Early P1800 Rev Counter wanted

[asneddon]

My original Jensen Rev counter seems to be dead. The sender unit was missing so I tried hooking it up through a 12v to 12v transformer, and nothing. Then tried a direct hookup and nothing. I guess the sender using is something more complex. This is a single spade connector type. I haven't pulled it apart yet.

I've borrowed another earlier rev counter from Charlie at the Oxford Classic Volvo place and that would just spin around to full revs when power was supplied. Its a strange two spade connector one I couldn't find decent wiring diagrams for. I pulled it apart (with Charlies blessing) and its just a transformer hooked up to the electro magnet windings. No resistors or diodes in sight!

I'm now looking for a simple induction pickup type (The one where you wrap the low tension coil wire around the pickup) to see if I have any luck with that. Anyone have one around?

Thanks

[agent_strangelove]

If you can't find one locally, I may have one or two of the black box tachs about. If all else fails, you get a late '63 or '64 car and there was a small supplimental harness that hooked up to the coil and distributor (dizzy) and the tachs from those years read off that. Most of the folks that I know that have Jensen cars, had the black box sender unit go bad and went to a '63-64 tach with the additional bit of wire. I have done this on my own car (not a Jensen car but shortly after production moved back to Sweden) as it left the factory with a black box sender in the nose...


Chris

[asneddon]

Thanks. Can you tell me more about the supplimental harness?

The two spade connector rev counter I borrowed had one connector market + and the other was unmarked. I tried all the combinations of hooking it up I could think of:

+ to 12V, other to distributor
+ to distributor, other to 12V

coil to +, other to distributor
coil to -, other to distributior

Body earthed in all cases.

The action of the guage was always to ram at full speed over to max as soon as power was enabled (either through connection to battery or when ignition was turned on), or not to move at all.

The rev counter I still have is a 6000rpm red line one, and has one spade connector on the back, and one other connector that looks like a screw on clamp connector which is isolated from the guage body. I'll take photos some time. Ive never connected this second connection up to anything. My car is a 1963, but I dont know if its early or late in that year.

Allister

[asneddon]

I've attached some of the reference stuff Ive found.

the first two are from the Volvo service manual. Ive cut out all the other stuff as it was in the way.

The third one is stolen off the web. Sorry whoever I stole it from.

The last one came up on a google search and was interesting. Also stolen with no reference.

Hopefully this can help someone else

[agent_strangelove]

I can't promiss any info off the top of my head so I will wait till my car is in front of me. I will take some photos this evening when I am home and post them up...


Chris

[asneddon]

Here are some reference photos of the two types of tachs I've tried out.