Electronic tach

[Guest]

The tach on my 84 1150 was all over the place. Seemed accurate from idle to 2500 rpm then would jump to 4000 and as you increased speed it would come back down and settle around 2500 regardless of speed. Thinking I had a defective unit I replaced it with a ebay unit. The replacement is doing the same thing. Should I be looking elsewhere. Is there a trigger or is it sent by something else.

[rustybronco]

http://thegsresources.com/_forum/showthread.php?p=1547324#post1547324

[OLDENUFF]

Is anyone out there doing this repair? I would be happy to send my tach to be fixxed.

[rustybronco]

The original I.C. used in the tach doesn't appear to be available. You can try changing all the capacitors, but if that doesn't fix the problem you need to find someone who will make up that replacement unit for you.

I know of no one who repairs those types of units.

[JEEPRUSTY]

DO you have a photo of the unit?
I wonder if my spare 550 electronic tach setup would work?

[OLDENUFF]

backside...

[OLDENUFF]

inside....

[OLDENUFF]

faceplate...

[JEEPRUSTY]

mine looks identical but for the pcb
pics to follow when my gd battery is charged back up.

This may be a good alternate for these bits

One of the guys on here is parting out a 550

[JEEPRUSTY]

[IMG] [/IMG]

[OLDENUFF]

I'd be willing to take a chance on it if you're sure it works properly. PM me a price and your paypal info. Thanks, Bob

[JEEPRUSTY]

I would not part with my spare cos a bird in hand is...........

http://www.thegsresources.com/_forum/showthread.php?t=185789

Apparently this issue was being worked on by another member

[nater]

The tach on my 84 1150 was all over the place. Seemed accurate from idle to 2500 rpm then would jump to 4000 and as you increased speed it would come back down and settle around 2500 regardless of speed. Thinking I had a defective unit I replaced it with a ebay unit. The replacement is doing the same thing. Should I be looking elsewhere. Is there a trigger or is it sent by something else.

As Rusty said, you can try changing out the caps on the board as these are easily found and tend to dry up with age. Sometimes, an overvoltage causes that black chip to fail. Other times, you can see burn marks on the large white resistor which also indicates its been overdriven.

If you're having the same issue as before, did you replace just the board or the tach as well? Make sure your three connections going to the board are clean and solid.

[OLDENUFF]

I replaced the entire tach with the same results. Connections are all good. That's why I was thinking it was the trigger or whatever pulses the tach. I have zero electronic savy.

[OLDENUFF]

All components look very clean with no discolorization and nothing appears to have moved. Everything is solid.