Help with 5 pin switch connection

[Luca FumagalliParticipant @lucafumagalli33838]

Hello,

I'd need some help troubleshooting an electrical problem with a bandsaw (Central Machinery 7×12).

The problem is this: while I push the ON button the saw runs fine, however it won't stay ON when I stop pushing the button with my finger.

At first I thought that the problem was with the 5 pin Switch (KJD17), so I've replaced it with a new one and nothing actually changed; the saw still works only while I keep pushing the button.

I've read an interesting post here (https://www.model-engineer.co.uk/forums/postings.asp?th=142254) where I've understood that the A1 connection is the one which keeps the saw running when the motor is under load (pardon my lack of technical wording). So, I was wondering:

1) Can it be a faulty A1 connection that causes this issue? Since I've replaced the switch, maybe the A1 cable is broken somewhere else?

2) In the (not) remote possibility that I'm missing something big, is there a specific procedure to operate this switch? I'm thinking something like the switch has to be reset or operate in some specific way which I cannot imagine. The saw manual doesn't mention anything like that, but worth checking I think..

Thanks, Luca

[Luca FumagalliParticipant @lucafumagalli33838]

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Luca, with your switch the A1 connection is used with an emergency stop button, so the A1 should go to one side of the emergency stop, and the other side of the stop should go to the neutral side of the output side of the main switch. If you don't have an emergency stop button, the A1 should be connected directly to the output side of the main switch.

Regards Nick.

[Luca FumagalliParticipant @lucafumagalli33838]

Posted by Nicholas Farr on 17/07/2023 21:26:23:

Hi Luca, with your switch the A1 connection is used with an emergency stop button, so the A1 should go to one side of the emergency stop, and the other side of the stop should go to the neutral side of the output side of the main switch. If you don't have an emergency stop button, the A1 should be connected directly to the output side of the main switch.

Regards Nick.

Thank you Nick, for the feedback.

I've connected the A1 to the output and now it works. Two more questions, if I may:

– Why did the saw arrived with the A1 not connected to the output but instead connected to the motor? Or at least I think it is connected to the motor because I see the A1 wire going that direction, but I can't confirm.

– In order to optimize the wiring in the box, can I just install a KJD17 with 4 pins instead of 5? (I see that it is sold on Amazon). In this way I will not have any loose cable in the box.

Thank you, Luca

Edited By Luca Fumagalli on 17/07/2023 21:59:39

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Luca, I don't know why it arrived without the A1 connected, but it's possible the wrong switch was in the assembly line by mistake, as you could just replace it with the one without the A1 connection.

Regards Nick.

[Luca FumagalliParticipant @lucafumagalli33838]

To clarify, the saw arrived with the A1 disconnected from the output but connected to the motor, so I think it is intentionally made like this. This wiring may be to use the A1 as a safety stop that triggers if the motor shorts or fail. Unfortunately there is no easy access to the wiring to double check this. The only way to get there is to disassemble the saw, and that's a big nope because it is about 300lbs and here in New Mexico is around 110F.

By the way, thank you again, I really appreciate it.

Luca

[Luca FumagalliParticipant @lucafumagalli33838]

I've figured out what's going on: the A1 pin was connected to the breaker that stops the saw when it goes full down, i.e. after the cut is done.

So, the saw simply didn't stay ON because I was testing it full down, i.e. with the breaker triggered… I can't find a facepalm face here but you got the point..

Luca

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Luca, that makes sense, the A1 being connected to the neutral side of the coil, so in your case, it's acting a bit like an e-stop. Good to hear you've got it sorted.

Regards Nick.

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