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Washed Out Spedo LCD

jsinga

Well-known member
Joined
Nov 23, 2001
Messages
280
Location
Savannah, GA, USA
Corvette
87 Silver Coupe Way over 200k miles
Is there a fix for a washed out LCD besides replacement?
My speedo is to the point where the only way you can seen anything besides a totally lit up display is to put on your polarized sunglasses.
If I can't fix the one I have might as well go for a reworked cluster? I've seen someone does them for @$200.

Thanks

JS
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Give a better description

Are the other gauges fine?

You know the LCD display is backlit..if the bulbs on that side are OUT
it will be very DIM...

Vig!
 

jsinga

Well-known member
Joined
Nov 23, 2001
Messages
280
Location
Savannah, GA, USA
Corvette
87 Silver Coupe Way over 200k miles
All the gauges and the tach are readable and bright enough. The spedo is bright enough you just can't "see" any numbers. The entire oval areas where the numbers are displayed are all bright and the whole spedo graph is bright. But, if you have on polarized glasses you can make out the numbers.
I haven't pulled the front off to look at the bulbs yet but I can turn them up and down and it changes the brightness all across the displays.

JS
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
OH I get it

ALL the segments are ON... the whole thing is lit up.. and there is no contrast.... WOW that's a new one.

Did I get the correct picture?

Vig!
 
N

nickjgj

Guest
Hey Vig

That is the same problem I am having with mine all lights lit and no contrast except with mine it is all the gauges except the digital part of the speedo you can vaguely see them if you stare I posted about it before but have not had time to check on the ground wires you told me about( or even find them for that matter)
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
WOW that's weird

I have NEVER run across that problem before.

But here's the theory....


The Circut boards are NOT getting the 5 volts needed to drive the chips ( Internal to the dash )

SO all the segments are ON like the dash would NORMALLY self test when 1st turned on.

Remember the dash works like an LCD watch

BUT INVERTED..

So when a segment is OFF the backlight shines thru!

So I would assume that the gauges are all off, from a functionality standpoint or IF they are working ( with your 3D glasses on) The lower board ( which has the actual drivers for the display) are just leaking current not actually DRIVING the displays.

Really weird stuff.

Send me one.

Vig!
 
D

ddmau

Guest
All my LCD seem to work fine other than the speedo. It is lit well enough but there is no movement at all. I thought perhaps the cable was broken coming off the transmission, but then, is there a cable at all?
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Is the speedo just sitting @ "0"

It could be the speedo sensor in the tranny tail shaft either electrically KAPUT of the gear drive is stripped/ missing/out of alignment.

Vig!
 

vigman

Motor head!!!!
Joined
Feb 13, 2001
Messages
3,471
Location
Valencia, CA,USA
Corvette
88 Convert ( SOLD ) /1973 coupe 4 speed/1964 Vert!
Oops

Didn't answer YOUR question.

The speed sensor is a shaft encoder which is gear driven internally of the tranny.. then an electrical pulse train goes up to the dash electronics.

No cable!


Vig!
 
D

ddmau

Guest
Hmmm, that will take a little research on my part...not as simple as replacing a cable, I suppose. Thanks.:hb
 

CorvetteArchives

Well-known member
Joined
Apr 19, 2001
Messages
547
Location
Carbon County, PA
Corvette
1984 Z51 Silver/Gray & as Much SS & CFibre we find
Sorry no help........ just amused that Vigman's avatar with that quizical look on his face really is appropriate in this case!

I have NEVER even heard of this problem before! This may be worthy of a call to Gordon Killebrew its so odd.

besides the low voltage Vig mentioned......Could it be leaking the LCD fluid itself?? Or too much pressure somehow on the fluid...like how if you press on a cheap watch crystal it distorts?

In any event this may be worth the $200 for a reworked cluster to save some hair pulling! (although I'd be carefull of the core charge since most point out the cluster must be "rebuildable")
:w
 

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