Electronics > Repair
Agilent 33220A display problem
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chilternview:
I have an Agilent 33220A 20MHz function generator which has a display problem - basically it looks like the display backlight has gone. It's just about possible to read a little on the left of the display, but not enough to read it. Factory reset does not help.

Anyone managed to fix one of these before? I've not opened it up yet to find out if the display has to be replaced as a unit or whether there is a LED tucked away that can be replaced.

Edit: I read the service manual, seems like the LCD display uses a CCFL backlight. I'm guessing that's gone; apart from that the 33220A seems to be working correctly. I wonder if the backlight can be replaced with a 12v LED strip?
coromonadalix:
in some cases you can convert some ccfl   to led ... it depends on how it is made,  or some lcd could substitute your's   if its really a dead ccfl supply ....

but you have to check all the supply lines, there was known cases of leaked caps in theses
chilternview:
Yes, checked supplies and they are ok (and the unit passes self-test).

The LCD display is a module on its own with a +12V supply and an inverter driving the CCFL. The CCFL is a plain straight tube about 3 inches long integrated into the display. I guess it may be possible to remove it and replace it although everything in that module is tightly packed.
chilternview:
Keysight quoted me £104 for a new 33220A display module which is less than I thought it would be.
coromonadalix:
could be a very standard one,  see in the service manual the specs 

but  you could try with a small led flashlight to the lcd side  if it is really working, and the ccfl just died,  some ccfl lamp can be found ...
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