Panasonic Water Heater Repair

By on January 3, 2017



fix-panasonic-water-heater-intermittent

 

 

 

 

 

 

 

 

 

 

 

I have come across a number of Panasonic water heaters Model: DH-360M with  fault that the power LED lighted up but the heater won’t work or turn on.

                 panasonic-water-heater-repair

The symptom will be the water temperature may be intermittent warm or totally not heating at all. The first impression will be the heater was faulty.




The heater resistance measured was 17.12 ohm (photo 1)  which was normal with reference  to the specification of the heater (photo2). By  calculation the power is (V*V)/R=240*240/17.12=3.36KW.

fix-panasonic-water-heater-repair

The triac which act like a switch to  switch on the heater was measured and found to be not faulty. Since the triac is not short or open circuit, the fault must be in the main board. Next, I check the flow switch function. The heater cannot turn on if the flow switch was faulty.  The fault of the flow switch can be easily confirm by shorting the flow switch wires temporary. In this case, it did not turn on the heater even though the flow was closed i.e shorted together.

The final step will be to check on the main board. On removing  the main board I feel nauseating to see some areas of the pcb component side and copper side are covered with black sticky paste which smell like tar. (Photo 3 & 4)

how-to-fix-water-heater

how-to-repair-water-heater

Removing the tar was very messy and tedious but If you do not remove it you will not be able to trouble-shoot. The tar has to be carefully remove as not to accidentally throw away some of the damaged resistors due to corrosion. I think the tar has turned corrosive after a period of time . Due to the corrosion, a number of the resistors with leads were either broken or missing (Photo 5)

fixing-water-heater-national

Photo 5- Resistor leads damaged due to corrosion

After replacing all damaged resistors, the water heater still not functioning as normal . The corrosion due to the tar was much more serious problems than expected. The voltages  measured on the board were weird and abnormal. The tar being sticky was quite messy to remove and clean completely even with thinner or industrial alcohol. After thorough cleaning of the copper side of the pcb, the problem can be seen. There were corrosion on all the terminal leads which resulted in dry joint  (see photo 6).

national-water-heater-repair

After all the connectors were re-soldered, the water heater was functioning  back to normal. I did elaborate on  the method of testing the water heater as I have highlighted it in one of my earlier article. Anybody wanted to know more about water heater testing , please refer to my previous article below:

http://jestineyong.com/joven-water-shower-heater-repair/

 

skwong

This article was prepared for you by SK Wong from Malaysia and he graduated from London with a degree in Electronics and Electrical Engineering. He has more than 40 years of experience in the consumer product manufacturing. With the passion to repair electronic products from young , he has been doing it part time until now.

Currently, he can provide turnkey solutions for consumer products including services from idea or concept to design , prototyping , finished products (including electronic,mechanical and plastic parts) and manufacturing.




 

Please give a support by clicking on the social buttons below. Your feedback on the post is welcome. Please leave it in the comments.

P.S-  If you enjoyed reading this, click here to subscribe to my blog (free subscription). That way, you’ll never miss a post. You can also forward this website link to your friends and colleagues-thanks!

Note: You can check his previous repair articles below:

http://jestineyong.com/sony-tv-standby-led-blinking-6-times-solved/

 

Likes(83)Dislikes(0)





11 Comments

  1. tyrone

    January 3, 2017 at 9:11 pm

    if the bulb is dim or not glowing(in the bulb test method) does it indicate that there is a problem in the circuit?

    Likes(0)Dislikes(0)
    • Bulent NUR

      January 4, 2017 at 1:10 am

      Yes its a problem indicate, no glow show is faulty component, dim bulb is show loosen connection or corroded wire.

      Likes(0)Dislikes(0)
  2. Albert van Bemmelen

    January 3, 2017 at 11:42 pm

    You accomplished a very tedious job by removing the pile of tar Mr.SK Wong! Not something that one should expect. I wonder though if you also had tried to remove the tar with Acetone? Terpentine and in particular Alcohol I found to be useless in similar cases. Like when we for instance want to remove old cooling paste on CPUs or GPUs before adding any new Paste.

    Likes(1)Dislikes(0)
    • skwong

      January 7, 2017 at 4:59 pm

      I agree with you, alcohol is useless in this case. I think turpentine can dissolve the tar but it is oil based which I do not like to use. Finally, I used thinner since I have it in stock, although it does not react or dissolve well with the tar.

      Likes(1)Dislikes(0)
  3. Parasuraman S

    January 3, 2017 at 11:57 pm

    Good work! You require a lot of patience to handle such jobs!

    Likes(0)Dislikes(0)
  4. Bulent NUR

    January 4, 2017 at 1:05 am

    Very good job thanks for sharing.

    Likes(0)Dislikes(0)
  5. Anthony

    January 4, 2017 at 2:45 am

    Wow, what a mess ! Great repair work Mr S K Wong as it was in such a bad state. Thanks for sharing.

    Likes(0)Dislikes(0)
  6. mahmoud_tajpour

    January 4, 2017 at 3:25 am

    Hello dear Wong I must say you are also brave to open this device for repair because it is so hard therefore well done.

    Likes(0)Dislikes(1)
  7. Robert Calk

    January 4, 2017 at 12:16 pm

    Nice work, Mr. Wong. Thanks for sharing the repair with us.

    Likes(0)Dislikes(0)
  8. Yogesh Panchal

    January 4, 2017 at 3:27 pm

    Mr.WONG,
    Thanks for sharing your experience.

    Likes(0)Dislikes(0)
  9. Humberto

    January 14, 2017 at 12:05 am

    Good repair and thanks for sharing it with us.

    Likes(0)Dislikes(0)

Leave a Reply

Your email address will not be published. Required fields are marked *