Samsung HP-R5072 Plasma problems

[phrost]

Got a tv donated to fix, was taking awhile to give a picture previously before it quit working all together. TV does not turn on, relay clicks a few times in back and front power light blinks a couple times.

Cracked it open and found 1 bulging 10v 2200uf cap which i have since replaced. TV is still showing the same problem except since replacing the capacitor the display flicks on for about a half a second every 10 seconds maybe. I can hear something in the back of the tv charging and discharging in relationship with the tv flashing.

Any suggestions? I can get some pictures up if needed, thanks in advance.

[phrost]

Re: Samsung HP-R5072 Plasma problems

Vs voltage drops off everytime the screen goes off, when the screen is off the charge on Vs builds from nothing and comes back at 197~v before building up to 199.8v then the screen comes on again for a split second before dropping the voltage again. It seems something is not able to hold the 200v load needed to run the PDP. any ideas what it could be? I hear some noise that sounds like the transformer getting juice just as the screen comes on aswell. Any suggestions or leads are greatly appreciated.

Power supply PCB: bn96-01801b

"Sub" Power Supply PCB: bn96-01805a

[phrost]

Re: Samsung HP-R5072 Plasma problems

We'll i replaced all of the 10v 2200uf caps, now the tv comes on i get picture. I was forced to turn the brightness all the way down as thats the only way i was able to get the picture to stay on most of the time. Any ideas what might cause the screen to black out during bright scenes or when i turn up the brightness? Thanks in advance

[tom66]

Re: Samsung HP-R5072 Plasma problems

My guess would be a Yrr/Yfr problem. These are the adjusments on the Y-main. Or, it could be a Vset voltage issue, or a bad capacitor on the Vs or Y-main.

[phrost]

Re: Samsung HP-R5072 Plasma problems

Would you mind telling me which is which and how to test their voltages? Here is a picture of the board i'm working with. Any help is greatly appreciated, thanks for the epic fast response too



You can tell me the one on the left and right, as the picture is sideways. I already know where the pots are located just need to know which is which and what they should read and how to read their current value.

[tom66]

Re: Samsung HP-R5072 Plasma problems

Can you get a video of the flickering first?

[phrost]

Re: Samsung HP-R5072 Plasma problems

I can, if it starts to happen again that is.. i just within the 2 hours replaced the capacitors and readjusted all of the vset, vs etc.. I left the tv running while scouring the forums and decided to try to crank the brightness up for the heck of it and it didn't cut out. I am able to view the brightness with all its glory. I find it hard to believe its fixed tho. If it happens again a video will be gladly uploaded.

Once again i can't thank you enough for helping and don't disappear quite yet

[phrost]

Re: Samsung HP-R5072 Plasma problems

It seems to be related to how long the tv has "warmed up" as this morning after leaving it unplugged overnight i got no picture again only audio, after some minutes of being plugged in i started to get the screen flashing on and off about once every 2 seconds, i will keep it plugged in and running to see if it turns on after warming up even more. I will upload a video in a little bit. Any leads?

[tom66]

Re: Samsung HP-R5072 Plasma problems

Thermal sensitivity is a good clue -- you can try heating up parts to see if it will "boot up" quicker.

[tw2005]

Re: Samsung HP-R5072 Plasma problems

Not saying this is what the problem is but How did you go with the Vset? Was it nice and steady or erratic?

I had trouble with a Samsung PS50Q7 with erratic Vset and it would shutdown the panel below a certain level. I could never get it set right and the levels seemed to just run away.

I discovered the trimmer pot had a dead spot, possibly burnt on a board similar to this.

[phrost]

Re: Samsung HP-R5072 Plasma problems

@tw2005
As far as i recall all adjustments were steady, i will double check as i do in fact have that board.

@Tom66,
Yes i notice the heatsinks on the main psu warm up gradually before i start to get flashes out of the PDP, once i get flashes i put it to a channel with no signal which is black and usually comes on reliably where i let it sit to warm up even more before attempting to tune a channel again. I'm not sure where to start so i will start at the beginning and work my way towards the y-main and x-main. Any tips on what to try to warm up with a blow dryer would be great.



Here is another question when i am adjusting the Vs and the screen is working i have about 197v, the sticker on the PDP says 200v. When the screen is flashing however and is off i am reading 203~v, should i be adjusting the pot when the screen is on to dial in 200v or is there a risk in burning something up as the voltage is a few volts higher when the screen is not working.


Thanks again for the help guys

[tw2005]

Re: Samsung HP-R5072 Plasma problems

My general understanding is it should be set when the panel is at maximum output or a white screen. Myself I would not be too concerned seeing 197V on , 203 off with no load probably normal?

Tom would have the best data for this though.

I only mentioned that board because it caught me out. I set it then forgot about assuming it was good and had ongoing screen issues and when I went back to it I found it was always different from where I had it and with heat the voltages just ran away. it was never consistent.

[phrost]

Re: Samsung HP-R5072 Plasma problems

Ok, yeah i'm almost 100% there is no load when it hits 203v i hear no transformer buzz or anything, as soon as it hits 197v and the screen is on i hear the transformers buzzing.

I will wait for a second opinion from tom before i dive in though

[tom66]

Re: Samsung HP-R5072 Plasma problems

Vs should be within 1V, ideally, within 0.5V, of the panel sticker for proper operation.

[phrost]

Re: Samsung HP-R5072 Plasma problems

Ok, they are all tuned there i just double checked. I think the issue is heat related i'm going to try to track it down. I notice the Y-main heat sink with the mosfets is much warmer then all the rest is this normal?

I let the TV cool off for about 5 minutes and it failed to power up again, screen flashed until i turned brightness down to 0.

[phrost]

Re: Samsung HP-R5072 Plasma problems

Quick question for tom66, should Vs fluctuate when the screen is not on (no load) as compared to when the screen is on (load)?

[tom66]

Re: Samsung HP-R5072 Plasma problems

It should be within 1V from full dark to full white, measured at the PSU end. On the sustain board some fluctuation may be tolerable.

[phrost]

Re: Samsung HP-R5072 Plasma problems

great thanks again

[ozbloke74]

Re: Samsung HP-R5072 Plasma problems

Hi , my first post so be gentle , I have watched from the sidelines for sometime and the information provided allowed me to repair my BN44-00161A power board that had a couple of dodgy looking solder joints and one bulging capacitor .

Thanks heaps for the information provided


I know have taken possession of a Samsung BN96-0180B 50 inch plasma and the problem with it is I get the standby light come on and the relay clicks but I get no picture or sound .

I have removed power supply and thought I might be able to find some dodgy looking solder joints that jumped out like the BN44 board ( after I read this forum and saw where to check ) but the soldering effort looks like a really professional job .

I have noticed on the two outside boards that the grease that sits under heat sinks has ran all over boards , could this cause no picture , or am I way off track ?

Regards