GE 14" Safety Question
 

So, I nabbed a pretty sweet little GE 14T007.

https://i.ibb.co/rM59tmw/IMG-0126.jpg

Although I currently am enjoying just admiring it on display, I do plan on embarking on a fair amount of testing. I'm fairly new to this hobby and haven't worked on anything like a GE, which has most of its components hidden on the other side of a chassis "firewall".

https://i.ibb.co/qkpYLVL/IMG-0131.jpg

I want to put a CRT tester on it and then later test for at normal power for raster with test patterns and will want to discharge the CRT before removing the chassis. I don't see anyway to do that before doing so since I can't get to the anode from the back.

Is there a safety concern in handling the chassis before the picture tube can be discharged?

Have you restored a vintage radio or two first? That is always a good start.

I wouldn't bother trying to power up the set before you at least replaced the electrolytic capacitors, you could damage expensive parts. Testing the CRT as well as the other tubes first is also a good idea. Clean up the interior is best done before you start the re-cap. When you pull the CRT socket off the tube be extra careful, if there is a bakelite tube base on the CRT it can come loose. It is a good idea to pry the base and the socket apart with a small screwdriver the first time at least, age can make the two stick together. Speaking of safety, be very careful with the neck of the CRT, the glass is the thinnest there, about as thick as a wine glass. The difference of air pressure due to the vacuum is almost 15 lbs per square inch. That means an area 8 inch square has a total pressure of about half a ton on it.

This article by Phil Nelson (a member here) about a RCA set that has a similar cabinet and chassis construction.
https://www.antiqueradio.org/RCA_14-...Television.htm

Yeah I’ve done some restoration and have some experience. Just haven’t worked on a set where the crt anode cap is inaccessible unless u remove the chassis. Just wondering if there’s a way to discharge everything before handling the chassis. Of course the chassis won’t be hot because of it not being plugged in but there may be a possiblilty of charge caps or crt.

Not familiar with this chassis, but it looks like the panel with the high voltage dischage label swings open to reveal the flyback and rectifier, so you can discharge at the rectifier output.

Now THERES an idea! :D

What makes this set even more rare is the UHF tuner. You rarely saw them until they were made mandatory in the 1960s (unless you had a dominant UHF station in your market). This set is definitely worth restoring if no major component is dead.

Yeah and the dial string is broke. You can see the broken end sticking up.

I don't remember if you can remove the chassis from the back on this one, or if you have to remove the CRT and go out the front, either way you should be able to have enough slack to reach in and remove the anode connector from the tube, just slip a grounded screwdriver under the cap to discharge it.

You have to slide the yoke off the CRT as you go so loosen the clamp and remove it first,

Except the CRT anode is connected to the rectifier BASE, not the cap.

I'm no stranger to working on that set! It's kind of tricky to remove the chassis. You have to reach in from the right side to remove the second anode lead, after removing the yoke. You might have to remove the speaker too?
The last one I took apart, I scrapped.
The one shown is the real cheapie model, no handle!
IDK if that's the early or late production? The early one uses a 5AN8 in the horiz AFC and audio IF, where the later one uses a 3AU6 and diodes for the AFC.
I had a Motorola that was similar, but was a lot better.

Thanks for the responses thus far!

I'm really in no hurry to jumpstart the TV, so I think I'm going to take my time and play it safe and at least test the filter and HV caps before proceeding. I do want to test the CRT, even though I've seen pics of it working from the previous owner.

I have some problems with the CRT tester (B&K 465) and am prioritizing that a bit, replacing some aging components, such as totally open and dry Sprague Atoms, and treating oxidation. The meter is wacked out and quite inaccurate and so I probably need to replace diodes - but thats a topic for another time.

BTW, I've taken a picture of the removal procedure from the Sams in case anyone's interested. Step 6 seems the most tricky!

https://i.ibb.co/6bknsYK/IMG-0153.jpg

Someone mentioned the UHF tuner. Yes, it's pretty cool that it has that option, even though it seems like it's basically unusable these days (?) And, yes the UHF dial cord has broken off. Here's a pic of the dial cord diagram from the Sams...

https://i.ibb.co/7Rh0mgN/IMG-0154.jpg

And here's the other side of the chassis, where the party's at. I'm pretty much all "Mousered Up" so I have what I need for a recap...Even a 1KV .015!

https://i.ibb.co/vJsVL1y/IMG-0155.jpg

Quote:

Originally Posted by dieseljeep (Post 3224556) I'm no stranger to working on that set! It's kind of tricky to remove the chassis. You have to reach in from the right side to remove the second anode lead, after removing the yoke. You might have to remove the speaker too? The last one I took apart, I scrapped. The one shown is the real cheapie model, no handle! IDK if that's the early or late production? The early one uses a 5AN8 in the horiz AFC and audio IF, where the later one uses a 3AU6 and diodes for the AFC. I had a Motorola that was similar, but was a lot better.

