UA32C6900 continuous restaring

[tiny68]

Re: UA32C6900 continuous restaring

Davi.p thanks for your response.

[tiny68]

Re: UA32C6900 continuous restaring

Thank for your comment re-atari. After a long delay due to other distractions, I just got around to checking the main board and what looks like solder blob in the photo is a reflection for some flux on the board.

[re-atari]

Re: UA32C6900 continuous restaring

For future reference for others, here are the photos of the full layout of the boards in this TV.
The area I heated on the main board to initiate the change in display response (post#17) was near the antenna input at the bottom and the generally within about 60mm of this. Unfortunately I was unable to work out any more precisely the location that made the difference as the display never reverted to the previous fault image and now I dont have any image at all.

Judging by your photo 3, it appears someone has already tried to fix the mainboard. It looks like the left side of IC 2 contains a large blob of solder, where IC 1 does not. See the attached photo, the area in question is encircled in red.
I don't know if this is how it's supposed to be, have no experience with fixing Samsung TV's.

re-atari

[Davi.p]

Re: UA32C6900 continuous restaring

Tcon not good or in protection because of panel problem, difficult to say , models behave differently, unless you find smps chip datasheet you can't manage to discover this.

[tiny68]

Re: UA32C6900 continuous restaring

I tested the tcon on the bench (nothing else connected to it). I supplied 12VDC to the input fuse.
The current draw cycled from about 40mA to about 65mA every second (or less). I assumed this should have been relatively stable (I checked a tcon from a similar model which was steady on 70mA).
The test-point measurements were a mixture of stable voltages for some test points and cyclic variation for other test points.
VCC33 = 3.3V
AVDD = (3.3 <-> 1.4)V
VCC12 - 1.2V
VREFU_H = (3.3 <-> 1.3)V
VREFU_L = (2.0 <-> 0.8)V
VREFL_H = (1.6 <-> 0.7)V
VREFL_L = 0.04V
VDDMHL_1 = (1.1 <-> 0.03)V
VCOMS2 = (2.0 <-> 1.35)V
VCOMS1 = (1.1 <-> 0.03)V
F_VCOML (2.0 <-> 0.7)V
VGAMA18 = (0.75 <-> 1.3)V
VGAMA17 = 0V
VGAMA16 = 0V
VGAMA15 = 0V
VGAMA14 = 0V
VGAMA13 = 0V
VGAMA13 = 0V
VGAMA12 = 0V
VGAMA11 = 0V
VGAMA10 = (1.5 <-> 0.7)V
VGAMA9 = (2.7 <->0)V
VGAMA8 = 0V
VGAMA7 = 0V
VGAMA6 = 0V
VGAMA5 = 0V
VGAMA4 = 0V
VGAMA3 = 0V
VGAMA2 = 0V
VGAMA1 = (3.5 <-> 0)V

I assume that this tcon is bad based on the above measurements?

[Davi.p]

Re: UA32C6900 continuous restaring

i can't help you with theese few infos, i can't see by the photos where there is a damage by hot hair, it's up to you, in the mean time you can try the tcon test.

[tiny68]

Re: UA32C6900 continuous restaring

For future reference for others, here are the photos of the full layout of the boards in this TV.
The area I heated on the main board to initiate the change in display response (post#17) was near the antenna input at the bottom and the generally within about 60mm of this. Unfortunately I was unable to work out any more precisely the location that made the difference as the display never reverted to the previous fault image and now I dont have any image at all.

[Davi.p]

Re: UA32C6900 continuous restaring

sorry, i forgot to say the tcon only connected to test psu, ok i saw you changed the board behaviour but you can be more precise, what you have warmed up, the processor? how much? until a level of reflowing? have you ever done refllows? it's easy to make some poor reflows that belongs to a not booting board, so i was suggesting to inspect for an original fault, if it's tcon then evaluate the global damage if you cant do reballings

[tiny68]

Re: UA32C6900 continuous restaring

Davi.p I don't understand. Are you saying I should try to connect an external 12VDC supply to the TCON while it is connected to everything else in the TV (VLDS and panel ribbon cables) or are you talking about doing the test of the TCON board on the bench alone? This is not a test I have done/seen before.
The symptoms I explained in post #16 changed after I applied some heat to the bottom area of the main board(refer to post#17), not the TCON, and have not returned even after being turned off for the past 2 hours. There is no image on the display at all anymore, and no chime, but the TV is still rebooting every 7 seconds or so.

[Davi.p]

Re: UA32C6900 continuous restaring

The fault was not explained well since the first post through 17 posts, next time try to post a picture earlier, it is not funny to do investigation on the nothing, now i see that something can be.wrong on tcon.board, try to hook that one to an external 12v p.supply and see if if goes into protection.

[tiny68]

Re: UA32C6900 continuous restaring

I've just tried the heat gun pointed at the bottom of the mainboard and initially I had just the vertical lines shown on the previous image I attached (with regular reboots still) but then the image no longer came up at all and there is no chime between the reboots (relay clicks every 7secs). I tried to let it cool down a bit and tried a little bit of butane (carefully) to try to cool the area but it remains in the 7sec boot state, without any image or chime.
Ill try it again after it fully cools down.

Any further thoughts?

[tiny68]

Re: UA32C6900 continuous restaring

Ive attached a still image from the restarting TV. This is what I see after the start up chine and before it reboots. I haven't taken the back off again yet, but will do so to try applying some heat and cooling of the main board.

[Davi.p]

Re: UA32C6900 continuous restaring

Which image shows? Is it the Logo and stop? This almost always is software conflict. Is it yours? Which is the story? it was connected to the net before the fault? Have you a new if settings has been reset? This can explain why colors are not ok..

[tiny68]

Re: UA32C6900 continuous restaring

Budm - yes sounds very similar to OP, with constant reboots and the voltages seeming ok, although I can't be certain that the image issues I see are the same as OP. I will try to upload a photo later in the week (I've put it aside to work on a different TV for the moment.
Davi.p - you could be right about needing a board replacement, but I don't like to give up without a bit of a fight!
I'll get the heat gun out and also find some freeze air to see if I can induce any change in behaviour.

[Davi.p]

Re: UA32C6900 continuous restaring

Theese recent boards has no shields on them, Petehall is having mistake i guess. The problem is much probably software and has no other solution than MB change, anyway there's a little chance that that BGA chip that has lines that feed the LVDS cable (FRC chip) has soldering problems. Another little chance of any other thing connected to this chip like ram or V reg. is half short circ.

[budm]

Re: UA32C6900 continuous restaring

No metal shield on my main board other than the TV tuner can - I assume this is not what you are (were) talking about?

So are you having the same issue as the OP?

[petehall347]

Re: UA32C6900 continuous restaring

I use lighter gas/butane for freezing. It's cheap, readily available and is the propellant they use in the cheap cans of air anyway.

be careful with that .it has a habit of hanging around on the floor ready for a spark

[diif]

Re: UA32C6900 continuous restaring

I use lighter gas/butane for freezing. It's cheap, readily available and is the propellant they use in the cheap cans of air anyway.

[dick_barton]

Re: UA32C6900 continuous restaring

For cooling you can use a can of freezer spray or turn a can of compressed air (for dusting keyboards) upside down and spray.

[petehall347]

Re: UA32C6900 continuous restaring

was a metal shield with holes in if i remember rightly . try warming areas up anyway .