EHT safety and all

[tvtech]

Hi all

Continuing from here: https://www.electro-tech-online.com/threads/safety-guidelines.98675/#post1082139

Regards,
tvtech

 

[tvtech]

Hi All

No response is also cool. Somebody had to start the thread. So I did it.

Regards,
tvtech

 

[Sceadwian]

In all honesty I believe that the typical new user here should simply be told not to touch mains/high voltage stuff at all. I'd be curious if 1 in 100 users that every visit this forum will ever even touch something like that, outside of mains power, but mains isn't all that bad to work with I think the guidelines could be simplified a bit and modernized as CRT displays are VERY quickly becoming obsolete.

 

[KeepItSimpleStupid]

Wood may be inadequate at times. Take a look at tree after it's been hit with lightning.

Discharging can be tricky because of the fact that there can be enough energy to make the object fly. Large discharge sticks, or at least theones I used had about a #0 cable on it, with a 4' fiberglass tube and a 4" diameter circle with about 20 degrees cut out of it.

High currents was ignored in the FAQ and they are differently dangerous. I worked around 3000 Amps at 6V at the current end and 100 kV at 0.1 A at the voltage end for DC voltages. 3000 VDC was present in a 1 KW tube transmitter and the 15 K VDC 1.5A shunt regulated Power supply (used a tube) was quite impressive. The transmitter was 1000 W at around 15.56 MHz into 50 ohms.

I fall into that 1%.

 

[tvtech]

In all honesty I believe that the typical new user here should simply be told not to touch mains/high voltage stuff at all. I'd be curious if 1 in 100 users that every visit this forum will ever even touch something like that, outside of mains power, but mains isn't all that bad to work with I think the guidelines could be simplified a bit and modernized as CRT displays are VERY quickly becoming obsolete.

Hi Scead

The very last of CRT are being dumped here...what I don't get though is that CRT is generally repairable at a reasonable cost...unlike LCD/Plasma etc.

Me, personally....only CRT in my place. No larney looking, flat screen, bolt to the wall changing picture stuff.

I promise you, if I manage to buy a second hand Sansui 74 CM CRT from a customer here..in good condition...it will outlast all the thin miserable bolt-to-the wall-look-impressive-picture frame stuff on sale to the general public.

Plus, I can fix it when it maybe goes faulty......@ a reasonable cost....not throw it away as in all the new stuff...

I will not have a Super Duper looking thing to watch TV on...I watch TV to relax...not impress.

Sorry to shout, but I had to get it out. CRT forever

tvtech

 

[throbscottle]

I note in the original thread mention of the "one hand in pocket" rule, which reminds me. I have a scar on my thumb where I burnt a hole in it on a live mains connection (UK 240 volts) whilst holding the earthed metal chassis of the amp I was fault finding on with both hands. It was a weird thermal fault and I'd got sick of plug in, test, unplug, test... ad nauseum - left plugged in whilst examining board, thumb strayed onto live. Very, very, stupid, considering I lived on my own and was at home, alone, since the current through my arms stopped me being able to let go of the chassis until I found some muscles I could still use.

Word to the wise - one hand in pocket is a very good rule, even when it's really inconvenient.

 

[RichTheDude]

CRT's still have many advantages, apart from being more fixable they have superior dynamic range and response times. I still find them easier on the eye than LCD...

Wood can easily track, and the one hand rule is imperative especially in official labs as pretty much anything metal is grounded...

 

[tvtech]

CRT's still have many advantages, apart from being more fixable they have superior dynamic range and response times. I still find them easier on the eye than LCD...

Hi Rich

Easier on the eye and easier on the pocket and repairable is why I will stick to CRT as long as I can. Heavy, sure. Big and cumbersome, sure. But how often does one carry a TV around?

With a quality set and a good Tech setting it all up...you can kick any LCD/PLASMA into touch with a CRT.

Remember Rear Projection Sets....never seen one that beat a good CRT. Sure, they had a huge screen...but you had to watch it from the exact place designated otherwise the picture was crappy.

And in the last "dying throes" of CRT, Thomson has some huge tubes we are seeing now only. Flat screen CRT....with perfect convergence, EW correction and stunning picture quality....and as heavy as hell. So, build the thing into your Lounge wall and you are good to go.

I feel like a Dinosaur right now....but I appreciate a quality picture when relaxing and actually WATCHING a TV...not fixing it.

Regards,
tvtech

 

[Nigel Goodwin]

Flat screen CRT....with perfect convergence, EW correction and stunning picture quality....and as heavy as hell.

I don't know where you're getting those ideas from - ALL the large CRT's had poor convergence, poor EW, poor geometry, poor purity etc.

Thomson did do an HD CRT set - and that was REALLY crap.

We deliver hundreds of new LCD TV's to customers, and almost always it's a far better picture than their perfectly working top brand CRT set - which are then taken away and scrapped.

If you care to come to the UK and fetch them, we're binning probably ten Sony's or Panasonic's a week

 

[tvtech]

Hi Nigel

I am not kidding you. LG/Phillips for example are still putting stuff on the Market here. Also Flat Screen CRT. And they too look good.

Come visit Africa. I ain't going to the UK. What I am telling you is true.

Best regards,
tvtech

 

[Nigel Goodwin]

Hi Nigel

I am not kidding you. LG/Phillips for example are still putting stuff on the Market here. Also Flat Screen CRT. And they too look good.

We must have different ideas of 'good'

What do you mean by 'flat screen' CRT?.

 

[JimB]

Cathode Ray Tubes have served well for many years.
Some screens look really nice with a nice brilliant phoshor. (Wow did I just say that? I must be waxing lyrical this afternoon).

