Testing a digital dashboard clock with AC power?

Old 11-23-16, 07:28 PM
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Testing a digital dashboard clock with AC power?

I have been buying car parts and reselling them and I would like to try my hand at digital dashboard clocks. I have seen other sellers powering up the clocks in pictures to show that they work and I would like to know how to do that. A gentleman at Radio Shack helped me by making a tester out of a 120 volt AC to 12 volt 2 amp DC converter. He cut off the output end, separated the wires and soldered posts on to them. Supposedly I can touch the + and - posts to the corresponding inputs on the clock and power it up, but I cant seem to get it work no matter which post touches which terminal. I'm not terribly technically/electrically inclined and I don't want to set my house on fire, so any advice would be much appreciated. Thanks! - Tony
Old 11-23-16, 07:54 PM
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In general, what you describe should be capable of powering a clock module, although if it is an old one with several filament lamps for illumination, 2 amps may not be enough.

You probably need the wiring diagram for the particular clock module(s) you want to test.

There may be more than one connection to +12 and or more than one to common.

Some modules may be damaged (ruined) by incorrect connection, so it's not a good idea to randomly try connections.
Old 11-23-16, 10:03 PM
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Welcome to the forums.

I would like to try my hand at digital dashboard clocks.
I installed and serviced auto electronic products for years. I don't recall many cars having a separate clock. The clocks have been in the radios for ages.

What make and model car(s) are we talking about here ?
Before electronic radios I sold a lot of aftermarket digital clocks but there is an extremely limited market for that today.

Paul is on the right track. There are three or four power connections on those aftermarket clocks.
+12v for memory / switched +12v for display / -12v for ground

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