Hello all, I was watching soccer and I started to smell somke, So I shut the TV off, A few seconds latter smoke started to come from the tv, So I pulled it away from the wall and a bright spark shot from behind it and the house fuse blew. I unpluged it and saw little flames from the power cord.

Question is can I just put a thicker power cord on it and bypass the pins on the back?

http://i1118.photobucket.com/albums/k603/Caramel_Shower/0707142330a1_zpsad5ae300.jpg (http://s1118.photobucket.com/user/Caramel_Shower/media/0707142330a1_zpsad5ae300.jpg.html)

I thought it would be more dramatic :) Just a loose connection at the power cord.

The purpose of the plug and socket is to prevent people from operating the TV with the back off and burning themselves on tubes.

If you can trust yourself not to do that then any sort of power cord will work just fine - of course, the UL rating of the TV will be violated, but no reason it won't work.

Take the wires on the other side of the socket back to where they aren't crispy and splice in a new cord.

Eek! Depends on what is actually wrong with the set, you might just need a new cord. I'd check it out carefully to ensure that nothing is failing and drawing too much current. But... most likely, the cord itself was just failing. I've not had one catch fire like this, but I've had a couple of cords that have broken down right at the plug due to the wire being flexed for the last 40-something years, and they get really hot. I've also had some that visibly started to crack right at that plug.

I'd try another cord, and carefully monitor the current draw of the set, but, something tells me that the cord itself just overheated from being damaged from age right at the plug.

Do they even still make "cheater cords" any more? I need to get some more myself, I've had to throw out several due to damage right at that plug before, and I have more sets than cords. You can, in many cases, just cram-a-lam a modern two-prong cord like from a PlayStation or a boom box onto the pins on a TV for testing, but it's far from ideal. Heh.

-Ian

Just grab the power cord off your RCA. They should be the same. Wonder how the hell that could have happened?!?!?! It was fine when it left here.....unless it somehow got pinched in transport?

Yes the rca cord works fine, I was looking over the set to make shure nothing was wrong, I was wondering if you ever opend the HV cage? Because I'm not quite shure how to check in there, because I heard some odd snaping. Just to check make shure nothing is wrong. But again I love it, And everyone is happy that we have a TV again.

Sure did. Everything was fine in there, and as I mentioned, I used the snot out of that set. In fact, here's a shot of me, my son, and my cat curled up around the 1920s kerosene heater watching it during the blizzard back in January :)

The fact that you heard snapping AFTER you shut the set off, in this case, pretty much limited the issue to the line cord.

I'm just hoping the line voltage issue didn't do something to the flyback. Does anything happen on the screen when you hear snapping?

So I took a you tube video of whats its doing, And there isn't a snaping so much as a hiss.

Sorry I'm being a bother :/
https://www.youtube.com/watch?v=FbVdij6fKaA&feature=youtu.be

Sure did. Everything was fine in there, and as I mentioned, I used the snot out of that set. In fact, here's a shot of me, my son, and my cat curled up around the 1920s kerosene heater watching it during the blizzard back in January :)
The white-faced General Instrument cable box and its matching LCC 58 remote make yet another photographic appearance. Very cool.

There was a NOS unit on eBay a while back but I didn't grab it dangit. :mad:

That's why we're here :)

The hiss makes sense. The flyback is arcing to chassis and bleeding off the HV causing a dark picture. Unplug the set, turn it on, let it sit for a couple hours to bleed out (you should technically discharge the anode to ground but we're not gonna have you do more than inspect), then undo the two push pins holding the flyback cover on, which is in the middle of the back of the chassis under the picture tube. I can just bet that the problem is there.

Then, power the set up, and watch from a distance with the lights off and see if you can see it arcing, and where it's arcing to. Might want to pick up a tube of RTV silicone, you'll probably need to seal up the flyback wherever it's arcing from.

I thought it would be more dramatic :) Just a loose connection at the power cord.

The purpose of the plug and socket is to prevent people from operating the TV with the back off and burning themselves on tubes.

If you can trust yourself not to do that then any sort of power cord will work just fine - of course, the UL rating of the TV will be violated, but no reason it won't work.

Take the wires on the other side of the socket back to where they aren't crispy and splice in a new cord.
The original idea for an interlocking power cord was to prevent electrical shock, especially on hot chassis sets and from the hv supply.
The cord shown, doesn't look like the original power cord. It could've been a polarized cord, forced on the two same size pins. The same thing, with using a standard power cord, on a set, that takes a polarized cord.
At this stage, just cut the connector off and splice it to the leads, that are soldered to the interlock male connector. :yes:

:tears: First off, OW!

