China crt TV faced multiple complaint & solved

Hi dear repair friends
After a long time i am Writing this article by bringing you one more interesting topic in Electronic Repair articles, Hope you will enjoy this.
With an advantage of UNIVERSAL China pcbs (AKHIRA PCB)TV repair is become very easy nowadays. From long back people use to repair existing tv without internet knowledge.
Repair manuals are the main sources which they are mainly depended to resolve the issue.
When i was beginning even i have followed above methods.
Universal Tv kits like Fonda tv kit /AKHIRA TV Kits revolutionized the TV Repair easy and to run good business and save TECHNICANS valuable time.
I Don’t want you to bore you by bringing old stories in this article. Let us directly go for repair story for china TV.
One of my customer brought the TV for repair saying that TV is not on. Once when i opened the chassis it is completely power supply dead. Since its power supply issue we are happy to attained such cases confidently. Found NTC, FUSE, Mains rectifier diodes & power supply chopper transistor completely burned. Replaced the same and power up with series bulb, Happy to see their respective Voltages in SMPS Output area.

Burned chopper transistor

Conformed the SMPS Working with the Dummy load 60watts Bulb on 110v DC Path & Worked fine.
Now Powered up the TV as usual to see the overall performance. Happy to see the blue back screen & came to conclusion its completely ready & Ready to deliver the costumer.
As a final check-up when i connected AV cable to see the clarity of the video on screen i was quite un happy because there are some noisy lines at the top end of the screen. Its Completely Noisy, The same when i communicated with the costumer about multiple complaint and he has given green signal for further Investigation.

As a professional i am not happy to deliver it because it is not 100% correct. Really it’s a challenging task for me.
These kind of H noisy lines leads to multiple reason. Could be EEPROM Corrupt/Settings, Vertical IC Defective or their Voltages Abnormal. Could be filter caps.
Before proceeding Checked all the Vertical Filter caps ESR and their dry joints no result, Changed the vertical IC LA78040 no result, Finally EEPROME setting done in Vertical adjustment and related codes no Result.
Now i don’t have any way to catch the culprit When everything ok then what could be the reason to cause the Noisy H-Lines??? .But in my mind i am sensing something got bad in Vertical section. I googled the internet and Checked the LA78040 IC Data sheet and started to change the Filter caps even though their ESR Value is good.

Started from VCC Filter caps100mfd/35 changed with new. To my surprise the TV Runned with a fine clear picture without any noisy H-line.

Ultimately i successed in catching the route cause for the noisy H-line. Delivered the costumer who felt very happy.

 This is how i solved the China TV Multiple complaint. Take care let us meet in the next session with warm regards.





Regards
BASAVARAJ :BM