I don't know if I have ever noticed this before, but when I came home from work, I usually put my wallet and keys on top of my TV. Well while taking my shoes off I put my hand on the top of the TV to get balance, and noticed that the top of it was warm.

Why would the TV be warm, if it has been off for 10 hours? When I turn the power switch off on these old TV's, doesn't it essentially disconnect the AC line? I thought they did.

I'm a little baffled now. My father has been in bed sick all day, so he sure hasn't used the TV.

What type of TV is it? Does it have an instant on feature?

It's the Samsung in my sig. Being solid state I don't think it needs an instant on.

Are you sure the sun wasn't beaming on it through a window? ;)

That set may have a constant power supply to keep the CRT filaments half-way, which could possibly make the top of the cabinet warm to the touch if the room is cold, I guess. I personally don't think it should be noticeably warm though. My advice is unplug it 'til you solve the mystery. The only malfunction I can think of, which could do that if it's NOT a normal cause, would be if the degaussing thermistor is going bad and is randomly turning the degaussing coil on. That would make the front of the top of the cabinet warm for sure. But it would likely also burn out quickly, and you'd hear it humming for a second or two on & off.

Charles

I get home at midnight, I doubt sunlight was the cause. ;)

I sure hope it doesn't keep the CRT filaments on a little, no wonder why the CRT is tired then for a TV that "looks" like it's a low hours set. Haven't heard the degauser run, but I'll check for that though.

Well I found something. When off the filaments continue to glow. No hv though.

I'm confused because it doesn't turn on fast.

That's strange. "Instant on" pretty much went away by the mid '70's. By the time this Samsung was made, most TV's relied on a secondary winding from the flyback transformer to provide filament voltage, as well as other voltages for the set. The only way for the flyback to produce any output would be for both the power supply and horizontal oscillator/driver circuits to be powered on. It's possible that someone installed a seperate filament transformer for the CRT and didn't wire the primary winding past the switch. If that's the case, it wouldn't be a problem to wire the filament transformer after the switch so that it will be switched on and off with the TV.

Well I found something. When off the filaments continue to glow. No hv though.

I'm confused because it doesn't turn on fast.

When the set is on the standby position, did you observe the briteness of the CRT heater? It should be dim in comparison to the operating mode.
You have to look at the connections on the on-off switch.

You may have a stuck power relay. If so, the power may be on all the time, but audio and video muted by system control. BUT, you said there was no HV, and that sort of kills my idea. I figured I'd throw it out there anyway just for something to think about.
Try this....put an AC ammeter in series with one side of the power cord and see if it is pulling any juice. An easy way to do that is to pop the fuse out of the set and clip the ammeter to the fuse clips.
Another idea: Do you have a cat? Cats are warm and I understand they like to sleep on top of stuff like a TV

EDIT: I just looked at the picture again, and see that it looks like a non-remote set. Probably no relay, but the on/off switch may be stuck on

No cats. I'm allergic.

I have a killawatt meter, I could use that.

When the set is on the standby position, did you observe the briteness of the CRT heater? It should be dim in comparison to the operating mode.
You have to look at the connections on the on-off switch.

It did look a little dimmer.

I don't know if these pictures help. Hard to get board pictures without pulling it out, and I don't feel like disconnecting everything.

The power switch does go open when off, so it's getting power from somewhere else.

http://img.photobucket.com/albums/v395/Evilweredragon/tvboard1.jpg
http://img.photobucket.com/albums/v395/Evilweredragon/tvboard2.jpg
http://img.photobucket.com/albums/v395/Evilweredragon/tvboard3.jpg

