A battery charger was brought to life. Mosta: MT1008
A carpenter and a friend of mine brought this battery charger to my shop. The complaint was it does not charge. It was not completely dead but it was not charging.
When I measured the positive and the negative terminal of the charger it was giving me 31 volts. There was no power led on. As suggested in the picture that you see. The moment it was plugged in power, it was suppose to give a green blinking light. If the battery was inserted in the charging port, it suppose to give a steady red light but it was not doing any of that although the 31 volts reading was at the negative and the positive charger terminals.
Few screws off and I was able to see what inside the charger.
Everything checked ok in this charger except one main suspect. It was a component that I could not recognize at all. It looked like a diode but it has a line in the middle. According to the writing printed on the board, it says R14. I checked with Mr. Jestine yong and he suggested that it was a diac and he informed me how to test it with an analog multi meter.
He told me to set the meter to x10 K Ohm and it should have no reading on either side. The moment I tested it with the analog meter, I got a slight reading on both side indicating a faulty diac. I bought a brand new one from the shop and the moment I tested it with the meter, it gave me no reading whatsoever indicating that the one I have is a faulty one.
The moment I replaced the diac and I powered it up, the light power indicator started to flash on and off. According to the instructions on the front of the battery charger, that is a working battery charger. I plugged a battery in and the light changed to steady red, which is an indicator of a charging mode.
I never tested a diac before but thanks to Mr. Jestine and his experience I was able to do that today. Today I gained more experience in electronic repair and I am sharing this knowledge with you today. 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. 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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Zed
October 19, 2013 at 10:58 am
Thanks waleed for sharing another new experience in repairing. we learned new as we encounter new components design.
Waleed Rishmawi
October 19, 2013 at 4:20 pm
you are welcome Zed.
moshe
October 19, 2013 at 10:58 am
waleed, thanks for taking the time to share this (and your other posts).
Waleed Rishmawi
October 19, 2013 at 4:21 pm
thanks Moshe.
Tayo
October 19, 2013 at 11:08 am
Well done!
For those (like me) who had no idea what a DIAC was here's an excerpt from Wikipedia:
The DIAC, or "diode for alternating current", is a diode that conducts current only after its breakover voltage, VBO, has been reached momentarily.
When this occurs, the diode enters the region of negative dynamic resistance, leading to a decrease in the voltage drop across the diode and, usually, a sharp increase in current through the diode. The diode remains "in conduction" until the current through it drops below a value characteristic for the device, called the holding current, IH. Below this value, the diode switches back to its high-resistance (non-conducting) state. This behavior is bidirectional, meaning typically the same for both directions of current.
Most DIACs have a three-layer structure with breakover voltage around 30 V. Their behavior is somewhat similar to that of a neon lamp, but it is much more precisely controlled and takes place at a lower voltage.
DIACs have no gate electrode, unlike some other thyristors that they are commonly used to trigger, such as TRIACs. Some TRIACs, like Quadrac, contain a built-in DIAC in series with the TRIAC's "gate" terminal for this purpose.
DIACs are also called symmetrical trigger diodes due to the symmetry of their characteristic curve. Because DIACs are bidirectional devices, their terminals are not labeled as anode and cathode but as A1 and A2 or MT1 ("Main Terminal") and MT2.
Omowright
October 19, 2013 at 1:57 pm
This is very educative. I will now use this information to modify the schematic of an automatic voltage switch that I was designing. I can see that the triggering of my output triacs can be delayed whilst capacitors holding the information of the peak value of "this" cycle are discharged (or refreshed) for information of the next cycle.
Thank you very much for sharing. I am glad to be a part of such a community ...
Waleed Rishmawi
October 19, 2013 at 4:24 pm
you are welcome Omowright. I am glad you are part of this community to. thanks
Waleed Rishmawi
October 19, 2013 at 4:22 pm
Tayo: thanks for sharing information about the diac.
sreenivasak
October 20, 2013 at 7:28 am
thanks for information
Henry Mayanja
October 22, 2013 at 1:54 pm
Mr Tayo,thank you very much for that very educative information, i have realy learnt a lot.
Zed
October 19, 2013 at 11:27 am
I AM CURIOUS ONLY DOES DIAC HAS PARTNUMBER OR IT IS WHEN YOU BUY IT IS GENERAL EVEN WHAT PARTNUMBER YOU BUY. OR YOU ONLY SHOW THE COMPONENTS. THANKS
Robert Calk
October 19, 2013 at 12:04 pm
Thanks for the article, Waleed. I've read many books and never heard of a diac. I wonder if my Peak Atlas DCA75 Pro would recognize it??
