Harrison M300 Electrical Fault

[Welderpaul]

Thanks guys. Electrics aren't my thing. Will a continuity test be what is needed at the switches?

A continuity test will tell you if they are working or not. I rebuilt the control circuits for a M300 so know the electonics inside out.
The limit switches are all the normally closed type so if you get open circuit they may be faulty or need a clean up of the plungers. The limit switch for the foot brake is round the back just above the suds tank so likely to be bunged up and sticking. Mine was.
The contactors are also worth checking.

Have you got a photo of inside of the control cabinet. It could be a number of things that are at fault tbh.

 

[Burdekin]

A continuity test will tell you if they are working or not. I rebuilt the control circuits for a M300 so know the electonics inside out.
The limit switches are all the normally closed type so if you get open circuit they may be faulty or need a clean up of the plungers. The limit switch for the foot brake is round the back just above the suds tank so likely to be bunged up and sticking. Mine was.
The contactors are also worth checking.

Have you got a photo of inside of the control cabinet. It could be a number of things that are at fault tbh.

Thanks for the info. Not got a photo but will get one tonight. Not much room round the back but will have a gander tonight. I don't use coolant but I will check the foot break, got the feeling either it or the chuck guard. The chuck guard switch has a nut and bolt holding the cover on and no access to the nut so might need to get creative.

Regarding the chuck guard switch, should it be fully out to work?

 

[daedalusminos]

As far as I remember, all those interlock switches are wired in series and connect to the main control panel at two terminals - shorting those two terminals will over ride the interlocks and at least determine whether they are at fault

 

[Burdekin]

As far as I remember, all those interlock switches are wired in series and connect to the main control panel at two terminals - shorting those two terminals will over ride the interlocks and at least determine whether they are at fault

Where in the drawing would that be?

 

[Welderpaul]

Where in the drawing would that be?

That's this bit.

 

[Burdekin]

That's this bit.

View attachment 380413

Thanks, so bypass/short the top and bottom switches. Electrics aren't really my thing, I understand some but it also scares me. At the moment the magic smoke is still contained, I don't want to let it out.

 

[Welderpaul]

Thanks, so bypass/short the top and bottom switches. Electrics aren't really my thing, I understand some but it also scares me. At the moment the magic smoke is still contained, I don't want to let it out.

You can probably bypass the whole lot as they are in series. The terminal block at the top of the control panel is well labelled so you should just be able to identify the two ends you need. The red arrow points to what looks like the symbol for the chuck guard.
The control circuit is run by a transformer so either 110V or 240V, still gonna go pop though

Like I say its hard to know without seeing it.

 

[Burdekin]

Pic of the board.

 

[Burdekin]

Hooked it up to the transformer 110v to location 22, still nothing. Any more ideas?

 

[scottmk1]

Do you have voltage into the transformer?

 

[Burdekin]

Do you have voltage into the transformer?

How would I test that?

 

[Brad93]

Check you have 400v on the input side of transformer and 110v out with multimeter.

or use a electrical screwdriver to push the contactor in manually see if the spindle turns

 

[scottmk1]

Put a multimeter on the terminals with the two black wires on the bottom left of the transformer terminal block, 0v and 415v

 

[Burdekin]

Do you have voltage into the transformer?

Across the two black wires?

 

[scottmk1]

Across the two black wires?

View attachment 380483

Yes

 

[Burdekin]

Do you have voltage into the transformer?

Across the two black wires?

Yes

Nothing from the 415v or 110v sides.

 

[scottmk1]

Then you need to go further back in the supply to find out where it’s losing the supply. Check the voltage at the main switch

 

[Burdekin]

Then you need to go further back in the supply to find out where it’s losing the supply. Check the voltage at the main switch

I tried it on another outlet still nothing. Checked all the big fuses they are ok. Could it be be the plug? Any easy way to check it?

 

[scottmk1]

You could check continuity between each pin in the plug and the terminals on main switch input side

 

[scottmk1]

Have you checked the voltage at the source?