Samsung PS-50C96HD - No picture - help needed

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

OK, I took the easy route. I have never dealt with surface mount components and only have a basic soldering iron. Too much room for problems to creep in.

The parts, Y-MAIN + SCAN boards will be in the post in the morning. 1 week turnaround.

I will update when the parts are returned and installed. Wish me luck.

[newtothis]

Re: Samsung PS-50C96HD - No picture - help needed

Shame your not close, I have an SMD rework station.

Good Luck

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

I HATE Royal Mail!

Parts posted 1st Class 21/11 which should be a next day delivery. Turned up at repairers today! I had expected to have them back last week.

I have arranged for the parts to be returned by City Link.

Now waiting.......

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

Am I surprised? Parts returned and carefully fitted. NOTHING!

Power lead plugged in and a single click from a relay. No blue light as before and NOTHING on pressing the on/off button on the front or the remote.

Where do I go from here? Christmas is rapidly approaching and time for repairs is getting precariously short.

[tom66]

Re: Samsung PS-50C96HD - No picture - help needed

If you get no blue standby light, you could well be missing one of the connections between the main and PSU board.

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

The connection from the PSU board goes to the top right of the Y-MAIN board. It is connected and the fuse is OK.

I have checked the other fuses which are also OK. I can see no missing connections - all sockets on the PSU have leads plugged into other boards.

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

There appears to be a test point connector on the bottom right of the PSU board. The readings are as follows. Using a mounting screw as a ground for the DVM reading VDC.

STBY = 5.12
VS-ON = 0.00
N.C. = 0.00
PS-ON = 0.526
RTN = 0.00
5.3V = 5.36
RTN = 0.01
RTN = 0.01
5.3V = 5.36
5.3V> = 5.36

Edit for typo

[tom66]

Re: Samsung PS-50C96HD - No picture - help needed

If you unplug the Y-main completely, what do you get?

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

OK (or NOT!!!).

If you look at the overall wiring diagram attached, the thick Black line (7) goes from what I believed was a test point to the Logic Board. The $!*&# lead is not there!

I know the previous owner said someone looked at it but this is just stupid.

I will have to remove the Main Board to get to the Logic Board to try to work out which pin goes to which. I can also dig in the Service Manual that the attached image came from to work it out from there.

I do not have the lead so will have to bodge one or get one from eBay.

Life never was meant to be easy was it?

[tom66]

Re: Samsung PS-50C96HD - No picture - help needed

You should still have a standby light without that cable.

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

That thought had occurred to me seeing it was there before starting all of this.

Any idea what to check for on that one?

[tom66]

Re: Samsung PS-50C96HD - No picture - help needed

Unplug Y-main completely, does it appear?

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

I have the set in bits at the moment trying to solder a 10 core strip of floppy drive cable to the 2 connectors. Not the best solution but it should work. It is somewhat delicate so needs to be secured against vibration induced solder joint failure. I am having some trouble due to the fiddly nature of the job coupled with the eye sight of a near 60 year old.

I am going to call it a night today as I have other commitments this evening.

Once the lead is fitted I will try your logical suggestion and post the results.

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

A thought while work is on hold. Does anyone have a spare lead to go between PSU CN807 and Logic Board CN2000?

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

I have reassembled and put the power lead on hold so I could do the diagnostic requested.

Plug in power lead, Blue light on, relay click, Blue light off. Light on for about 3 seconds. Same result with Y-MAIN completely disconnected.

As it was a few weeks ago I am now unsure what I originally saw.

Is this normal behaviour? Is it possible that getting power to the logic board will now generate a picture?

[tom66]

Re: Samsung PS-50C96HD - No picture - help needed

Check for Vs, Va with and without Y-main connected. Also try isolating X-main board.

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

Not what I was expecting.
Va stable at +65.2
Vs varied and was not stable.
See the attached image of the notes I made during this.

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

While waiting for a response I did some digging in the Service Repair manual and found that Vs should be 205V. SMPS board faulty as well!

The manual just says to replace the board. There are various kits available but I am unsure which to go for so I contacted EMOS who repaired the Y boards. Sending the PSU to them but doubt it will be back for Christmas.

[Paul-G]

Re: Samsung PS-50C96HD - No picture - help needed

The miserable saga continues. The power board was damaged in transit. Thanks for nothing City Link! The nice people at EMOS sold me a board from one of their test sets. Cost £45 + VAT + P&P = £59.98. BONUS, when the package arrived they had also included the missing lead from the power to logic board. That has saved me a LOT of hassle.

No picture? The set now seems to be working but I can not get anything on screen.

What I see
Power on, one click from relay, Blue light on. No flashes, just on.
Remote - Press TV, On/Off button. Blue light flashes 4 times then goes off.
Remote - Press Menu button (or any other), Blue light flickers. NOTHING ON SCREEN.

What on earth is going on now?

[tw2005]

Re: Samsung PS-50C96HD - No picture - help needed

What I see
Power on, one click from relay, Blue light on. No flashes, just on.
Remote - Press TV, On/Off button. Blue light flashes 4 times then goes off.
Remote - Press Menu button (or any other), Blue light flickers. NOTHING ON SCREEN.

What on earth is going on now?

Power on, one click from relay, Blue light on. No flashes, just on. power available, in standby
Remote - Press TV, On/Off button. Blue light flashes 4 times then goes off.normal main board bootup, TV on when light is out
Remote - Press Menu button (or any other), Blue light flickers. NOTHING ON SCREEN.normal remote activity indication

What on earth is going on now?

Sounds like you may still have Ymain/buffer issues.

If a source was hooked up to AV with audio, I believe the symptoms would be described as Sound. But no picture.

Classic description for these when the Upper buffer and Ymain go.

I would not rule out the possibility of a failed repair by EMOS either on the Y section.

Things you could check after turning the set on and the blue light goes out.

Voltages present for the panel especially Vsus

The green activity LED on the Logic Ctrl board, is it blinking at a steady rate, I think it maybe 0.5 sec intervals.

All ribbons/cables connected, (logic to Y ?)

Any audible faint buzzing noises from the X or Y mains indicating activity.

Are the heatsinks getting warm on the X & Y or stone cold.

Have you checked any of the work on the Y main and buffers? Are the shorts cleared, fuse good etc?


One thing to be careful with are those E,F,G buffers at the bottom which I would not mess with. This is the model I learnt what happens if you reconnect the power cable to those boards whilst there is residual charge after the PSU is turned off.

They get spiked and blow(non repairable chips on the panel ribbons)
There is a aluminium strip that sits across those too(heatsink) I thought was just a bracket, they fry quick smart and same deal, dead panel.

I've only touched 3 of these and lucky they were straight forward, all failed the same.

Upper buffer short, 88N30W FETs shorted. no blown fuses or anything else.

I know more can blow than that , but I got it easy.

Don't know if any of that will help you, those are my thoughts.