I'm stumped. The on/off switch opens when off. I would expect that to shut off all power to the set. The heaters are lit when the set is off, but there is no HV. Wierd. I'm pretty sure those sets get the heater voltage from a winding on the flyback, so HV and heater should come and go together. Is it possible someone rewired the set to get heater voltage from someplace else? Even if so, the heater only burns a couple watts so I wouldn't expect any noticeable heat. Perhaps a leaky or shorted capacitor across the power switch? Nah. that doesn't explain the heater staying on but no HV. Charles mentioned the deguass coil staying on. That would hum, and make a mess out of the picture, but it would run warm, at least until something (thermistor?) dies. Try unhooking the deguassing coil and see what happens. RCA used to activate the coil when the TV went OFF, not ON, so a leaky thermistor might keep it going. I dont think I have ever seen that design on a Samsung, but there's a lot of stuff I have never seen. Still, all of this deguass talk doesn't explain the heater staying on. :saywhat:
I'm going to bed.
:boring:

Well, there's a couple point to point wires on the bottom of the PCB. Here's a picture I took several months ago when I first got this TV.

http://img.photobucket.com/albums/v395/Evilweredragon/TV%20Board/IMG_0394.jpg

Two wires, black and orange. I don't know if these could be causing it.

Are there 4 wires to the ON/OFF switch? If so, you cut in a standby supply to the CRT when the main is cut off. Sony and Toshiba, along with most of the Korean sets did that in the 70s-80s, and many others did too. That's my guess, and a quick look at the schematic would tell all.

Charles

No cats. I'm allergic.

I have a killawatt meter, I could use that.
Too bad, no cats. I have three black cats. :thmbsp:
My Watt-watcher is a great item to have around. I use it for a lot of diagnostics.
That set seems to be a little new to have a standby CRT heater circuit. :scratch2:

Just double checked, it only has two wires. Inside is this however, stamped on the side. Doesn't reveal too much though.

http://img.photobucket.com/albums/v395/Evilweredragon/tvlayout.jpg

I did notice an extra transformer near the flyback though.

Just double checked, it only has two wires. Inside is this however, stamped on the side. Doesn't reveal too much though.

http://img.photobucket.com/albums/v395/Evilweredragon/tvlayout.jpg

I did notice an extra transformer near the flyback though.

The small transformer near the flyback is the horizontal driver transformer.
Looks like a mouse was in there nibbling on the labels.

Hmm ok.

T601, in the audio circuit, gives me good hopes for being able to install a small headphone socket on the side of the TV. I'd assume the transformer is isolating the speaker from the rest of the circuit, so headphones would be safe.

Ever get to the bottom of this? Did you try putting it on the kill-a-watt and see if it's drawing any power when off?

Yea, oddly a killawatt is reading 0 watt draw. So I don't know how acurrate those things are when it comes down to low wattage readings. Because it fluctuates between .3 and 0 watts. I'm sure those filaments draw more than that.

I use those to work on even little netbook computers....so if your particular Kill-A-Watt unit is working, they are good down to pretty small loads.

I use those to work on even little netbook computers....so if your particular Kill-A-Watt unit is working, they are good down to pretty small loads.What is the smallest load yours will display?

I don't have it here at work with me today, but I've seen single watt numbers in some netbooks in "sleep" mode. I don't recall if I have ever seen less than one watt...but know for sure I've seen down to one, as the little ASUS 900HA netbook "sleeps" at around 1.5W. I do know it will register ZERO watts....just can't recall if I have seen "500mw" or " .5 " before.

If you are seeing anything less than 5-10 watts.....you are not generating any noticeable heat, nevermind enough to actually warm the top of the set. I know the little wattage display on my APC ups I have on my "entertainment" center in the front room shows 18 watts at "off"....but that damn Cox cable box DOES seem to ALWAYS be warm whether off or on. I'm getting that "18w" display on the APC with the Samsung 55" on standby...cable box on (or off...no difference)...and my little Archos AV700 playing into the little HLLY transmitter (those two run 24/7).

So actually.....I don't know what to believe sometimes, but the Kill-A-Watt always seems to give me a much more believable number (I should put the Kill-A-Watt after the ups someday and see)

I'm not sure if the UPS is also showing me what it's OWN circuitry is drawing as well...but I suspect it's just the load to it's sockets in back. It will go to zero if nothing is plugged into it...and will go back and forth between 2 and 3 watts if I unplug JUST the Scientific Atlanta HD box (and THAT thing gets pretty warm!)