However when you consider the corrections which have to be made because of the geometry, particularly with wide deflection angle CRTs, it is a wonder that the poor old electrons can hit the required phosphor dot at all.

Bring on the new upstart LCD panels etc.
Some of them look really nice as well.
You want to light up the dot at X=475 Y=396 ? No problem! Just set the appropriate addresses, job done, every time!

So, farewell CRT, it has been good knowing you, enjoy your retirement.
We will meet again sometime in the back corner of the Science Museum and reminisce about the old days of RADAR, oscilloscopes with 10Mhz bandwidth and the fine detail which could be displayed on an old broadcast quality black and white studio monitor.
As for the day to day hurly burly of the modern world, you just cannot cut the custard any more!

JimB

 

[tvtech]

What do you mean by 'flat screen' CRT?.

I will take some photo's in the Workshop tomorrow. And post here.

 

[RichTheDude]

I don't know where you're getting those ideas from - ALL the large CRT's had poor convergence, poor EW, poor geometry, poor purity etc.

Thomson did do an HD CRT set - and that was REALLY crap.

We deliver hundreds of new LCD TV's to customers, and almost always it's a far better picture than their perfectly working top brand CRT set - which are then taken away and scrapped.

If you care to come to the UK and fetch them, we're binning probably ten Sony's or Panasonic's a week

My old CRT monitor can leave ANY LCD monitor for dust in resolution and colour gamut (can your LCD monitor do 1920 x 1440?). I own LCD monitors (Samsung) and an LCD TV as well (Sharp) for reference.

Not that I proclaim to be a specialist but some of my friends in the design industry are still using CRT's for the aforementioned reasons.

 

[DerStrom8]

What do you mean by 'flat screen' CRT?.

I believe he's referring to a CRT with a flat screen.

I had a 32 inch flat screen CRT tv a couple of years ago. It was massive, took up about three cubic feet of my livingroom. I have a very small house, so I really couldn't deal with that much space being wasted, so I broke down and bought a 32 inch LED flat panel TV. Overall I'm very glad I did. The picture was a hundred times better, I get more channels, and I prefer the widescreen format. It also runs cooler, uses less energy, and it fits in a very tiny space. I used to prefer CRT tvs, but since the prices of flat panel sets have come down, it is actually cheaper for me now to buy a new LCD/LED television set than repair an old CRT. Besides, I no longer have to lug my 300 lb CRT out to the car just to get it repaired. It's not worth it anymore to me. Buying a flat panel television was probably the best choice I've made in a long time.

That's my 2 cents.

--Matt

 

[Nigel Goodwin]

I believe he's referring to a CRT with a flat screen.

Flat screen CRT's don't meet any of the claims he made

Which was why I asked.

The picture was a hundred times better, I get more channels, and I prefer the widescreen format.

Europe went widescreen many years ago, long before Plasma/LCD sets ever appeared - it was only the USA that stuck with the old 4:3 format. I suppose it might have been because the lower resolution NTSC format wasn't really capable of widescreen?.

 

[DerStrom8]

Flat screen CRT's don't meet any of the claims he made

Which was why I asked.

Europe went widescreen many years ago, long before Plasma/LCD sets ever appeared - it was only the USA that stuck with the old 4:3 format. I suppose it might have been because the lower resolution NTSC format wasn't really capable of widescreen?.

Oh really? I need to get out more

 

[tvtech]

Hello All

Anyways, I am not going to get into a scrap here. All I can say is that I am a CRT Tech. And that is all I know.

I am in Africa remember...and here we (the ones that care) try and do the best with what we have with the quality of people we deal with daily. It has everything to do with trying to help honest poor people to the best of our combined ability. These people can barely afford a CRT TV repair. Never mind a smart new Flatscreen LCD or whatever is on the market now. We deal with strictly NON GOVERNMENT employees who don't steal.

I am over it. After almost 5 Years of sacrifice....I have had enough.

So, I have decided I am bailing out. I am stuck in a time warp here where I am tired of helping people that remain stupid..no matter what I try here in South Africa.

Stuff the poor sheeple masses here. They can work it out for themselves. They voted the ANC in...they can surely vote them out too.

And yes, I would like a nice new Flat screen non CRT TV one day. It ain't going to happen here though. Unless I get dishonest....and that is something that will not happen with me. I walk taller than my shadow. Always.

Be good all of you.

See you when things improve here.

As always
tvtech

 

[debe]

Well TVtech, Jump on a refugee boat & come to Australia every body else seems to be. Weve got plenty of CRT TVs in scrap yards & good working ones cant be given away, no body wants them. LCD TVs are so cheep even they arent worth repairing. I gave up reparing TVs about 5Yrs ago, no money in it any more.

 

[Reloadron]

Among my early safety memories was being told you do not pee on B+.

Gone are those days for the better part with the highest voltages being mains voltage in not all but most circuits today.

As to the TV world the migration was slow but sure. We went from all vacuum tubes with their high voltage needs and current drawing filaments, to sort of hybrid flavors to what we have today. We have a 50" Sony TV in the living room that I can pick up and carry around. We have a 21" flat screen CRT 25 year old Panasonic in the bedroom that I have trouble moving around. I have a 21" old Sony Trinitron monitor laying here that weighs in at about 70 Pounds (US Pounds). When I finally dump it I'll need a strong neighbor kid! I wish the Panasonic would up and die so I could justify a new one. I may have to help it along.

Electronics, in my overall humble opinion has become much safer. Despite safety precautions, over the years I got bit my share of times. The number of times getting bit seems to be proportional to the number of times one gets complacent. Go figure huh?

Ron