SOLVED: Hantek DSO5102P (5202P firmware) stuck on Auto Set

[don.r]

As the title. Scope boots in Auto set every time. Press Auto Set and it goes out for 2 seconds only to come back on. Any ideas?

[don.r]

After returning back to life the scope still exhibits some odd behaviour. Sometimes the controls will freeze. Most push buttons still operate but the rotary encoders are non-responsive. The scope is still operational and works from USB remote control. It can be fine for hours and then lock up. Some times it will boot up locked up already. Occasionally it crashes and reboots. Is this just normal Hantek behaviour?

[Microcheap]

I don't have this model so I can't say for sure, but I own some others Hantek equipment and they are famous for having buggy firmware.

Your oscilloscope model is a some what mature series and I would expect that its firmware is stable now. I don't think the behavior you are experiencing with your scope is normal. Make sure you have the latest version installed (http://www.hantek.com.cn/products/detail/26).

Is this a new device, do you have the option to return it? You can also try to send an email to Hantek or post a message in their forum (https://www.eediscuss.com/forum.php), it can take some time but, eventually, they will reply to you.

[don.r]

I don't have this model so I can't say for sure, but I own some others Hantek equipment and they are famous for having buggy firmware.

Your oscilloscope model is a some what mature series and I would expect that its firmware is stable now. I don't think the behavior you are experiencing with your scope is normal. Make sure you have the latest version installed (http://www.hantek.com.cn/products/detail/26).

Is this a new device, do you have the option to return it? You can also try to send an email to Hantek or post a message in their forum (https://www.eediscuss.com/forum.php), it can take some time but, eventually, they will reply to you.

Thanks. Its an old scope I picked up second hand some time ago. Its on the latest firmware (17FEB2020). I have done a factory reset and recovery. Looking at the behaviour its almost as if the front end muxes aren't working properly. The scope is plenty responsive from USB so its not the FPGA. Sometimes when she is in her "frozen" state, when I press a button or turn an encoder a completely unrelated action will happen. Sometimes when I spin an encoder slowly the reaction is jittery like every second click is missed. All voltages are spot on and there is no noise on the power rails. Cable between front panel and mainboard checks out. Connections are solid. I may check solder joints on the muxes on the front panel board.

[don.r]

I reflowed U2 (74HC4051) pins 1 and 2 on the front panel board as well as the decoupling caps on all the ICs on the front panel. These 2 pins appear to be the signal outputs for all the rotary encoders. If all your rotary encoders die on your Hantek scope but the front panel buttons still mostly work, try reflowing these two pins. My scope now works fine.

[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.