Second, It was arcing So I took a very stiff tooth brush to the carbon and cleaned all the dust out. and Put Friction tape around the fly-back.
Turned it on and Tada! Bright picture but no Vertical deflection.

http://i1118.photobucket.com/albums/k603/Caramel_Shower/07081409591_zpse689388a.jpg (http://s1118.photobucket.com/user/Caramel_Shower/media/07081409591_zpse689388a.jpg.html)

Well, you do have *some* vertical deflection, but the rolled up picture tells me you've probably got a bad vertical oscillator or vertical output tube. Time to pull tubes and test them. You're not far off now....

:tears: First off, OW!

Second, It was arcing So I took a very stiff tooth brush to the carbon and cleaned all the dust out. and Put Friction tape around the fly-back.
Turned it on and Tada! Bright picture but no Vertical deflection.

http://i1118.photobucket.com/albums/k603/Caramel_Shower/07081409591_zpse689388a.jpg (http://s1118.photobucket.com/user/Caramel_Shower/media/07081409591_zpse689388a.jpg.html)

Strange, turns of events, with that set.
The AC cord burning up, shouldn't have anything to do with the vertical sweep. :boring:

The original idea for an interlocking power cord was to prevent electrical shock, especially on hot chassis sets and from the hv supply.
The cord shown, doesn't look like the original power cord. It could've been a polarized cord, forced on the two same size pins. The same thing, with using a standard power cord, on a set, that takes a polarized cord.

It was the correct type cord. I sold him the TV, and the power cord was disconnected and not in place on the set when it was shipped. The only thing I can think of that it might have happened in the first place is if the cord got jammed in the back hard. I removed the back to install and remove the cord.

...

The insulation was probably cracking and damaged right where it goes into the interlock plug. I've thrown out several cords because they had copper showing at one end due to the extra stress on the insulation.

I found some of my cords are getting brittle after 40 some years. I have several pieces, Ive had that long or longer.
BTW, the cords on the equipment, sold today, are inpossibly stiff. I understand they're removing the plastisizer, as it's lead based. :scratch2:

Did the cord have the famous "green goo" forming and bleeding around the plug and interlock? I've never seen a cord flame out from the goo but I have seen them sparking very slightly and it looks like interference on the picture. I clean them but it comes back eventually. I have soldered cords to the back of the pins on some to be on the safe side.
As for the vertical, it may be a resistor opened or went way up in value. My RCA KCS166 did that and I finally couldn't adjust the height anymore. Once I changed three resistors it was fine again!

The interlocked AC power cord has another purpose besides protection from hot tube burns. Its primary purpose is to disconnect AC power from the TV when the back is removed so that the user will not get shocked from B+, or, worse, the 2nd anode voltage on the CRT.

These interlocks are not supposed to be defeated; if they are, of course, the safety feature is instantly lost, and anyone working on the TV will be doing so at their own risk. "Cheater" cords were used in the days of tube-type TVs to allow technicians to operate the set for testing purposes, although some TVs were used for years or decades (!) with cheater cords when the set's interlock cord frayed at the end that plugged into the interlock pins on the chassis. The TV may have worked with this lashup, but the safety feature of the interlock was destroyed immediately.

I would not recommend bypassing the AC interlock for any reason. These were installed on TVs and even some AC-DC radios for a reason: to prevent electric shock. There is almost always a warning on the back covers of 1950s-'60s AC-DC radios and, of course, televisions, stating that the interlock must not be defeated. To service the tubes, remove the back cover completely; do not try to service the set with the back on. I mention this because I'm sure some folks may have tried this; i. e. they would take the screws out of the top of the back cover, leaving the bottom and/or side ones in, and try to replace bad tubes while the unit was still plugged into the wall socket and turned on. :eek: I don't know how many people were shocked or killed this way; however, I will say this is a mighty foolish way to repair any radio or TV.

BTW: One series of radios I can think of right now that did not have AC interlocks were the Zenith H511s (H511Y, G, W, et al) of the early 1950s. These sets were potential death traps due, at least in part, to the lack of an interlock power cord, and also because they were "hot chassis" devices, meaning one side of the AC line was connected directly to the chassis. I sometimes wonder if these sets were UL approved, or even if Underwriters' Labs was even in existence in the early '50s. If they were, I cannot see how these Zenith radios would pass inspection without an AC interlock. :scratch2:

I just aired and threw out a very weak A63, or 25V CRT with an old power cord tied to one of the mounting lugs in order to lower it into the dumpster to avoid a loud noise. Once the cord got the full weight of the CRT it was cut clean through. Still, far less noise than expected.

Defeating the interlock though is especially risky when there's a polarized plug involved. One wrong move could "liven up" a chassis that is normally connected to neutral.

