JYE Tech Forum

At the end it was bad soldering on U3 (bad 3.3V signal). Now it works nice.

Thank you for all your support and patience. An oscilloscope under 30$ is pretty awesome

Thank you for your answer: 1) As it can be seen in the next picture, the firmware is 113-13801-045 https://www.dropbox.com/s/wps6dpd3baighba/IMG_20150820_132338.jpg?dl=0 ( https://www.dropbox.com/s/wps6dpd3baighba/IMG_20150820_132338.jpg?dl=0 ) 2) The Front side: https://www.dropbox.com/s/pvvj7rihr3...

Please, don't ignore your customers.
Can you please let me know what can I do in order to get the product I bought from you working?

Thank you for your time.

I will try again:

there is anything I can do to get the DSO138 I bought working?

Thank you.

Hello unordung,

Since July 28th they have not answered again.

Hello again:

¿there is anything I can do to get my DSO138 working?

Thank you.

Of course, the new values are: V+=8.14V AV-=0.66V AV+=4.91V Step 1: Check voltage at the lead of R40 that connects to U1 pin 46 (the node marked VGEN in schematic). This voltage should read about 0.8V. If you get a value close to 0V or 3.3V then the pin 46 of U1 may be open, or the pin inside is dam...

You are right. I put 78L05 in place of 79L05. I changed by new 78L05 and new 7905 in the correct place, but still I get the same values. But now neither 78L05, 79L05 and Q1 and Q2 gets hot.

What should I do next?
Thank you for your time.

Hello, I have the No AV- (No Trace) problem: These are the values: V+=8.09V AV-=0.69V AV+=5.6V U5 gets really hot. Tried replacing Q1 and Q2. Similar behavior. L2 is not shorted or open. Step 1: Check voltage at the lead of R40 that connects to U1 pin 46 (the node marked VGEN in schematic). This vol...