Thorn 65thl4kst1

[mrsith]

Re: Thorn 65thl4kst1

Just in case you can try replacing the T-Con, it won't hurt but probably won't help. The parts you'd like to cannibalise are the two little boards between the T-Con and the panel itself. Not an easy job to replace.
Double check the capacitors on these board (on your faulty screen), put diode mode and check each capacitor leg-to-leg, also check each leg against the ground. If your meter doesn't beep it's gonna proba ly show ~030 for shorted caps vs ~600+ healthy ones. Most likely you will find quite a lot of shorted caps, the problem is determining which one of them actually causes it.
In diode mode, just put one probe to one side of capacitor and another one to the other side. Or put negative probe on the ground (i.e. chassis), and positive to each leg of the capacitor. One leg should return high value, while the other should be clpse to 0. If both are suspiciously low then its probably.a short there.
Do this with everything connected, but without power cable in.

[viewerau]

Re: Thorn 65thl4kst1

THANKS,
The 10th post on page. 6 shows the readings in continuity, giving a set of numbers according to how I put the probes on each end. I did this with all boards and strips attached as normal, but unplugged from the wall. My panel has 4 of those edge boards . Given nothing has changed, I think the values will be the same. Does this all mean, if I took out every board and replaced them, that it still would not work as one of the four edge boards would still be faulty.?

Thanks

[nomoresonys]

Re: Thorn 65thl4kst1

try both the tcon and mainboard from the broken screen tv, see if it works.

[nomoresonys]

Re: Thorn 65thl4kst1

important to know is that the same model tv can have many different mainboard and tcons and they are not usually all compatible, that's why you need to match up the white sticker numbers, the silkscreening on the board is just generic, then they populate it with what they need to. NOW do you have a match between any of the boards you are trying to work with?

[nomoresonys]

Re: Thorn 65thl4kst1

do the test in post #121, with tv unplugged from power and tcon cable unplugged from driver board/s, it's a simple test. We NEED conclusive test results so we can eliminate possible problems and move on, stay with it, trying every couple months isn't a very effective method, there's no tv these pros can't fix.

[viewerau]

Re: Thorn 65thl4kst1

Thank you chaps...I do appreciate this additional help.

In the daytime tomorrow (getting dark here now) I will measure all the 4 boards again, and report the readings.

This is what I got before, will be interesting if I see differences.

I note mrsith recommends all things connected and unplugged, and nomoresonys recommends the tcon cable unplugged from the driver boards.

Which way do you both concur with please, as I do want to do this accurately, and eliminate data I may be supplying incorrectly?

Again...thanks.

[viewerau]

Re: Thorn 65thl4kst1

Woops...forgot old readings

[nomoresonys]

Re: Thorn 65thl4kst1

I tell you to unhook cables from mainboard to driverboard to isolate, because issues can travel, that way you know if there is a problem it isn't traveling from the mainboard to panel driver thru the cable. Also explained in post #94.

[nomoresonys]

Re: Thorn 65thl4kst1

.

[nomoresonys]

Re: Thorn 65thl4kst1

.

[nomoresonys]

Re: Thorn 65thl4kst1

answer this question, exactly HOW are you testing these caps? I can not help without answers to each question.

[nomoresonys]

Re: Thorn 65thl4kst1

HERE is what i want you to do, for THIS test forget how he does it in the video. go ahead and isolate the boards like he does if possible, NOW read carefully, 1 put meter in diode mode, so for this do NOT use ohm mode, 2 put one probe on chassis metal ground, 3 put other probe on each side of cap while never moving the probe on chassis ground, one side should read close to 000 the other should read something much larger than 000, do it exactly like that.

[viewerau]

Re: Thorn 65thl4kst1

Thank you .. I will do this exactly as you advise. Again, your assistance is greatly appreciated.

[viewerau]

Re: Thorn 65thl4kst1

Well...

The tv has remained unplugged from the wall, and checks suggested are undertaken.

The multimeter is set in diode mode....the reading on the multimeter is a single "1" digit.

If I touch the probes together, then the reading changes to "003"

I have disconnected the 2 x cables leading from the t-con board to the side edge boards.

With the black probe on the chassis, and at the same time, touching red probe on any side of ALL the caps, nothing but a single "1" changes.

So now I get nothing at all.

To double check myself, I went and located some same caps on the t-con board, and measured them in the same process as above. In this case, one side of the the caps looked at, they would show "001", and then the red probe changed to the other side of the cap, the display is "171".

To me this indicates that the multimeter is working ok?

What test do I move to next please?

Thank you.

[nomoresonys]

Re: Thorn 65thl4kst1

ok, it seems like there's a short on the panel driver board.

[nomoresonys]

Re: Thorn 65thl4kst1

sometimes you can get lucky and the shorted component is hotter than the rest, i think i would go to those caps that are reading 0 ohms, remove one at a time and check them off the board, if it is a cap issue, when you hit the right one the short will be cleared, check the pads where the cap comes off same way as described and check the cap off the board, because it's usually only one cap that is bad, it just can be a real pain finding it, could also be a different component causing the short.

[nomoresonys]

Re: Thorn 65thl4kst1

there's a good video on the subject, i'll check.

[viewerau]

Re: Thorn 65thl4kst1

Thank you...

When you say "ok, it seems like there's a short on the panel driver board" I assume you refer to one of the 4 edge boards?

I count 38 caps on the 4 side boards in total.

Being a novice, how do I work out what type of capacitors I need to purchase please?

Further, will a hot soldering iron remove them easily?

Not too sure I am capable of this either.

Lastly, if all the removeable boards are the same on the broken screen replacement I have sourced, and match my faulty one's to put into my tv, if the edge boards are the problem, could this cause damage to the replacement parts, if I swapped them out?

Thanks

[nomoresonys]

Re: Thorn 65thl4kst1

video here, he talks about testing and finding the bad component, he uses his tool to find the bad component that's reading less than an ohm, in other cases he injects voltage to find the bad component, there's also a wealth of knowledge in the comments: https://www.youtube.com/watch?v=77tymvTJDxo

[nomoresonys]

Re: Thorn 65thl4kst1

Thank you...

When you say "ok, it seems like there's a short on the panel driver board" I assume you refer to one of the 4 edge boards?

I count 38 caps on the 4 side boards in total.

Being a novice, how do I work out what type of capacitors I need to purchase please?

Further, will a hot soldering iron remove them easily?

Not too sure I am capable of this either.

Lastly, if all the removeable boards are the same on the broken screen replacement I have sourced, and match my faulty one's to put into my tv, if the edge boards are the problem, could this cause damage to the replacement parts, if I swapped them out?

Thanks

yes the "edge boards", was this the one with the stand alone tcon? there is a definite possibility of damaging the tcon if the driver board is faulty but keep in mind. If you have a problem with the driver board, you will not solve it by replacing the other boards, the panel driver board/s must be repaired if possible, unless the "tape cut-off" method will work.