thanks. It's that sort of info I am after. That or whatever resistor/capacitor on the logic board needs looking at. I am pretty much certain it cannot be a firmware/software issue by now.

 

[AphoticD]

I have a PBG4 1.25GHz, in which the function keys on top of the number row have never worked except for the eject button.

I have tried:
a] Resetting the SMC
b) Resetting the PRAM
c) Reinstalling the OS, trying both Tiger and Leopard.
d) Checking over all the keyboard/Assistive devices settings in System Prefs
e) Swapping the keyboard over for another of the same generation PBG4
f) Swapping the power supply
g) Googling for ideas

Nothing has worked. The brightness control slider in SysPrefs is still there but I can't control it from the keyboard. Does anyone have any ideas what the issue could be? The PB has 2 good batteries and one wonky one, which sometimes charges and sometimes doesn't but the DC-in looks fine to me.

It sounds like you have exhausted every configuration option. If the row of keys don't function in any capacity (as F1, F2, etc keys or as volume/brightness controls) and you've tried a known working replacement keyboard, then I'd say it would be a logic board issue.

Maybe a series of pins on the connector are specific to the function key row. Try cleaning the socket on the logic board and then looking around near the connection to follow a few of the traces. You might get lucky and find a blown resistor you can bridge, a diode to replace or even just some build up/oxidization on the components to clean off.

 

[drewsof07]

Thanks. It's that sort of info I am after. That or whatever resistor/capacitor on the logic board needs looking at. I am pretty much certain it cannot be a firmware/software issue by now.

If it were a power delivery issue, I would think the entire keyboard would fail to function. You're probably looking at a physical connection or data line issue rather than component failure. If you need to go further, you would be looking at an issue somewhere on the ADB bus.