Mark VII dilemma

[hdfirefightin]

I am new to the forum but have had a Mark V for about a year now and love using it in my small shop. About a month ago I picked up a Mark VII that had a joiner, bandsaw, belt sander, and a bunch of small parts/woodworking tools with it. The Mark VII does not run. The previous owner said it was the start-up capacitor. Has anyone had any experience replacing the start-up capacitor? Should I try fix the machine and use it or sell it and keep the Mark V? If I decide to sell it, what would be a fair price for a Mark VII? Besides for not running, the machine is in excellent shape. There is no rust and the plastic parts I can see all appear to be in great shape.

Thanks.

[JPG]

Define 'not running'.

plugged in, switch on(for) and humming noise(brief test).

plugged in, switch on(for) and motor runs, but shafts do not.

plugged in, switch on(for) and nothing.

Same thing in (rev)?

A bad start capacitor is unlikely. They rarely fail.

An open start switch is more likely.

A bad switch(for/run/stop) is possible.

A bad power cord is possible.

A loose/broken wire?

The most important 'plastic' part is the speed control cam visible by removing the backside logo plate.

P.S. do not force the speed control dial.

[hdfirefightin]

Thanks for the quick response JPG.

I have not messed with the machine at all. The PO said he got the machine and used it some, then one day he cut it on and it threw the breaker. He reset the breaker and tried again and it worked. He continued to use it this way and eventually it got to the point it would just throw the breaker. He told me an electrician friend looked at the motor and determined it to be the start-up capacitor.

I will try to plug the ol girl in this evening and see what happens and respond.

Thanks again.

[JPG]

Thanks for the quick response JPG.

I have not messed with the machine at all. The PO said he got the machine and used it some, then one day he cut it on and it threw the breaker. He reset the breaker and tried again and it worked. He continued to use it this way and eventually it got to the point it would just throw the breaker. He told me an electrician friend looked at the motor and determined it to be the start-up capacitor.

I will try to plug the ol girl in this evening and see what happens and respond.

Thanks again.

Sounds like crud preventing the start switch from making. Repeated failing cycles are not good. I hope the breaker he had was a small one(15A).

Unless that electrician actually got into the motor, he was shotgunning.

If you turn it on and it does not start up immediately, do not wait for the breaker to trip.

It having an intermittant history, it may be a loose wire.

Hopefully the run windings are still viable.

With a Mark VII the power switch can also be a culprit. The direction switching can cause the start winding to not become energized on startup.

As a 'test'(assuming it is consistently not starting), put the Mark V sanding disc on and spin it as you turn it on. Observe if it tries to run with a 'push'. Again short duration.

The Mark V disk is larger and has more inertia.

[billmayo]

Sounds like crud preventing the start switch from making. Repeated failing cycles are not good. I hope the breaker he had was a small one(15A).

Unless that electrician actually got into the motor, he was shotgunning.

If you turn it on and it does not start up immediately, do not wait for the breaker to trip.

It having an intermittant history, it may be a loose wire.

Hopefully the run windings are still viable.

With a Mark VII the power switch can also be a culprit. The direction switching can cause the start winding to not become energized on startup.

As a 'test'(assuming it is consistently not starting), put the Mark V sanding disc on and spin it as you turn it on. Observe if it tries to run with a 'push'. Again short duration.

The Mark V disk is larger and has more inertia.

Good advise. I found the push button switches was the reason that several Mark VII motors will not operate. I ended up replacing the pushbuttons with a ON/OFF toggle switch and a FWD/REV toggle switch side by side on a replacement plate. If you can identify the color of all the switch wires and make of the motor, I am sure someone has a wiring diagram to allow you to do testing and maybe replacement of the pushbutton switches.

[backhertz]

A start up capacitor can be easily checked with no tools. I found this out on my mother's old Kenmore dryer that had a push button start switch. This switch simply put a start capacitor in the circuit which simply provides an electrical "push" to get the motor moving.

When the start cap went out on my mother's dryer, I simply would set the timer and open the dryer door and give the drum a spin & shut the door quickly. The dryer would 9 times out of 10 take off as if there was no problem and it would run for the desired time.

If you ever suspect a start capacitor on a device, you can alway try to give the motor shaft a slight spin- be careful to get your hand out of the way and don't be surprised if the motor takes off.

On a Shopsmith, there can be a number of other problems other than a start capacitor. So it's best to check the motor and related electronics like the power switch for all problems. It is very possible you have a reparable motor, but by attempting to troubleshoot or play around with it, you might end up burning a winding which might happen in only 10-15 seconds.

The best way to prevent motor problems is to simply do the suggested preventive maintenance and be sure to lube the motor shaft and sheave after using compressed air to blow the dust out.

I've never had a bad motor. I bought a used Mark V for half price because the seller thought the motor was bad & neglected to share that with me. I was just looking for cheap Mark Vs which I planned to rebuild. I offered half his asking price and he said sold! In 10-15 minutes I had the Shopsmith broken down & in the rear of my Honda Civic.

When I got home, I simply pulled the belt cover off, blew out the dust & lubed the motor shaft & sheave. Unbeknownst to the seller, I knew from another Shopsmith buyer in Philly that had looked at this Shopsmith a day or two prior & thought the motor was bad. So I never even checked to see if it ran as the price was right, about $75. The seller was in no hurry to stick around as he gave me the exit code to the facility and took off. I think he was just wanting to empty his storage unit.

Apparently the storage place where the Shopsmith was had no power to the outlet as the motor came on immediately when I plugged it in at home. <smile> I've learned though to always pull a belt cover off before buying a Mark V. You get an idea of the headstock condition and can inspect to the inside of the headstock & make sure the eccentric ears are not broken or see any other easily seen problems items like neglect. This was a pre-1984 model as it only had a single bearing quill.

[hdfirefightin]

Thanks for all the information everyone.

I did some testing last night. I plugged the machine in, turned the key and hit the forward switch with the Mark V sanding disk on the machine. The motor hesitated for between 1 to 2 seconds and then slowly started to move. I turned the machine off at 3 seconds. I then turned it on forward again, and I immediately spun the sanding disk. The motor took off at what seems like the right speed for what the speed control is set to. Total test cycle was around 5 seconds. I then tried it in reverse, and it acted the same way. The total time in reverse was around 5 seconds again.

That concluded my testing. I picked up the power cord to unplug it from the wall and it was warm, too warm for my comfort level. I then went back to the machine, and there was a faint "electrical motor not running right" smell. So, I pulled the inspection plate on the back side to make sure nothing was on fire/melting down. Everything on the inside looks to be in good shape including wires, belts and speed control cam. There was little to no dust inside the headstock.

The machine never tripped the breaker. I had it plugged into my dedicated saw outlet that has a 15 amp breaker. That circuit was installed less than a year ago and runs my Mark V and other saws just fine.

Any additional thoughts?

Thanks again.

[dusty]

Since the motor ran, I would conclude that there is nothing seriously wrong with the motor. The power cord itself may be heating up.

I would resist running the motor with a load until the system is checked out.