Tachometer is under reading

[GDII]

I'm surprised I didn't manage to get any photos of the negative stripe on the capacitors when I took the tacho out to grab to photos. I have one of the circuit board but that isn't much help. Unless someone has a gauge cluster sitting around they can look at, I'll go back and pull mine out of the car again to grab more info.

[GDII]

I took my Tacho out again last night to grab some photos. I had to remove the dash again to check some of the light bulbs anyway. I will edit this post later with the photos showing the negative pins and circuit so you can put them in the right way.

Photos showing the negative pin of the capacitors.

Negative of the top capacitor.

Tachometer Capacitor MR2 SW20 1.jpg (180.51 KiB) Viewed 2966 times

Negative of the bottom capacitor.

Tachometer Capacitor MR2 SW20 2.jpg (255.17 KiB) Viewed 2966 times

This shows the PCB. Marked in red are the negative pins of each capacitor.

Tachometer Capacitor Negitive pins MR2 SW20 2.jpg (531.55 KiB) Viewed 2966 times

[Benckj]

Wonder if you could also do a short write up on LED conversion for the dash lights. Been meaning to do this for a few years now but never found the time.

[GDII]

What did you have in mind? If you get the correct LEDs (wattage and physical size) that fit the standard bulb fittings you can change most of them with no issues. I think some bulbs can't be replaced as the cause issues.

This seems to show a how to anyway. http://www.mr2.com/forums/threads/29633 ... ster-Bulbs

[imagineer]

Hi guys, I just repaired this problem on my 1990 MR2 SW20, thanks to your post here. Marvelous, one of the capacitor legs appeared to be completely corroded away. The photo marking the negative contacts was particularly helpful, made soldering in the new capacitors a cinch. (Jaycars gave me 16 V, though I asked for 25V).
Thanks again - had the problem diagnosed within 5 minutes of sitting down at the computer to google this under-reading tacho thanks to you guys!

[Crawls]

I just done this on my MR, and I turned the key on and the needle went to 1000rpm. But car wasn't going, did I solder one in wrong or put needle in wrong place haha

[GDII]

I just done this on my MR, and I turned the key on and the needle went to 1000rpm. But car wasn't going, did I solder one in wrong or put needle in wrong place haha

Did you take the needle off when you did this?

[Crawls]

Ah yes I did. Do I power up tacho then put needle at zero

[GDII]

No need to take the needle off to do this fix. But to fix that I guess this will be the best way.
If you aren't sure if it's then correct ask for some RPM vs speedo readings from some other users.

[Crawls]

Thanks mate. Kinda new to this

[GDII]

Fair enough. Feel free to ask any questions here if you are unsure of anything.