No handle is right! More classy that way!

Interesting info - Looks like late prod maybe - I'm seeing a 3AU6 for the audio IF.

Discharging at the HV cage, whodathunk!.

On my kcs96 (chassis wrapped around the picture tube neck) it didn't matter how many times I discharged the HV lead with the long screwdriver it still managed to zap me when I reached my arm in there to unhook it from the pic tube. On that set if I take the yoke off I can get my arm in there between the chassis and pic tube neck.

I have done 3 of these sets. You have the early version. Chassis removal is a pain....I think I got the chassis half way out such that I could reach the HV connector on the CRT and discharged it with a probe. I have the Beitmans service manual (a reprint of GE service manual) for the late set and it reccomends crushing defective original caps and resistors on the PCBs and twisting the old and new component leads together and soldering....I have to agree with that approach....the solder side of the PCB is blocked by the chassis and unscrewing the boards to get at the solder side usually destroys the factory board standoff grounds and involves unsoldering several wires...

HV dielectric bounce back!...It is a treacherous bitch. On almost all sets you will get it if you dead short the HV to discharge. The best way to avoid bounce back is to discharge the HV through a resistor 1M or higher....I almost always use my HV probe to discharge and never get zapped when I do....it's always when I cheat and dead short the HV (or neglect to discharge it at all) that I get shocked....

getting shocked ( i mean by the HV) is half the fun with old sets like these!
:D
you have not lived until POW-ZAP! your hair is standing on end!

I have a 465. I doubt very much the diodes are a problem. Five of the six are silicon and the sixth is germanium in the meter circuit. Much more likely is the switches and pots, even the cable is a possibility since it is flexed in use.
Hopefully the panel meter itself is OK.

Ooh I've lived plenty...Ever seen the movie office space?...I kinda regard the HV stored in a powered off set like the protagonist regards that staticy doorknob: a necessary annoyance. I hardly even flinch in most screwups...just cus a bit.
The real scary thing to get bit off of is the yoke and the H output top cap of a powered on set...those can supply lethal current, and even if you don't get it across the chest and live to tell they will still char your skin and leave a nasty burn...I have learned that the hard way twice. :stupid: :withstpd:

When dealing with a powered up set everyone should always keep one hand in a pocket or wear rubber gloves...

I love the smell of skin burn in the afternoon, it smells like... YUCK! :o

I remember working on a Zenith hybrid in HS, got a little TOO CLOSE to one of the many electrified metal tabs in it that are sticking up (300v+ or so ), instant automatic reaction was to pull my arm back, this caused the tab to cut in deeper and burn a nice long line on my arm as it went. :( instantly cauterizing as it went.

Still have the scar.

Ouch! That had to have been a bad day.:thumbsdn:

Burnt skin is up there with 'strand of hair lands on the soldering iron' in the least appatizing smells working on electronics department.

Ever had an RF burn from a transmitter feed line? There's no feel or sensation at all, just the wafting smell of burning hide. :yuck::eek:

I'm not sure about this chassis, but a GE that I have with much the same chassis as this is hot and sits on nylon insulators, and insulated tuner shafts.

All metal parts, chassis, HV cage, tuner are connected to 1 line of the 115 volts ac.
If this is the case with yours also keep this in mind and also check the insulators and take note of the screw lenghts. And check the cabinet with a meter after you reassemble.
Also seing as you're new to tv's, save yourself a great deal of hassle and mark the position of the ion trap on the crt neck with a marking pen before you take it off.

Nice looking set. Best of luck.

Quote:

Originally Posted by Electronic M (Post 3224578) I have done 3 of these sets. You have the early version. Chassis removal is a pain....I think I got the chassis half way out such that I could reach the HV connector on the CRT and discharged it with a probe. I have the Beitmans service manual (a reprint of GE service manual) for the late set and it reccomends crushing defective original caps and resistors on the PCBs and twisting the old and new component leads together and soldering....I have to agree with that approach....the solder side of the PCB is blocked by the chassis and unscrewing the boards to get at the solder side usually destroys the factory board standoff grounds and involves unsoldering several wires... HV dielectric bounce back!...It is a treacherous bitch. On almost all sets you will get it if you dead short the HV to discharge. The best way to avoid bounce back is to discharge the HV through a resistor 1M or higher....I almost always use my HV probe to discharge and never get zapped when I do....it's always when I cheat and dead short the HV (or neglect to discharge it at all) that I get shocked....

