Bypassing an electronic switch. Help!!!

[Peter915]

Hi, I have a friend that is in a little pickle. He has a mobility scooter that has seen better days but I believe it can saved to get him out the house. My knowledge on electronics is limited but I know somethings. The scooter has an e brake connected to the PMC that mechanically works but no mater what orientation the switch is in i still can’t get power to the motors. I am getting 60ohms across the coil on the switch with it on and off. Would I be able to replace the switch with a potentiometer to by-pass the switch? I hope this makes sense, I have attached the brake in question similar to the one I have problem with. Thanks Peter

WR225A115P2 Warner 24VDC 4.0nm electric motor brake for Mobility scooter and power wheelchair brakes

WR225A115P2 Warner 24VDC 4.0nm electric motor brake for Mobility scooter and power wheelchair brakes

gbr.grandado.com

 

[rjenkinsgb]

OK, I found a photo that shows the connections clearly:

It has a microswitch on top which is operated by the back edge of the rotary lever. If nothing is happening when the lever rotates, either that switch has failed or the position needs adjusting.

That switch appears to be a standard "V4" form factor one, though it's difficult judging the exact size.

Check the dimensions against this info? If they are the same, at least the screw spacing and operating button position relative to the screws, it should be easy enough to find one that has the correct electrical ratings.

See the top of page 5 for detailed dimensions:

https://omronfs.omron.com/en_US/ecb/products/pdf/en-ss.pdf

Otherwise, can you measure that switch as accurately as possible?

ps. A pot would not work, it's a straight on/off switch in series with the brake coil.

 

[Peter915]

Thank you for your help. The brake he has does not have a micro switch and the lever is slightly different. but it is the closest thing I could find.

The PMC he has is a Curtis 1225. Am just wondering if it is easy as placing a jumper across terminals

 

[Musicmanager]

Morning

Changing direction for a moment .. .. . the schematic also shows an 'Inhibit Switch' connected to Power Enable. Have you checked this is functional ?
On my scooter there are two .. they are hidden away .. under the seat .. and must be some sort of inertia tripped switch; if either are tripped .. the brakes work but no power to the motors !
On my scooter it is just a matter of a pushbutton to reset.

MM

 

[Diver300]

Some photos might help us.

The first thing that I would check is that power is available to all the places it should be when expected. For instance, between B- and pin 12 there should be battery voltage when the FWD control is pressed, and a lower voltage, probably near zero, when it's released.

When running, there has to be a voltage between POT LO and POT HI. That will come out of the controller, but it may only be there when everything else is ready to run. I would expect 5 V or 12 V or similar, but the actual voltage is set by the controller design.

The SPEED LIMIT and POT WIPER voltages should be near the POT LO voltage when the speed limit and throttle respectively are at zero, and should move gradually up to the POT HI voltage when those controls are moved up to their maximum settings.

It doesn't matter if the full voltage range isn't available, as if too little range is available, the top speed and possibly the lowest speed won't be as high or low as expected, but you can fix that later when you get the scooter running.

For instance, when the scooter is ready to run, if you found that the voltage on POT LO is 1 V, and the voltage on POT HI is 5 V, and when the throttle is released, the voltage on POT WIPER is 1.5 V, and pressing the throttle takes that progressively up to 4V, that's would be most likely correct.

If there's never any voltage difference between POT LO and POT HI, disconnect the throttle and the speed limiter from the controller. If there's still no voltage, most likely some switch or fuse or wiring is wrong, but it could be a controller fault. If there is a voltage between POT LO and POT HI with the throttle and the speed limiter disconnected, it is probably a fault in the speed controls.

 

[shokjok]

I'm curious as to what the controller outcome will be when the horn is sounded.
It appears the INHIBIT switch is a cutoff switch if the user leaves the seat or the chair tips over.