Dash has bright spots

[Critter]

Hello all!

One morning, I started the '85 vette and it looks like there is two bright spots behind the the dash (in the middle of the speedometer, and the bottom of the fuel gauge)



I've tried poking around to find what would cause the problem. I'm assuming a bulb in the dash, but not sure if that would make it look brighter. Any help on what causes it would be extremley helpful! (Or even what to search for; most of my searches end up with results about the lights being completely dark)

Thanks a bunch!

[XQIZT]

Bulbs, bad grounds, "sunburnt" LCD panels, age. Mine does the same thing and has for YEARS. It's just one of those things that annoys me, but not enough to dig into. There is a great website (although the name escapes me now) that is basically the end-all-be-all to digi-dash issues. Some one will chime in.

[Critter]

Yeah, I think it was Batee (or something similar). Had every problem listed but the brightness!

[XQIZT]

Originally Posted by Critter

Yeah, I think it was Batee (or something similar). Had every problem listed but the brightness!

Batee...Thats it!

[PNHNDLE96CE]

No help what so ever but I always loved those early C4 dashes.

[wildcatlock]

Originally Posted by Critter

Hello all!

One morning, I started the '85 vette and it looks like there is two bright spots behind the the dash (in the middle of the speedometer, and the bottom of the fuel gauge)



I've tried poking around to find what would cause the problem. I'm assuming a bulb in the dash, but not sure if that would make it look brighter. Any help on what causes it would be extremley helpful! (Or even what to search for; most of my searches end up with results about the lights being completely dark)

Thanks a bunch!

Judging from you picture I would have to say your LCD is "sunburnt". The fix is to replace the polarizing film on the face of the lcd displays. There are articles out there about how to do it, and I think the best one is either on Batee or linked from there. Film isnt "cheap" but will make a world of difference. I have done three clusters myself and it isnt real hard, just time consuming. Most owners have forgotten that a proper digidash will show only lit portions of the display and not the unlit portions, i.e. squares the numbers appear in, arch for tach and speedo, etc. Anyway that is your bright spot problem and the fix for it. I have the link saved just need to find it. If I do I will post for you..

[Critter]

Thank you very much!!! I have run across some of the tutorials about replacing the polarizing film, but never found a photo to compare it to. I have to admit, I'm terrified of removing the dash, but I think it'll be an after-Christmas Saturday project.

Thanks again!

[wildcatlock]

Originally Posted by Critter

Thank you very much!!! I have run across some of the tutorials about replacing the polarizing film, but never found a photo to compare it to. I have to admit, I'm terrified of removing the dash, but I think it'll be an after-Christmas Saturday project.

Thanks again!

Dont let it scare you. If you follow the batee instructions you will be fine. Pretty simple just be careful and cautious. When replacing the film try to remove the old film first or the displsy wont be as dark as it should be. The lcd displays are glass on both sides and the contacts are internal so no worries there. Use a new single edge razor blade and go about it like you are removing a sticker from a window. If you keep the display on a towel laid over a hard flat surface you will have very little chance of damaging them. If you need help or have questions just PM me and I will try to help. Good luck and let us know how it goes.

[Critter]

Will do, thanks for the info! Should I replace the bulbs back there while it's out?

[wildcatlock]

Originally Posted by Critter

Will do, thanks for the info! Should I replace the bulbs back there while it's out?

I would as you will be right there. No need for the expensive halogen originals though. I always replace with IIRC a 557 bulb. Inexpensive and run much cooler than the halogen originals. When you pull the cluster out you will probably see brown spots around the plastic where the bulbs are. This is from the bulbs getting so hot they soften and burn the plastic frame. Factory used halogen for longevity but heat is a killer for all parts around them. The 557 bulbs dont last as long but run much cooler and are almost as bright. Bulbs are available at local auto parts if you go this route also. The halogens are getting harder and harder to find.

[Critter]

Thanks for all of the input! I've got the polarization film ordered; another question: any recommendation on what to use to clean the contacts in the back?

[wildcatlock]

Originally Posted by Critter

Thanks for all of the input! I've got the polarization film ordered; another question: any recommendation on what to use to clean the contacts in the back?

I have always used rubbing alchohol ( isopropyl alchohol ) and a lint free towel. Super cheap and worked every time. Your "contacts" will be a small block of rubber. Dont worry if they come off the glass or the board as it wont hurt anything. They are not attached with any adhesive just stuck from heat and time. I always remove them from the glass and the board to clean the contacts on both sides. Makes scraping the old film easier also. Good luck to you and remember we are here if you need us. That is what makes DC such a great place.

[Critter]

SUCCESS!!!!!!!

... well, mostly...

First, for the good news! I took the cluster out; it came out fine. (Much more easily then I assumed) Took it all apart, scraped the old film off, applied the new, replaced the bulbs, and put it back together, and it looks magnificent!!!

The only small challenge I ran into: there is a multi-pin connector going from one of the boards to the other, and I had to use a small pin to loosen the connections while applying force to slowly wedge it off. It worked, but I think I was just paranoid while prying up the top board.

The re-polarized display looks absolutely great!!

... BUT, I lost the light for the 15mph marker. (The text and 2 bars). Any thoughts on what I would have done wrong to make it not show up?

And for my general cluster knowledge; I'm assuming the way it works is the 4 light bulbs reflect through the thick cut-out glass pieces under the display glass. There is also a sheet that has the colors mapped out that is on top of the thick glass. Does the light angle thought the glass, and then certain parts of the color sheet light up to show what should be displayed?

Thanks everyone for all the comments and help on this, I felt like quite a bad ass when I was all done! :]

[wildcatlock]

Originally Posted by Critter

SUCCESS!!!!!!!

... well, mostly...

First, for the good news! I took the cluster out; it came out fine. (Much more easily then I assumed) Took it all apart, scraped the old film off, applied the new, replaced the bulbs, and put it back together, and it looks magnificent!!!

The only small challenge I ran into: there is a multi-pin connector going from one of the boards to the other, and I had to use a small pin to loosen the connections while applying force to slowly wedge it off. It worked, but I think I was just paranoid while prying up the top board.

The re-polarized display looks absolutely great!!

... BUT, I lost the light for the 15mph marker. (The text and 2 bars). Any thoughts on what I would have done wrong to make it not show up?

And for my general cluster knowledge; I'm assuming the way it works is the 4 light bulbs reflect through the thick cut-out glass pieces under the display glass. There is also a sheet that has the colors mapped out that is on top of the thick glass. Does the light angle thought the glass, and then certain parts of the color sheet light up to show what should be displayed?

Thanks everyone for all the comments and help on this, I felt like quite a bad ass when I was all done! :]

Congrats on the job well done. The segments on the speedo may come back on their own. That is all on the lcd and signal/current is transmitted through the little rubber contacts. You did remove them and clean them, the lcd, and the board where they make contact correct? You are pretty much correct on how the display works. The "clear" areas of the lcd will go dark when power is applied. The digits are actually the dead spots that allow the light through. The color sheet gives the different colors to the display. There are mods to change the color to green, red, blue, etc. You can see them on ebay all the time. Anyway the segment you are missing may come back with a bit of time. Probably just not making good contact. The ones I have done almost always had a spot or two that wasnt displayed but always work itself out, usually with the heat of summer baking the conection. I would give it a few miles and see if it clears itself up. If not at least you know how to take it all apart now. It will be the little rubber conductor on the speedo lcd. Post some after pics so we can all judge your work.

[Critter]

In all fairness, I forgot to clean the contacts on the rubber pieces.... I did remember the next morning, but, you know.... :]

(I'm planning on taking it apart again on the next nice weekend and clean them, out of principal)