CRT TVs

[momaka]

Re: CRT TVs

aye, make sure they understand that they should never throw away anything thats still working. doing so just generates e-waste unnecessarily. u'd also be playing russian roulette and gambling with your money by buying "modern junk".

Yes, I think they know that as I've repeated it (to them and many other people) probably over a billion times before. It's just that they have quite a few other friends who believe that newer is always better (the worst case being, this one couple, who thinks appliances need to be changed every 5 years, because they are bound to break). So sometimes they do feel a bit pressured to renovate things around the house. But in general, I've been able to convince them not to.

PLASTIC gears?! Are you kidding me?? Wow.

The HP OfficeJet Pro printer line says hello too.
As far as I know, the 2007-2013 models (and possibly current ones too) had this issue where a cheap thin plastic gear on the main paper feed/drive drive axle would break. This would make the printer throw an error and render it completely inoperable. I've seen a lot of those HP printers on eBay / CL described as "make grinding noises when trying to print". The fix is to remove that gear, drill through the metal drive axle, and put a metal insert.... that is, only if you don't mind taking the whole printer apart - down to the smallest detail to get to that part.

IF?! I think you mean WHEN Eventually you'll come across one and you won't be able to pass it up!

You're right, it's only a matter of time. But that WHEN is when I move to my own place some day... SOME DAY...

Even being 14 years old?

My KFC Smile CRT monitor has Jamicon, G-Luxon, and Elite caps in it. The picture does take a long time to "fill" the screen now (a possible indication that some of the caps may be starting to fail). But it still works. For a nearly 18 year-old monitor (made in 1998), I can totally forgive its flaws. I am actually more worried about the (formerly) beige plastic crumbling apart and the tube falling through . It is dark yellow now.

To discharge, you just put a grounded screwdriver under the anode "cup" ?

That will do it.

There's actually more danger from the primary bulk cap still being charged. But that really applies to any SMPS.

What I be at any risk just pulling the back off of one and analyzing it?

For just looking at it? - Nope. Zilch. None.
Cleaning? - Hardly any, especially if the TV is unplugged and has been off for an hour or more.
Pulling the boards? - No risk if you discharge the anode and primary bulk cap. The B+ filer cap usually self-discharges by itself too. But B+ is typically 120V DC, which even with sweaty hands won't hurt too much.

I heard that a lot of units after the 90's had bleed resistors on the tube itself, is this true?

Some do, some don't. But either way, many of them do self-discharge relatively quickly. That static "sparking" noise you hear when you turn the TV OFF is the anode discharging. Of course the tube could still have some residual charge, but it's unlikely that it will get you - not unless you stick your hand under the anode cap anyways.

Since it's a true flat tube, doesn't that mean it has an aperture grille instead of a shadow mask?

Nope. Shadow mask flat tubes became rather popular in the early 2000's - especially Samsung tubes. Those tubs are actually still slightly curved on the inside, but you can't really tell by looking at the image. The only way you might be able to tell is from the reflection of the screen: if you see two reflections - one from anti-reflective coating and another "curved" one on top of it, you're probably looking at a shadow mask.

[Pentium4]

Re: CRT TVs

That will do it.

There's actually more danger from the primary bulk cap still being charged. But that really applies to any SMPS.

Do I have to worry about scratching the coating on the surface of the tube itself?? I will check the voltage main caps on the PSU.

For just looking at it? - Nope. Zilch. None.
Cleaning? - Hardly any, especially if the TV is unplugged and has been off for an hour or more.
Pulling the boards? - No risk if you discharge the anode and primary bulk cap. The B+ filer cap usually self-discharges by itself too. But B+ is typically 120V DC, which even with sweaty hands won't hurt too much.

The thing has been unplugged for about a week, yet I am still scared of it I can't reach the bulk cap to check for voltage without removing the board. Would rubber gloves be good enough to pull that board out to discharge it?

Nope. Shadow mask flat tubes became rather popular in the early 2000's - especially Samsung tubes. Those tubs are actually still slightly curved on the inside, but you can't really tell by looking at the image. The only way you might be able to tell is from the reflection of the screen: if you see two reflections - one from anti-reflective coating and another "curved" one on top of it, you're probably looking at a shadow mask.

Hmmmm, this may be one of them. Check out the pics I will study the front more closely when it isn't lying on its face.

There are a lot of Toshiba parts in here! ICs and most of the FETs I can see. I wasn't expecting to see Samsung or Toshiba parts in such an obscure brand.

You can see all of the Jianghai/JH caps, and a brand I have never seen before. AS?? I was going to make a list of all the caps in this thing. Is it even worth the trouble to replace all these small ones? I do plan on never getting rid of the TV...Most of the caps are 85C. How would such a unit react to replacing all the caps with, say nichicon PW, even the little ones?

Edit: The soldering looks pretty good, actually. Lots of flux though. I took pictures of the logo that is on every part of the unit except the tube. Anyone recognize it? How does the build quality of this thing look?

[kaboom]

Re: CRT TVs

*WARNING*

*WARNING*


When discharging CRT aquadag capacitance, do NOT use "any old ground!"

