Longwei power supply mod: TPR3005-2D

[asterix2344]

Greetings to everyone, my LONGWEI power supply mod: TPR 3005-2D has broken down, I don't have the wiring diagram. The fault is that the left section does not work on the front the DC LED is on, the voltage can be adjusted but the amperage does not work. The right section works perfectly. Can someone kindly help me?

[Jwillis]

Linear? Based on the HY3005 linear supply. Mastech or Volteq. There are many re-brands. https://elektrotanya.com/mastech_hy-3005f-3_matrix_mps-3500l_2x30v,5a_psu_sch.pdf/download.html
The front pots fail and can cause problems. 


Edit for better link

[asterix2344]

Jwillis thanks for replying. Can you explain to me what the: The front pots , are you perhaps referring to the final power circuits?

[Jwillis]

Jwillis thanks for replying. Can you explain to me what the: The front pots , are you perhaps referring to the final power circuits?

What can happen is the wiper of the Current limit adjustment pot fails. The potentiometer (W10) is a voltage divider for the non inverting input of 741 op amp 2N2. That input needs 0V to 12V to adjust the current limit to output. If that input remains 0V because of a failed wiper on current adjustment pot, then you get no current to the output.
I pointed to the potentiometer as a cause because it's common for mechanical devices to fail first.

[asterix2344]

I solved the problem in the following way: since the two control boards are identical, I disassembled the operational amplifier that controls the ic:N2 current of the board that doesn't work, with that of the section that works, and I found the culprit. Now the instrument has started working perfectly again. Thanks for your help, regards.

P.s.  sorry for my bad English, I use a translator.