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SOLVED: Hantek DSO5102P (5202P firmware) stuck on Auto Set
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Microcheap:
I was going to suggest you to check Hantek's forum because there are other people with the same issue but it's good to hear you already fixed the problem.
Znida:
I have DSO5072P and the rotating knobs stopped working, but everything else is working fine, only rotating knobs are not working. Push buttons work. I have checked the keyboard, also changed all the logical IC on the keyboard (74HC393, 74HC595, 2x 74HC4051), but the problem is still there. I am out of ideas what to do. Oscilloscope is 2,5years old, but was in use less than an hour in this time. After 2 years I powered it on and the knobs are not working.

I measured pin 1 and pin 2 of 74HC4051 U2, and there is noisy signal on one pin and almost nothing on the other pin. If I understand correctly it should be a nice square signal on both pins, with different phases?


Znida:
I fixed it. I desoldered all the diodes to the knobs and added them back one by one. It was a faulty trigger level knob. I unsoldered the knob and took it apart. It seemed ok. I put it back and now it is working again.

I wrote this here so If someone else will have the same problem. Unsolder all diodes and put them back one by one and test the knob that have the diodes back. It will stop working and you will know which one is it. 
morgan_flint:
I see the thread is old, but in case somebody lands here after a search, I had a similar problem. I think there's no need to unsolder and solder the diodes, as in my case, very similar to this one,  the failure was caused by a faulty rotary encoder that, due to bad design, had one of its terminals short-circuited to the case and, hence, to ground, blocking not only its signal but that of the rest of the encoders, as they all share the same row in the front panel scanning matrix.

Technical details here, and the initial debugging of the problem in the posts from here at the same thread.

Basically, you have to detect which of the encoders have the problem checking continuity form both sides to ground and then replace it or repair it with some isolation tape.

BTW, this problem affects not only the DSO5102 but also the DSO2000 series (mine) as these models share the same type of encoders and user interface scanning solution. The video that I saw that describes the problem and its solution is for a DSO5202P.
jbboyd:
Thank you thank you thank you.  I had the problem exactly as you describe and your excellent description here saved me a lot of time debugging.  Zero of the knobs on my DSO2D15 were working.  Checking the pins to ground on all the encoder I found one that was around 16 ohms.  Removed it and then tried it with that encoder missing and the rest worked which confirmed your analysis.  Out of the scope that encoder pin was also shorted to ground.  I took the encoder apart for fun, couldn't see a problem, and when I put it back together it wasn't shorted.  Put it back in the scope and now everything is working.  I should probably buy a replacement I suppose in case it wonks out again.
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