. I sometimes wonder if these sets were UL approved, or even if Underwriters' Labs was even in existence in the early '50s.

UL was founded in 1894.

Just grab the power cord off your RCA. They should be the same. Wonder how the hell that could have happened?!?!?! It was fine when it left here.....unless it somehow got pinched in transport?Gosh I feel terribnle this happend........... I hope she didnt get hurt!!!


I hope you can save her buddy :):)

I thought it might have been pinched in transport, but my friend Al, who did the transport, reminded me that I removed the cord prior to the move from Buffalo to Maryland.

The interlocked AC power cord has another purpose besides protection from hot tube burns. Its primary purpose is to disconnect AC power from the TV when the back is removed so that the user will not get shocked from B+, or, worse, the 2nd anode voltage on the CRT.

These interlocks are not supposed to be defeated; if they are, of course, the safety feature is instantly lost, and anyone working on the TV will be doing so at their own risk. "Cheater" cords were used in the days of tube-type TVs to allow technicians to operate the set for testing purposes, although some TVs were used for years or decades (!) with cheater cords when the set's interlock cord frayed at the end that plugged into the interlock pins on the chassis. The TV may have worked with this lashup, but the safety feature of the interlock was destroyed immediately.

I would not recommend bypassing the AC interlock for any reason. These were installed on TVs and even some AC-DC radios for a reason: to prevent electric shock. There is almost always a warning on the back covers of 1950s-'60s AC-DC radios and, of course, televisions, stating that the interlock must not be defeated. To service the tubes, remove the back cover completely; do not try to service the set with the back on. I mention this because I'm sure some folks may have tried this; i. e. they would take the screws out of the top of the back cover, leaving the bottom and/or side ones in, and try to replace bad tubes while the unit was still plugged into the wall socket and turned on. :eek: I don't know how many people were shocked or killed this way; however, I will say this is a mighty foolish way to repair any radio or TV.

BTW: One series of radios I can think of right now that did not have AC interlocks were the Zenith H511s (H511Y, G, W, et al) of the early 1950s. These sets were potential death traps due, at least in part, to the lack of an interlock power cord, and also because they were "hot chassis" devices, meaning one side of the AC line was connected directly to the chassis. I sometimes wonder if these sets were UL approved, or even if Underwriters' Labs was even in existence in the early '50s. If they were, I cannot see how these Zenith radios would pass inspection without an AC interlock. :scratch2:
Your first statement was covered in an early entry.
All the warning language, stated on an electronic product, is to remove the liability of the manufacturer and to satisfy U/L requirements.
If someone disregards the warnings on the product and is injured or killed, they don't have a legal leg to stand on.
Regarding the Zenith H511 radio, if you look at the schematic, you'll see C-4, that is connected from B- to the chassis. Technically, it is not a hot-chassis design and can meet U/L standards.
Sixty years later, I'm sure that the cap is leaky and will pass more than the original designed voltage level.

5v3 was going bad I replaced it and the screen got bigger. But the power serge managed to kill the refrigerator too.
still not up to where it was but still

http://i1118.photobucket.com/albums/k603/Caramel_Shower/07091400061_zpsb1d673a7.jpg (http://s1118.photobucket.com/user/Caramel_Shower/media/07091400061_zpsb1d673a7.jpg.html)

try to replace bad tubes while the unit was still plugged into the wall socket and turned on.

Perhaps I am missing something here, or does this not just speak to a complete lack of common sense and stupidity?

I'm not sure how this interlock thing works, but it would seem that anyone with half a wit about them should START with unplugging ANYTHING consumer related, or at least anything not operating AFTER an isolated external transformer at low voltage, from the WALL socket. I get that this interlock thing I guess was designed to be a secondary "gateway" required before the set could be opened or whatever, but I'd have to assume anyone browsing this forum has enough common sense not to need such a nanny device and unplug the thing that could potentially kill you before doing anything else.

I suppose you could be liable if you sell the TV on to someone else or someone inherits it after you bypassed it. Is that where the concern lies?

This cord failure may have been caused by the reduction in conductor strands due to most being broken. The remaining few strands have to carry 2 amps (18 gauge cords are usually rated for 7 amps) and likely acted like a fuse, heating up, opening and then arcing to cause that much damage.

The stress at the interlock cap is very high. The cords are pulled enough in its 53-year life to have been severly compromised. I have many sets with cords that look OK but some do have the green slime (copper oxide?) but I hate to remove an OEM part unless I notice obvious tension damage or exposed conductors.

