110V Motor electrical issue

[ssdedee]

I have been lurking on here for months but I have finally ran into an into a problem that I can't seem to find a fix for by reading though the forums. I am in need of help from you smart electrical guys so here goes.

I was given a used 13 year old Birmingham 1126 lathe. The motor was pretty much shot so I took it to a re-builder who advised buying a new motor rather than trying to fix it.

The motor is a Chinese 1 hp, model YL8024. As it turns out the ShopFox M1088 sold by Grizzly uses the same motor. The motor and wiring diagrams are the same as the Birmingham however the contactor is wired differently. Anyhow I ordered a new motor along with two new capacitors.

My problem is that when I connect all the wires to the motor without any jumpers (the original configuration}, all the motor does is hum in both Forward and Reverse. I am using the original drum switch for all the tests. I can get it to run Forward if I jump connections (U1-V1) however If I jump connections (W2-U2) and turn to Reverse, the switch sparks and throws the breaker. If I jump V1-U2 it hums. And finally connecting W2-U1 throws the breaker.

Here is what I have done so far:

- Tested and installed new motor
- Capacitance tested and installed the start & run capacitors
- I bought a new 26-20 switch. (I installed it but nothing worked at all so from reading other threads on here I am going to need to do some configuring.) Anyhow I didn't want to introduce new problems so I reinstalled the old switch
- Disconnected all wires and tested for continuity. All were fine.
- Tested the e-stop and start buttons and they both appear to operate correctly
- Tested the contactor. The coils have ohm readings and the contacts have continuity when active. All the contacts look clean.

I have included pics of the connections and a snippit from the M1088 user manual showing those connections.

I am considering buying a new capacitor that is on the M1088 parts list. It is the same model number as the one I have but it is wired differently. ie no jumper wires. My guess is that I'll have to figure out the drum switch as well. I thought I'd see if anyone has any suggestions before replacing more parts.

Thanks in advance for the help.

Carl

 

[MikeInOr]

Usually the capacitors are the first thing to die in a single phase motor. I would definitely replace the start and run capacitors if you haven't done so? If there is room I would put in high quality capacitors of approximately the same capacitance (uF - micro-farad) and higher voltage rating. Cheap Chinese capacitors have a habit of dying untimely deaths.

 

[markba633csi]

It's miswired- give me a few min. to cogitate- I shall return
Looks like the miswire is at the motor- there should only be 4 wires needed not 6
Try this:
Take off the yellow and white wires at the motor- insulate them
Take off the two brass jumper strips at the motor - leave the 4 wires in place

 

[ssdedee]

Usually the capacitors are the first thing to die in a single phase motor. I would definitely replace the start and run capacitors if you haven't done so? If there is room I would put in high quality capacitors of approximately the same capacitance (uF - micro-farad) and higher voltage rating. Cheap Chinese capacitors have a habit of dying untimely deaths.

Thanks for the reply Mike. I bought new capacitors when I bought the motor. They have tested out okay however they are the standard Chinese fare that usually comes with these machines. I will look into getting some better quality ones.

 

[ssdedee]

It's miswired- give me a few min. to cogitate- I shall return
Looks like the miswire is at the motor- there should only be 4 wires needed not 6
Try this:
Take off the yellow and white wires at the motor- insulate them
Take off the two brass jumper strips at the motor - leave the 4 wires in place

Thanks for the reply and suggestion.

I disconnected the white (v2) and yellow (w1) and removed the jumpers. Unfortunately nothing happened. I left the brass jumpers off and reconnected the wires.

I did a couple tests using wire jumpers. No connections- both Forward and Reverse hum. Connecting u1-v1 Forward runs , Reverse hums. Connecting u1-w2 Reverse runs, Forward hums.

 

[MikeInOr]

Thanks for the reply Mike. I bought new capacitors when I bought the motor. They have tested out okay however they are the standard Chinese fare that usually comes with these machines. I will look into getting some better quality ones.

Better quality ones will last longer, usually a lot longer. Even the cheap Chinese ones should be able to get you going. Personally I wouldn't worry about it until the ones you have fail.

 

[markba633csi]

OK you might have a bad switch or a broken wire
If you have a multimeter that will measure 120 AC volts you can test as follows:

With power off, disconnect all 4 wires U1,U2, V1 and W2 from motor
Re-power
Measure between U1 and U2, should read 120 volts AC both forward and reverse
Measure between V1 and W2 should read 120 volts AC both forward and reverse

 

[ssdedee]

Thanks Mark. I think you got it right about the switch. U1–U2 reads ~30 when Forward. 120 Reverse. V1-W2 are 120 both ways.

I have another 26-20 switch. As I mentioned earlier in the op I iinstalled but wasn’t getting anything so I took it off. I assumed that I would need to do some configuring to get it working. Anyhow I will reinstall it and see what readings I get.

 

[markba633csi]

Bingo! yes the switch might have gotten arced before pulling the brass jumpers- those switches are not real robust
You can get a brand new switch on Amazon if need be

 

[ssdedee]

These switches apparently aren't as universal as advertised so I guess I will need to investigate and get another one. I can't get good readings through it. Just to be sure I bypassed it and got 120V on all wires. More to come. Thanks for your help.