Repairing LCD burnt screen on Volvo Penta EVC tacho
The tacho LCD screen on my 2009 Bavaria developed a ‘burn’ mark across the screen making it unreadable. Engine hours and alarms were not accessible. I Googled the issue and it appears to be common. There were plenty of sites with YouTube instructions on how to dissemble and replace the lcd screen on VDO tachos, but I found nothing on EVC tachos. There are no spare parts available for the EVC tacho that I could find. The VDO replacement screens do not fit EVC tachos.
I repaired mine and would like to share how I did it.
First thing I did was find a dealer that had a replacement tacho in case I stuffed it up. I found a replacement at AUD$1,300. This was Plan B.
I then purchased an A4 size sheet of ‘Polarized Film’ for A$25. It has a protective plastic sheet on both sides of the film and one side only has glue on it. The film is marked which side has the glue on it.
https://www.kentfaith.com.au/polarized-film/KF31.074_polarized-film-300-200mmx1-with-a-film-scraper-two-bags-of-dI removed the tacho from the boat which is pretty well straight forward.
They do not appear to be designed to take apart easily. There are no screws on the back of it and it all comes out the front after the lens is removed.
I removed the bezel by pulling it straight back. Snap on fit.
The lens is held in place by bayonets all the way around the circumference and fitting in to slots on the housing. Push on fit with no easy way to remove it without damage. I sprayed the edge of the lens with silicon spray and tried a suction cup to pull the lens out, resigned to the fact that some damage may occur. No luck with that so I pried it open with a small screw driver which caused some of the housing parts to snap off. I directed this force to the lower section of the tacho so that after re-assembly the weakest point for leakage would be at the bottom of the tacho.
The lens came out easily after damaging some of the retaining slot plastic.
I then removed the tacho needle. It is a push on fit and was very tight requiring a flat screwdriver to lever it out.
There are 3 torx head screws to remove. Once they are out the whole unit can be removed from the housing. The pins for the plugs go out the back of the housing and may need a push through whilst working the rest of it out. There are no other screws holding it in place.
The display is a sheet of glass with a white plastic backing piece and a sheet of polarized film glued to the top surface. I used a box cutter knife to pull the burnt polarized sheet off of the glass. It came off easily in one piece. This leaves some glue on the glass which must all be removed. I used alcohol wipe fluid and a cotton bud. I also used a cotton bud dipped in acetone.
After I was happy with the glass I brought the tacho back down to the boat and plugged it in whilst disassembled. Be very careful as the connector can be plugged in 180 degrees from correct orientation whilst the housing is off, which could destroy the electronics. The correct way will be obvious if you bring the housing with you.
With the tacho powered up I held the A4 sheet of polarized film in front of the display with the glue side towards the tacho. I then rotated the film through 360 degrees. The display will change from not visible through to crystal clear as the film is rotated. When you have the sweet spot mark the polarized film with a marker pen with an arrow to indicate up. This mark will be on the protective cover and not the actual film.
Take the tacho back to your work space and cut out a rectangle the same size as the glass display. Mark the side with the glue in case your cutout is not over your arrow.
Make sure the new cut out film is not larger than the glass as it will foul when inserting it in to its holder later.
Peel the protective layer from the glue side and then apply it to the glass working it with a flat plastic scraper to make sure there are no air pockets. Then remove the protective cover from the top side of the film.
Reassemble the tacho but do not put the plastic lens on yet. Insert the tacho needle partially at the zero mark. Then plug the tacho in to the boat and start the engine. Stop the engine and make sure the needle stops at zero. When it is correct push the needle home and then install the lens.
The lens has a rubber labyrinth seal gasket that fits over a lip on the lens and then this slides inside the housing. This type does not rely on pressure from the lens against a flat surface so I was confident that the damaged retaining slots would not compromise the seal. I coated this section with silicon for peace of mind and then pushed the bezel cover back on.
Reinstalled the tacho on the boat and the display works perfectly. Total cost $25.