With old radios, and I sell quite a few, its easy to replace the pigtail (non-interlock) and put on some appropriately colored 18/2 SPT cord with a vintage-looking plug, be it polarized or not. Otherwise, if Im feeling cheap, I liberate a polarized one from a derelict chinese appliance, which are never in short supply.

This "event" with the 1961 Zenith gives pause because it probably looked OK. Collectively, we would do good to find some NOS replacement interlock cords and replace them as a matter of course when selling a set. I would never wire one direct, bypassing the interlock device.

5v3 was going bad I replaced it and the screen got bigger. But the power serge managed to kill the refrigerator too.
still not up to where it was but still
]
Some real wild occurances there! A defective power cord connection, caused all that.
Is the refrigerator on the same branch circuit as the TV?
Does the refer have the fancy control board in it? They're rather sensitive to surges and power dips.
The newer NEC, now requires arc-fault circuit breakers, that prevent the type fault, that occured. They are rather sensitive and sometimes they trip with a non-fault condition.
BTW, the set looks like it needs power supply electrolytics. :boring:

The set had all new filters, unless running them at 137V and then this short caused something with them.

This set has all new electrolytics, new by-pass caps and had been performing flawlessly for half a year.

The power cord was in perfect condition and transported NOT attached to the set. No visible damage to cord or plug socket.

Not sure what caused the cord to fry like that, but remember you ran it at 137 volts for some time. That may have done some damage. :tears:

Why was the set run at 137VAC?

Why was the set run at 137VAC?

Live neutral issue for the building, according to the power company tech who came out to fix it. 137v might not be the highest it saw, actually.

Have they since resolved that? That's a major issue.

Was the problem isolated to being within the building, or is it coming from the power company? If the former, then the building owner/landlord must have it corrected. If the latter, then it should be taken up with your state's public utilities commission.

The set's power transformer's core would start to magnetically saturate at around 137VAC. When that happens, the transformer primary starts drawing lots more current, acting like a coil of wire without the transformer lams. That could make a marginal cheater cord connection fail spectacularly. And the transformer will be unhappy as well, and it may be luck that the connector opened up vs the transformer burning out. Temporary excessive B+ won't be kind to some of the TV circuits either.

Bad neutrals are bad news to everything in the house.

The set's power transformer's core would start to magnetically saturate at around 137VAC. When that happens, the transformer primary starts drawing lots more current, acting like a coil of wire without the transformer lams. That could make a marginal cheater cord connection fail spectacularly. And the transformer will be unhappy as well, and it may be luck that the connector opened up vs the transformer burning out. Temporary excessive B+ won't be kind to some of the TV circuits either.

Bad neutrals are bad news to everything in the house.

The excessively high B+ is what probably distroyed the power supply electrolytics. The B+, really went to the sky when the set was first turned on and the rest of the circuits weren't drawing any current.
I thought that model had a three amp line fuse in it. It's a slo-blo and it would survive the inrush. :scratch2:

This was a home I believe. The power company did come out and fix his issue. However the set did have some run time at minimum 137VAC and maybe more. I believe the home was reading over 200VAC somewhere in the basement. I would guess that the issues the set is having now stem from the run time at these higher voltages.

This was a home I believe. The power company did come out and fix his issue. However the set did have some run time at minimum 137VAC and maybe more. I believe the home was reading over 200VAC somewhere in the basement. I would guess that the issues the set is having now stem from the run time at these higher voltages.

If it managed to kill the fridge, I'm surprised the TV actually put up with it for as long as it did, and only "failed" after the line voltage was corrected...

Aside from the warranty on the refrigerator being voided, The tv is good as new!
It was the vertical linearity pot. the wire that was wound up inside had poped out and went everywhere. as well as a few caps in the power went so I replace all that. And took a pot from the RCA and it works perfectly now. Thanks again for your help guys!

Damn I thought it was fixed now its doing this,
What the hell could it be now??
http://i1118.photobucket.com/albums/k603/Caramel_Shower/07121411021_zpsc5fa66e6.jpg (http://s1118.photobucket.com/user/Caramel_Shower/media/07121411021_zpsc5fa66e6.jpg.html)

You've lost vertical, don't run it like that much or you'll burn a line in the middle of the tube. (Turn the brightness control down while troubleshooting.)

I'd check the vertical osc/output tube first, then the vertical output transformer. The most likely suspect is the tube, as eight out of every ten failures in older tube-powered televisions are due to defective tubes. Also, the vertical hold control may be open, as could the vertical height and/or linearity controls.

I have a new in box VOT for that set if you need one.

Ok, So the Potentiometer I replaced? Yea replacing it with one from 1949.. Not good idea. So I replaced it again with a brand new one! works like new and it has full control now :D I'm so happy. Also Whats a VOT?

Vertical output transformer....