Hantek PPS2116a reverse engineering

[fqahmad66]

My Hantek PPS2116a finally died so took it apart to study and do some reverse engineering. Starting with the power board (usually the culprit), noted that it has AC fault sensing which the Korads lack.

Attachments updated

[fqahmad66]

Next Trying to understand the Main Board. Does somebody managed to successfully download the hex file? Never mind.. I got it.

[fqahmad66]

Main Board Layout and schematic. Can somebody educate how is the OVP implemented? Cannot trace it.

[fqahmad66]

Latest destination of this power supply.

https://www.circuitspecialists.com/pps2116a-programmable-dc-power-supply.html

There is no programmable OVP...just  a built in AC fault shut down.

[fqahmad66]

Display, Keyboard and USB schematics..

[miatarexx66]

THANK YOU for posting the attached schematics.

I work as a bench technician and my company has 40+ of these specific units so the information is greatly appreciated.  I have repaired quite a few of them but have had some that I couldn't quite figure out without more info or schematics.  Some of the suspected parts also appear to be obsolete or out of stock when I search for those.

What kind of issues did you have with yours?  Problems, symptoms?  If you fixed it, what was it?

I'm currently working on one that just stopped working during some ESD testing some of the other engineers were performing, the control board doesn't appear to be functioning at all.  Can't adjust voltage or current.  Other than showing all 0's, it's basically a boat anchor currently.

[fqahmad66]

Hi,

I am glad you find those usefull. I did reverse engg just for fun. The supply is now resting dismantled in a box. I replaced it with a Rigol. You may check the diode across supply on Power board and also TLO82s on Main board. Mine had that diode blown due to connecting a reverse battery. The code protection on MCus is enabled so it that is fried then a replacemet board is the only solution.

Best regards
Farooq

[rvalente]

Well done!

Would you share more about the reversing engineering techniques you've used?

Is this cad capture from altium? Does not seems to be eagle or kicad?

470uF as output cap seems a little high to me, does that PS has big overshoot on short?

[fqahmad66]

Took out the boards and visually followed the layout and traces. Did you ever replaced the MC is any of the controller boards? No overshoots. It was a very good supply in my opinion. However it will fry a Zener or LED if touched with live voltage...not through the soft on/off.

[tikicarver]

My Hantek stopped working.
It comes on and I can change the voltage and current settings,
but when I select OUTPUT, the LED comes on but there is no voltage on the output jacks.
I have not used it in a while but i seem to remember hearing a relay click when you select OUTPUT.
Now I do not hear anything.

Do you think the relay is bad?

I can't find the output relay on the schematics. Can you tell me where it is and if you have seen this problem.

[jjohnson873]

My Hantek PPS2116A has a flaky rotary encoder that sets voltage & current (part designation: RV102).  The encoder jumps when setting the output voltage or current.  Does anyone know the correct replacement part for this encoder (pulses/rotation)?  It's a 3 terminal encoder that I suspect has two internal switches and a ground.  I've removed the Switch board and sprayed it with DeOxit and used compressed air on the encoder, but it appears to be a relatively sealed unit since one of the encoder switches doesn't seem to fully short to ground when the encoder shaft is rotated.
*** Update. The DeOxit and compressed air apparently did help and, after reassembling the PS, the rotary encoder is working again, for the time being.  I did some measurements and this encoder appears to be a dual output, 12-step/full rotation encoder.  The internal contacts close and open at 90 degrees out-of-phase of each other, with one leg leading the other in a CW rotation and then the other leg leads in a CCW rotation.  I'm certain there are many substitutes for this 3-leaded encoder if one were to query Digi-key.