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Help repairing power lift

dmccoyks

Sep 26, 2017
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I am disabled and have a power lift for my wheelchair. Recently The two momentary push buttons broke off that move it up and down. I am hoping that I can replace the current switches with an aftermarket switch and just solder it to the board or jumper it from the wires. Please see attached pictures. Thank you for any help. I really appreciate it.

Yellow - 3 prong switch locations
Red top right - 12V DC input
Red top left - 12V DC power to the motor
 

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Tha fios agaibh

Aug 11, 2014
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Only problem is figuring what wire goes where. If you have the broken part of the switch it might lend some clues. Or, if the black bases of the switches have numbers on them, that'd help too.

Plan B is to guess at it.

I'm guessing the common pin of the switch is the center pin. The two outside pins are normally open and normally closed.
I believe the normally closed of one switch must be closed in order for the other direction switch to work. This is a safety interlock feature.
 

dmccoyks

Sep 26, 2017
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Thank you so much for your quick replay. I will put a multimeter to it tom and see if I can give you some more information. Do you know what type of switch i need? Is it considered an SPDT On On Or?

Also I don't believe it has any interlock safety feature because when it broke the UP button was pushed in and it continued going up until I turned it off?
 
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Tha fios agaibh

Aug 11, 2014
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Momentary Spdt like this one but I'm not certain of orientation of pins. Some have common pin on one side as opposed to the center.
 

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Tha fios agaibh

Aug 11, 2014
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Looks like they are only using the normally open portion of the switch in the circuit.
In other words, any switch that will close the top two pins circled in yellow (last picture) should work provided it has an adequate current rating.
 

73's de Edd

Aug 21, 2015
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Sir dmccoyks . . . .

Need for you to tell me if I am being right on that units manner of operation.
Your original switches . . . . . that are now gutted of both their shafts and internal switching contacts by extreme blunt force trauma. . . . .INITIALLY worked like this.
You turned on the end POWER switch and then hit the appropriate PUSHBUTTON ACTION switch such it that made initial contact long enough for the motor unit that ran that linear actuator arm (YELLOW) will be moving on its own.
(There are limit switches and a cam that are inside of its motor end plate . . .that then keeps the motor still running, after you let up on the initial temporary switch press, that you intiated the start up action with.)
The linear drive arm internal limit switches will STOP the system automatically at either extreme limits of its movement.
That NEC POWER RELAY takes care of the motors POWER aspects, so the pushbutton switches will actually only carry the meager power necessary to power the coil units of that POWER relay . . . which identification and the specs I give you as:

http://pdf.datasheetcatalog.com/datasheet/nec/EP1F-B3L2TT.pdf

Each pushbutton switch is a SINGLE POLE DOUBLE THROW . . .SPDT . . . momentary contact unit and you want to check the possible 180 degree rotation possibility / ambiguity such that its installed contacts that are normally OPEN are being connected across the designated two RED or BLUE positions. My marked YELLOW No Connection . . .contacts are not even being used.
That way, when you press a switch, either the RED or BLUE contacts go into a shorted condition, as long as you have the button pushed down, then it pops up and disconnects as you release pressure on it, of course the motor is auto running by itself by then..
I believe that this is being your unit and its linear activator drive that does the lifting.

Photo Referencing of boards two sides:

tYCPTqT.jpg


Photo Referencing of installed SYSTEM:

wIH5Ut9.jpg


73's de Edd

.
 
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dmccoyks

Sep 26, 2017
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Thanks for all the help. Here are some more pictures and hopefully helpful information. When I connect the green lines the lift moves up and down accordingly. I can't get me mind around how the switches work.

Board
A - Input
A1 - 12v
A2- Gnd

B - D.C. Motor output
B1 - 12v
B2 - Gnd

C - UP Button switch - top to bottom of switch
C1 - 12v
C2 - Gnd
C3 - Post

D - Down Button switch - top to bottom of switch
D1 - 12v
D2 - Gnd
D3 - Post

E - Power On/Off Switch
E1 - 12v
E2 - Gnd


Switch sizes - 1/2 x 1/4 x 1
 

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dmccoyks

Sep 26, 2017
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This is how it works and yes that is the correct Armstrong lift in the picture.

1. I turn the unit on with the Toggle Power Switch on the end (Ref E)
2. Press and hold either power Up or Down (Ref C and D) and release when it is in correct position. There doesn't seem to be any limits or safety functions because it continues to run as long as the buttons are held in


"Each pushbutton switch is a SINGLE POLE DOUBLE THROW . . .SPDT . . . momentary contact unit and you want to check the possible 180 degree rotation possibility / ambiguity such that its installed contacts that are normally OPEN are being connected across the designated two RED or BLUE positions. My marked YELLOW No Connection . . .contacts are not even being used.
That way, when you press a switch, either the RED or BLUE contacts go into a shorted condition, as long as you have the button pushed down, then it pops up and disconnects as you release pressure on it, of course the motor is auto running by itself by then..
I believe that this is being your unit and its linear activator drive that does the lifting."

Please see my last post with my picture referencing the Green Lines connected to make the switch move up and Down. I don't believe I won't to short RED or BLUE since C1 D1 are 12v and C2, D2 are Gnd?

Please let me know what other information I can provide that is helpful. Thanks so much for everyone's help
 

dmccoyks

Sep 26, 2017
23
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Sep 26, 2017
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Thanks for all the help. Here are some more pictures and hopefully helpful information. When I connect the green lines the lift moves up and down accordingly. I can't get me mind around how the switches work.

Board
A - Input
A1 - 12v
A2- Gnd

B - D.C. Motor output
B1 - 12v
B2 - Gnd

C - UP Button switch - top to bottom of switch
C1 - 12v
C2 - Gnd
C3 - Post

D - Down Button switch - top to bottom of switch
D1 - 12v
D2 - Gnd
D3 - Post

E - Power On/Off Switch
E1 - 12v
E2 - Gnd


Switch sizes - 1/2 x 1/4 x 1
 

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Tha fios agaibh

Aug 11, 2014
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It works by changing polarity to the motor with an H-bridge circuit. It's not a short. Positive feeds relay and Negative is switched through the switch.

If you scared you could use a 1 amp glass automotive fuse to short it out.
 
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dmccoyks

Sep 26, 2017
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Ok thanks. Can you recommend a switch that might work then. The pin spacing is approximately 1/8" and the switch is Approx 1/2 x 1/4 x 1. I can drill the holes or modify as needed once I find an appropriate switch. The hole size is 1/4 x 1/4"
 
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Tha fios agaibh

Aug 11, 2014
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Read the specs to see if it meets your needs.

Was there a problem with the Oem switch I posted?
It's certainly more robust.
 

dmccoyks

Sep 26, 2017
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Read the specs to see if it meets your needs.

Was there a problem with the Oem switch I posted?
It's certainly more robust.

The size is a little bigger which isn't an issue but the distance between the pins is only .154". It shows the common on this switch as position 2 is that correct configuration?
 

Tha fios agaibh

Aug 11, 2014
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I got the number EB2011 from the picture you posted so I assume it's what you want.

Good luck.
 
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