2021-10-03

Logitech MX518 mouse

Logitech MX518 Legendary, model number MU0053 (G-series refresh), black version ("Nightfall").

Very lightly used (almost unused?) but not working when received, enumerating with VID 0, PID 0.


I hate these screws under feet. Here feet have also two layers - external and some kind of foam and when removing top foot I've left this foam, probably bad decision.
Watch out for the tape that is connecting switches from top part of the shell.

HERO Hg11 optical sensor.

STM32L100R8T6

  • 64 kB FLASH
  • 8 kB RAM
  • 2 kB EEPROM (pretty rare from STM32)
  • USB
  • LQFP64 - seems like there would be many unused pins
  • currently not recommended for new designs


Failure: broken DATA- USB cable line.
Cable usually breaks near the plug or near the mouse itself, but cutting it blindly would be wasteful, especially considering fancy mounting inside the mouse (H-shaped injection holding the cable near the screws).

I've measured DATA- line capacitance from both ends and it turns out it was very low (~17 pF) near USB plug. This plug did not look well anyway, with two pins sticking out, so I've cut cable few centimetres from the plug.

Overall cable quality seems fine, with decent shielding, few (nylon?) threads between the lines and thread inside each line.
I've used plug from some old Apple Lightning (probably knockoff) cable, wrapped with few layers of different sizes heatshrink tubes working as strain relief plus some epoxy glue. This should be more solid than original.
Mouse feet are slightly warped, but I believe they should still serve well. In worst case, as this is quite popular brand and model, replacement sets are available and not that expensive, starting from $1.50 if you don't mind waiting for shipping from China.

In hindsight, I could probably avoided opening mouse altogether if I would have thought of measuring cable capacitance first.



2021-10-02

Asus TUF M3 mouse

 Asus TUF M3 gaming mouse.






Screws hidden under feet - I hate this, I don't know if it is possible to disassemble it without warping feet.

Kailh switches and Kailh mouse wheel encoder.

Board marking: P2W13076A1.

Optical sensor: Pixart PWM3325.
U4716 - can't find nothing about it.

9VM - seems like 2V LDO.

USB MCU: CY7C64356.

Mouse is currently not working, failing to enumerate over USB (VID 0, PID 0). No obvious problem - USB connection is fine, MCU is receiving power and I've resoldered it just in case I couldn't see some broken joint.


Board marking: MG628U-D V10



2021-10-01

Swapping heater in WEP 858D hot air station

WEP 858D - cheap popular hot air station.

Bought 3 years ago for ~$30. Lightly used, mostly for desoldering and heatshrink tubes, perhaps total 10 hour of work. Heater silently (without sparks or anything like that) failed last week.

Threaded sleeve at the front + two screws at the back.
Wiring:

  • heater
  • thermocouple (inside heater element)
  • fan
  • miniature reed switch, working together with magnet in holder on base unit
  • ground

Heater is insulated with glass-like (box on new one says this is actually mica) canvas.

Failed heating wire. As it was broken near the end I actually could try to save it by removing shorter part completely, though it might be difficult to connect this type of wire - low temperature soldering would definitely not be an option.
Thermocouple at the working end of the heater.
New heater costs ~$4 + shipping.

Fun stuff: "Gift" label on the box itself. 


Don't forget to remove piece of transparent tape that is holding insulation together.

Watch out for thermocouple polarity.

Bottom side of the PCB connecting wires.
Heater resistance: 98 Ohm, matching original.


2021-09-30

Trust GXT 105 Izza USB mouse

Cheap (prices starting from ~$8) fashionable USB gaming style mouse.
Switchable 800-2400 dpi, though it seems like wider range when tested.



Not quite matching picture on the box and some other pictures I've found on the Internet - side panels mounted with screws and style of these side panels is different. They are purely for decoration and I would not recommend as plastic underneath would not survive repeated reassembling - some glue might be needed then.

As there are some holes under big sticker on the bottom side (see cross cut below) I though at first this is where screws are hidden, but they are under feet.


Fortunately mouse is easy to disassemble after removing these four screws at the bottom.
Single all-in-one chip: SPCP180-126.
PCB marking: TY_V300_SPCP186 20180906.

Piece of steel adding weight.



I do not recognize brands of these switches.

There is some space for extra switch under DPI +/- button and there are also two pegs sticking from top part of the shell. Perhaps there was some variant using it.

Mouse was completely dead when I've received it, it was probably product returned to Amazon. Surprisingly this was easiest fix ever - USB cable plug was not attached properly.

H13 scroll encoder.
Three RGB LEDs seem to be some kind of "smart" 2-pin diodes, perhaps pulse controlled: https://www.youtube.com/watch?v=gxdgRHmOuIo
Special switch for mouse wheel.
Other minor issue: scroll wheel was slightly blocked by pieces of cable insulation (I've cut it off).

Mechanically this mouse seems similar to https://mysku.ru/blog/aliexpress/67695.html - same scroll wheel, similar top shell made from two kinds of plastic.