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DSO 138 Mini error

PostPosted: Fri Mar 09, 2018 7:40 pm
by nationwide1945
Just confirmed by JYE Tech that instruction sheet for mini is in error. Instruction that came with the mini show the JP1, JP2, JP3 and JP5 are shorted, Keep JP4 open is left open. According to th circuit diagram this would leave no power to the display. Also the instructions call for power to be plugged into J7. J7 is the signal input.
There is also a problem, which I'm still trying to suss out, concerning trim cap C6, which is hooked to the 1V SEN1 switch. This is to trim the edges of the square wave on the 1V power setting. Has no effect, yet the square wave on that setting requires adjusting. I've checked out the circuit, and is ok.
C4 does the job on the 0.1V and 10mV.
Apart from these errors, the scope works just fine. Worth 16 quid from Banggood. Gonna need a very fine tip, especially for the 3 switch's. Getting a bridge between two contacts is a nightmare to to sort out, especially when I ain't got no solder braid yet.

Re: DSO 138 Mini error

PostPosted: Sat Mar 10, 2018 9:52 pm
by johng
>> Getting a bridge between two contacts is a nightmare to to sort out, especially when I ain't got no solder braid yet.

When you get the braid... if it doesn't seem to be wicking up the solder very well, try adding a bit of extra flux to it (liquid or paste). Also, a solder sucker (aka desoldering pump) is a very useful alternate tool for removing solder. Both flux and sucker are available from Banggood.

hth,
John