KP184 - Rotary Encoder Issues

[Ziggo]

I bought three KP184 electronic loads in 2019, but didn't use them much until recently. I am experiencing issues with entering values using the knob/rotary encoder. It's difficult to get the values to change smoothly. The values will go up or down even when the knob if being turned only one way. The values will also jump between the various digit positions.

One unit is mostly OK if I turn the knob slowly. Another can be made to work by turning in very small increments (less than a "notch"). The third is nearly unusable so I try to keep it set to a certain value.

I use them for battery capacity testing and they work fine in other respects. No issues with the buttons or the actual load testing. I'm not sure if a firmware update would help or is even possible.

I wanted to see of others had experienced this issue and had found a solution.

Thanks

[voltsandjolts]

The rotary encoders are often of poor quality in this type of far east stuff.
It's probably a standrd footprint so I would start by replacing it with something better.

[Peabody]

It sounds like typical low-quality or dirty encoders.  If they worked properly in the beginning, you might be able to restore proper function by taking them apart and cleaning them.  Of course that's hit or miss, but I've had some luck doing that.

If you decide to replace them, you need to remove one and see what you'll need to order.  There are basically two kinds of mechanical encoders - those with the same number of pulses as detents per revolution, and those with half as many pulses as detents.  A "pulse" is one complete cycle of both switches.  So the first kind always comes to rest at a detent with both switches open.  The second kind can be either both-open or both-closed at a detent.  You need to get the right kind because the firmware will be written for that kind of encoder.

[Ziggo]

Thanks for the suggestions. I'll try cleaning the encoder on the worst unit. Today, the other two units were working OK, but one was still barely usable.

[interflexo]

You can also control it by software and forget the whole ordeal for now.

[aristarchus]

Thanks for the suggestions. I'll try cleaning the encoder on the worst unit. Today, the other two units were working OK, but one was still barely usable.

@Ziggo
If possible, please give us a photo of the pcb that has the encoder's circuit, it could reveal if the design is filtering noise on encoder's contacts or not.

[Ziggo]

OK, I'll open one of the units up and get some pics. But not today. I want to fix other things with my test equipment, not fix my test equipment. The encoder issues are back on all three units and an additional issue popped up.

I couldn't start a battery discharge at 9A (40V). I had to lower it to 5A before it would start. Then, I could increase it to 9A without issue (other than the issue of the rotary encoders being flaky). I tried lowering the ramp up/down rate but couldn't find a solution. Same problem on two different units.

[interflexo]

I want to fix other things with my test equipment, not fix my test equipment. ...

That's why I suggested the full software control for now and you don't have to touch the Kunkin operating panel again.
If you have a suitable USB to serial adapter at hand you may have a go with it:

https://www.eevblog.com/forum/testgear/serial-to-usb-on-kunkin-kp184-electronic-load/msg3787289/#msg3787289

[Ziggo]

Thanks for the link to that thread. I had tried to use the KP184 software from the mfg in 2019 but couldn't get it to run. I'll try again.