JVC LT-50CF890(C) I’ll let you lads decide what the issue is haha.

[Donny2derby]

Here goes then. My first thread. I'll be quick with the introduction to try and help you good people help me. I'm an electrician so I have an understanding of ohms law and some knowledge of electronic components but I am absolutely not an expert on them. I have enough to get by in my day to day role as a shift maintenance role.

I have a vague understanding of their relation to each other and can probably read a schematic ok but their interactions with each other I will definitely need help with.

I've (hopefully) managed to attach some images for you all. And I think it's best for you lot to tell me what you feel the issue is as I am completely new to this field but determined to give it a best and not be a fly by night on the forum after repairing my own telly then legging it!

Many thanks in advance.

[Donny2derby]

Re: JVC LT-50CF890(C) I'll let you lads decide what the issue is haha.

Have I said something wrong?

I was hoping that the pictures would help the knowledgeable people on here decipher what the issue appears to be. If I’m looking at a defective screen I can just strip it for parts and move onto the next project.

Or if there may be a fix I’d like to try and find it with some help. I keep reading about a tape method so wondered if that’s worth a try?

Any feedback would be great.

Thanks.

[nomoresonys]

Re: JVC LT-50CF890(C) I'll let you lads decide what the issue is haha.

Yep, thats the first thing I would try, been over it many times here, many other tutorials on youtube covering the procedure. Also, yes those pictures with a description of symptoms are the PERFECT way to start a thread. One example there many more too: https://www.youtube.com/watch?v=pfrRhw7-ZII

[nomoresonys]

Re: JVC LT-50CF890(C) I'll let you lads decide what the issue is haha.

Keep reading there's a ton here, I just put tape method in the search box you get when you select it towards the top of this page, see it there, pages of results: https://www.badcaps.net/forum/search...rchid=33559615

[Donny2derby]

Re: JVC LT-50CF890(C) I'll let you lads decide what the issue is haha.

Thanks Sonys.

I'm 42 now so my eyes don't work as well as what they used to so I can't QUITE make out which pins I need to mask off. I've ordered a magnifying glass on a slow boat from china so will carry on with the attempt at repair when it arrives.

One other question. I can see what looks like the denoted pins beginning with Cl which goes to the right hand side ribbon cable. Would it be best to try and mask all these at once or one by one? Am I right that these are the correct ones?

Surely I need to replicate the masking off procedure to the left hand side as well? But I don't see any markings indicating there are clock pins to the left hand side which I find odd. Pictures below.

[nomoresonys]

Re: JVC LT-50CF890(C) I'll let you lads decide what the issue is haha.

That video gives a lot of info, sometimes you can get it down to only having to mask off 1 pin, depends on where the short is, most of the time you only need to mask prolly 4 to 8 pins on one side only, I think the reason people have a hard time with knowing which to mask is the short can be in different lines so trial and error will probably be the way to go, as in how many and which lines to mask. Some here have spent many many hours trying to get it just right, I haven't had to do it lately, my memory is pretty bad but some here have been diving pretty deep into this recently, maybe check recent posts.

[Donny2derby]

Re: JVC LT-50CF890(C) I'll let you lads decide what the issue is haha.

My magnifying glasses have arrived and I'm currently sat here trying to look closely at the pins on this ribbon cable.

They start at C12 and 13 and then jump up in seemingly no logical pattern until C36 and run through diodes in parallel or on their own to the IC.

They come through what appears to be something marked “pin section” 4 separate joints marked T2 through to T5.

Any ideas what these are? I think I'll mask off the pins running through the blocks marked T2 through to 5 in pairs to begin with.

Picture attached.

[Donny2derby]

Re: JVC LT-50CF890(C) I'll let you lads decide what the issue is haha.

Ok this is interesting. Or maybe it’s not and quite normal. Hopefully one of you will tell me.

I masked off the first couple of pins on the ribbon cable and got no difference in picture. I then decided to trace back the pins from the ribbon onto the main board and test what I assume to be the transistors on CN124. They all either climb when putting my meter across them or are open circuit except one which reads 1.5 ohm. I don’t know for certain how to identify it in the picture below but I’ll try. If I can’t it’s the first one reading from the bottom up.

Edit. That’s actually pretty accurate. The first transistor closest to the ribbon cable. Measures 1.5ohm whereas the rest all either charge or read open circuit.

Any help much appreciated and needed haha.

If that IS a faulty part then how in the name of all that’s holy do you unsolder and replace something that size?? It’s impossible surely!!??

Further edit. Ok all clock signals are now blocked and the picture distortion/lines have actually got worse. Now there’s no JVC logo visible at all and where as before the lines were pretty stationary they’re now jumping about all over the place.

So it seems we’re on the right track?

I’ll await feedback before going any further.

The floor is yours lads ��

[Donny2derby]

Re: JVC LT-50CF890(C) I'll let you lads decide what the issue is haha.

Anyone?

Am I on the right track or pissing in the wind with this?

Is there a schematic available for this?

[Chrissygizmo]

Did you get your tv sorted mate? I've got the same issue with a JVC LT-50CA890B , I'm going to put a post on it tomorrow, hopefully I will get more response on here than you did, I've had loads of help in the past on here , I'm really surprised you didn't get more members helping you, have you been a naughty boy on here or something haha