Failed SMPS Revived With Module And Amp Added In PANASONIC DVD Player Model DVD-S2
This DVD player was first brought to me in July 2015 when it was totally dead. That time, after several futile attempts to revive the SMPS section, I removed all the components from the primary switching section and the feedback section of secondary and connected a module to set it right.
I had also added an audio amplifier board of PAM8403, which works on 5V supply and drawing negligible current and gives a 3W output. Please see specifications here: https://pdf1.alldatasheet.com/datasheet-pdf/view/246505/PAM/PAM8403.html
I had provided a volume control and an optional switch for on/off as you can see from the following pictures:
This DVD player revisited in September, 2022, i.e., after seven years of service! I had replaced all the electrolytic capacitors during its first visit and also did thorough retouch of solder on the board. This is a peculiar DVD player with a very large power supply board with the front panel and display fixed on it and mother board (servo board) inserted from the top! I used to wonder why the manufacturers resorted to such very complicated designs on DVD players! Perhaps that time the CD/DVD players were in prime demand!
This visit was once again with the complaint of totally dead. Since technology had advanced and now we have five or four wire modules which take feedback and correct the voltage to the desired level automatically, I made another attempt to connect a five wire STR module instead of the three wire module (on which we connect only the red and black wire and ignore green wire. As I have covered quite lot about this module in several of my previous articles, especially that of CRT repair, I am not repeating it here!), for which I restored the feedback circuit and run DC circuit as these are required for its connection. But the power supply did not work and it was a clear indication of the failure of second winding on the primary section of SMPS transformer. As a replacement transformer was not available, I had to look into the reasons for the failure of the module that I had fit in it. First of all I removed the components that I had restored and tried with a new module from my stock and got the outputs of 12V and 5V. So far so good! Then I took the defective module and did a thorough retouch of the module and replaced all the electrolytic caps on it. The output was missing even then. So, I started checking the fixed caps and found 0.1uF 250V AC yellow capacitor reading weird!
The power supply worked very well after replacing this cap. So, fixed the module back in its place where I had done it last time! Now let us have a look on some of the pictures to understand all my statements better. I have provided notes for easy understanding (Please use control and upward arrow to zoom pictures):
I replaced the flexible connector of eye unit, as it had got strained. After assembling everything back, I played a few CDs in full (playing CDs in full is very essential so that the eye unit will travel until the last and return back.
If we do not do it, it any defect in the sliding motor or its circuit will go unnoticed and the set would come back soon!). I fixed the top cover as I did not find any further issues.
Mission accomplished and satisfaction got gathered happily as usual!
This article was prepared for you by Parasuraman Subramanian from India. He is 72 years old and has more than 30 years’ experience in handling antique equipment like Valve Radio, Amps, Reel Tape Recorders and currently studying latest tech-classes conducted by Kerala State Electronics Technicians’ Association. He has done graduation in BBA degree, private diploma in Radio Engineering and retired as MD of a USA company. Presently working as Consultant to Hospital and other institutions.
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