Fluke 85 Display

[skylinrcr01]

Hey all,

I have a fluke 85 DMM that has a display with some segments that don't work. I tried replacing the elastomers for the LCD, and also cleaning the contact strip on the LCD as well as the main board, but the problem persists. I did notice that the contact pads on the main board are black, which I have never seen before, typically they are gold or silver. The LCD is chipped in the corner as well, but at certain viewing angles it's fine, so I'm not sure the chip is affecting it at all.

Any ideas?

[ModemHead]

The b and g segments are all out, also the lo-bat, MIN and others connected to the H2 backplane.  That implies that H2 is dead (or weak), which is pin 20 on the LCD, driven from pin 61 on the QFP chip.  LCD pin 20 is the one on the top row, left end.  Which just happens to be where that chipped glass is...

[retiredcaps]

Reminds me of this case over at badcaps.net almost 4 years ago (you have to be a member to see the pictures)

http://www.badcaps.net/forum/showthread.php?t=27198

Same problem with chipped glass leading to missing segments.

PS. How time flies.  Modemhead was also participating in that thread.

[SeanB]

Chipped and missing LCD drive from the display. The black pads are designed that way, with a conductive carbon coat so the Zebra strip does not have contact issues from oxide formation, it is a deposited carbon layer there so there is only a carbon to carbon connection ( and thus no corrosion) to the zebra strip, nothing to worry about.

What you need is a new LCD display.

[skylinrcr01]

Chipped and missing LCD drive from the display. The black pads are designed that way, with a conductive carbon coat so the Zebra strip does not have contact issues from oxide formation, it is a deposited carbon layer there so there is only a carbon to carbon connection ( and thus no corrosion) to the zebra strip, nothing to worry about.

What you need is a new LCD display.

Ah, that makes sense. Thanks for the replies everyone.