Do i measure right(osciloscope) ?

Thread Starter

disturbed123

Joined Jun 11, 2020
52
hi there.
i have inverter IC FAN7314a and want to see forms of power pin and the four outputs.
I am only touching the probe without connecting ground somewhere. Before days i have read again the lcd monitor repair book and they dont tell to put the ground somewhere in this measurement.

*LCD monitor

output 1.jpgoutput 2.jpgoutput 3.jpgoutput 4.jpgvin 2.jpgVin.jpg


thanks

if i remember right have replaced all the caps on power board
 

AlbertHall

Joined Jun 4, 2014
11,102
it`s wall powered. where to clip ground - entry capacitor -, the suns on the board where the screw go or at the ic ground?
Anywhere on the 0V line will do for low frequencies. For higher frequencies it would be better to connect the ground clip as close as possible the 0V on the chip.
 

tautech

Joined Oct 8, 2019
196
hi there.
i have inverter IC FAN7314a and want to see forms of power pin and the four outputs.
I am only touching the probe without connecting ground somewhere. Before days i have read again the lcd monitor repair book and they dont tell to put the ground somewhere in this measurement.

*LCD monitor

View attachment 231918View attachment 231919View attachment 231920View attachment 231921View attachment 231922View attachment 231923


thanks

if i remember right have replaced all the caps on power board
You are failing to use the trigger correctly to get a stable waveform which is the reason for all the junk at the top of the display in your screenshots.
For a repetitive waveform press the trigger level control to set the trigger to 50% of the waveforms amplitude.
To examine a power rail for spikes or ripple the channel you use needs to be AC coupled so press the channel button to bring up its menu and then change the input coupling to your needs.

Further, to take screenshots and still have menus displayed that can convey more info about how the scope is set, press the blue Print button that drops a screenshot straight to a USB stick.

Which model is that, it looks like a SDS1102X.
 

Thread Starter

disturbed123

Joined Jun 11, 2020
52
I will. I have service 8th year but i do very with mobile phones except computer equipment. My interest in pc technique are monitors power supplys and in past trying with motherboards.
Today obviously made some short and there was little smoke. The fuse is gone. Have paid for such from aliexpress and when they come i will continue this monitor analysing.
 

tautech

Joined Oct 8, 2019
196
Good.
Sing out if you need any guidance. One of the great improvements is more indication of input settings in the channel tabs which conveys better info about how the DSO is set in a screenshot.
Earlier SDS1102/1202X models did not have that feature but it was added to the X-E range a couple of years ago.
 

Thread Starter

disturbed123

Joined Jun 11, 2020
52
Just in theory
Lcd monitor starts without any backlight. Usually they start for seconds and after that backlights are going off.
I have working ccfls and connect them for test but they react same way. I have buyd new inverter ic and will put it in action. Some advice about fixing the monitor?
 
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