Samsung LN46A550 Power Cycling

[v.i-guy]

Re: Samsung LN46A550 Power Cycling

hello everyone I have the same problem as most guys do that have a 46 Samsung. I got this tv off of a guy for free he said it wouldn't turn on will when I got it home it turned on and worked for a couple of months but once in awhile the right side of the screen would go kinda black brown shady .if I moved the screen or tapped the tv it would go back to a good pic again. will I went to turn it on two days ago and the dreaded flashing red light and clicking. so I pulled the power supply and found that someone had replaced the capacitors but they were not soldered very will they were cold soldered so I resoldered them and put it back in and made a mistake I crossed the two plugins at the bottom of the board cn1808 cn1809. I still don't know I how I could have done that but the tv still came on for about 5 minutes and the picture was great but then it shut down again and back to the dreaded flashing and clicking. so did I fry something else by getting them backwards any help with would be great.

[martino]

Re: Samsung LN46A550 Power Cycling

switching those doesn't really matter. To me it sound like you either have a bad connection to the ccfl tubes or a bad tube as tapping the tv helped.

[v.i-guy]

Re: Samsung LN46A550 Power Cycling

thanx for your reply martino. I have looked up ccfl tubes and they say it could be a bad tube or a bad inverter. but would that cause it to power cycle.

[dreamliner77]

Re: Samsung LN46A550 Power Cycling

Thanks to everyone in this thread but especially budm and Terryfictv! I was able to fix my LN46A550 that had reached the point of not staying on at all through hours of power cycles. I soldered 100uf caps in parallel with C102 and C131 and all seems fine now; it powers on just like it used to many, many months ago.

budm, first of all thanks for the extremely well documented pictures. Also, it seems that you've done a number of these repairs, have any failed that you've done the parallel fix on?

[skywkr666]

Re: Samsung LN46A550 Power Cycling

I hate to bring up an old post, but I feel it's ultimately fitting rather than start a new one. This is my 3rd project Samsung; I replaced 102 and 131 with 16v 100uf caps and get a steady 5v at c131; Haven't flipped and reconnected cables to read 102 yet; but would believe to be working just fine. I still have the 8 second cycle click. Thinking about going and replacing cap by cap in the power supply just to be sure, even though I don't believe it to be a problem. Any suggestions whilst I go have a smoke?


img free

[budm]

Re: Samsung LN46A550 Power Cycling

How did you install the cap positive and the negative leg?
The original TANTALUM cap has white bar which is POSITIVE, it is opposite from lytic cap which the white stripe is negative. Look at your pictures it looks like you have the polarity backward.
Look at my pictures.

[skywkr666]

Re: Samsung LN46A550 Power Cycling

Stripes on my caps are negative; I would've sworn I followed that...I see what you mean, must've spun round in my hand; Thanks! To the iron!

[budm]

Re: Samsung LN46A550 Power Cycling

stripes on my caps are negative; i would've sworn i followed that...i see what you mean, must've spun round in my hand; thanks! To the iron!

ok.

[skywkr666]

Re: Samsung LN46A550 Power Cycling

I swapped it out for a fresh cap; didn't change anything. :/

[Johnny.ricer]

Re: Samsung LN46A550 Power Cycling

@skywkr666 Did you get your TV working? I have this exact TV and have replaced most of the caps on the power supply as well as the two tantalum pad capacitors (C102 and C131). I hear the clicking sound from the relay about every 25 seconds. Any other suggestions as to what to replace/test?

[neilc6]

Re: Samsung LN46A550 Power Cycling

Had a LN46A530 that wouldn't turn on. Relay clicking every 30 seconds. Replaced C102 on the main board and TV turned on. Symptoms when I replaced this capacitor before were green screen and squealing. IC101 is also suspect if replacing C102 doesn't fix it.

I then had an intermittent dark area in the middle right area of the screen which could have been an AS15F fault. Replaced it and it was the same and realized it was probably bad tab bonds. Opened up the panel to access the tab bonds and when I turned it on again, screen was all whitewashed. Tried replacing AS15F again a few times and no improvement so probably another panel fault.

Giving up and scrapping TV for parts.

[keysal]

Re: Samsung LN46A550 Power Cycling

Picked up a LN40A550 that had bad Power supply caps, replaced them been using the TV for probably over a year. Started to do the start up cycling. checked power supply and replaced any other caps that might be bad. Didnt help, still starts up displays channel and station identity then after a minute or so it restarts.

I think I have tried every suggestion in this thread.

Purchased new Tantalum caps Kemet brand low esr and the IC's MP2368DN replaced all four items. Still cycles.

Tested off board the original tantalum caps and they tested good.
Not sure how to test the MP2368DN.

Added 100uf electrolytic in parallel with the tantalum. (correct polarity double checked) Still cycles

added 47uf with much lower esr in parallel. Still cycles

took off the Tantalums added just electrolytic. Just blinking red led now wont turn on.

I'm stumped. Not sure what else to check or test or possibly replace.
Any suggestions?

[dreamliner77]

Re: Samsung LN46A550 Power Cycling

Has anyone had the parallel fix fail on them? I replaced caps and did the parallel fix 12/2016 and my LN46A550 is starting to show power issues again (power on/relay/power cycle, finally on or occasional green screen). I'm debating if it's even worth opening up again at this point?

[nomoresonys]

Re: Samsung LN46A550 Power Cycling

Been seeing a lot of articles about samsung using caps without enough volts for the job required, wonder if that could apply to a lot of these sets?

[JunkmanJimbo]

Re: Samsung LN46A550 Power Cycling

Hey budm, does the capacitor have to be a 100uf or can it be a lower or higher value?

[tvtimmy]

Re: Samsung LN46A550 Power Cycling

Use a 47uf 10v as the designers of the board used. They are cheap as hell on ebay. Order 20 or so like I did and always have spares for repairs.

[JunkmanJimbo]

Re: Samsung LN46A550 Power Cycling

Thank you tvtimmy, I will give it a try.

[tvtimmy]

Re: Samsung LN46A550 Power Cycling

Make sure you get the correct size to fit the pads.

[JunkmanJimbo]

Re: Samsung LN46A550 Power Cycling

tvtimmy, Do you by chance have a link to the capacitors i need to get? Thanks in advance.

[xtrmedia]

Re: Samsung LN46A550 Power Cycling

This work great for my TV set