JYE Tech Forum

I have uploaded version -066. I noticed that if you use auto trigger mode and position the bar in the Horizontal Position display to the far right it does act like roll mode. Events enter on the right side of the display and move to the left. Hold will freeze the display when you see something of in...

If V2 changed from the nominal 1.66V to 1.5V when you connected the 9V battery the trace ought to be at the bottom of the display. V2 should be changing from 1.66V to 1.73V I see in the Dec 04 photo the display says the switches are set for 2V. The trace is one division above the center which says t...

There may be a bad connection, a solder short or parts may be in the wrong position. Set the switches to DC, 1V, X5. Touch the test leads to the 9V battery. The voltage at V1 should be 1/100th of the input with the switches set as above. Expect about 0.08V at that point. Change from 1V to 0.1V. The ...

If the trace did not go to zero after the resets and you have about 1.66V at V2 I don't know what else to suggest. Maybe it would be worth loading the latest firmware, especially if you don't have version -65. You will find it here: https://www.jyetech.com/forum/viewtopic.php?f=18&t=1101&sta...

The voltage at test point V2 should be about 1.66V, a few tenths off is OK. If that voltage is alright try doing a factory reset and the Vpos Alignment. I have had the settings in my DSO138 suddenly change for no reason and give similar problems. Restore Factory Default Hold down [+] and [-] buttons...

The -10 volts at TP25 (V-) is OK as long as the voltage at -AV is -5 volts. The -10 volts is regulated to -5 by U4.

What test point are you referring to when you say you have a normal offset of -5 volts?
What do you see that tells you something is wrong?

If the voltage at AV- is OK don't worry about the slightly high voltage at TP25. That voltage is regulated down to -5V by U3. Anything over 8V at TP25 will work. TP26 is the same point as AV-. V2 is the last test point before the signal enters the microprocessor. The voltage at V2 with no input shou...

It's hard to imagine a hardware fault that would cause your problem. Perhaps the EEPROM is corrupted.
Try restoring the factory default values. Hold down [+] and [-] buttons simultaneously for 2 seconds.
Of course you will need to do the Vpos alignment again too.

Try restoring the factory default values. Hold down [+] and [-] buttons simultaneously for 2 seconds.
Then do the Vpos alignment.
That worked for me when the trace was stuck at the top of the screen.

Have you checked the voltage out of the AC adapter? An unregulated supply can go as much as 40% higher when lightly loaded. I connected 12V to my DSO138 and measured -15V at test point V- ( L1 ). 12V is the upper limit of the power supply voltage specification. The regulator will run warmer but it s...