Well here's what I've noticed since. No, there hasn't been any more heat noticed. But, the filaments in the CRT do continue to glow after power off. Could they draw 0.5 watts and still have a noticeable glow?

I don't know why I felt it warm before. It was warm, but I just don't know why.

My K-A-W model P4460 will not indicate the power of a single 4 watt night light bulb, but if I turn on 2 of them, it indicates the correct 8 watts.

jr

Just tried real quick my KAW P4400

Running the wall wart for the Panasonic TR-1020 (REAL little TV)...the thing draws 2.3w charging it's internal battery...and climbs to 5.4w when I turn the little 1020 on.

So I guess it does appear to measure to .1 watt increments.

what is the model number and exact year. cant we look at a sams on this and see exactly what is going on?
Sounds like it doesnt meet omambas zero energy no coal powered TVs energy star agenda. Let me help you get to the bottom of this before the EPA SWAT team shows up and confiscates all your electronic toys...

SAMs website doesn't find this TV. It finds the chassis though. I'm not at home but the pic I posted earlier should show its chassis number.

My K-A-W model P4460 will not indicate the power of a single 4 watt night light bulb, but if I turn on 2 of them, it indicates the correct 8 watts.

jr
Yep I have a 4460 and about 5-6 Watts is the lowest it measures before it goes blank. Not much good for checking low standby power.

Dunno if it makes any difference, but my little Kill-A-Watt P4400 unit has a pink "P3" designation on the front. I've long since tossed the little blister pack the thing came in, so no idea what the P3 means. I think I got this just under two years ago....likely was on sale at Fry's or something.

I have the sams here for a 20K20 chassis the parts layout says 20K20 and its not too likely that would cross to a samsung and the board looks like yours from the parts layout if it wasnt it. This is from 1994 and uses an electronic tuner.

Its possible they used the main board for years with different accessories.

Anyway, in this set the power switch is 100% so nothing is on when the set is off.

I can scan this if you wanna look.

If you want to get me the exact model number and date it was made I can maybe find the exact sams.

Dunno if it makes any difference, but my little Kill-A-Watt P4400 unit has a pink "P3" designation on the front.My P4460 has the same P3 International company logo.

The problem is, this TV had no date. All plaques including internal for manufacturer date, are empty. Don't forget, my board even says engineering sample on the ICs.

Nothing makes sense right now as to why the filaments still glow. The power just shouldn't be coming from anywhere.

I'd probly put that on a power strip till you find out what the story is. I've got two old solid states sets with that "instant on" or whatever each of the companies calls this "feature"....and they are on power strips so I don't slowly piss away the CRT.

<shrugs/> whatever, I have the samsung 20k20 scanned to a pdf. its your board.

Oh dear god I feel like such an idiot right now!

I was never seeing filament glow like I thought. I was actually seeing the reflection of my ceiling fans light on the guns metal surface inside.

Ugh, shoot me now please.

I thought it looked brother with the TV on because I was seeing glow AND reflection.

As for the heat, I think I know what's going on here. Directly above the TV is the HVAC vent. It started getting colder outside here in Florida, so the heat has started kicking in, and I bet it's blowing directly on top of the TV.

EDIT: It's time I get new prescriptions for my glasses.

Sounds like you had a Homer moment! DOOOOHHHHH!

LOL!!

I was next gonna ask if you had a CAT :-P

I keep all the "collection" sets on powerstrips just to avoid having "instant on" keep a set's filaments running for MONTHS on a set I might actually turn on once every two months. Only have a couple "clock" sets like the Panasonic one with the mirror inside....and the RCA Lunar with the flip clock on the "hot all the time" power strip. I also do have a "modern" little Panasonic 9" color set on that strip to keep me from having to do it's "setup" every time it's plugged in. I did check to see it's not running the heaters when off. I have a feeling I'm gonna have to put the new "prison TV" on that as well...but it also doesn't appear to run the heaters when off.