I have no problem with the crushing/J-hook method. I just did some of that on my Philco. I didn't even have to take the chassis out - just worked on the IF board with the back open.

The term "dielectric bounce back" is a new one to me. I didn't know what this was called, however I was observing this phenomenon the other day with a pair of electrolytics, a voltmeter, and test clips with and without a bleed resistor, and sure enough it's the case.

Quote:

Originally Posted by old_coot88 (Post 3224596) Ever had an RF burn from a transmitter feed line? There's no feel or sensation at all, just the wafting smell of burning hide. :yuck::eek:

Negative. I haven't experienced that and I'm an Extra class ham!

Quote:

Originally Posted by Tube TV (Post 3224599) I'm not sure about this chassis, but a GE that I have with much the same chassis as this is hot and sits on nylon insulators, and insulated tuner shafts. All metal parts, chassis, HV cage, tuner are connected to 1 line of the 115 volts ac. If this is the case with yours also keep this in mind and also check the insulators and take note of the screw lenghts. And check the cabinet with a meter after you reassemble. Also seing as you're new to tv's, save yourself a great deal of hassle and mark the position of the ion trap on the crt neck with a marking pen before you take it off. Nice looking set. Best of luck.

Great advice. Will do!

https://en.wikipedia.org/wiki/Dielec...y%20discharged.

Quote:

Originally Posted by Electronic M (Post 3224593) Ooh I've lived plenty...Ever seen the movie office space?...I kinda regard the HV stored in a powered off set like the protagonist regards that staticy doorknob: a necessary annoyance. I hardly even flinch in most screwups...just cus a bit. The real scary thing to get bit off of is the yoke and the H output top cap of a powered on set...those can supply lethal current, and even if you don't get it across the chest and live to tell they will still char your skin and leave a nasty burn...I have learned that the hard way twice. :stupid: :withstpd: When dealing with a powered up set everyone should always keep one hand in a pocket or wear rubber gloves...

Yeah man. I hear you loud and clear. I have a healthy respect for the dangers inherent in this hobby. There is a touch of excitement derived from "riding the lightning" that, but rest assured I have no desire to get zapped. I'm trying to do as much homework before getting started, and yes I wear rubber padded gloves, kinda like a mechanic wears, or I have the super rubber gloves.

I've been zapped already from a non discharged CRT once and that time really wasn't too bad. It just felt and sounded like discharging to a doorknob during a dry winter. I've gotten AC zaps off of transformers and chassis countless time, even once across my chest and I definitely dont want to repeat that mistake. I do the one hand in pocket thing.

Quote:

Originally Posted by Notimetolooz (Post 3224590) I have a 465. I doubt very much the diodes are a problem. Five of the six are silicon and the sixth is germanium in the meter circuit. Much more likely is the switches and pots, even the cable is a possibility since it is flexed in use. Hopefully the panel meter itself is OK.

I missed your post earlier, and you're right, all of the diodes I tested (couldn't find the 5th Silicon) were fine. It was a case of bad electrolytics, dirty pots, and an out of cal meter.

Now it reads fairly accurately.

I'm not sure if the Cutoff test works though. The meter didn't go anywhere on the test, adjusting the G2 knob. Not sure what's going on there...

The CRT on the GE tests fine - low end of 'GOOD' which I think is pretty decent for a 65 YO

I have the Hotpoint version of this GE and have worked on some others. The WORST discharge I ever got was from a '68 GE color when I was 14, I was running it with the shunt regulator cap off thinking that was intermittent HV cause, and when it did not fix the issue, I leaned over the metal escutcheon to replace the insulated cap onto the 6EJ4, and pow - just like that I was tossed backward. I saw stars!

That view of the PC board brought back memories of being dumbfounded any one would design this way. At least RCA 14" from 56-57 was hand wired, not like PC board sets of 1958 and later, that also required clip and hook replacements.

The CRTS were survivors - 70 degree with a standard tube gun. The first step to take is replace the selenium rectifiers, input doubler cap and the filter caps.

GE tended to use better (still bad by now) wax caps and you may be surprised if you do just the power supply, then fire it up.

I call that a viability test, to see if yoke-fly-crt-vot is OK. The wax caps are still needed, or it won't work for long. That UHF tuner is a definite plus, I never saw one on a GE.