Waleed Rishmawi
October 19, 2013 at 4:25 pm
Robert: I am mot sure because I do not have a Peak Atlas to try it out. the best way to check it is with an anolog multi meter.
Robert
October 20, 2013 at 11:36 am
The Peak Atlas analyzers really come in handy on newer components. I fixed a new A/C window unit that was less than a year old. The plug had a breaker switch in it and water got in it and rusted it up while it was in storage during the winter. Inside were two transistor looking components that I figured were Silicon Controlled Rectifiers(SCR's) but I didn't know for sure because the component part numbers weren't in the books yet. I searched several websites. I bought the Peak Atlas DCA 75 Pro and it told me they were SCR's but it could not check it further because the Gate current was over 10mA. I bought the Peak Atlas SCR 100 Thyristor & Triac tester and it gave more info so I new they were good.
I wish I could've wrote an article on it but I wasn't ready at that time. Anyway, I cleaned the rust out, replaced 2 diodes and fixed the LED that had a broken lead and it's been cooling great all summer.
Eliseo espanto
October 19, 2013 at 12:27 pm
Thank you very much. Ive already done it with power tools charger( ryobi) whit the same case . I replace the diac the charger back to life.
Waleed Rishmawi
October 19, 2013 at 4:26 pm
Eliseo:good job on your repair. I am glad. thanks for sharing
Thanh H. Le
October 19, 2013 at 12:48 pm
Thank you very much for sharing, Waleed! This is new experience to me.
thulani
October 19, 2013 at 12:58 pm
Thanks this was a mission accomplish so how do you tell that this a diac?
Waleed Rishmawi
October 19, 2013 at 4:28 pm
well, I have seen the article that Mr. Jestine put on his web site. I have seen diacs in blenders, emergency lights and battery chargers.
nahum baylon
October 19, 2013 at 1:14 pm
thanks a lot for your untiring efforton sharing many electronic repair techniques presently i have not started doing troubleshooting job on electronic appliancessince i am just in the stage of learning the electronic components testing and having to understand its use and application.sooner or later i can apply this field since this is very interestingand and as far as i know these can help me a lot in my earnings in the future once i am in these field of endeavor again thank you very much for this wonderful learning experience
Waleed Rishmawi
October 19, 2013 at 4:30 pm
Nahum: that is the best way to start. knowing how test electronic parts because if you do not know how to do it then you are wasting your time. keep up the good work. thanks for the ecouragement.
beh
October 19, 2013 at 1:22 pm
hi waleed
thanks for good job
beh
Waleed Rishmawi
October 19, 2013 at 4:30 pm
you are welcome Beh
beh
October 19, 2013 at 1:23 pm
hi tayo
thanks for your explanations.
beh
peter sumo
October 19, 2013 at 2:36 pm
Thanks for this repair article.I have been having broblem with the name and testing of this component called diac.
your articles help me to have a better understanding of the component.
May God give you long life to keep helping electronics repair workers around the world.
Thanks.
Waleed Rishmawi
October 19, 2013 at 4:32 pm
thanks Peter. I had problem testing it to but thanks to Mr jestine, he was able to help me out with this. so My gain is yours as well. keep up the good work
Olusegun
October 19, 2013 at 2:46 pm
Wonderful thanks mr Waleed & Jestine for enlight us.
Waleed Rishmawi
October 19, 2013 at 4:32 pm
you are welcome Olusegun. glad you liked it
mustabz
October 19, 2013 at 3:18 pm
Thanks for that vital info. Its good to know what I will do when my power drill charger breaks down.
However i have a small querry abt some noise crtv make.
After you get it working. Picture fine then each time a bright white image is displayed, there is a motor boating sound in the speakers.
This sound only appears when a white image is displayed on the screen and not any other colours.
What causes it?
Thanks
Waleed Rishmawi
October 19, 2013 at 4:35 pm
sorry I can not help you since I have not ecountered this kind of problem before. if others can help. please feel free to jumb in.
Gavin
October 21, 2013 at 6:21 pm
The motorboating that you hear is normally only found in old CRT TV's and has to do with the extra power required from the power supply to display the picture and giving an unstable power supply to the Audio Amplifier. Usually caused by electrolitic capacitors starting to fail.
Alex Obara
October 19, 2013 at 4:19 pm
guys what you're doing is wonderful!
