Decided to go ahead and attempt the replacement of the polarization film on my 87's digi-dash as the speedometer portion had gotten so bad I could no longer read the 1st or 2nd digits unless I was wearing polarized sunglasses. Read the instructions and watched the videos from batee.com. Followed all of his steps including reflowing the suggested solder joints. Took me about 3 hours, $57, and a few new gray hairs. Few things for anyone wanting to do this:

-The pink rubber blocks were all stuck to the LCD glass, fortunately they came off with no tearing.

-The first panel I removed the original film from was the tach panel, I had to pull on it so hard to remove it I was afraid I'd break the glass, then I realized the original had 2 layers and I was only removing the top layer, once I got under the bottom layer it peeled off just fine.

-I also put new film on the tach panel first, I got some air bubbles in it and this stuff is not very forgiving. Fortunately by cutting the other pieces to size very closely I had just enough left over to redo the panel.

-The pink rubber blocks were distorted, they had been squished in there for 26 years now. After putting it back together I had one segment on the tach from 2000-3000 RPM that would not light up. Took it back apart and reseated the pink rubber blocks and that fixed it.

-I was concerned that with the number of screws and them all being self-threading into plastic that I would encounter some breakage, fortunately no plastic broke.

-On a side note, doing this made me wonder how many "real" low mileage cars are really out there? Disconnecting the odometer on this is way too easy. Don't know if unplugging that causes any other problems but for the corrupt people out there this design seems to easy to get away with.

Very happy to now have a completely black dash with the key off and everything lighting up like Star Wars with her running!


Very faded speedo section

Back cover off

Circuit boards removed

Removing old film and cleaning LCD glass

Reassembled and "blacked out"

Key on test. I do see one line missing from 1st digit of 4 of the sections (speedo, coolant temp, range trip, average instant) as well as the last digit in oil pressure. Since I plan on replacing the photo cell next I will check the pink rubber connections again then and hopefully get this 100%. Until then I'm happy to be able to read everything now!

 

Check your light bulbs, the one looks like it might be burnt out, but it could just be the picture I am not real sure.

Also good job, took me about hours to do mine and most of that was getting the plastic connector out of the car which took an hour itself.

 

Doh! Now that I look at the picture again it does look like both bottom bulbs are out! I just went out and looked at it again in a completely dark garage, looks better than before but now I do see the bottom portion is darker than the rest. I'll have to take care of this when I do the photocell too.

 

Yeah, when I did mine I had one bulb out so I replaced all with new ones from here.

http://shop.vettesport.com/1984-1989...IT-BUBLKIT.htm

Or you can get LED ones for a higher price from here.

http://www.usmracer.com/LED%20set.html

 

Thanks for the links. I did accidentally fix a lot of rattling and squeaking yesterday doing this. Before I thought all the noise was coming from the front of the passenger side door panel but must have been the dash pad as now it's the quietest its ever been inside!

 

Very nice job. Thanks for the addendum.

I'd be very interested in this. Do you have a source for the replacement?

 

Looks like I spoke too soon, I haven't been able to find anything on a replacement sensor. Not sure how much it's really needed? I've driven mine in the day and night with only the top 2 bulbs working and haven't had any problems, those dim just fine with the headlight switch so I might not worry too much about replacing this sensor.

 

I'd replace the two burned out bulbs first before you go looking for photo cells. With half the bulbs out the lighting circuit has twice the parallel resistance which might (?) defeat the voltage regulator (which is driven by the photo cell output I think). Just a guess here -not having a schematic makes troubleshooting these units pretty difficult.

 

I haven't been able to either. All my dash lights work, but the photcell dims them too much, so I've just bypassed it for now.

 

I'm looking into photocells right now. My dash is dim 90% of the time (sometimes it works correctly -- most of the time not). It acts like it thinks the headlights are on. I don't know yet if it's a photocell issue or something else is going on. From what I can tell the photocell circuit is in parallel with the headlight switch circuit -- interesting. The FSM diagrams are not much help. The FSM says, "If it doesn't work send it out for repair", so the info is very sketchy.

Anyhow, I found the company that made the original photocells (Vactec -- they've been bought multiple times and it's now Excelitas Technologies). The originals have a VT6861 number on them, but that number is no longer available. Also the originals have a plastic light shield that I can't find a source for (probably a Vactec part that is no longer made). The photocells are glued into the light shield. I pushed pretty hard but I couldn't get the photocell out. I'm not sure you need the light shield anyway, given the geometry of the hole in the bezel, etc.

I've been tracing out the photocell circuit. I got temporarily stopped when it disappeared into an unknown Delco IC -- hate those. Just the last 4 digits of the part number and no way to find a data sheet for a part this old. I had to put the dash back in the car so I can drive it so that limits what I can do.

Interesting tidbit from the FSM: the dash goes to maximum brightness if any of the alarm lights come on. That includes the oil pressure, oil temperature, coolant temperature, voltage and fuel reserve.

Still investigating...