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Silvertone 1484 -- Adding Grounding


jimSG

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I have had an '67 vintage Silvertone 1484 for several years now. It does not have a ground with the main power cable. I have ignored that over the years but recently my son was mildly shocked while playing it so I would like to add a ground the chassis/power supply. I have a good bit of experience with digital electronics but very little with power supplies. I was thinking of simply replacing the two prong power cable with a three prong and attaching the grounding wire to the chassis. But...I really don't want to mess things up or build up a false sense of security with an ineffective "fix". I would appriciate any suggestions from the forum.

 

I am attempting to add a link to the schematic that I have uploaded to photobucket -- not to sure how to do this.

 

http://i50.photobucket.com/albums/f302/jimsg/silvertone1484version2.jpg

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The best way would be to bypass the ground switch and/or (if you can't figure out how to do that) simply add a three prong plug by soldering the new wires to the existing terminals that you pulled the old ones off of. As for the ground wire (green), I used a grounding clip and cliped the exposed wire to the piece of metal on the back of the lamp of my 1484. If you have a meter you might want to check it first to make sure that it's making a good ground to chassis first.

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Originally posted by Bowie

The best way would be to bypass the ground switch and/or (if you can't figure out how to do that) simply add a three prong plug by soldering the new wires to the existing terminals that you pulled the old ones off of. As for the ground wire (green), I used a grounding clip and cliped the exposed wire to the piece of metal on the back of the lamp of my 1484.

 

 

Thanks for the quick reply! I have a couple questions. First, when you mention the back of the lamp, are you refering to the power indicator lamp on the front panel? My other question is about the grounding switch: what is is for?!? Looking at the schematic I could not see how that switch effected a ground. I'm just not used to seeing that switch on my modern amps and I never had a user's guide for the Silvertone. Thanks again.

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pull the old power cable out and put a three prong plug in.put a ring terminal on the ground wire on the new plug and bolt it down under one of the transformer mounting bolts.do away with the old polarity switch and you should be good to go.

 

the old polarity switch is not a ground switch- reverses the polarity in the old two prong wiring scheme (does the same thing as pulling the plug out of the wall and flipping it over).

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Originally posted by garfight

....the old polarity switch is not a ground switch- reverses the polarity in the old two prong wiring scheme (does the same thing as pulling the plug out of the wall and flipping it over).

 

 

That confirms my suspicions about the "ground" switch. If I do not bypass the switch, will the grounding scheme that you described in your reply be compromised? I'm hoping to make the upgrade this weekend and my plate is already pretty full.

 

Thanks again to all who replied!

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bypassing the switch won't take any longer than not bypassing it.it's just a matter of connecting into the power supply at a different spot.just cut the wires off the switch and solder them to the wires from the new power cable and heatshrink the joint.you can even leave the switch in the chassis if you like to maintain the original look. :)

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