Electronic Repair Questions/Answers And Testimonials Part 2
First Allow me to congratulate you on this excellent site with the wishes you continued success and progress. I repaired some Monitors and televisions. Now I have a problem in two Monitors the problem is ashort in the power supply I looked at the power supply primary side and found mosft k2645 ,ic u3842 , some zener shorted I exchanged all bad components with new one , and checked it agine to sure they all good but when I connect the power I found the short again.
It could be a shorted primary winding in the power transformer or other semiconductor at the secondary side. You have to use a coil tester to test the transformer primary winding.
I have encountered a problem regarding a fuse on my monitor. My monitor is a 15″ CRT Samsung 591S. I replaced my 3.15A 250VAC defective fuse with same rating glass fuse. And, after 2 days, it blows again. When I inspected the fuse, there are no black or brown color on the glass fuse. Well, I guess there are no problems with my internal circuits on my monitor. The original fuse has a powder inside and cased with something like a porcelain. Now, the question is, is there a problem with the fuse that I replaced?
You have to use a slow blow fuse and if the fuse keep blowing again then direct replace the posistor.
I have Dell LCD monitor with a fault that when it when it went sleeping mode, and then after i move the mouse or press the any on the key board it does not come active mode. To come active mode then i must have to reset the power. The monitor model is dell D1025HE. So can u give me the information to identify and locate this fault on the circuit wise. Thank You
I need more information from you such as how long does the lcd operate before go down to sleeping mode? Sometimes a bad inverter or mainboard could cause the display to appear for a while before shutting down. A bad backlight also could cause such problem.
greetings my friend, hope all is well with you.
I am working on the studio lights. it is kind of light that reacts to camera flash. It is working except the test button is not working and when I flash a camera flash light, the light does not light back. but as a steady light, it is working fine. I found this silicon NPN Phototransistor and I am not sure how to check it out with the meter. any ideas? because of the name I think it should be tested as a normal transistor but I am not sure.
Yes you can test it like normal transistor. The transistor in the optoisolator also a phototransistor.
Dear Yong,You are a great man of intellegence. I enjoy every bit of
i have also read one of
Thanks for your very kind words! Here are your questions and answers:
“Well,may I ask, how do one know the polarity of the suj30 modulation diode(i mean where to position the catiode or anode side the pcb as the case of other diode with color band on them)?”The cathode side always have a marked with a white line and the anode have to be connected to ground for a modulation diode.
“i have also read one of
If a technician is new in the monitor repair, he or she may have difficulty in identifying parts in the monitor circuit. My suggestion to you is to download free monitor schematic and compare it with the actual board (if possible get the same model). From there you will slowly get the ideas how all this components are joint together that we call as a circuit. There are many different types of crt monitor in the market thus you would encountered many different type of circuits. Some use one HOT to control the flyback while some have two HOT (one to control the flyback while the other one to control the horizontal deflection). Besides looking at the size of the transistor, one also have to look at the part numbers. Pat number will reveal everything about the components. Hope this helps!
Sir can you help me about narrow display in crt monitor. Thanks.
Narrow picture usually due to the defective B+ circuit (not enough voltage to flyback) or the horizontal size/pincushion circuit problem. Make sure the B+ voltage is within spec and try trace from the pincushion transistor like d669a, b649a, d2012, c2800 and etc. Get some free monitor schematic and study the circuit as this will surely help a alot. Sometimes a defective picture tube (shorted horizontal yoke coil) and the safety capacitor value out will also cause narrow picture.
Hai jestine…baru-baru ni saya ada membaiki sebuah tv jenama sony 21 inci yang
mempunyai color.Paparan gambar semua ok cuma color dia bertukar ke color red macam pink pun ada colornya.Saya dah check kat bahagian crt board dan semua komponen dalam keadaan baik dan tiada dry joint.Pada mulanya saya suspect ic color ada problem tapi setelah saya menukar ic color yang baru masalahnya tetap sama,red color tu tidak hilang juga.Jadi disini saya minta jasa baik Mr.Jestine agar dapat memberikan sedikit tips kepada saya bagaimana nak membaiki tv sony dengan masalah red color ni.
