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-   -   FnR switch high pitch noise (https://www.buggiesgonewild.com/showthread.php?t=76761)

fishb8 03-03-2013 12:13 PM

FnR switch high pitch noise
 
Once again my son has created another challenge for me :help:. Yesterday he went to drive the buggy and all it did was click. and it has a hum or high pitched noise. The LED error light on the controller does not come on at all. :thumbdown:
This morning I went out and the buggy moved just fine. Then he drove it around for a 5 minutes and it stopped. Same thing. Click and high pitch noise. It is coming from the FnR switch.

And yes I realize the command thing is always my son. But, I have to keep him :lhmo:

Battery Pack is 51v
reserve sound works fine.
All cables are tight

fishb8 03-03-2013 01:08 PM

Re: FnR switch high pitch noise
 
NOW, Key switch ON, gear selector in FORWARD, Place the (+) probe on the battery side of the solenoid's large post (If the reading is below battery voltage, check all wiring and terminals).
50.4v which is the same as the battery pack

Place the (+) probe to the controller side of the solenoid's large post. The reading should be 0.1 to 3 volts less than battery voltage. If the reading is more than 3 volts less the battery voltage, the resistor is faulty. If the voltage is the same as the battery voltage, replace the solenoid.
47.0v. So it is 3.4v lower.
It seems that the resistor is faulty, but with the high pitch noise, I wondering if it could be something else.

JohnnieB 03-03-2013 02:12 PM

Re: FnR switch high pitch noise
 
That 0.1V to 3V lower is for a 36V system with a 250 Ohm precharge resistor and a 48V system should have a 400 Ohm resistor, so the voltage drop won't be the same.
Anyway, the resistor isn't the problem, since the cart will run with or without it.

I'm speculating, but I suspect the high pitched noise is the Pulse Width Modulated (PWM) DC arcing across the F/R switch contacts or a broken cable.
The PWM frequency is in the high audio range (15-18 kHz)

Jack the rear end of the cart up so it doesn't run over anybody.
Connect your voltmeter test leads between the B- and M- terminals on the controller.
You should read FULL battery pack voltage when the solenoid first clicks.
If not, trace the high current cables back until you find it.

fishb8 03-03-2013 02:31 PM

Re: FnR switch high pitch noise
 
B- and M- when it clicks is 27.? volts.
Johnnie, help me with the "trace the high current cables back". where do I go next.

I just noticed that if I push the forward switch hard towards forward, the reverse buzzer comes on. So the buzzer comes on in reverse and "all the way" forward. but if i pull back on it so the buzzer stops, it still does the same thing

JohnnieB 03-04-2013 06:25 AM

Re: FnR switch high pitch noise
 
3 Attachment(s)
The beeper problem and the voltage problem are separate electrical issues, but may have a common mechanical cause. That being a loose, worn out or maladjusted F/R assembly.

The beeper issue first. The beeper sounds when the roller on the arm of MS-4 (Labeled MS-1 on attached drawing) drops into one of the two indentations on the outer edge (circumference) of the F/R moveable cam.

Unless, in addition to being rotated by the shift lever assembly, the cam is somehow being moved from side to side, I'm not sure why the beeper sounds when the lever is pushed further in the Forward direction. Perhaps the F/R assembly is assembled correctly, or the nut in the red box on second drawing is too loose.
(That nut being too loose might also be causing the voltage and high pitched noise issues)



The voltage problem:
In a Series cart there is a single current path starting at the battery pack's main positive terminal, going though the solenoid to a set of contacts in the F/R switch, then through the stator windings in the motor, then to a different set of contacts in the F/R switch, then through the motor's armature, then to the M- terminal on the controller and through the MOSFETs inside the controller to the B- terminal which is connected to the main negative terminal on the battery pack and then the current flows through the batteries and cables within the battery pack back to the main positive terminal, completing the high current loop.

Any resistance in any cable, connection or set of contacts will develop a voltage drop when current flows through it and reduce the amount of voltage applied to the motor windings.

When the pedal is only pushed until the solenoid first clicks, the MOSFETs in the controller are not conducting (or shouldn't if the ITS is adjusted properly), so the entire battery pack voltage should be dropped between the M- and B- terminals on the controller.

Attached is a schematic of a stock Series cart. The order the high current cables are connected to the A, B, C and D studs on the F/R switch may be different, but the rest of the high current loop is the same.

The first place I would measure is the "A" stud on the F/R switch. That is where B+ attaches to the F/R switch initially.

fishb8 03-04-2013 05:25 PM

Re: FnR switch high pitch noise
 
Thanks for the help help johnnieb.
I tested the high current path. From the negative post of the battery pack i tested A,B,C,D thru the motor and back to M-. I dont have full pack but close. It drops a little at each stop.
I did find that is i remove the black wire from ms2 or the orange wire from ms2 that the noise goes away.(I think it is ms2).

I also tightened the nut you mentioned and it did not help. but it did make it very tough to move the FnR switch.

JohnnieB 03-05-2013 04:58 AM

Re: FnR switch high pitch noise
 
Can you post a picture showing the two microswitches and wiring?
According to the schematic, the orange wire should be attached to MS-4 and the black wire should be attached to the beeper.

Apply a small amount of dielectric grease to the F/R switch contacts so it shifts easier and loosen the nut a little if need be.
It is a balancing act, tight enough to insure full contact, loose enough to shift.

fishb8 03-05-2013 09:47 AM

Re: FnR switch high pitch noise
 
2 Attachment(s)
I wish I saw this before I left this morning. I had my wife send me pix.
I think I described it incorrectly. If i remove the black wire from the buzzer side of the microswitch it stops humming. The one with the spade connection

It also stops when I remove the orange wire.

JohnnieB 03-05-2013 10:54 AM

Re: FnR switch high pitch noise
 
Okay, that clears that up. The black wire doesn't connect to any of micro-switch's terminals, it just uses one of its mounting screws as a junction point.

What had me concerned is the black wire connects to B- and the red wires on the microswitches connect to B+.

Apparently the high-pitched sound is coming from the beeper. Why, I don't know.

Disconnecting the black wire disables the beeper, but the orange wire is what tells the controller to go into half-speed mode when cart is in reverse.

I believe the high-pitched noise problem is a separate issue from the cart not running. Get the cart running first.

BTW: That is MS-4 in the picture. All it does is turn the beeper on when F/R is in reverse and but B+ on the orange wire to tell the controller to limit the motor to at half speed. Cart will run without it connected.

---------
What voltage do you measure across the motor?
Connect your voltmeter's negative test lead to the A1 stud on motor.
Connect the positive test lead to either the S1 or S2 lead, whichever reads the highest voltage when pedal is pushed.
If you get something close to the battery pack voltage and the motor isn't spinning, the motor is sick.

fishb8 03-05-2013 11:15 AM

Re: FnR switch high pitch noise
 
I will check that as soon I get home.

BTW: the humming is happening when the key switch is off and on.


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