Help Identify Blown Component

[Nigel Goodwin]

At least they are keeping you in a skilled job!
I'm curious, how do you know it is the coil and not the circuit driving it? (don't tell me, you've seen the same fault many times...)

It usually gives a fairly unique fault symptom, something that can't be caused by anything else - as I said I've only ever seen a couple of failures, and I didn't waste time looking for anything else - it just screamed 'scan coils' at me (even when I've never seen one before).

The problem now though, is that CRT's have been PIL (Precision In Line) for decades, so there's no adjustments, it's all done during the manufacturing process, I presume by actually altering the scan coils to correct convergence and purity. The exception was Sony, who never made PIL tubes.

So tvtech was pretty well stuffed, no way to do a decent job - and as he said, accept it, or bin it - the 'proper' way to repair would be to fit a new CRT, but it's unlikely one would be available, and it would cost more than a new TV anyway.

 

[tvtech]

Nope. So far only Tedelex and Samsung last CRT affected. As crazy as it may sound. Normally, you can pull scan coils off and check....not anymore...no burnt areas visibile. No evidence of any corrosion. Etc.
You gotta thorougly know your CRT stuff to work things like this out.

yip
tvtech

 

[tvtech]

Another thing...I see ALL here...not just well built sets. No nice well known brands only....EVERYTHING.

Everything here now is the very last of CRT. Every day factory modified sets arrive....modified from the 'factory' they were built in. Some I save, some I dont. If noone has messed with the chassis my chances are better. You gotta CRT well....CURRENT CRT...not from long ago. Things have changed.

 

[Nigel Goodwin]

An old friend of mine (I was his apprentice when I first started) in later years set up on his own, in a small rented shop selling and repairing TV's - and I was talking to him once, and he told me about a really strange fault he had. It was an Hitachi CRT set and it was doing all manner of really strange things (which I can't remember now, but it wasn't just one obvious fault).

After considerable effort he eventually realised that the set shouldn't have had a SCART socket on it (which is a European multipin AV/RGB IN/OUT socket), and the customer )or someone else had added one. There was space on the PCB for it, along with all the other required components, but they weren't fitted on this specific model because it was LIVE CHASSIS - so couldn't have external inputs unless the sockets were isolated. The TV model that had the SCART socket fitted, also added an isolated mains PSU to keep it safe. He removed all the spurious components, and the set then behaved perfectly.

I also had something 'similar' (but not a bodged set), it belonged to a very old friend of mine (I knew him from the pub when I was still at school) called Walter Warmsley - and this also was doing all manner of weird things, Again, after considerable time I noticed a bright reflection from a tiny point on the board when you looked at a certain angle.

I investigated closer, and the area in question was the isolated safety barrier (marked with painted white lines) between the primary and secondary of the PSU. With this very close examination I was able to spot a small piece of artificial Christmas tree, one of the tiny 'leaves', which was metallic and shorting across the safety barrier. Removing that cured all the problems.

 

[tvtech]

While I appreciate your cool memories of CRT way back.....my crap with CRT is here and now. Things have changed......picture this:

The peolpe trying to get rid of the last of CRT.....spares and parts and tubes they have left in the Chinese 'factories'. The crap I am working on now has to be seen to be believed. Almost every set consists of bits and pieces salvaged from old scrap from old CRT factories. Rusted CRT metal 'housing or frame' that holds the tube in place. Some look like they have been been lying outside for years. Glass doesnt rust..CRT pins do. Like I said, Im more than happy to take photos of the sets im dealing with now. Im not moaninng.....im saying im used to working on rubbish now. For a change today, a Panasonic FX 74 landed on my bench. Frame collapse. Took me 30 mins and sorted. Noone had messed with it either. An absolute pleasure to work on. A set designed and built by a proper company....not a POS built from leftover old scraps.

 

[unclejed613]

i repaired CRT computer monitors as a business until LCD monitors became available for $150.00 (that was in 1997 i think). after that i repaired CRT monitors for a banking equipment company for another 7 years, and only because the CRT monitors were still part of the "standard" sets of equipment that the banks were having maintained. once they replaced all of their legacy equipment, i had a warehouse rack full of working color 10 inch SVGA monitors. we would use them as loaners and such for other clients, like smaller banks, etc... that couldn't afford to upgrade everything at once. eventually the boss told all the employees to "remove them" after months without any of them being used. for the company to dump them in the trash would have cost the company extra fees, because they had leaded glass, so the boss just gave them away instead. i used to have the software i wrote way back when (Video Test Bench) posted here on ETO after i made it freeware and open source, but that was before ETO got upgraded. however it can now be found at https://github.com/unclejed613/video-test-bench-dos-freeware back when i released it on ETO, i was surprised to see people were actually using it.

if you want to see it work, there's a DOSBOX instance of it at https://archive.org/details/Video_Test_Bench_4.5F_Freeware