Desperate Korad KA3005p repair - repaired :)

[Matthew98]

Hi guis. I fucked up ! Litelary !
I was gonna measure something and connected leads of my power supply to mains ! (230V) I mixed up my V meter leads and ps leeds. The Ps was turned off, but when i connected it (- on N, + on L) the breakers wen out. :/ When i flipped them back in and turned the Ps on, it turned on ok, but when I turned the output On, the thransformer started to make 50hz noise and there is Short between the Ps leads, so voltage drops to 0.something and there is NO current flowing.
Luckely Dave have reviewed and teard down this Ps, so i have his footage here. My version is little bit newer, but it should be overall the same.




Guis, im really desperate without my Ps. Please, help me bring him back to live
This is my version :

[cowana]

If you're lucky, it'll be the big diode underneath the current shunt that has blown short-circuit. Can you disconnect all the internal cables connecting to the front panel board, then check that diode for continuity (in both directions)?

[Matthew98]

Shorted in both directions.

I have GP30M diode :
http://pdf1.alldatasheet.com/datasheet-pdf/view/34870/ZOWIE/GP30M.html

Thats perfect match to oreginal blown 1N5408 :
http://pdf1.alldatasheet.com/datasheet-pdf/view/2821/MOTOROLA/1N5408.html

Right ?

[Armadillo]

Disconnect the power board [near the fan] "COMPLETELY"
check the output for shorts, check Q1 and Q2 and the bridge rectifier diodes.

With the power board disconnected, power up the unit.
[Main Board]
1. Measure U4 pin 2 for 3.3v
2. Confirm display is working
2. Measure Q4 emitter with respect to earth, confirm that as you adjust the front panel voltage, the Q4 emitter voltage change proportionally.

Let's explore how much damage first.

[Matthew98]

Hi ! Nice to see you again.
I have checked the diode, as cowana sad and reconnected everything. It seems to be fine now !
Is it necessary to do your check to be sure, or i can just measure the output voltage and amps by a multimeter to check it ?
Guys thank you, thank you, thank you, thank you !!!!! You rock !!! 

* Checked all sort of things - tried to drive few power hungry motors and measured all types of voltage. Everything is Fine

[Armadillo]

Good, it's all done up so fast.

 

[cowana]

Excellent - glad the repair was quick and easy for you to carry out! And glad the diode sacrificed itself to save the rest of the components.

[Matthew98]

I was already finding deals for new Psu I cannot live without it ! It really made my day
Thank you ! Without you i would have lost around 120dollars this week, which is kinda lot to me...
I love this forum.