Desperate Korad KA3005p repair - repaired :)  - Page 1
Forum section: electronics / repair

author: Matthew98
author_rank: Regular Contributor
timestamp: February 17, 2017, 11:32:45 am
content: 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 liveThis is my version :

author: cowana
author_rank: Frequent Contributor
timestamp: February 17, 2017, 12:24:32 pm
content: 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)?

author: Matthew98
author_rank: Regular Contributor
timestamp: February 17, 2017, 12:38:02 pm
content: Shorted in both directions.I have GP30M diode :http://pdf1.alldatasheet.com/datasheet-pdf/view/34870/ZOWIE/GP30M.htmlThats perfect match to oreginal blown 1N5408 :http://pdf1.alldatasheet.com/datasheet-pdf/view/2821/MOTOROLA/1N5408.htmlRight ?

author: Armadillo
author_rank: Super Contributor
timestamp: February 17, 2017, 12:50:48 pm
content: 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 3.3v2. Confirm display is working2. 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.

author: Matthew98
author_rank: Regular Contributor
timestamp: February 17, 2017, 01:14:16 pm
content: 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

author: Armadillo
author_rank: Super Contributor
timestamp: February 17, 2017, 01:46:02 pm
content: Good, it's all done up so fast.

author: cowana
author_rank: Frequent Contributor
timestamp: February 17, 2017, 02:53:52 pm
content: 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.

author: Matthew98
author_rank: Regular Contributor
timestamp: February 17, 2017, 03:17:41 pm
content: I was already finding deals for new PsuI cannot live without it !It really made my dayThank you !Without you i would have lost around 120dollars this week, which is kinda lot to me...I love this forum.