Burst PWM IC And Caps Found In Panasonic DVD Player
This DVD Player was brought to me with the complaint that it was not used for a few months and it was found dead when switched on. As usual, I opened the set and was taken aback to see a lump of dusty fibre particles that looked like a mini ball, stuck to its mother board and tiny such balls elsewhere. I also saw the PWM IC was cracked and one of the main Filter capacitors bulged.
There were a lot of dry solders too. The fuse was also blown, obviously. The broken portion of the IC, unfortunately got lost in my blower use, before detecting it; a mistake that one should not do! A thorough Visual examination should have been done! Sometimes we fail to practice what we preach!
After a thorough cleaning of inside, I posted the model number of the DVD player in technicians’ whatsapp group, requesting for the IC number. In came the reply within minutes by a photo of this SMPS showing the number of the IC, which was TNY177PN. I procured a replacement from the spares shop. After replacing all the electrolytic capacitors (I had two 15uF/500V caps in stock) on the power supply board and this IC and cleaning the board thoroughly using IPA, I allowed time for the IPA to get fully evaporated and applied power.
I got the 5V and 12V correctly. So I applied lubricating oil in the connector and fit it to the main board. When I switched on, it worked perfectly well. Though usually, I do dismantle the mother board, loading tray and all connectors, do a thorough lubrication of all connectors, tray moving tracks etc. I did not do that in order not to disturb the original connections. When I tried the DVD playing CD and USB, it worked very well for several hours. So, there was no need for me to do anything further on the player.
Work finished sooner than expected and satisfaction got collected to its capacity enlarged bag!
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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You may check on his previous repair article below:
https://jestineyong.com/power-supply-backlight-and-scaler-board-ic-failure-solved-in-vu-led-tv/
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Henrique J. G. Ulbrich
April 6, 2021 at 7:00 pm
Thanks for sharing. I wonder about the size of your bad el-caps bag. Do you have enough space in your shop for this?
Parasuraman S
April 6, 2021 at 11:51 pm
As a routine practice, I always give all the defective parts to the customer. Though they decline to receive, I insist saying that it is a part of my principle that I follow in carrying out repairs. It increases our credibility as well as avoids collection of junk at our end. As you might already know, I am not running a shop. I am using one of my bedroom converted as Service Room. Hence it is all the more important to follow this practice! Many thanks for your comments!
Godson
April 7, 2021 at 5:55 pm
Good job sir.Thank you for sharing your wealth of knowledge for us all to learn.in your write up you mentioned about Whatsup group can I join the group or do you anyone I can join in order to improve my repair skills
Albert van Bemmelen
April 6, 2021 at 7:54 pm
Those TNY chips always mean trouble and we today frequently find these in all kind of devices to lower power consumption in standby power off mode. I say trouble because I know these from many washingmachines and dryers I had fixed in the past that use these in the primary AC input, but always are the cause of many dead machines. And often also mean a burned through series resistor too that also needs to be replaced because of it! Probably always because the TNY chip collapses in shorting the internal output mosfet!
Parasuraman S
April 6, 2021 at 11:53 pm
Yes, your observation and expert comment is absolutely true! These devices fail quite often. Many thanks for your comments!
William Shaw
April 8, 2021 at 3:39 am
Albert, you refer to a TNY chip whereas Parasuraman refers to a PWM chip. Am I missing something here?
Albert van Bemmelen
April 9, 2021 at 11:25 pm
You are right here that the part is not a real PWM chip William!
If you look at its datasheet you'll notice that it is in fact an Energy Efficient, Offline Switcher with Enhanced Flexibility and Extended Power Range. Only because it is used in the PWM controlled power circuit Parasuraman probably used the PWM reference in the title. See the TNY177PN datasheet here.
Yogesh Panchal
April 7, 2021 at 2:51 pm
Good Repair Sir,
Waleed Rishmawi
April 8, 2021 at 2:47 pm
that is a lot of parts to be replaced, I hope it was worth your time and profit but it was a successful repair though. have a blessed day
Parasuraman S
April 11, 2021 at 1:42 pm
Yes, dear! It was worth as customer was ready to bear the cost! Many thanks for your comments!