Color problem yang anda jelaskan kemungkinan masalahnya berada di bahagian sekitar color ic itu. Sekiranya ada scope, ia memang mudah untuk troubleshoot color problem kerana anda boleh bandingkan dengan color yang lain. Sekiranya anda tiada scope, pilihan kamu hanya teletak pada voltage testing. Bandingkan voltan di bahagian output IC dengan output biru dan hijau. Sekiranya okay kamu hendaklah concentrate di bahagian crt board. Sekiranya ada perbezaan, check lah bahagian input ic dan juga komponen sekitar color ic itu. Picture tube yang rosak juga boleh menyebabkan warna merah hilang juga.
i would like to ask if what was the reason why my adapter always get destroyed when i connect it to my computer where the power input of my computer is 20V 5A…the Adapter has 20V 5-6Amperes but it always get destroyed.. i tried an adapter with the output voltage of 19V 3.42 -4A and it turns on my pc without destroying anytime. Can you tell me what was the reason?
Thanks for your interest in my book. As in your case, by right it should work beautifully with the high amp and the only reason i could think of is the quality of the adapter. Not all computer requires that much of ampere and the exact voltage to run. A 19 Volt with max of 4 amp may run but i’m afraid in the long run could cause the internal transformer to get hot and eventually burnt the adapter again. Hope the amp consumption of your computer is less than 4 amp!
allow me to thank you alot for your work
I ve LEARNED ALOT OF YOU
YOUR BLOG AND SITE WAS A GREAT HELP THANK YOU SIR
AND I HOPE YOU BE IN GOOD HEALTH AND HAPPINESS
AND YOU ACHIEAVE ALL YOU WANT
SHOKRAN( THANK YOU)
hi, mr jestine, how are you. have you repaired monitor with philips tea 1504 command circuit. is there a method how to troubleshoot this kind of circuit, as i know smps that uses this kind of circuit works in many modes: burst mode, off mode and normal mode. i tell you that because i am face an ibm monitor ( chassis d99 ). i have changed tea 1504 with a new good one and tested all components. there is no voltage at the output. good day.
Sometimesthe ic itself could have problem. try replace with another ic. Make sure you must check the secondary side for any shorted components. A shorted component could cause no output voltage. For your information TEA1504 and TEA 1504AP is not the same.
I download you E-book.thank you very much.
Thanks for your support.
I want to buy some testers.I have
but i want something better.
Are this testers good?
Atlas DCA-Semiconductor Analyser,
Atlas LCR -Passive Component Analyser
Atlas ESR-Capacitor Analyser
Atlas SCR-Thyristor and Triac Analyser
I have only the atlas component analyzer and found it to be good especially to test out components that do not have part number or identification. Once i clip the test probes on it, the tester will tell me if the component is fet, scr, transistor and etc. As for the other tester i guess i have to post the questions to my blog and see if there is anyone have experience using it before and hope they would give comment.
Also i want to know what is the differents of this two Analyzer tester if
CAPANALYZER 88A – £139.00 UK pounds
UNBRANDED- UNIVERSAL ANALYSER – £179.38 UK pounds
IS BOTH FOR CAPACITOR ANALYSER.
IF YOU KNOW PLEASE TELL ME.
I know about the capanalyzer 88a because i own one but have no idea of the unbranded universal analyzer is. Do you have a website where i can visit the unbranded universal analyzer? As for the capanalyzer i passed it to my technician to use and he loved it very much but one disadvantage is that it can’t test low ohms resistor and some non polar capacitor. The blue esr meter by bob parker could test the low ohm resistor, non polar cap from 0.1 uf and above and the esr value of e-caps too. If you need the blue esr meter, you may order from my website at http://www.electronicrepairguide.com/blue-esr-meter.html
If you have other questions please do email me again. Thanks and have a great day!