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Replace power cord of fisher x 100b to 3 prong. Good idea?

B

Blakeb123

New Member
Hello,

I have a working all original Fisher x100b, I took it to our local tube tech and he mentioned that he was getting some grounding noise out of the speakers when moving the unit or touching the faceplate. He suggested replacing the power cord with a three prong one. Is this worth doing or am I lowering the value in having that done?

thanks,
Blake
 
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Blakeb123 said:
Hello,

I have a working all original Fisher x100b, I took it to our local tube tech and he mentioned that he was getting some grounding noise out of the speakers when moving the unit or touching the faceplate. He suggested replacing the power cord with a three prong one. Is this worth doing or am I lowering the value in having that done?

thanks,
Blake
Click to expand...
It will enhance your safety, provided it is connected in a grounded outlet.
 
peterh said:
It will enhance your safety, provided it is connected in a grounded outlet.
Click to expand...
Thank you Peter,

Can you elaborate when you say safety? Pardon my ignorance but I’m new to tube gear.

And would just keeping the two prong power cord and running it through a grounded power strip not do the same?
-blake
 
My Fisher 400 has a non-polarized 2 prong plug ..it is plugged into a grounded power strip .. was considering the same change

(but unit does not hum, and cord is in good shape physically)
 
kappclark said:
My Fisher 400 has a non-polarized 2 prong plug ..it is plugged into a grounded power strip .. was considering the same change

(but unit does not hum, and cord is in good shape physically)
Click to expand...
Yea my cord is in good shape too. The unit was in a console with the original owner for 58 years before I bought it. Always in the living room and not moved.
Why were you thinking about changing the cord?
 
A grounding cord should only be there for safety reasons, not for noise issues.
Or the noise should at least not rely on it.
 
Blakeb123 said:
Thank you Peter,

Can you elaborate when you say safety? Pardon my ignorance but I’m new to tube gear.

And would just keeping the two prong power cord and running it through a grounded power strip not do the same?
-blake
Click to expand...
It will make sure that the amp and everything connected to it will not be a source of
electrocution. If any isolation gets broken the current will go through the ground connection
and the fuze or ground isolation fuze ( if you have) will break the voltage.

Without ground connection a fault somewhere in the amp might cause it to be transmitting
the 120V AC to the chassis.

In europe this is even more important as we have 230Volt as mains voltage.
 
peterh said:
In europe this is even more important as we have 230Volt as mains voltage.
Click to expand...
Common made mistake, but it's the current that's dangerous, not the voltage!
You can technically kill someone with a 9V battery at the right spot.
Yet an electrical fence with couple of thousands volts on it, won't kill you.

The only disadvantage of 230Vac, is that the clearance/creepage distance will be bigger.
But for the same amount of power, you will only half the current

In fact, I find working on low voltage (very) high current (big battery packs and such) far more dangerous.
 
Blakeb123 said:
Yea my cord is in good shape too. The unit was in a console with the original owner for 58 years before I bought it. Always in the living room and not moved.
Why were you thinking about changing the cord?
Click to expand...
Interesting discussion - After more reading, figure I will keep cord as is -- no safety issues, and sound is good ..
 
kappclark said:
Interesting discussion - After more reading, figure I will keep cord as is -- no safety issues, and sound is good ..
Click to expand...
Safety is very relative.

Normally I would suggest grounding any steel/metal chassis.
In fact, it's mandatory these days (unless you really take the extra step to double insulate everything).

However, in my opinion that is a different case when equipment is being used (and repaired) by people who are aware of these things.
Specially when most of these people really take good care of their equipment (sometimes seems even more than their own kids, hihihi)

In the end it's basically just statistics, just the change (probability) something bad will happen.

But it's an interesting subject if you dive into it. Also when you look at different parts of the world and what they consider to be "safe".
I am talking about the differences, not what is better or worse.

For example, the amount of people directly killed by mains is very low.
The number of people indirectly being killed by mains (falling of a ladder or so because of a shock reaction etc), is all of a sudden a lot bigger.
 
I would be careful with the cord replacement, you can introduce all sorts of ground loop issues. It may be better to replace with a modern polarized 2 prong plug, at least for the US market.
 
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