I have a pre 50s electric cuved glass speedo with a round 3 pin plug , I have spent 3 hrs hear & on google looking for information on what type of Sender used Or any wireing digrams or any photos , none found !! I am trying to find out how the older ones worked & why they where used, Pre 50s Does any one know where to look , Or. Does S&W have a tech line for the many thousands of gauges they have made for over the last 100 plus years .
The part you have is the cheapest part of the setup (hope you did not pay a lot ). The senders and cables with the plugs are hard to find and are specific to the distributor they fit. If you look under my posts you will find pictures of a complete setup. Gary
Thanks Roaster1927 , did you catch that it's a Speedo ,, not a tach . I seen a post that you replied to , on a stool there was a tach & distributor , ? If so you Referenced to a tail shaft sender , is it like the modern senders ? Any literature or wiring diagrams or photos .
They also made some transmission senders. They are all small generators to run the motor on the back of the head unit. They seem to be even harder to find! If you search the old tach threads, I seem to remember some old catalog pages with the senders pictured. Gary
Yeah, the senders are wicked tough to find. I've seen folks basically open em up, toss the guts and go ahead and retrofit the speedo with modern guts as to avoid trying to find a sender. JohnnyA I borrowed these pictures from the classifieds awhile back...first sender I'd ever seen.
A follow up on my question about Electric S-W speedo with a sender No. 762-R ( thanks to Rusty @ Speedometer services , A HAMB alliance member ) & a few more hrs I found This about how the sender works , ( this is from a nother web site) The way that the unit is wired is that the gauge receives positive voltage on one of its three brushes, or phases. The sending unit has the alternate brush receiving negative voltage. When the gauge is turned, the voltage spikes and effectively doubles inside the sending unit creating an impulse or a rotation which the gauge decodes and turns into dial movement. In the past, I had wired the gauge by providing positive voltage to one phase, and negative to another brush on the sending unit side. This effectively created an instantaneous short because the two phases were shorting each other out instead of talking through the gauge to one another. When wired incorrectly the gauge was drawing over 5 amps of current. Now that it is wired correctly, as seen in my diagram, it draws about 0.55 amps in non working condition to power up the tachometer. When the sending unit is working, current draw jumps to ~0.75 amps which is in line with the little SW literature I have on this gauge. Finally, finally after all of this time I know how to wire this gauge! I am so excited and am sharing all that I know about this gauge for you to see. It is a model 760 tachometer and 762 sending unit. And the photo is a break down on what in side Tach & speedo that requires the 762-R sender. I hope this will held with more interest and more feed back on these Old S-W electric speedo's & tach's! I would hope that there is some HAMBER's that have some old Teck & catalog's ((1961 and earlier )). Will post
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