Possible purchase - Proscan 55 LCD 55lc55s240v69

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

Hey Tom there is no pin labeled PSON unfortunately. Could you have a look at the image and see if you can recognize it?

I've looked for service manual and cannot locate.

I was using a 1K resistor as well. I will find a 100.


Thanks!

[tom66]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

1k could possibly work too...

[tom66]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

Now I look at PSU, SW is ON/OFF for backlight, and ON/OFF is ON/OFF for PSU.

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

When jumping 5v(w/ 150 ohm) to ON/OFF(psu) I get constant relay clicking??

Do I need to jumper the BLON as well to get the PSU to start properly?

Thanks again!

[tom66]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

Nope, PSU should switch on and stay on even without backlight switched on.

So, what do the rails do when the click? The clicking indicates PSU is trying to start up, but for some reason failing, shutting down, then restarting again. How often are the clicks? Once a second?

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

Clicks are fast, at least one per second if not faster.

What's weird is with the connector to main board hooked up(no jumper), it clicks once, then delays about three seconds and clicks off.

I get 0V on all other rails while the fast clicking is happening(forced), yet I get proper voltages everywhere connected normally.(but only for the 3 seconds that it stays on)

I appreciate the guidance.

[tom66]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

OK, so S5V, you should see 5V, with or without jumper.
And for M5V, you should see 5V when jumpered.

But you do not see M5V when doing the jumper trick?

Are you using S5V or M5V to jumper to? If you use M5V, you could create a feedback loop, which might be causing the clicking.

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

Sorry, correction: With main board connected, I get 17V where it should be 14V. See attached image. (thanks)

[johnboy1313]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

This is exactly what I was going through with the X460BV on my bench now. The unit will power up briefly and then power down with everything connected. Forcing the PSU on results in a clicking PSU and fluctuating voltages. I finally broke down and bought a used PSU, though I'm still not certain that this will be the only problem. The one before that needed a PSU and then a main board, but it wouldn't power up at all.

[tom66]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

The 14V is probably for the audio and is usually unregulated, so may be high with no sound. Will likely fall when playing normal audio content.

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

Thanks for the input johnnyboy1313. The only difference I see is that whilst it's clicking during force on I get no fluctuating voltages. Just 0V. Maybe my fluke can't read it fast enough. It's cycling pretty fast!

Tom66, you are correct:

* S5V always has 5V no matter what
* Nothing on M5V when jumpered (and nothing anywhere else)
* I am jumping off S5V, not M5V

Damn it would be nice to have a service manual...

Thanks as always!

** added: Makes sense about the 14V Tom, although I was hoping this was leading somewhere

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

I wonder if 5V is too high for the PLON? When in normal operation it's always 3V. I will try with two 1.5V batteries.

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

Nope, 3.2 volts does the exact same. It seems I am not doing the force on properly!

[tom66]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

Try the SW too, just in case that does control something else, seems strange to me though!

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

It is strange! I'm not sure what the M5V are for but starting to think maybe that needs to be jumped.

I did try SW as well but will try once more.

I checked the other end of the cable(main board) and you were correct:

SW = Backlight
BRI = Dim

The M5V just say +5v on the main.

Something has to give, with just the lower cable in, I get the three second start up try. But when removing it and putting 3.2V on PLON the relay cycles. That tells me something else on that cable needs to be hooked up.

[tom66]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

M5V is the main 5V which comes up when the PSU switches on.
Can you see what line might be toggling when PSU comes on using the main board installed.

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

I don't see anything toggle. Everything comes up to normal then it all goes down when relay clicks off.(standby remains 5v all time)

Is it safe to put the three volts on PSON while the cable is connected? (I thought I read it's a bad thing). If not, can I cut just that wire and hook it to my 3V?

Or am I just plain crazy lol?


Marty

ps. thanks for all your help, it's truly appreciated.

[tom66]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

It's not a good idea to do that, as the main board may try to pull it low and damage the control pull-down transistor.

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

Update!! Hair dryer trick started the TV Wooooo!!!!

I heated all the caps on the secondary side and it fired right up. I can't believe how much time I spent wondering and searching, without at least trying the basics(heat,cold)...

So, caps will be ordered and then I will update this thread with the(hopefully) good news

Thanks badcaps.net, this friggin forum rocks!

[martyparish]

Re: Possible purchase - Proscan 55 LCD 55lc55s240v69

Just want to follow up and say thanks to tom66, johnnyboy1313 and all others on badcaps.net! THANK YOU!!!

I have just replaced all of the lytics and put the tv back together. It's working like a champ!!! Got a 55" LCD for ~$55 and some tlc (just in time for the Superbowl)