How To Repair Trackball Mouse

The Logitech M570 is one of very few thumb-operated trackballs on the market place. For anyone, similar me, who suffers from RSI in the wrist, it is an ideal replacement for a mouse equally it removes all the moving back and forth – your wrist stays in one position and does not motion when using information technology.

I have had several of these over the years and they have all suffered from the same trouble: after just a few weeks of using them, they beginning to develop bug like double-clicking and dropping files when you are trying to drag. I posted a blog near this earlier. You lot tin read it here.

In this post nosotros will teardown the M570 and repair the cause of the trouble.

Tear down of the Logitech M570

To open the trackball first remove all the major external removable parts: The ball; battery encompass and micro-receiver if it is all the same hiding inside the battery compartment.

Side by side remove iii of the small rubber pads – they cover some of the case screws. They can exist hands lifted out and if y'all are careful you tin can put them back once more afterwards without whatsoever damage. You don't need to remove the pad nearest the ball hole, there is no spiral hiding under in that location.

At present remove the five case screws, ane from under each of the pads y'all removed, and i near the brawl hole. There is one more screw to notice, and it hides netherthe battery compartment label. Gently feel for the screw hole under the lable using the tip of the screwdriver, y'all'll find information technology correct beneath the 'five' where it says "1.5V AA". I estimate this is Logitech's try at detecting tampering with the device since you lot accept to damage or remove the characterization to get to the fifth case spiral.

With all the screws removed the 2 case halves just pull apart, there are no catches or lugs. Looking at the case you can encounter a lot of blueprint and applied science has gone into producing this device. It'southward a shame it is let down by the minor problem that it becomes unusable after just a few weeks! (Your mileage my vary, I use mine all day every day).

With the case separated nosotros can see that this trackball uses a single board, and an optical paradigm sensor for tracking the ball movements. It uses ii sub-minature microswitches for the left and right buttons and two board mounted captive tactile switches for the auxiliary buttons.

By removing 4 more than screws you can remove the entire circuit board complete.  Look out for the one but below the ii auxiliary switches it is easy to miss. The circuit board lifts out when you gently pull the battery contacts out from the guides. Once you lot lift out the PCB be conscientious not to lose the tiny plastic switch embrace that forms the ON/OFF switch. Information technology will be lying in it'southward position in the lower example merely waiting to drib out onto the floor, never to be seen again.

That's all there is to it, a nice design, like shooting fish in a barrel to disassemble and easy to reassemble. In the time honoured mode: Reassembly is the reverse of the disassembly procedure.  When re-assembling be careful to align the on-off switch with the tiny slide switch on the bottom of the PCB, then that it is in the correct position for operating the switch once it's all put back together. Click the thumbnail to a higher place to see all the components laid out.

Investigating the trouble.

There are many reports of this trouble with these trackballs, the reviews on sites such equally Amazon almost always mention it.

Originally I thought the cause of the trouble was probably cheap microswitches with a horrible debounce pattern. To check this I hooked up my oscilloscope to the buttons inside the device, and compared their debounce patterns to some high quality C&1000 switches from digi-fundamental. As information technology turned out the debounce patterns were almost identical without too much noise at all. Anyhow that wouldn't explicate why information technology was condign incommunicable to drag with the trackball – it was like the button was letting go.  So I compared the buttons in the trackball with the C&K ones from DigiKey. They measured exactly the same physical dimensions, and had identical characteristics with 2 minor differences:

1. The operating pressure required to operate the switch was slightly lower with the factory fitted switches.
2. The factory switches went open circuit almost equally shortly as yous started to release any pressure level, whereas the C&Yard Switches didn't go open up till you had released almost all the pressure.

This 2d point turned out to be the crusade of the failures: The switches were making contact when pressed, but releasing with almost unnoticeable reduction in pressure – and then when you were trying to click, the natural movement of your finger was causing multiple clicks, and the same when dragging  – the natural variation in pressure from your finger was enough to allow the switch contacts open and close repeatedly, thus ruining your drag operation.

I purchased a agglomeration of replacement switches from DigiKey – they are DigiKey part number: 401-1742-ND, and C&K Manufacturer function number: ZMCJF7P0T.

I have had several of these trackballs over the years. The primeval ones used some cheap looking unbranded switches, but the latest ones used 18-carat OMRON switches, but they all suffered the same mistake. I think the real problem here is that Logitech only specified a switch with with too low an operating pressure, probably in order to make the buttons feel easier to utilize.

Repairing the trackball

With the device disassembled, remove all the solder from the three pins on each of the microswitches. I simply used a soldering atomic number 26 at 385℃ and some ii.5mm solder wick. If you tin can't get the pins cleared so y'all could try using some ChipQuik.

This picture shows a comparison of the factory Omron switches (top two) with the C&G Switches I purchased. (lower 2, with white bases). Click the image for a larger view. They are pretty much identical in terms of physical dimensions, but the C&K ones have a much more positive click and feel to them. The actuator might be but a smidgeon higher, but's difficult to see.

Solder the two new switches in place, and clean up any solder flux residue with some IPA and the jobs done. Hither's a picture of the board with the two new switches soldered in place. Re-gather the trackball using the reverse of the process for vehement it downwards and Bob'southward your auntie'due south husband significant other.

And then that's information technology for the repair of the Logitech M570 Trackball. Having put it all back together and put the batteries back in I'thousand delighted with the results, no more double-clicking when information technology shouldn't and I tin drag and drop without hitch, and the switches accept a nice positive feel to them, they are not besides heavy to operate at all and take lovely haptic feedback. I would say they experience, audio and work better than they did when brand new out the box.

All in all the full price of repairing the trackball was less then iii.50 GBP ($5.00). I bought 10 of these switches from DigiKey, and accept used iv repairing my two M570's. Then I have six left over if anyone needs a repair doing….

Accept intendance.
-Kenny.

Source: https://wphost.spider-e.com/?p=139

Posted by: watershasked.blogspot.com

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