Attention: TDR Forum Junkies Hi all, As many of you know. I have been repairing the 90 threw 93 electronic speedometers for some time now. Normally the problem is broken gears in the odometer. So clean it up replace the gears and your good to go. Well lately I have been getting speedo's where the problem is the speedometer quit
and the odometer is working fine... In the past I would just pull one out of the pile of cores and fix it.
Now I am out of good cores. So I sat down and figured out the electronics. It turns out that when the IC chip malfunctions the speedometer quits. There are also 2 electrolytic capacitors on the circuit board that fail as well. Electrolytic capacitors are kind of like flashlight batteries. When all the juice inside evaporates or leaks out the cap quits working. The good news is that I have located some of the IC chips and electrolytic capacitors to repair them with.
Another problem I have found is that the speedo and the odometer are too often not in sync .
If you want to check yours run the truck up to 60 mph . The odometer should turn 1 mile in 60 seconds .
If not I have found the best way to correct it is to replace one of the resistors with one half its value then install a potentiometer (like a volume switch) beside it to make up the difference . The potentiometer adjusts the resistance value . This in turn allows you to adjust the speedo to be exactly in sync with the odometer ...
Call me or email me with your needs... /// Terry 301-219-7399
and the odometer is working fine... In the past I would just pull one out of the pile of cores and fix it.
Now I am out of good cores. So I sat down and figured out the electronics. It turns out that when the IC chip malfunctions the speedometer quits. There are also 2 electrolytic capacitors on the circuit board that fail as well. Electrolytic capacitors are kind of like flashlight batteries. When all the juice inside evaporates or leaks out the cap quits working. The good news is that I have located some of the IC chips and electrolytic capacitors to repair them with.
Another problem I have found is that the speedo and the odometer are too often not in sync .
If you want to check yours run the truck up to 60 mph . The odometer should turn 1 mile in 60 seconds .
If not I have found the best way to correct it is to replace one of the resistors with one half its value then install a potentiometer (like a volume switch) beside it to make up the difference . The potentiometer adjusts the resistance value . This in turn allows you to adjust the speedo to be exactly in sync with the odometer ...
Call me or email me with your needs... /// Terry 301-219-7399
