Problem with Speed Controller on a Delta 1220 Midi Lathe

[bonsaipeter]

A friend of mine asked me to take a look at his Delta 1220 Midi Lathe (Delta Model #46-460 VS) which has a variable speed controller which has stopped working and to see if I could repair it for him. I disconnected the motor from the speed controller and it ran fine when connected it another variable DC speed controller I have. Conclusion, motor good, speed controller bad. Delta Parts has been less than helpful and claim that a replacement controller circuit board is no longer available. Inspection of the defunct controller does not show any obvious signs of damage such as burned areas or components or any classic "electrical burnt odor."

Questions:

Has anyone run into this or a similar problem with this lathe?

Were you able to find a solution to replacing or repairing the circuit board?

Does anyone know of someone that can analyze and repair the board?

Does anyone know which of the components on the board are the most suspect?

Any suggestions are most appreciated. Thanks, Peter Toch

 

[john lucas]

I've run into that problem on other lathes but not my Delta. It's very hard to trouble shoot without a schematic and someone who is really good. I've done a lot of electronic repair but not to the component level. I managed to find a schematic for the old controller I had and found a local guy who could fix it. It was fairly expensive but in my case back then buying a new controller was even more expensive. they have come down in price a lot so replacing it might an option nowdays if you can't get Delta to work with you.

 

[hockenbery]

With phone help I did some troubleshooting on a General 260 controller.
Just testing voltages where the wires connect to the controller.
When we got no voltage the technician pronounced the controller "fried" :-(

You may have a motor repair shop in your area. One I have dealt with works with controllers.

I assume you ruled out any problem in the switch or potentiometer?
Sometimes dust gets in the switch.

Al

 

[Bill Boehme]

Typically when electronics fail, the cause is an open circuit somewhere which means that seeing or smelling something burned is very unlikely. By far, the component that is most likely to fail is the potentiometer -- in other words, the component with the knob. You might not be able to find a "drop-in" replacement, but you should find one close enough. Mouser is a good source for components. The resistance value of the pot is usually marked on it somewhere or you could measure the end-to-end resistance and replace it with one that has a linear taper. Do not get one with an audio taper or any other specialized taper.

I'm very surprised that Delta no longer does product support. I'll scratch them from my list for any future purchases. Too bad because they were the top brand once upon a time.

 

[Odie]

Isn't a potentiometer and a variable rheostat the same thing?

I can remember the 1950's when my Dad was operating his home shop......Delta was the top of the line for private home shops back then. They've slid a long ways down to where they are now. It's only a name, and nothing like the company it once was. Corporate priorities has killed it with profit more important than product, I suspect.

ko

 

[Bill Boehme]

Isn't a potentiometer and a variable rheostat the same thing?

Not really from a strict definition. A rheostat is generally a power device to limit current. I once had some old wirewound vitreous enamel rheostats. One had a total resistance of one ohm and a power rating of about a kilowatt. It probably weighed around 30 or 40 pounds. There were some autotransformer variants called Variacs. A typical potentiometer has a very low power rating and is basically a high impedance voltage divider. I often hear people call a speed controller or a light dimmer a rheostat, but rheostats became an endangered species over 50 years ago and are all but extinct now. The devices that have replaced them are far more energy efficient.

I can remember the 1950's when my Dad was operating his home shop......Delta was the top of the line for private home shops back then. They've slid a long ways down to where they are now. It's only a name, and nothing like the company it once was. Corporate priorities has killed it with profit more important than product, I suspect.

ko

Delta has spent most of its life being bought and sold. Just in my lifetime, I remember Rockwell, Invicta, Pentair, Black & Decker, Stanley, and now a Taiwanese investment group. I think that the current owners would like to make Delta become a respected brand again, but B&D is the main culprit that ruined the company.