Power Supply With Ticking Sound On The Relay Repaired And Maintained
A friend of mine brought this power supply for repair and the moment I powered it up I heard a continues ticking sound coming from the relay so I took it apart and started checking things around that spot.
At this moment I had the IC taken out and soldered a base in its position to test IC’s without soldering them to board every time I check for faults.
Also if you have noticed that I have taken a resistor to right side of that IC for check up.
Click here to access the LNK304 IC Datasheet
This is the IC I was suspecting but it was ok; it was just paint on it which is why it looked like it has holes on it.
When I checked the power reaching the relay, there was voltage reading there but it was pulsing causing the relay to click on and off and when I traced the line it lead me to this 16K resistor.
I checked all the traces that lead to this IC and as seen I found this resistor faulty and it has to be replaced.
All other components on this same line checked ok.
Once I replaced that resistor, the relay clicked once and I was getting the 17 DC at the main socket to run the motor; it was working just fine.
If look carefully, you will not see the resistor back in its place due to the fact I could not find the right resistor value so I put an SMD resistor in its place and it tested just fine.
The customer came and picked it up and tested it in his work place and informed me later on that is was working fine.
Mission Accomplished.
This article was prepared for you by Waleed Rishmawi, one of our ‘Master Authors’ and currently working in the Bethlehem area of Palestine repairing electrical and electronic equipment.
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Note: You can check his previous article on A UPS Device Powers On But Does Not Hold Charge Repaired
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Parasuraman S
September 21, 2024 at 7:56 pm
Through hole replaced with SMD, an advancement in technical service! Well done! Many thanks for sharing, dear friend!
Waleed Rishmawi
September 21, 2024 at 11:13 pm
Parasuraman: thank you dear friend. It was fun to work on it and see the board alive again. Have a blessed day.
Yogesh Panchal
September 21, 2024 at 11:20 pm
Good job ! Waleed
Waleed Rishmawi
September 23, 2024 at 4:11 pm
Yogesh: thanks man. have a blessed day
Albert van Bemmelen
September 22, 2024 at 12:51 am
I take it that the smd resistor was soldered on the solder side of the board since it wasn't visible on the component sides of the shown photos.
If the max power rating of the smd replacement resistor at least was the same I guess it won't be any problem. So long as the defect resistor was not a 1% resistor, which is normally not always easily available (only the special EIA-96 resistors).
Waleed Rishmawi
September 23, 2024 at 4:12 pm
Albert: yes the smd resistor was installed on the other side of the board and yes, the device is still up and running. have a blessed day
Imoudu.O
September 22, 2024 at 2:58 am
Learning one more thing:replacing through hole resistor with smd...hmmm! good idea and job.
Waleed Rishmawi
September 23, 2024 at 4:14 pm
Imoudu: thanks man. we are all still learning because that is the beauty of this repair field everyday is a new day and new experience we learn so never give up and keep up the good work. have a blessed day
Mark J
September 22, 2024 at 4:13 am
Waleed good job on the repair.
Waleed Rishmawi
September 23, 2024 at 4:14 pm
Mark: thanks man. have a blessed day
Eric Rice
September 22, 2024 at 10:17 am
Very good repair! Recently working on a Fluke 8845A, I had to replace 2 smd schottky diodes with 2 thru-the-hole schottky diodes. Replacements were exact spec.
Waleed Rishmawi
September 23, 2024 at 4:15 pm
Eric: thanks man. yes as long they are the same specs we are on the safe side. keep up the good work and have a blessed day
Tito Kanshulu
September 24, 2024 at 1:15 pm
Good step by step explanation Waleed. I enjoyed reading it and at the same time adding to the knowledge on the same
Waleed Rishmawi
September 24, 2024 at 4:03 pm
Tito: you are most welcome. I am glad to hear you are gaining more information about electronics; that is such an encouragment to me as well. keep up the good work and have a blessed day