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DSO138 troubleshooting - AV+ is negative (no trace)
Posted: Wed Apr 11, 2018 12:54 am
by KeaganJ
The device boots and has the screen come up but no trace appears. I went through the AV- (no trace) guide but didn't see any issues. Using the voltage reference guide I measured AV- at -4.95V, AV+ at -2.1V, V1 at -1.29, V2 at -1.22V and all other voltages were correct (the voltages with a single star were all lower than the shown voltages). Any Ideas what the problem is?
Thanks
Re: DSO138 troubleshooting - AV+ is negative (no trace)
Posted: Wed Apr 11, 2018 12:17 pm
by MNTech
If the display works you have 3.3V and the 5 volts that feeds the 3.3V regulator.
The 5 volt supply is connected to +AV through L3.
Check L3 with your ohmmeter and resolder its connections.
Re: DSO138 troubleshooting - AV+ is negative (no trace)
Posted: Thu Apr 12, 2018 9:45 pm
by KeaganJ
The inductor was bad and is now replaced. AV+ is now around 5v but still no trace.
Re: DSO138 troubleshooting - AV+ is negative (no trace)
Posted: Fri Apr 13, 2018 4:21 am
by MNTech
You may have the same problem as in this post
https://www.jyetech.com/forum/viewtopic.php?f=18&t=1658
If not provide more details.
Re: DSO138 troubleshooting - AV+ is negative (no trace)
Posted: Fri Apr 13, 2018 7:10 pm
by KeaganJ
All better now. Thanks for the help.