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Sho_Bud
Semi Newbie
Joined: 04 Oct 2009
Posts: 5
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 Posted: Tue Oct 13, 2009 7:37 pm Post subject: updating old electronics with 3 prong plug |
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I've done some research on how to do this, but i have this old sony microphone pre amp that seems to have been originally wired up differently than other gear that i've looked at.
The original plug had one wire going to the fuse, which then went to the transformer. The other wire went to the on/off switch, and then went from the on/off switch to the transformer.
The original cable prongs were not polarized.
How should i wire up a new cable that has a ground cable...it's black, white, and green.
Thanks! |
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Sho_Bud
Semi Newbie
Joined: 04 Oct 2009
Posts: 5
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| Posted: Fri Oct 16, 2009 11:25 am Post subject: |
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| Really? Nobody has input on this subject? Hacked Gadgets electronics help forum? Really? |
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Alan
Site Admin
Joined: 29 Jan 2006
Posts: 1318
Location: Winnipeg, MB
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| Posted: Fri Oct 16, 2009 2:36 pm Post subject: |
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| Sho_Bud wrote: | | Really? Nobody has input on this subject? Hacked Gadgets electronics help forum? Really? |
LOL, I didn't see the question until now. 
You would take your black wire and connect it to the switch. This will allow the switch to disconnect the live circuit from the device when switched off.
The white wire would get connected to the fuse.
The green wire would get bolted to the metal chassis of the unit.
Normally the fuse and the switch are both on the hot side but since it was manufactured this way there is no sense in changing it. |
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Sho_Bud
Semi Newbie
Joined: 04 Oct 2009
Posts: 5
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| Posted: Fri Oct 16, 2009 3:27 pm Post subject: |
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Thanks for the reply Alan!
with the original wiring i was having problems with input level on the amp. When i touched the chassis with my finger, the input level behaves fine it seems. By touching the chassis, is this the same affect of an added ground wire?
I posted this on another forum and got this response. Please tell me what you think:
"Generally speaking the ground wire is connected to the chassis. But considering the circuit wasn't designed with a saftey ground in mind the whole thing could explode if you wire it like that so proceed at your own risk" |
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Alan
Site Admin
Joined: 29 Jan 2006
Posts: 1318
Location: Winnipeg, MB
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| Posted: Fri Oct 16, 2009 3:38 pm Post subject: |
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| Sho_Bud wrote: | Thanks for the reply Alan!
with the original wiring i was having problems with input level on the amp. When i touched the chassis with my finger, the input level behaves fine it seems. By touching the chassis, is this the same affect of an added ground wire?
I posted this on another forum and got this response. Please tell me what you think:
"Generally speaking the ground wire is connected to the chassis. But considering the circuit wasn't designed with a saftey ground in mind the whole thing could explode if you wire it like that so proceed at your own risk" |
I don't think you have any issues with it exploding. Since the original design would just have no connection to the chassis. The hot and neutral would have no reference to it. |
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