DSO138 oscilloscope - dim display

[Bushbaby]

Hi
I have managed to build one of these kits in 3 days, on and off, and it one of the Sainsmart kits. It apeears to be fully functioning BUT the LCD display is much dimmer than I expected it to be and its a bit flickery too. I'm using one of the usb voltage booster using a 5v mobile phone supply set at 9.03v (I also have one of the official JYE power modules too but not tried this). I have also replaced all of the 'cheap 100uF elctrolytics' supplied for ones that I had although the ones I've added are 35v and not 16v as I couldn't find any. I cant see that these will be a problem though even though they are a wee bit bigger.

I have a JYE DSO138 kit to build as a standbye in case the first one went wrong (they are that cheap it doesnt make much of a dent in the bank).

Regards

Rob

[Mark Hennessy]

The brightness is dependant on supply voltage with these kits, so it will be a bit dim on only 9V. As for the flickering, I'm sure what the cause could be, but I'd try it on a different power supply, just in case the boost converter is playing up. A variable bench power supply is ideal for this sort of thing.

[Bushbaby]

Hi Mark
Thanks for the reply. I do have a bench power supply so I shall give it a try. I have a feeling that the MT3608 DC-DC Voltage Step Up Adjustable Boost Converter Module 2A USB unit may not be right for the job although the voltage can be adjusted to as much as 28v. Shall i up the power to say 9.5/10v??

Best Regards

Rob

[Refugee]

I have a Samsung screen on my computer that runs the back-light from the power input directly.
It will run on 9V to 14V with a widely variable screen brightness. The wall warts from E-bay do not last however a shortwave transmitter power unit with a transmit power of 12 volts at a few amps runs stone cold but shows a little bit of screen dimming when an electric shower is used.
I got the screen FOC more than 10 years ago.

[Nick]

Whilst the MT3608 is not a bad device, some of the stupidly cheap eBay boards using it may have compromised performance due to component choice. The DSO138 only needs 150mA.

The data sheet is pretty explicit about this - it'd be interesting to know what diode they're using and the quality of the capacitors and inductor.

If the components are indeed good, then the converter should work well...

Note that there are a lot of fake DSO138s around - the originals are made by JYE Tech - see https://jyetech.com/Products/LcdScope/e138.php

It may be an issue with the DSO itself... As Mark says, first thing is to eliminate the boost converter...

[Bushbaby]

I'm now working on the 2nd one I have which is a JYE issue. The quality appears so much better than the Sainsmart....I will let you know when complete