A wet dead walkie talkie repaired. Model: Midland LXT500
My nephew brought this walkie talkie to my shop and the complaint was wet and dead. He left it laying outside the house and someone by mistake poured water on it. It was left there, wet with battery in for about three days.
From experience, when battery is left in a wet device for a long time, the chance is very slim to be repaired. I was willing to give it a try simply because I love my nephew so much and the disappointed look on his face made me sad. I took the cover off and I could see it was really wet. I had to clean it with a chemical solution. It was shinny again but that did come make the walkie talkie come alive.
After cleaning, I re soldered every single soldering joint on that board. That brought the walkie talkie back to life but when I tried to connect with the other walkie talkie that he had, it did not work. The RX was being displayed on the screen. For your information, the RX being displayed on the screen mean, this walkie talkie was in receiving mode. It has to be on TX mode to accept the other calls. Everything on this walkie talkie was working except making and receiving calls which tells me that the program in this device is doing its job and it does not need reprogramming on the EPROM IC.
The only thing that I could think about is the crystal on that board. Many times when I worked on cordless phones and there was no connection to base was because of this crystal.
I changed the crystal (20.950y*B) and to my surprised it worked. I could see TX being displayed on the screen and that brought a big smile on my face.
Deep in my mind, I was thinking if I could not fix this walki talki, I was willing to buy a new one for my nephew just to avoid seeing that disappointed look on his face.
A few minutes later, my nephew came to the shop and asked me in a low disappointed voice if it was working or not. I replied with a smile that it worked. I could see his face lighting up and that was my pay for this short fast repair of this walkie talkie.
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. Please give a support by clicking on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments.
By the way if you have any good repair article that you want me to publish in this blog please do contact me HERE.
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shihab kably
July 16, 2013 at 11:04 pm
You repaired the device , made your nephew happy and still have time to write this valuable article for us. God bless you my friend
Waleed Rishmawi
July 18, 2013 at 3:29 pm
Shihab..sometimes the repair does not take that long to do and most of the time, I have plenty of time on my hands.it is fun to do even sometimes it takes more time.
KYBOSH
July 16, 2013 at 11:49 pm
Excellent story. Your nephew will always smile when he hears your name.
Few questions (and I guess anyone can answer):
Which cleaning solution is good for this kind of job?
Why the need to resolder every single joint on the board? Did you discover (actually see) multiple open contacts and thought it best to do it for the ones that you could not see? How long did that take you?
Finally, where is the crystal located in the picture? Is there a way to test it easily?
Thanks!
shihab kably
July 17, 2013 at 1:25 pm
I think we can not test crystal oscillator except by an Oscilloscope or a frequency counter may be our experts can shed more light on this
Waleed Rishmawi
July 18, 2013 at 3:39 pm
KYBOSH: thanks for the comment.
I use a Ethyl Alcohol. it is 95% pure. I do not apply too much other wise it will leave white leftovers.
yes, I felt the need to re solder every joints. when it was wet, the joints on that board were dark even after cleaing, the joint still dark and cold. so instead of checking every one on that board..I just resolder everything..
I never tested the crystal before and I do not know what kind of testing equipment that does that. if someone knows let me know. the cystal usually a wide white peace on the frond of the board. I think you can see it in the second picture. it is next to the ic that has 14 legs.
beh
July 17, 2013 at 9:02 am
HI MR WALEED
thanks for this happy ending repair report and say hello to all the family
beh
Waleed Rishmawi
July 18, 2013 at 3:40 pm
Thanks Beh. God bless you
Amir Mukhtar
July 17, 2013 at 4:06 pm
Mr. Waleed first of all thanks you for your experience sharing and next you did a astonish job for your love ones nephiew. God Bless you and him also, Aameen.
thanks you
Amir MUkhtar
Waleed Rishmawi
July 18, 2013 at 3:42 pm
Thanks Amir. I appreciate your comment.
PARASURAMAN S
July 17, 2013 at 10:00 pm
Excellent! Simply superb! Any electronic technician/engineer should always be like a doctor, who works towards bringing back the patient to normal life! We have to be committed to our profession and should not live on the surface, just for the sake of making money, like many do today! I always get my fuel from the satisfied customer's sparkle in the eyes and face! Good job! Pl keep it up! All the best to you! With best regards and thanks, SPR
Waleed Rishmawi
July 18, 2013 at 3:43 pm
PARASURAMAN S: thanks for the comment and the encoragement. I appreciate it very much
lee tucker
July 17, 2013 at 11:06 pm
@kybosh
the reason i think that waleed re-solderd every joint is beacause when water hits solder a lot of the time it will form calcium a white hard chemical that can cause the joint to crack,leaving a dry joint,that combined with the battery still in the device its charge will also react with water and cause the calcification of the joints.for the testing of the crystal you need a scope, with the device powerd on ,you should see a square waveform on the scope from measuring from both pins of the crystal to the probes on the scope.hope this helps !
Waleed Rishmawi
July 18, 2013 at 3:46 pm
Lee: thanks that is part of it..also, inspecting every joint is a long time spent..just resolder and get it over with. I have a scope but I never used it to test the crystal..I just took a lucky guess and it worked. I will test the crystal next time with a scope. thanks for your imput.
Dan
March 10, 2014 at 7:00 am
Way to go. I liked this insightful web site. Keep do this, I am happy to read these tips you guys love to share with the rest of us. Thanks again.
Taring K Arioka
April 16, 2015 at 2:21 pm
This is a nice article. I really enjoyed reading it. Thank you again.
Bulent
June 27, 2015 at 5:34 pm
Good job Big smile!