Author Topic: SDA /SDT Generator Manual copy available and question on de-magnetised generator  (Read 4515 times)

ajaffa1

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Hi Alex, nothing to panic about. The important thing is that you now have continuity between 1 and 13, so it should be able to generate electricity. The slightly odd reading you get might be caused by dirty brushes or slip rings, it could also be caused by the two radio frequency condensers if they are still connected or it might be that the very low voltages produced by a multi meter are not high enough to quickly trigger the diodes in a bridge rectifier rated at 400 volts 60 amps.

Could you please check the resistance between 13 and 14 (black probe on 13) should read 0.1 ohms, 13 and 15 (black probe on 13) should read 2.7  ohms, 13 and 16 (black probe on 13) should read 0.3 ohms and lastly 13 and 17 (black probe on 13) should read 0.1 ohms.

Let me know what you get, no surrender!

Bob

Alexdick

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ok i have continuity between 13 + 14 but it is up at 112 ohms! 13 + 15jumps up to between 40 - 120 ohms then back down to 1 straight away. i can't get continuity between 13 + 16 and between 13 + 17....... I am beginning to wonder id i should strip it down and rewire it?! thanks. alex

ajaffa1

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Hi Alex, I think we are getting close to diagnosing the problem, You should have continuity between 13 and 16/17. Without it you will not energize the main field. Please confirm continuity between 13 and 19; please also confirm continuity between 22 and 16/17.

Bob

Alexdick

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Hi Bob
no continuity between 13 and 19 (the battery negative input)
no continuity between 22 and 16 / 17
The engine turns over ok with the starter pressed down.
when the problem started originally it was generating fine but i let it shut down whilst still connected to the house so i feel everything is ok albeit a little antiquated? what do you think'?
thanks
alex

ajaffa1

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Hi Alex, I`m pretty sure everything on the output side of things is OK. Start it up and see what happens, the main field winding should be energized during the starting process. My only concern is the lack of continuity across that main field winding. The problem might be the connections on the wire wound rheostat.

Bob

Alexdick

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Hi Bob

great news....it's working. I attached a lamp to the red/black outputs in the top box and the bulb is burning brightly! Thank you for all the help with this, I really do appreciate it. OK, my next project is to strip it down and rewire everything....it is filthy and some of the wires have been nibbled by mice so it is long overdue. What do you think? I can't see how to open it up for a start and, secondly, don't know which wire is should be looking to buy....
thanks
Alex

ajaffa1

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Well done Alex! I am so glad to hear the old family heirloom is back in action. You should certainly repair any wiring that has been damaged by mice or age. I would recommend that you try to find as close a match to the original wires as possible, When I did mine I found that some auto parts places had a very good range of different coloured wires in different gauges.

Looking forward to seeing the results.

Bob

Alexdick

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Thanks Bob. One question, is there an easy way to dismantle it? I canít see an obvious way of gaining access to the internals!