Does anyone have a correct wiring diagram for inside an 1800 tach? I have seen several but the specs for the various resistors are incorrect. Looking at a resistor with color bars that decode to 333 ohms the diagram reads 3R3.


Arctic Bob

 

Arctic Bob
Did you ever figure out the wiring diagram for your 1800 rev counter? Get it fixed?
Jamie, also from Victoria

 

when you measure resistors it is always best practice to lift one leg to take it out of circuit, otherwise there may be another electrical path around the resistor.

If there is another path around the resistor, that can't increase resistance it can only lower the resistance.

I have the same tach in my 122 if it's on top of the dash. is this something I could check to compare to yours without disassembly? on mine the outer housing is cracked so it doesn't tighten properly when I screw the front on but otherwise it's fine.

I work a lot on antique radios so I change them often and mostly when they get old the resistance increases. sometimes they go open, they never seem to go down to a lower resistance. the rule of thumb for the stuff I work on is that plus or minus 10% is still ok. more than that constitute replacement. usually stuff from that era uses the colored bands to show it's value but I have seen military style resistors where they print the value on them.

if the resistor seems to follow the normal color bands then reading the lines and color should be ok.. I might be able to drop one in the mail if you need it. what does your measure?
Phil