Modify an m104 tachometer to work with an om603?
Modify an m104 tachometer to work with an om603?
![[Image: NVIB48q.jpg?1]](http://i.imgur.com/NVIB48q.jpg?1)
After the fix I found that the tach was reading about 200rpm too low so I adjusted it with the potentiometer built into the circuit board.
![[Image: 4jl9ONV.jpg?1]](http://i.imgur.com/4jl9ONV.jpg?1)
While I had the 300D and E320 clusters apart side by side, I swapped the E320 outside temperature gauge and plug (mine was broken), light tubes for improved lighting at night and orange needles. Mine were faded to yellow.
![[Image: 7n0dvCz.jpg?1]](http://i.imgur.com/7n0dvCz.jpg?1)
Ignore the 7k tach lol
![[Image: ctrwzjz.jpg?1]](http://i.imgur.com/ctrwzjz.jpg?1)
Light tubes. These carry light from the back of the cluster to the front. They can be swapped out by drilling out the plastic pins holding them in place. The 87 one is on the left, 94 on the right.
![[Image: FoMyylO.jpg?1]](http://i.imgur.com/FoMyylO.jpg?1)
![[Image: 208104.png]](http://badges.fuelly.com/images/sig-us/208104.png)
I was able to fix the 6k diesel tach by replacing the 2 electrolytic capacitors and 1 burned up 51ohm resistor. The Caps are 50v 1uF and 100v 10uf. The 10uF cap was short circuited internally. There was no resistance across the 2 pins. The new caps are on the right and the blue resistor on the left. I used a 2w vs 1w originally. EDIT: I also replaced the little black diode in the upper left hand corner because I had one on hand. The new blue resistor still gets warm to the touch which is probably not good but the old 1w resistor survived 30 years so the 2w resistor I installed should last at least as long.
After the fix I found that the tach was reading about 200rpm too low so I adjusted it with the potentiometer built into the circuit board.
While I had the 300D and E320 clusters apart side by side, I swapped the E320 outside temperature gauge and plug (mine was broken), light tubes for improved lighting at night and orange needles. Mine were faded to yellow.
Ignore the 7k tach lol
Light tubes. These carry light from the back of the cluster to the front. They can be swapped out by drilling out the plastic pins holding them in place. The 87 one is on the left, 94 on the right.
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