Rusted Components Found In KEMAI USB Radio Model MD-1800UR
Make and model Number: Kemai USB Radio – MD-1800UR
Problem reported: Dead.
Preliminary work and observations: Opened the set and found a lot of dust collections. The screws were rusted due to battery leak. Some of the components were also found rusted. Removed the dead and leaky battery. Cleaned inside thoroughly. Dismantled and cleaned the boards using IPA.
Rectification done: Replaced an open resistor in the power supply section. Replaced the built in rechargeable battery.
Caution: Noticed that red wire was used for negative and black wire was used for positive! A typical Chinese trick, either done by mistake or with purpose, as I have seen such cheap tricks in a few Chinese made devices! Replaced all the electrolytic capacitors as ESR were out of range. My action was justified when I checked the capacitance after removal, which showed either way out or going for a short. Replaced rusted resistors as well. Checked for any other component failure. Applied power and checked Radio and USB, both of which were working very well. Assembled the setback for ageing test. Found it to be working without any problems. Charging was taking place and the set worked from Battery superbly. Looks like this set is meant for use from Battery and to be connected to mains only for recharging. I advised the customer accordingly.
Anyhow satisfaction got collected as usual!
Here are the pictures:
This article was prepared for you by Parasuraman Subramanian from India. He is 70 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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You may check on his previous repair article below:
https://jestineyong.com/restoring-a-sharp-jhankar-tube-radio-7a57/
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Albert van Bemmelen
July 11, 2020 at 5:58 pm
Rust is never a good sign for electronic devices. I really only know about the very good made Philips Senseo Coffee machines that hardly ever have any problem with water, moisture or coffee leakages. The controller boards in those machines are very good protected with varnish or some sort of waterprotective coating! Which is also very important for safety because the 230VAC power input to the pcb is directly connected under the coffee cups that constantly get filled with hot coffee water.
Parasuraman S
July 11, 2020 at 8:22 pm
Yes, very true! Many thanks for your valuable input!
Humberto
July 12, 2020 at 10:34 am
Some Chinese manufacturers are always doing things in a bad way, maybe due to cheap appliances.
Parasuraman S
July 12, 2020 at 2:24 pm
Could be! Many thanks!
Waleed Rishmawi
July 12, 2020 at 1:46 pm
A TLC ( tender loving care) done in success. Good job my friend. Dead rusty unit come in and leaves your shop alive and clean..that is what repair is all about. Have a blessed day
Parasuraman S
July 12, 2020 at 11:14 pm
Very nice of you, dear friend! Many thanks for your encouragement!