Grundig 55 GUB 8860 - bad T-Con or bad panel?

[Diah]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

I thought it would be smarter to heat up the main chip with a heatgun on low blow setting, while I monitored the chips temperature with an infrared thermometer. Slowly heated it up until the surface reached 250 very briefly, then went down to 190 then let it cool.
That killed it.

what ...??we didn't mentioned at all to use hot air gun.. however if some one read this thread in case using normal hot air gun we should cover the chips and all components around with type to avoid one of them move or flying out. and this what happen now.

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

Its time to give up unless I find a really cheap mainboard I think.
Thank you for the help, I have now taken it to the point where the mainboard is definetly toast.
I thought it would be smarter to heat up the main chip with a heatgun on low blow setting, while I monitored the chips temperature with an infrared thermometer. Slowly heated it up until the surface reached 250 very briefly, then went down to 190 then let it cool.
That killed it.

Now when I plug the set in, the PSU makes a humming noise and the blue led is no longer blinking

[Diah]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

200°not enough..in the factory when they apply the soldering pasta first and then the components , it move to the oven which first step 200 then to 310 then back to 150 to the cooling station. t´he worry you have about sockets you can apply kitchen aluminum paper to shape it like cups to cover them. put don't let the paper touch them. this is the packing which i use. beside other method to use Korean in room infrared grill if i want to go only on specification area / chips

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

I went up until 200°C with the oven and left the board in for 10 minutes.
No change at all and I fear if I go higher the plastic ob the connectors could melt.

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

Yes,if it is L it's okay

[Diah]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

it is L not C so it read continues ?

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

Do you mean this tiny C? With all cables disconnected I'm reading 0V.
Might be short but didn't check for other parts in parallel yet

[Diah]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

Oh if you or anyone else has a chance to get their hands on the correct panel.bin I would still be very interested. As far as I understand I could use a replacement Mainboard from a TV with a different panel then so it would be way easier to find a used part

can you measure the reading of the small parts connected to pin 44 ? lvds most disconnected during measurements

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

Oh if you or anyone else has a chance to get their hands on the correct panel.bin I would still be very interested. As far as I understand I could use a replacement Mainboard from a TV with a different panel then so it would be way easier to find a used part

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

I don't remember what Temperature I used back then, it's been 15 years.
Some sites suggested starting at 100°c and working up from there so that's what I'll do
As far as I remember you can't really reach a temperature where the solder completely melts without proper tools, only enough for it to get soft and possibly regain connection.
Will report my results

[Diah]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

the way you did GPU use the same Temp ca 250 !! and time

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

What temperature do you suggest?
I once got a GPU back to life with this technique so I know it might be worth a try

[Diah]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

So a loose BGA maybe? That's probably not repairable. But it would be possible that the connection was bad/failing and when I applied cooling spray the temperature stress on the soldering joints made it worse.
So nothing else to do but get a replacement Mainboard?

well. before i go to buy replacement MB the stress you mentioned could be, in this case i encourage you to packing the MB. in the oven with out air flew after you remove from the down side i think there are rubber legs

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

So a loose BGA maybe? That's probably not repairable. But it would be possible that the connection was bad/failing and when I applied cooling spray the temperature stress on the soldering joints made it worse.
So nothing else to do but get a replacement Mainboard?

[Diah]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

if both pins 44 & 51 have V. then my early post #8 are in place... you have drooped signal feed with main IC on main boards.

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

I found that section of the SM earlier and checked. I'm not at home right now and don't remember the voltages but both were equal.12V I think. Definitely not 0

[Diah]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

Okay so I measured all the ribbons with a continiuty tester (beeping).
I slowly draged the probes over the contacts of the connectors on each side.
I admit I did not take the time to probe each of the tiny contacts perfectly individually so if lines are shorted I wouldn't know. But at least I did not find any broken lines

Okay. now every things in place and follow the S.M after turn on and you press menu ( BL go brightness) measure voltage on pin 44 & 51 if you have missing V on 44 check the yellow parts.

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

Okay so I measured all the ribbons with a continiuty tester (beeping).
I slowly draged the probes over the contacts of the connectors on each side.
I admit I did not take the time to probe each of the tiny contacts perfectly individually so if lines are shorted I wouldn't know. But at least I did not find any broken lines

[Diah]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

pressing menu the backlight goes brighhter but nothing apears on the screen.

okay,,, you need to inspect the LVDS cable and the 2 ribbon cable under good loop. the material they used on this TV are the cheapest one with bad quality easy the contact pin after 1-2 time take them out from the socket will brocken

[Ierwin]

Re: Grundig 55 GUB 8860 - bad T-Con or bad panel?

pressing menu the backlight goes brighhter but nothing apears on the screen.
I have never had a panel.bin on my USB stick, so it should never have overwritten. But because it stopped working after one of these flashing attempts I think the panel setting might have been deleted.

I found the ssticker on the chasis (fun fact: couldnt find it before because my multimeter was standing on it ).
But the number is the same as the small sticker on the back: 55C46P