Some (hopefully) useful information for beginners

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Joined: Thu Dec 15, 2016 2:47 pm

Some (hopefully) useful information for beginners

Post by Christopher »

In case it is of any help to any beginners to electronics I thought I would post a few helpful hints to make sure that assembling this surprisingly good 'scope goes smoothly. I hope I am not "trying to teach granny how to suck eggs" as the saying goes.

I purchased this kit out of curiosity, and was not expecting much for the extremely low price, so I was completly unprepared for just how good it was. The circuit board is incredibly well made and labeled. All of the components were there with no parts missing. The instructions are well written in good clear language. Ikea could learn a lot from JYE when it comes to supplying self assembly products as I have never purchased anything from them that wasn't missing something vital.

So, a few hints for making sure that everything works when assembled -

IMPORTANT ---- Take your time and double check everything!

1. Check that everything is present when unpacking.

2. Measure the resistors with a multimeter and check them off against the list of values. The resistors are tiny and they are using a four band value system which can throw new players at first. With the four band system there are three value colours followed by a multiplier colour, thus 570K would be Green, Violet, Black (for 5 7 0 ) followed by Orange for the three 0's multiplier.

3. Clean the circuit board on the solder side with Isopropyl alcohol, if available, to ensure that all of the solder pads are free from contamination. I use an old but clean toothbrush to scrub the board with.

4. Clean the leads of the components to remove any surface oxidisation. Very fine emery paper works Ok but my preferred method is to use an ink rubber. Cut a slit in the rubber then place the lead in the slit and squeeze the rubber while pulling the component through.

5. Follow the instructions for placing the components on the board. IMPORTANT check the resistor with a meter when placing on the board to double check that the correct value part is being inserted. Tick it off with a pencil on the instruction sheet.

6. Hold the resistor with needle nosed pliers at the body of the resistor and then bend the lead at right angles. Place the resistor through the hole and bend the lead on the solder side outward to about 45 degrees to hold it in place. Place a small group of resistors at a time, no more than five or six then turn the board over to solder in place. Putting too many on at one go just ends up with a forest of leads which make it difficult to get the soldering iron to the pad.

7. To solder the component do the following. Make sure that the tip of the iron is cleaned and tinned. Place the tip of the iron on the solder pad and against the component lead for about two seconds ( experience will tell you the optimum time for any particular board ) and bring the solder and touch it to the pad/lead/iron junction. The solder should melt and flow onto the pad and the lead resulting in a smooth joint. Remove the iron and make sure that the component is not moved for at least a couple of seconds until the solder has solidified otherwise the solder will fracture creating what is known as a dry joint. A good solder joint should resemble a volcano with the sides sloping gently up from the pad to the wire with a slight inward curve. If the joint is balooning outward resembling a football this is ususlly a pretty good indicator that the solder has not flowed onto the pad or the wire. also the surface of the solder should be shiny. If it looks a dull grey then this could indicate that the component moved before the solder hardened and is a dry joint.

8. Carry on placing all of the other components using the same procedure as for the resistors but be very carefull with the small capacitors as the leads can come detached if they are bent too much. Best to leave a small (2-3mm) of lead showing on the component side of the board.

9. The most difficult part to solder in by far is the BNC connector. Before placing it on the board rub the two studs on the body of the plug with emery paper to remove the surface, and when soldering to the board either use a large soldering iron or turn the heat up if you have a temperature adjustable iron. I had to set my iron to 375C and it took almost 20 seconds of holding the iron to the stud before I could get the solder to melt and form a good joint. But be careful not to over-heat the circuit board.

10. Once both boards are built perform the tests as indicated in the instrucion sheet. My 'scope only needed a very slight tweak to get the test square wave to look right.

It may be neccessary to trim the small piece of plastic that sticks out at the top of the front panel where the LCD screen fits. On mine this was preventing the screen from fitting flush with the front panel. Also I was unable to get the test signal terminal to fit through the holes on the board so I simply soldered in a small length of wire.

One thing that copuld be improved is to provide regulation on the 9 Volt supply. I found that when connected to a variable voltage power supply and the voltage turned down from 9V to about 6V (the point where the scope cut out) the trace would travel to the bottom of the screen and thus would need the SEC/DIV butten to be held down to re-center the trace. I have ordered a Pololu 9V Step-Up Voltage Regulator U3V12F9 which I plan to insert into the supply line just after the power switch. This will allow it to run on anything from 9v down to 2.5 volt so that should solve that problem.

The results obtainable from this scope far exceed the very small price, with a good stable display on an outstandingly readable screen. The rotary knob is a bit hit-and miss sometimes but this would appear to be a software problem as the knob is putting out the correct signals when checked with a scope.

So, hoping you have as good an experience as I did with this rather nice little project

Posts: 4
Joined: Mon Jul 04, 2016 3:02 pm

Re: Some (hopefully) useful information for beginners

Post by chris2u »

Thanks for some good constructional advice there :)
You could also use a simple 5v to 9v converter and then it would be easy to run from a power bank or usb socket for portability.. ... rter-Plug/
Posts: 24
Joined: Tue Nov 29, 2016 4:43 am

Re: Some (hopefully) useful information for beginners

Post by qu1ck »

Great info here, thanks for posting. I'll add my 2 cents.

Its says so in the instructions that it's better to use 60 watt soldering iron for it. Because it has much higher mass than all other components it needs much more heat. Turning temperature up helps but as Christopher pointed out it may overheat the board. Boards in this kit are really high quality and it's less of an issue but it's not unusual for copper layer to come off if the board is heated too much for too long so be careful. Best way to go about it is to have a high thermal capacity tip and do the deed quickly by pressing the tip firmly to both the pad and bnc connector until it heats up.
Another tip: with properly cleaned board and component leads you should have no trouble with solder flowing to fill the veer and bind with component lead properly. However if, like me, you don't have an eraser handy but have a flux pen instead, use it. Apply just a thin coating on the pads, that is enough. After you are done soldering clean it up with alcohol or flux remover if you have it, otherwise it will remain a sticky mess, which is no bueno.
Just as instructed by the manual, solder the encoder and connected pin header AFTER you aligned the front panel and mounted the small board with screws. Otherwise you won't be able to assemble the case.

Calibration and operation:
Again, make sure to follow ALL the instructions. When assembled properly the kit should work right away. I missed the step for resetting the ground (setting input coupling to GND and long press of sensitivity button) which caused the scope to act weird on 0.1v test signal and high sensitivity. Very similar symptoms to the other guy on the thread "No signal < 0.5V/Div".
The scope is absolutely awesome for what it is. But remember the limitations: it's only rated for 200khz bandwidth. That doesn't mean that it will give you accurate readings up to 200khz signal, it means that it won't (given that it's within spec) lie about the amplitude by more than 3db for 200khz signal. That's it. Your square wave will not look anything close to a square at that frequency and the amplitude measured will be less than actual signal. And that's expected. Watch this for more info
I was able to obtain decently shaped waveforms for up to 20khz signal, beyond that it gets wobbly and looks more and more like a sine.
That said, the scope is surprisingly accurate. I measured it against Uni-T UT71D 40000 count multimeter and on every and all test I could come up with it was well within spec.
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