Samsung PN50B650S1F clicks on plug-in with flashing voltages

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

@freakaftr8 can I ask you a few more questions? Did the ohms test I did on the x and y sustain boards conclusively prove those boards are good? Same question on the logic and t-con boards (or whatever they are called at the bottom of the TV). The only question I have on the SMPS is the 340V at the caps even though the other outputs are correct, but save for that it appears to be good? Thanks.

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

I was able to answer my own questions by getting the test patterns to come on, and when it does it looks good, save for a few slightly speckled black dots in random patterns across the top of the screen. That should confirm everything works but the main board! I had it on test patterns for four hours to check things when hot and it didn't skip a beat!

Now to find a main board......looks pretty thin!

[freakaftr8]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Yep definitely a main board problem. Most likely caused by a failed NVRAM. This is the rectangular chip that's about 1" long by 3/4 inch and has about 50 or so pins coming off of each side

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Holy cow man that thing is small and the pins are tiny! Can it be replaced without having to re-program the board?

[freakaftr8]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Cheapest I found. Looking closer at the pictures it does not have the Flash that I thought.

Here's the board.

https://rover.ebay.com/rover/0/0/0?m...2F152895763601

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Thanks for the link! I'm thinking I may wait and see if one of these pops up for sale locally with a busted screen or something like that.

Can the RAM chip be replaced you think? I wonder where I might find one. I googled it last night and didn't come up with anything. I'm kinda "technologically challenged" so maybe my search params were insufficient.

[freakaftr8]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

I think the only thing you could do it this board is replace eeprom. It doesn't have the NV ram that I thought it did. It could be at firmware problem or and an eeprom failure thou.

[nomoresonys]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Okay so while I'm asking for help I'm also trying to self-help.

I found this video: https://www.youtube.com/watch?v=VtbrQhwBiOc in which the person is testing the exact same SMPS I have. I followed this procedure as outlined in the video:

The board was connected to 120V AC, like in the video. All other connectors were unplugged.

Ps ON and STBY voltages are present and correct.

Jump Ps ON to ground: all voltages noted on the SMPS to main board connector are present and correct.

Jump STBY to Vs: All voltages are present and correct at Vs and Va, Vg is 15.1V DC but when voltage is read at the capacitor leg noted in the picture, voltage is only 340V DC, as compared to the 396V DC seen in the video.

Does anyone think this voltage difference may be a part of the problem?

I know very little about plasma tvs, doesnt the filter capacitor have to be about 380 or higher to get the backlights on?

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

I'm not sure about the exact specs, but they did come on when I finally got it to generate the test patterns. The screen seems as bright as it should be. On the other hand that seems to be the only spec that's low.

[nomoresonys]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

I'm not sure about the exact specs, but they did come on when I finally got it to generate the test patterns. The screen seems as bright as it should be. On the other hand that seems to be the only spec that's low.

I'm dumbfounded by it lol.

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

All the resources I saw were showing about 396V. Darned if I know either!

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

Hello all, this will likely be the last update on this TV.

Today I went to a recycle joint to look at over 50 TV's. They were in the process of getting them out of the shipping containers. Whist I was standing right there one of the workers pulled this exact model. I told him "I'll take that off your hands right now". Upon closer inspection it was complete and even had original promotional labeling and the original stand I needed!

I brought it back to the shop, plugged it in, turned it on and save for the left 1/4 of the screen it actually WORKED!

I pulled the main board out of it, put it in my B650 and now it works, click of death solved!

This is significant for me in that this was the very first TV I picked up to fix. To see it working is almost like coming full circle! I gave $10 for the TV and $15 for the parts TV and I have about 10 hours in it.

My thanks to all who helped me on the troubleshooting that led to a successful repair!

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

So in preparation for closing out the repair I ran in to something: While tightening all the screws, checking Vs, Va, Vsc and Ve voltages and making adjustments I decided to check the voltage at the main caps one last time.

I'm glad I did. The voltage is not stable. It's going from 388V to 408V. It tries to stabilize at 388 then you might see 396, 392 or as high as 408 with the next voltage spike, always returning to around 388.

Would anyone think this is a PFC issue, or maybe the main caps are getting ready to cash out? I guess it could be as simple as bad solder joints too?

[budm]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

May be bad PFC feedback resistor network.

[DXseekerMO]

Re: Samsung PN50B650S1F clicks on plug-in with flashing voltages

I only see a couple resistors on the top side of the board, and if they are a network there has to be more than that, so there must be a bunch of surface mount resistors on the bottom side of the PSU?

If so I'll get pix up tomorrow.