Waleed Rishmawi
October 20, 2013 at 3:58 am
thanks Alex. I am glad you are enjoying the article
Muftah
October 19, 2013 at 4:27 pm
thanks for this informative article , bcz most of the electronics repairing information focusing on home appliances , it is needed industrial electronics systems repair information in general.
thanks , best regards
Waleed Rishmawi
October 20, 2013 at 3:59 am
you are welcome Muftah.
raymundo saura
October 19, 2013 at 4:42 pm
wow great i learn a lot thanks and GOD bless
Waleed Rishmawi
October 20, 2013 at 4:00 am
hey Raymundo: I am glad, you are welcome. God bless you too
Piotr
October 19, 2013 at 4:52 pm
well to know thank you very much
Waleed Rishmawi
October 20, 2013 at 4:00 am
Piotr: you are most welcome
Amir Mukhtar
October 19, 2013 at 5:01 pm
Dear Sir,
thanks you for your Nice sharing and Knowledgeable information .
thanks you
God Bless you
Amir Mukhtar
Waleed Rishmawi
October 20, 2013 at 4:01 am
Amir. long time no hear from you. you are welcome. God bless you too
Patrick Mlengwe
October 19, 2013 at 7:16 pm
Thanks Mr J. Yong and Mr W. Rishmawi for sharing the experience. You can learn about a thing at school or from a friend but a practical experience is important.
P. Mlengwe
Waleed Rishmawi
October 20, 2013 at 4:03 am
Patrick. very true. knowledge is good and exeperience is good too. you are welcome
Tinapa Faletiute
October 19, 2013 at 8:41 pm
Thanks waleed,
I learn something new about a component called diac and how to test it. Thanks again Justine for the great website and help.
All the best
Waleed Rishmawi
October 20, 2013 at 4:04 am
Tinapa: I am glad you have learned something new. youa are welcome. God bless you
Morgen
October 19, 2013 at 9:59 pm
Thanks Mr Yong for this and many more articles i have received from you .I now know how to test a diac.
Jestine Yong
October 19, 2013 at 10:04 pm
You are welcome and special thanks to Waleed for his contribution of the article.
Waleed Rishmawi
October 20, 2013 at 4:05 am
thank you Jestine for having such a web site that we can share electronic experince and helping others. I have learned so many things from you. God bless you. keep up the good work
Jestine Yong
October 20, 2013 at 8:49 am
HI Waleed,
You are welcome!
Jestine
Richard
October 19, 2013 at 10:39 pm
Thanks very much for that nice tip.
Waleed Rishmawi
October 20, 2013 at 8:37 pm
Richard, you are welcome.
Noel Gervais Gerard Louis
October 20, 2013 at 12:56 am
Thanks Mr Waleed and Mr Jestine Yong for sharing this article on how to test a diac its very interesting to know about this thanks again
Waleed Rishmawi
October 20, 2013 at 8:38 pm
Noel. you are welcome. glad you have enjoyed the article.
reza
October 20, 2013 at 2:17 am
hi jestinge thanks for your good info
Mohamed Ashraf
October 20, 2013 at 4:29 pm
Thanks Mr. Waleed for sharing your experience with us and of course thanks to Mr. Jestine Yong for his support and cooperation to all of us.
Spear
October 20, 2013 at 6:18 pm
Thank your for everything your are the doctor of technology.
Waleed Rishmawi
October 21, 2013 at 2:54 am
spear: I would not go that far and call my self doctor of technology but thanks for the nice comment.
beh
October 20, 2013 at 9:48 pm
hi mustabz
for this problem go and check your big cap in power supply
also you may replace this cap (this is better)
and see what will happen
thanks
beh
Troy Woody
October 20, 2013 at 10:54 pm
Thanks for all the sharing. I am a devry online student, and all the sharing and trouble shooting that goes on here is so helpful. I intend to get into the repairing of music equipment, as I have a sound company now. The ''Testing Electronic Component'' is like the bible to me. All the questions people ask and share a lot of times are things I was think of and so helpful. THANK YOU THANK YOU THANK YOU.
Ps if anyone is doing repairs on pro audio power amps please share :). I have about 10 im working on.
Mohammed kasim
October 21, 2013 at 7:20 am
Thanks for the nice article. Does it has a part number and specification. It is in secondary side.is,nt it
Remy Francis
October 21, 2013 at 8:32 am
Thank you Waleed for sharing another good repair tip with us.
Winston Campbell
October 21, 2013 at 11:22 am
Good day! Thanks to Mr Yong and Mr Waleed for sharing your electronics experience with us, thousand of electronics repair technicians around the world, especially with this new information on the Diac, how it works and how to test it. I came across it before, but I did not know how to test it.