Quote:

Originally Posted by DavGoodlin (Post 3224733) I have the Hotpoint version of this GE and have worked on some others. The WORST discharge I ever got was from a '68 GE color when I was 14, I was running it with the shunt regulator cap off thinking that was intermittent HV cause, and when it did not fix the issue, I leaned over the metal escutcheon to replace the insulated cap onto the 6EJ4, and pow - just like that I was tossed backward. I saw stars! That view of the PC board brought back memories of being dumbfounded any one would design this way. At least RCA 14" from 56-57 was hand wired, not like PC board sets of 1958 and later, that also required clip and hook replacements. The CRTS were survivors - 70 degree with a standard tube gun. The first step to take is replace the selenium rectifiers, input doubler cap and the filter caps. GE tended to use better (still bad by now) wax caps and you may be surprised if you do just the power supply, then fire it up. I call that a viability test, to see if yoke-fly-crt-vot is OK. The wax caps are still needed, or it won't work for long. That UHF tuner is a definite plus, I never saw one on a GE.

You say you worked on a version of this TV? The one thing I would like to know is if it's possible to power on the set with the CRT outside the chassis, so you don't have to go in and out of the chassis as you're working on it.

It's series heaters so you have to short the heater pins or connect a dummy load resistor of correct value (which you compue the resistance and power of based on the current and voltage spec of the CRT heater on the CRT data sheet.

One option to service this set is to remove both the CRT and chassis from the cabinet then connect the 2 on the bench. If you have a long length of spare HV wire for the HV lead you could extend the HV and yoke leads to reach into the cabinet with the chassis outside the cabinet and use the sets own cabinet and CRT as a test jig for it.... probably good to put any floating HV connections in a glass jar or mug to prevent arcing.

Okay, time for one of Johnny's boring old timey stories:

My dad told me the time he was hanging around the parts counter of his favorite parts supplier (they had the best coffee) and a service man walked in the door with an unboxed picture tube in his arms. He didn't like to pay for the dud (that's what we called the core charge in the old days) and then have to return the dud for credit, so he brought the tube in bare to exchange in the carton right then and there.

As he walked towards the counter, a loud snap was heard and the guy tossed the tube straight up in the air. Dad says everyone hit the dirt like a grenade was tossed, but I think he was just reliving his war years.. Anyway, the guy caught the tube basket style that would have done Willie Mays proud and a tragedy of unimaginable proportions was avoided.

John

Couldn’t you just back the crt into the chassis, with anode and yoke connected, when both are outside the cabinet? Just park the crt where it was minus the cabinet, or am I missing something?

Situations like this are why they had Test CRT's.
For a set like this the 8XP4 would be used.

We can all share our stories in any applicable thread. I ALWAYS think about this when I handle a bare CRT!:scratch2: Zap and bang stories like this are endless, so keep them coming!

I have to pace myself Dave! I grew up in the business and could write a significantly sized book of stories from the trenches, but I'd like to contain myself to one every month or two. Certain threads will ping a long buried memory. Some day, someone will comment on constantly blowing fuses and I have a beauty ready to go.. :banana:

John

This TV does have a fuse, right after the AC interlock. It lists it at 1 6/10 Amp. I'm thinking of putting a thermistor after it.

Ok now you can go ahead with your fuse story...:smoke:

Rat.

Okay, this took place in the early 80s on a Zenith System 3 (which doesn't really fit this section). I was on a house call when I found the 4A slow blow fuse blown on the 9-160 power/sweep/HV module. Zenith guys know that when the 160 had a blown fuse, you swapped the module out - changing the fuse was a waste of time.

Meanwhile, the customer is all over my shoulder saying it must be the fuse - that's all it needs. I told him that a blown fuse in this board meant problems, but he wasn't convinced, so I found the biggest fuse I could find in my tool box which was an 8 amp IIRC.

I snapped the fuse in the holder, plugged the TV in, and had the customer get down near the fuse and keep a *real* close eye on it so he could tell me if it blew. I walked around the front of the TV and pushed the power button. I could hear the telltale soft pop of a blown fuse and the silhouette of the guy against the wall for a split second.

I asked him if the fuse blew. He came out from behind the TV wide-eyed. I'm sure he saw that flash every time he blinked for the next half hour.

He didn't question the replacement 9-160 board after that.

John

Haha
Keep a REAL CLOSE EYE on it

That fuse story is a hoot...I was kind of expecting fire and or a transistor to splode given the biggest fuse I could find line...

Yes, that is what I described in the first sentence of the second paragraph...the rest of the paragraph was describing lead extensions for if you wanted to keep the CRT in the cabinet.

hot chassis / cabinet
 

This may have been mentioned already or you may be familiar with HOT CHASSIS ,depending on how AC plug is in power outlet. These type TV's ,GE and others had a bad reputation in the 50's /early 60's for chassis that were hot and that shock hazard transferred to the metal cabinet in some cases.
There were even deaths reported caused by this problem on GE's in particular ,the feds investigated along with UL.

Check and recheck when you put this set back together.
Be careful

Al