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Discussion Starter · #1 ·
A DIY guide for those who might have a similar problem with the Odometer VFD (Vacuum fluorescent Display) no longer displaying the mileage. (possibly after fading out gradually over time)

First, you have to extract the instrument cluster from the dashboard.

The cluster itself must be completely disassembled to extract the main PCB board which has a small DC -> AC oscillator circuit mounted at one corner.

VFD's require pulsed voltage of around 16 volts to fluoresce. Some VFD's die of old age and cannot be regenerated, but in my case the problem lay in the DC -> AC power supply circuit.

You will need a solder sucker or similar to completely remove the solder from the 2 pins holding the metal casing on, and the 5 pins holding the oscillator sub-board onto the main PCB.

Mine had an obvious exploded transistor D1815 (No longer available) and extensive heat damage and loose components.

With a Digital Multi-meter, test all the resistors to make sure they are still giving readings close to spec. Test the diodes to ensure all are still working.

Note that while the transistor D1815 is no longer available, a compatible transistor that is still available is the *** Sanyo 2SD1815 ***.
In my case this was the only component I needed to replace, but i had to resolder ALL joints on the back of the board as they were all showing signs of cracking.

I set the main resistor (heat generator) up from the board a little, and while I have the metal case separated, I drilled a few small ventilation holes in the casing to help alleviate heat build up.

Soldered the mini-board and it's casing back on, re-assembled and.... Fixed.

Hope others have luck with this. The mileage is stored on the main PCB of the cluster, so the only way to retain the mileage of your vehicle is to fix the cluster as far as I know.

Enjoy.

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Thanks so very much. I've got a 1996 KA9 with 238K on the clock and I must say it has been a super reliable car until the odometer display suddenly died on me yesterday morning.
Armed with your excellent article with amazingly detailed photos I am going to inspect the instrument cluster starting tomorrow.

Many thanks once again
 

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Hi pnb, I've just found your solution for the failed odometer display.
I've got a '97 Legend with 120K miles on the clock. A great car that I've had for 10 years and has proved very reliable during that time. One or two big bills (ABS, suspension etc).
A few months ago the odometer display disappeared together with a smell of burning! It sounds like I've got a burnt-out transistor, exactly the same as yours.
Fortunately I have a friend who is an old-school electronics engineer and is up to doing the repair as described in your excellent post.
My questions are as follows:
1) What exactly are the steps you need to follow to remove the PCB board. This includes how to remove the instrument cluster.
2) I've found 2SD1815S and 2SD1815T transistors available on Ebay (you advise 2SD1815) - are either of these usable?
Many thanks
 

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Discussion Starter · #4 ·
Hi, The silver metal box covering that powersupply board is soldered onto the main cluster board, so you have to de-solder the legs of that first. (2 or 4 legs, I forget), (you will need a de-soldering tool. Once all the solder is gone you can lift that cover off.

Then the mini power supply board is also soldered to main board. (5 connections I think) once de-soldered you can remove and repair.

This was the transistor i used:

2SD1815T BY SANYO

I cannot post url as I am a new member. Ebay item was 160166156708

it's a bit of a job - back of centre console off, centre console up, center panel loose (only disconnect radio if you have the codes), centre vents out, cover below steering column off, then loosen cluster cover via access to all screws, then loosen cluster (and two wire harnesses on top) then remove cluster and break down. Still, I found $70 in change under my centre console, so the job was 'rewarding' lol.

Ps - while your under there would be worth checking out the clock for similar as per my other thread.
 
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