DSO SHELL 150 K, busted rotary encoder + fix


Update  : There is simpler way to fix it.

I had a DSO138 which is a very fun and cheap to do low end oscilloscope job
For basic hobbyist like me, it's perfect
I saw the new generation (DSO150K) with improved user interface, so i bought one

All went well, until i realized i managed to do *2* mistakes :
* Solder the power switch the wrong side, not a big deal
* Solder the rotary encoder the wrong side => That one is a common mistake it seems

After trying to unsolder it, realising there was a shortcircuit,  fixing it  again and breaking the small PCB holding it, more and more, i completely ruined the whole thing.

I had to dremel the original encoder out and cut the tracks to stop the shorts.

Ultimately, I managed to make it work, it's not that complicated.

First,  I bought a new rotary encoder.

The original 4 pins header is connected to  r5/r6/r7/gnd

If, like me you ruined it completely, you can solder small wires to r5/r6/r7, a handy ground is available bottom left (DGND)

Now time to solder the rotary encoder the following way (looking at the back of the encoder)

If the 4 pin header is still there , it's much easier. Double check for shorts !
If like me you have nasty shorts, just make a hole in the small PCB.


WHAT A MESS, but it works (tm)

Comments

  1. Kobi TyrkelAugust 2, 2019 at 2:21 PM

    Thanks MeanX,
    I managed to install the rotary encoder the other way around, remove it, install it again and realize that the connections 1, 2 and 3 on the small PCB are cut off.

    Your blog entry helped me probe the connections and easily repair the problem.

    It was fun and now it works great!

    ReplyDelete
  2. meanXAugust 3, 2019 at 11:04 AM

    next you need to do the lithium battery pack mod :)

    ReplyDelete
  3. マイコン利用者August 30, 2020 at 4:22 AM

    good jobs.

    ReplyDelete

Post a Comment

Popular posts from this blog

Component tester with STM32 : Part 1 ADC, Resistor

Image
I was always  fascinated by the so call "transistor testers" that identify and report pin out, features of pretty much whatever you throw at it. They are based on Atmel 328p chip, the same as arduino nano. So why not do the same thing with a STM32/Bluepill ? The STM32 is faster, has a better ADC accuracy, more memory, can do float etc... and is not more expensive. Warning : I'm doing this for fun & to learn, it might contain error & plain misunderstanding So, i watched a couple of video on the general principle on how they work. This is not a "port" but a rewrite from ~ scratch. When something is weird, i check what the original one does for comparison. Measuring resistance So first thing first :  Resistance & Capacitance. These 2 will unlock the other ones. So how do we measure resistance ? What we do is a resistor divider with a know resistance value: Measure = Vcc*(RtoTest/(RtoTest+Rknown)) As far as the ADC goes, it means ADC=
Read more

Fixing the INA3221

Image
It 's not too complicated to change the board we have seen  previously . You 'll need to cut some tracks, i did it with a dremel and i'm not very handy, so you'll do better. Red =Cut tracks Blue = Add wire 1- You'll need to separate the bottom connector from the ground, cut the 3 connectors BOTH SIDES. 2- Remove the small red area below the middle resistor to isolate each channels from each other Last, connect right side of each connector to the now isolated pad. Mine looks like this after the operation (ugly i know): Be wary of the small track on the left connector that leads to the left side of channel3 resistor. I cut it while isolating the right pad. Now it works, we can go back to the charger.
Read more

INA3221, weird wiring

Image
Continuing my "smart" battery charger, i've finally received the INA3221 module. It is the purple one you can find on ebay for ~ 5 bucks I soldered a couple of pins to be able to connect it so that i could test it and something immediately caught my attention. It is supposed to be a high side current/voltage sensor, typically in a setup like that : So you can measure the voltage supplied to the load, and the current going through it. Now, let's have a look at the module, look at the top of the following pic, where the sense connectors are. CH3/GND/CH2/GND/CH1/GND ? Wait ? What ? Yes, all the IN- pins are connected to ground, so it is a bottom current only sensor. Additionally, the - side of the shunts are ALSO connected to the ground, no only the connectors. The actual layout is like that : That raises two problems :  The voltage is meaningless as we are only measuring Current x ShuntValue, not the supply volt
Read more