Admiral Roundie Something explodes

[tvcollector]

I picked up an old Admiral console locally from an ad, i get it home and plugged it in and turned it on, and noticed the tubes lit up, and the high pitch noise, like any other crt noise, so i guess the flyback was getting HV, and i noticed a transformer humming noise, i was playing with the volume, and there was a little crackle, like a dirty control, no sound like a station not being picked up, and the picture didn't come on, and i noticed the CRT tube didn't lite up.. All of a sudden i heard a loud explosion, like air coming out of something, and a burst of white smoke that filled up the room for the most part, and a weird smell like a damp type smoke, looked like it was coming from under the chassis, near where the power transformer is.. I looked under there and could not see anything that looked like it got fried. and none of the tubes looked like they exploded. All i know is that i unplugged the damn thing right after.. I wonder what did this? anyone have a clue?


When i looked at the chassis, i saw all the paper caps still there and the huge original electrolytics.. I hope it was something replaceable that blew up..

[bandersen]

Looks like one of these: http://www.tvhistory.tv/1948-Admiral-7845.JPG

I really like that basketweave cabinet.

Most likely an old paper cap popped. You could also have one or more shorted electrolytics which cooked the 5U4 rectifier tube until it popped.

Hopefully, none of the hard to replace components fried. I strongly recommend you at least replace the electrolytics and any visible fried paper cps before trying to power it up again. Better yet, replace all the old paper caps. Some of the micas could be bad too.

[tvcollector]

I found a local guy in the area that restores old sets.. He's charging basically next to nothing, because he enjoys these projects.. I'm going to have him take a look at it, and have him replace all the bad components like caps, resistors, etc.. It's basically that same set pictured, other than a few minor differences like the legs on the bottom.. I would say for the $80 I spent, the cabinet is solid and in great shape other than a few nicks here and there..

[Jeffhs]

This is why just about everyone on VK (myself included) tells anyone about to restore an old TV or radio not to power up the set before recapping it (at very least replacing the power supply filters). Your Admiral TV is 63 years old; many if not most of its original capacitors are defective or are about to fail. Don't plug it in again until those filter caps are replaced with new ones; for the best possible performance, I'd replace the old wax paper caps as well. The job will take some time, but it will be worth it when you see the vastly improved results. When they are operating at peak efficiency, these older TVs can, and often do, outperform many times over today's CRT or flat-panel sets. Admiral was a well-known TV and radio manufacturer, known for quality products, from the '30s through the seventies, so your set was well-made and should serve you well once the caps are replaced, the tuner and controls are cleaned, and any weak or doubtful tubes replaced.

I would say you were extremely fortunate that the power transformer was not damaged or destroyed when the set started smoking (though the rectifier tube may well have been cooked as well, as bandersen mentioned). A short in a filter capacitor will put a direct short circuit across the transformer's B+ windings, ruining the latter in seconds if the set's power supply is not fused.

BTW, do not remove the rectifier tube while the set is plugged in and turned on, and never install the tube with the switch on and the set playing. This could damage or destroy the power transformer or other components of the power supply. I blush to admit I did just that about 40 years ago with a 1951 Majestic b&w roundie and got away with it (the set worked afterward), but I think that was a stroke of very good luck. Usually you do not get second chances with these; once the transformer burns out or shorts you may have a very difficult time finding an exact replacement.

BTW (2): Another thing that can and often does destroy the power transformer in parallel-filament televisions is if the horizontal oscillator stops or is far off frequency. The reason is that very old TVs had horizontal output stages that operated on grid leak bias. If this voltage is missing on the grid of the horizontal output tube for any reason, the plate current of that tube will go off the charts and will overload the power transformer. If the power supply is not fused, the transformer will burn out in very short order.

[miniman82]

Why doesn't each forum have a sticky that says 'DON'T PLUG IT IN!!!'

Every once in a while a post like this comes up, to remind me that what we do here is NOT common knowlege, or even common sense.

[tvcollector]

does any of these components in this set contain PCBs, I read something about the chemicals in old caps that explode could cause lung cancer later on if you breath in the fumes...