You must discharge the HV to the ground strap on the CRT. Always return current to its source, the other side of the dag capacitor. If you dump the HV into one of the signal grounds, you'll backfeed the low-level circuits and destroy them, just as if lightning came in the coax and left on the third wire of a grounded power cord (via multiple parallel paths inside the set)- such as on "modern" LCD/plasma sets.

Shithead local cable company does not bond the incoming coax to the electric service per NEC 820.100 and 250.94. They make it worse by driving "ground rods," which when unbonded, bring lightning impulses (step potential) right into the coax!!! It then "equalizes" to the building elec service by going thru TVs and other equipment, such as a cable modem and your motherboard.

Had a nasty storm a few days ago, and plenty of TVs were damaged/destroyed beyond feasible repair. The "evidence" abounded; boxes for "brand x" sets with "brand y" sets (dead) inside.


So discharge that dag HV to the CRT ground strap, and only the ground strap!

[Bungz]

Re: CRT TVs

I got rid of two 21" trinitron CRTs when I moved house about 8 or 9 years ago due to them being old and using LCD's.

Really wish I hadn't as they are bloody hard to find now!

Picked up a Samsung Syncmaster 957MB the other day, its a 19" and a fairly late run crt @ 2003.

Its superb for my older retro/gaming systems that I like to build, games look amazing on it.

Has a usb socket on it to control the OSD via the pc too which I hadn't seen before.

[momaka]

Re: CRT TVs

Do I have to worry about scratching the coating on the surface of the tube itself??

Not really. Of course, don't forcefully scrape it either.
That coating is usually connected to cold/output side ground.
When cleaning my CRTs, I always wipe the dust on it with a wet towel.

The thing has been unplugged for about a week, yet I am still scared of it

Yeah, most caps and the tube should definitely be discharged by now, especially since the TV is working.

Also, it's not the shock from the tube you should be worried about, but rather what you are holding in your hands and where you have them. That's because when you get shocked, your reflexes typically make you yank your hands back very quickly. And with a sharp tool in hand or with your hand near sharp parts, you can see how that can go wrong . This applies to any electronic device you work on, not just CRTs. As for CRTs, the HV supply is low current (typically 1 to 4 mA MAX) and will not kill you. As long as you have the TV unplugged and you're not messing with the anode, it's reasonably safe to open and work on.

I can't reach the bulk cap to check for voltage without removing the board. Would rubber gloves be good enough to pull that board out to discharge it?

If you can't reach it, then you don't have to worry about it. I mentioned the bulk cap only in case you DO have to remove the main board to work on it - in particular, just to be aware that it could still be charged so that you don't act surprised if you hold the board in your hand and find that something is "biting" you .

Hmmmm, this may be one of them. Check out the pics I will study the front more closely when it isn't lying on its face.

Yup, it's a Sammy (Samsung) tube, so I'm almost certain it's a shadow mask. That said, I do like Samsung tubes - at least for CRT monitors, as they tend to be quite sharp and always plenty bright. You can also tell this is at or past the peak of the CRT era, since the tube is made in China.

There are a lot of Toshiba parts in here! ICs and most of the FETs I can see. I wasn't expecting to see Samsung or Toshiba parts in such an obscure brand.

That's because China didn't have many tube companies at the time, if any... well either that, or they didn't export their tubes. Most CRTs are from Japanese companies (Nec, Sony, Mitsubishi, Panasonic, and Hitachi) and were made in Japan, USA , Singapore, and Mexico only (IIRC). I think only later in the 90's when Samsung and LG became more popular that Korean CRTs like Samsung emerged on the market. The only Chinese manufacturer I know made CRTs is Chunghwa (the same one that now makes cheap LCDs). But from what I understand, they came very late into the CRT game, which is why we don't really see their tubes anywhere. Had CRT technology remained popular today, I'm sure we would have seen a lot more Chinese brands.

You can see all of the Jianghai/JH caps, and a brand I have never seen before. AS?? I was going to make a list of all the caps in this thing. Is it even worth the trouble to replace all these small ones?

Depends.
In some CRT TVs, some of the small caps can be even more important than the big ones. I'm not a true CRT expert, so I can't tell you if your TV has any such important caps.

I do plan on never getting rid of the TV...Most of the caps are 85C. How would such a unit react to replacing all the caps with, say nichicon PW, even the little ones?

Should be fine.
I think CRTs don't use low ESR caps simply because they are not necessary.

That said, if you do find that you need a special size/voltage/capacitance, let me know, as I have quite a few pulled caps from TV boards. Even have some SamWha and SamYoung caps that came out of a Samsung-made TV.

I took pictures of the logo that is on every part of the unit except the tube. Anyone recognize it?

I think I have seen that logo before. I just can't remember where/on what.

How does the build quality of this thing look?

Looks pretty standard for a non-Sony CRT of that era .

[etype2]

Re: CRT TVs

speaking of crt tv i am going to indy to pick up a sony chromatron set.a kv-7010u.
very rare set!a friend spotted it at a yardsale for $15.
might be rarer than my rca ct100!

Hello,

Just joined today. I ran across your post about finding a Sony KV 7010U at a yard sale. Did you get it and most interested in knowing if it was a KV 7010U or a KV 7010UA. They look identical, but of course a big difference inside. I'm a collector of televisions.