16" Zenith roundie - Videokarma.org TV - Video

charokeeroad · #1 12-31-2011, 05:07 PM

Just picked up a 16" Zenith Roundie and would appreciate some feedback on how to get the chassis out of the cabinet. Is it possible to slide the chassis out while the CRT remains in place? I took off the Ion trap and I can see that if I took off the spring wire that's joining the chassis to the CRT metal frame it might be possible to just slide off the focus coil with the chassis. The CRT cap was Knocked off at some point but all five leads are still intact. Just don't want to take any chances of further damage at this point. This is a two chassis set. I've already taken out the lower unit. 24H20 &24H21 Chassis.

thanks

dieseljeep · #2 12-31-2011, 05:50 PM

You would have a bigger chance of damaging the CRT by trying to remove it separately. There is no other support in the cabinet. All the CRT support is on the chassis.

charokeeroad · #3 12-31-2011, 07:20 PM

Thanks It came right out. Much easier than I expected.

cwmoser · #4 01-01-2012, 05:22 PM

I have a restored Zenith porthole TV - 16".
Mine uses the 16EP4 CRT.

BTW, if yours is like mine, there is a slide switch you need to unscrew from the front escutcheon before removing the chassis.

Carl

charokeeroad · #5 01-01-2012, 09:05 PM

Mine doesn't have the switch. The first thing I did this morning was to go out and see if the CRT at least had continuity through the heater. After scrubbing the probe ends against the wires sticking out the neck I finally got two to show a short. At least I know that the heater isn't open. I made a little diagram of the long leads and short leads assuming that the short ones were probably not used originally. I compared my sketch with a end cap diagram that I downloaded for that tube. To my surprise they didn't match up. One the cap diagram all the leads are in a row all five. On the tube the two heaters are well apart from the grid and bias leads. This is where thing could get ugly. I'd like to put the cap back on but unless someone knows how to get the right wire in the right cap pin I'm stuck.

I suppose that it's possible that the Heater is open and that the short I'm getting is something else shorted inside the tube but for now I'm going to assume the two shorted leads are the heater leads.

charokeeroad · #6 01-01-2012, 09:15 PM

Quote:

Originally Posted by cwmoser

I have a restored Zenith porthole TV - 16".
Mine uses the 16EP4 CRT.

BTW, if yours is like mine, there is a slide switch you need to unscrew from the front escutcheon before removing the chassis.

Carl

I have a 14" with the switch like yours. It's pretty cool switching from full roundie to the trimed view. Both work equally well.

The seller pulled the CL add before I could capture the pics of the 16" so I'll have to get some up here to show. When I got the 16" home and compared it to my 14" the 16" has an identical cabinet with the exception that the 16" is two inches wider. That cabinet really filled up my trunk and that's saying a lot.
The trunk on a Crown Vic is huge.

kvflyer · #7 01-02-2012, 07:30 AM

Quote:

Originally Posted by cwmoser

...
BTW, if yours is like mine, there is a slide switch you need to unscrew from the front escutcheon before removing the chassis.

Carl

BTW, Carl, you are right. I found out long ago that there is that little slide switch. I managed to pull the guts right out of the switch by the wires the first time I removed the chassis.

But it is a common slide switch and mine went back together with no problem. I would guess that pulling that switch apart several times would necessitate replacement though!

cwmoser · #8 01-02-2012, 08:04 AM

Yep, done that too:-) First time I extracted the chassis from my Porthole TV, I took my TV outside because it was so filthy. I pulled the chassis yanking the small knobs off and pulling the wires off the slide switch. I lost the knobs in the grass but found them the next day after realising they were missing.

These Zenith Portholes are very desirable TVs and I found a lot of fun restoring.

Carl

charokeeroad · #9 01-02-2012, 12:04 PM

I made a diagram of the end of the CRT as best I could make out by looking through the tube neck. Hopefully someone can tell me which lead goes to which cap position. I can see that the two heater leads would go to 12 and 1 but the others I have no idea. What is the "A" designation on the Sylvania drawing? Is the grid closest to the end of the neck G1 or G2. Also curious about the short lead that's attached to the grid. Thanks in advance.

ChrisW6ATV · #10 01-02-2012, 03:03 PM

I have always only seen CRT connections go straight from the glass into pins on the connector. Your CRT diagram would be the first one I have seen where the wires do not match up. The nearest I would guess is that the three adjacent long wires go to pins 10, 11, and 12, the next one to pin 1, and the last (clockwise) goes to pin 2. Do you have a CRT tester, particularly one with a "universal" adapter that has wires with clips? You could try it to verify the connections I described.

ChrisW6ATV · #11 01-02-2012, 03:19 PM

"A" on the Sylvania diagram is the anode (the high-voltage connection, in this case the whole cone of the metal CRT).

UPDATE: I just looked at the gun of my 5AXP4 test CRT that has the same base as your 16GP4 (and all of the other early B&W CRTs), and it does not have connections that line up with the pins on the base either. The physical order of the gun elements from the base toward the face of the tube should be cathode ("K"), G1, and G2, with focus beyond G2 if I remember right on CRTs that have a focus connection (not on this CRT).

charokeeroad · #12 01-02-2012, 03:27 PM

I haven't seen that many CRTs without the connector but the few that I have seen all came out streight also like you are saying so that's what's confusing. The conncetor and the CRT look to be original. My CRT tester doesn't have the universal adapter unfortunately. I did do a continuity test on the two heater leads and it was a short. I'm thinking I could possibly add some credibility to the drawing by doing some more continuity testing for example all the leads that go to G1 (the lower grid in the drawing) should if the drawing is correct short together but not short to the heater leads and so on.

charokeeroad · #13 01-02-2012, 03:32 PM

Quote:

Originally Posted by ChrisW6ATV

"A" on the Sylvania diagram is the anode (the high-voltage connection, in this case the whole cone of the metal CRT).

UPDATE: I just looked at the gun of my 5AXP4 test CRT that has the same base as your 16GP4 (and all of the other early B&W CRTs), and it does not have connections that line up with the pins on the base either. The physical order of the gun elements from the base toward the face of the tube should be cathode ("K"), G1, and G2, with focus beyond G2 if I remember right on CRTs that have a focus connection (not on this CRT).

Ok I'll check that out and see how it fits.

charokeeroad · #14 01-02-2012, 03:37 PM

should there be one or two leads per gun element?

Electronic M · #15 01-02-2012, 04:07 PM

Usually only one long lead per pin...