[jpdylon]

If you're worried about being harmed by PCBs, you should NOT be working on old sets. These were all made before ANY environmental or health provisions were put into the manufacturing process.

Just use your head. Always keep the work area properly ventilated, wash your hands after handling parts, solder, or anything that could be considered questionable.....

and for God's sake, don't just plug something in like that! The chances of you destroying un-obtainable parts or starting a fire are huge. Always replace capacitors and any worn power supply parts, and do resistance checks before powering up. Power up without sweep tubes in to check voltages and waveforms, then do vertical sweep and boosted B+, then finally horizontal sweep and high voltage.

Take your time, use your head, and be careful and you'll end up with a great restoration and your health to boot!

[tvcollector]

well now i know, to not plug in and attempting to power up something that old, without replacing bad caps, and parts, i don't know how to run test equipment yet, thats why im going to have somebody come over and replace all the caps and bad bad parts, Im probably capable of replacing the caps my self, but id rather have the person i know come over and do it, and watch so i know what to do next time i find something this old.. Plus i don't have many caps either and would not know what to purchase to replace the paper caps and others with no writing on them..

[maxhifi]

Hazardous materials are there, but PCBs will only be in oil filled capacitors or transformers. These are quite rare in consumer electronics, maybe more common in commercial/industrial or military. I haven't seen any PCB filled capacitors or transformers in any of my old radios or TVs, but my old RCA MI series audio amplifiers have them.

There might be asbestos somewhere, as a heat shield - watch for it, it's a white fibre sheet used as heat shield, and just don't do anything to release the fibres. The solder is certainly not lead free, but I am not sure how much of an issue that is except when it comes to disposal. And plenty of nasty stuff in the picture tube, but I wouldn't worry too much about that, because it's sealed in, and is more of a disposal problem.

I'd also be worried about organic stuff, like mold, or debris left by rodents or insects. Don't know what your area is like, but some places are experiencing a bedbug outbreak, so be cautious about accepting anything from low rent apartments or places with a transient population. The whole bedbug scare has certainly prevented me from taking home as much 'stuff' as I would have otherwise.

[tvcollector]

I had my friend come for the first time, to look at it, and i told him, the fuse inside is blown, probably from me turning it on, he said the Power Transformer is probably fine, I'm giving him the project to work on without a huge rate, and he's going to first test the picture tube to make sure it's good.. Of course the set would not be worth fixing without a good CRT.. If good, He's going to then recap the whole chassis and then find out what and if other things like Resistors and tubes are bad..

[bandersen]

I'd definitely still restore it if the CRTs is bad. Replacements are floating around.

[tvcollector]

bandersen, you're right, i'll probably still have the set restored even if the CRT is no good or week.. I just don't know where to get another, other than finding someone who has the same size roundie CRT that would work in there parts collection.. Unless there is another source i don't know about..

[bandersen]

Originally Posted by tvcollector

bandersen, you're right, i'll probably still have the set restored even if the CRT is no good or week.. I just don't know where to get another, other than finding someone who has the same size roundie CRT that would work in there parts collection.. Unless there is another source i don't know about..

I figure it's either a 10BP4 or a 12LP4. 10BP4s pop of fairly regularly. Ask the collector community or check ebay. I think there's one or two on there know.

[tvcollector]

I'll have to check into that, if the CRT is week.. Thanks for the info..

[tvcollector]

I just did a test on the CRT using the universal Adapter on my Sencore CR70 following the instructions on where to put each labeled connector on the numbered pins, I set the voltage as followed, and when i get to the cut off setting, needle doesn't move when i power on the Sencore to set the cut off in between the range, also adjusting the the cut off does not make the needle budge, Also i go into emission test, needle does not move, when i check for G and HK shorts, needle goes to the upper good side, also the Sencore does not power up the tube (Makes it light up).. I'm guessing maybe the pins are not making contact, some of the pins also wobble real loosely.. I wonder if this is going to be a problem..

The crt is a 12Lp4..This looks to be a color set?