Help: some keys not working on a QFR

[infiniti]

My brother in law's QFR is acting up.  It's out of warranty and the following keys don't work:


Note: The Menu/FN key works but just doesn't show up in Aqua's Key Test.

F3   F7
BACKSPACE
TAB   T   Y   [{   ]}
CAPS LOCK
SHIFT (left)
WIN (left)

Things that I have tried but didn't work:

• swapping the controller out with the controller from a QFR known to work
• swapped out the switches that aren't working
• inspected the PCB and everything seems to be OK

Anything else I can do?

Edit:  Added that it is out of warranty.

[kolonelkadat]

I dont know anything without looking at/probing around the circuit but im going to go out on a limb and say that a diode may have failed. or maybe a short on a pull up/down resistor.

[phoenix1234]

I think a picture of the PCB would be helpful.

If you did :
+ swap the switches
+ swap the controller
but it still did not work

=> the PCB could be the one we need to inspect more.

[infiniti]

Thanks for the input guys!  I'll make some time to desolder the switches and see what up with the PCB.

*breaks out the soldering equipment*

[kolonelkadat]

before you start soldering, it might be useful to give the switch terminals a probe with a multimeter to see if its getting a current. If its not getting power at the switch, then the switch probably isnt an issue.

eta: you may need a multimeter with a  μamp range.

[infiniti]

before you start soldering, it might be useful to give the switch terminals a probe with a multimeter to see if its getting a current. If its not getting power at the switch, then the switch probably isnt an issue.

It's not getting any current.  It's most probably the PCB.

Going to start in a bit...

[tp4tissue]

My brother in law's QFR is acting up.  It's out of warranty and the following keys don't work:

Show Image

Note: The Menu/FN key works but just doesn't show up in Aqua's Key Test.

F3   F7
BACKSPACE
TAB   T   Y   [{   ]}
CAPS LOCK
SHIFT (left)
WIN (left)

Things that I have tried but didn't work:

• swapping the controller out with the controller from a QFR known to work
• swapped out the switches that aren't working
• inspected the PCB and everything seems to be OK

Anything else I can do?

Edit:  Added that it is out of warranty.

Um...... hmmm.. if the board looks fine.. and it's not multiple fractures..  then it's probably on the controller end..

Unfortunately the cost in "time" to fix this problem far exceed the cost of replacing the keyboard.. 

pull the daughter board off, check for damage..

You COULD get the qfr replacement controller board and try that.. at worst it's not the controller, and you can stick it in the NEW replacement QFR which you would've had to buy anyway... there was a GB around here some where.

[infiniti]

Yeah, I've considered the cost of my time but I think there's just something shorted between the plate and the PCB.

If the PCB is dead, at least I would have harvested all the switches already haha

[SpAmRaY]

As weird as it sounds some QFR problems are caused by the screws being too tight, your issue doesn't sound so simple but you never know.

[terran5992]

As weird as it sounds some QFR problems are caused by the screws being too tight, your issue doesn't sound so simple but you never know.

0.o Does that actually happen?

[SpAmRaY]

As weird as it sounds some QFR problems are caused by the screws being too tight, your issue doesn't sound so simple but you never know.

0.o Does that actually happen?

There have been many reported instances where people loosened the case screws and the problems went away. Not saying that is the issue here but for a certain batch of QFR's it was an issue.

[infiniti]

As weird as it sounds some QFR problems are caused by the screws being too tight, your issue doesn't sound so simple but you never know.

0.o Does that actually happen?

There have been many reported instances where people loosened the case screws and the problems went away. Not saying that is the issue here but for a certain batch of QFR's it was an issue.

Yes, this happened to my other QFR...the screw was too tight and was causing the bottom of the PCB to scratch against the top of the USB daughter board.

It wasn't the case for this one...problem persisted even with the top cover off.
________


Anyway...
THE CULPRIT:

More

An extra jumper wire that shorted other jumpers

It looks like it was left over from manufacturing.

[rowdy]

As weird as it sounds some QFR problems are caused by the screws being too tight, your issue doesn't sound so simple but you never know.

0.o Does that actually happen?

There have been many reported instances where people loosened the case screws and the problems went away. Not saying that is the issue here but for a certain batch of QFR's it was an issue.

Yes, this happened to my other QFR...the screw was too tight and was causing the bottom of the PCB to scratch against the top of the USB daughter board.

It wasn't the case for this one...problem persisted even with the top cover off.
________


Anyway...
THE CULPRIT:

More

An extra jumper wire that shorted other jumpers

It looks like it was left over from manufacturing.

Well found!

Have to try to remember this for future reference.