I am a train Radio, Television and Electronics coming from one of the old school, "National Technical School, Los Angeles, California USA".
I am also a College Graduate in Telecommunication Engineering Technician, and I am always studding, many different areas of electronics.
If you have a complete on line training course on LCD, PLASMA Television and Monitors.
If there is such a course, would you please send me all the necessary information and can it be paid for through the services offered by WESTERN UNION.
I would like to order some of your electronic books, but after getting back a reply from you, I will know if the WESTERN UNION payment can work.
Thanks for the good work been offered by you and your team.
Goodbye and have a nice day!
Jestine Yong
October 21, 2013 at 11:29 am
Hi Winston,
You are welcome. Sorry I do not have those online training course except the LCD Monitor. You may go to this link:\
http://www.noahtechelectronicstraining.com/lcd-monitor-repair-online-exam
and I do accept Western Union. For other ebooks you can visit this website:
https://www.jestineyong.com/resources-2/
Jestine
Phumlani
October 21, 2013 at 3:24 pm
Thanks a lot Walled,the article was very useful to me with a lot of information.
Farooq Bakali
October 21, 2013 at 5:38 pm
Dear Waleed Rishmawi Jazaakumullaho Khairun for the article,I would like to know,if any body has some information regarding Hybride Cars and how it works.it would would be very much appreciated.MY email is bakalife@hotmail.com
Waleed Rishmawi
October 21, 2013 at 10:29 pm
ahlan wasahlan Farooq. sorry I do not have any information about Hybride cars. sorry.
Humberto
October 21, 2013 at 7:45 pm
Good article. Keep on doing it.
Mark Tembo
October 21, 2013 at 8:42 pm
Thanks for the article. I have taken note and added it to my notes on 'Testing Electronic components'
Waleed Rishmawi
October 21, 2013 at 10:30 pm
Humberto: thanks I appreciate the support.
bong
October 22, 2013 at 11:35 am
thanks for the information that you have shared it enhance my knowledge about this particular component part.
Waleed Rishmawi
October 22, 2013 at 9:44 pm
hi Bong: you are welcome. I am glad it helped you
Nimal
October 22, 2013 at 1:22 pm
Thank you for the repair tip. It will be very helpful in the future.
Waleed Rishmawi
October 22, 2013 at 9:43 pm
Nimal: you are welcome. I am glad it was helpful to you
Nicholas Mifsud
October 22, 2013 at 3:22 pm
Very good tip thanks for all
Waleed Rishmawi
October 22, 2013 at 9:17 pm
Nicholas: you are welcome.
Jayaprakash
October 22, 2013 at 7:04 pm
thank u sir. it's very nice article
Waleed Rishmawi
October 22, 2013 at 9:16 pm
Jayaprakash: thanks and you are welcome
Clair Morrill
October 23, 2013 at 2:16 am
A diac is a bi-directional trigger device, it is used in lamp dimmers
and as an oscillator/driver in compact fluoresent lights. About 8 years ago I designed a (Holliday) circuit around a few of them where I used a diac as an oscillator/driver, simmular to a neon relaxation oscillator.
Waleed Rishmawi
October 23, 2013 at 5:09 pm
thanks for sharing Clair.
Andre Gopee
October 23, 2013 at 3:33 am
Hi Waleed, actually I came across that same Diac about a year ago and I was also confuse to what kind of component is that. I started to repair the equipment and not knowing what the component was I decided to put the equipment aside, after a long while I got the idea to contact the manufacture of the equipment and got the name and part Number of the Diac and bought it at the local store and installed it and the equipment came back to life.
Anyway Good article and keep up the good work.
Waleed Rishmawi
October 23, 2013 at 5:08 pm
Andre. congrats on your repair success. thank for sharing.
reychie canonigo
October 23, 2013 at 10:50 pm
im so thankful about you shared. We love you Mr. Wallen ang Sir Yong guiding us especially for me newly in electronic industry. Once again a mellion thanks. God bless you and Sir Yong
Waleed Rishmawi
October 24, 2013 at 3:28 pm
Reychie, thanks and you are most welcome. I am really gald you are benefiting from all these articles. God bless you too
Ulises Aguilar Pazzani
November 25, 2015 at 12:08 pm
thks for sharing this knowledge , I will keep in mind
S.Ramesh
January 2, 2017 at 11:13 pm
Thk for the info actually i gone gone true google, to plan bought new charger finally ur info gave me to repair thks a lot.
Syamsul
June 30, 2017 at 1:50 pm
Please tell me value R47 in this circuit....thanks