headstock rebuild

[wa2crk]

Hi Gang;
A few months ago I had to rebuild my headstock due to a motor bearing that was going bad. Don't know why that happend cuz it is only 27 years old!!
I removed the motor and the on/off switch as a complete assembly and taped up the switch so as not get a shock during the bench check. Had to run it to make sure it was actually a motor bearing and not something else.
I strapped the motor to the bench and used a power strip as a switch to energize the motor. When I flipped the switch the ground fault outlet immediately tripped!! I unplugged everything and removed the pigtail between the SS on/off switch and the motor and then the black covering of the wire and found the condition in the photo.
[ATTACH]9526[/ATTACH]
If you ever repair your headstock and have intermittent power problems you may want to check the old wiring. I was told by someone on this website that this condition is very common with GE motors.
Bill V

[beeg]

I hope ya repalced that wire with 12-3 wire.

[dusty]

I don't know about the wire in GE motors but I had about 100' of wire on a spool that I have been hoarding. A few weeks ago I planned to install some of that hoard on three different pieces of equipment in the shop. I pulled the wires out of the three and began to rewire with some of this hoard.

The entire spool of wire was like that in your photo. When I started using it, I could feel the insulation on the inside wires when the insulation cracked. It was all dry and brittle. I blamed it, at the time, on having been stored in the shed which gets very, very hot here during the summer. Maybe it was as much age as it was heat damage.

[backhertz]

This is one of the reasons a person should never break off the ground prong or use an adapter without securing the ground pigtail to the screw holding the outlet plate on. Yet so many do. It's another reason for using GFCIs when using tools or when faced with a no safety ground in older homes which never required a safety ground. If you have questions, please contact a qualified electrician and I am sure they will explain/demonstrate the benefits.

In this situation and also the situation with many old televisions- the chassis can be hot if the polarity is reversed. You might not even notice it until you touch something else and then have current flowing through your body- that could kill you. Power cords are very easy to replace; however, there is a reason for the wire colors which need to be connected properly. Do not assume on an older system that the wires were properly attached as someone may have been in there after the item was sold & before you ended up with it. Getting lit up is never fun.

[dusty]

[quote="backhertz"]This is one of the reasons a person should never break off the ground prong or use an adapter without securing the ground pigtail to the screw holding the outlet plate on. Yet so many do. It's another reason for using GFCIs when using tools or when faced with a no safety ground in older homes which never required a safety ground. If you have questions, please contact a qualified electrician and I am sure they will explain/demonstrate the benefits.

In this situation and also the situation with many old televisions- the chassis can be hot if the polarity is reversed. You might not even notice it until you touch something else and then have current flowing through your body- that could kill you. Power cords are very easy to replace]I used to have an Airstream Travel Trailer that would occasionally give me a shock. If I stood outside and lean up against the trailer it gave me a tingly feelings all over. That turned out to be an outlet for the charging system that was wired incorrectly.

I guess I am real fortunate that I never leaned on the trailer when the ground was unusually damp.

[wa2crk]

Beeg;
It was only 8" long so I used the 14-2. Over that distance it is not a problem. My machine is only used on a 20 amp dedicated line that the builder installed to be used to charge a golf cart. I on't golf!!
Bill

[beeg]

The distance isn't the problem, the 14-2 without the ground IS.

[dusty]

[quote="wa2crk"]Beeg]I see that you are into Amateur Radio so I must assume that you know all about grounding of equipment for safety purposes. But having said that, after you make the comment that you used 14-2 for the power cord, I must wonder where you get the safety ground for the Mark V chassis.

The nasty wire in the photo does not have the third wire for a ground.

For you guys with much older Mark 5 500s, were they originally without safety ground?

[wa2crk]

All;
I might have written that poorly. The machine IS grounded!! The main power cord is a three wire grounded type and the ground is attached directly to
the motor frame. The wire in the picture is the short pigtail between the DPDT switch and the motor that SS used in the eighties. This wire was hard wired into the motor. I had to cut the original pigtail from the motor windings and solder a new pigtail to the field windings. The original wiring between the switch and the motor was provided by GE as a part of the motor assembly. No additional ground is required other than the one in the main power cord.

[judaspre1982]

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