Zenith Porthole 19" H2447R - Videokarma.org TV - Video

StellarTV · #1 09-18-2013, 03:45 PM

Hey Guys,

Getting ready to restore a 19" Porthole; 24H20 chassis and I'm in the middle of doing the initial inspect to see if it's going to be worthwhile. CRT was replaced in '56 and has a brightener in it... the emissions came up to a useable range after I ran it on the tester for 15 minutes so I think I'm okay there.

The fuse in the HV cage is blown (this chassis has the flyback in a proper cage above the chassis)... given the difficulties with factory flys on these what does the jury say about the likelihood of this blown fuse indicating a bad fly? The coating on the donut is dried up and drooping off, nothing looks burnt or melted. I''ve got about 360 ohms between horizontal output plate caps and the top of the 1B3.

One thing I found interesting is that there is an extra 6au6 piggybacked on top of another 6au6 in the 2nd IF stage with a tunable coil attached. Will post pics later.

StellarTV · #2 09-18-2013, 10:56 PM

...and then that odd little double 6AU6 plugged into the 2nd I.F.:

cwmoser · #3 09-19-2013, 09:44 AM

Justin, I have that same TV too.
Mine is a 19" using the 19AP4 CRT but mine is a little weak.
The picture does get very viewable after it warms up a bit.

Big heavy cabinet especially when you compare it side by side to the 16" model. Note the tint difference between the 16EP4 CRT and the 19AP4.

Carl

John Marinello · #4 09-19-2013, 10:09 AM

I just picked up another one of those about 3 weeks ago, in remarkable condition.
Tempted to plug it in & see what happens. The "Byron". Yours is the first 19-incher I've seen that uses the angled 6AU6 IF strip, might be an early set. Curious to see if it uses an integrator or a diode. That set should have a 24H21 chassis in it.

cwmoser · #5 09-20-2013, 07:49 PM

Quote:

Originally Posted by John Marinello

I just picked up another one of those about 3 weeks ago, in remarkable condition.
Tempted to plug it in & see what happens. The "Byron". Yours is the first 19-incher I've seen that uses the angled 6AU6 IF strip, might be an early set. Curious to see if it uses an integrator or a diode. That set should have a 24H21 chassis in it.

John, you got an uncanny ability to sniff out the nicest Zenith Portholes.

Carl

StellarTV · #6 10-01-2013, 03:33 PM

First signs of life today... and what an interesting set of circumstances.

I recapped the power supply. I noticed that even after bringing the set up slowly on the variac that quad section filter was getting too hot to touch. Brought it up slowly afterward.... okay, I can hear the horizontal oscillator running.... can't hear the vertical oscillator at all and screen is dark.

I used a long screwdriver to check for HV at the 1B3... nope. Voltage at the top of the horizontal output... .nope, nothing. I have a decent multimeter that I've used before to check the raw DC level in horizontal circuits, except this time I made a mistake. I set the multimeter to OHMS instead of DC, touched the probe to the top of the 6DQ6... the multimeter buzzes and lights up from the inside (could see it through the plastic!) and the high voltage comes up on the TV!

So my multimeter is smoked but it seems to have somehow resuscitated the TV... Haha.... My reward was a nice bright raster about 1/3" tall. Glad the flyback is OK.

Quote:

Originally Posted by John Marinello

I just picked up another one of those about 3 weeks ago, in remarkable condition.
Tempted to plug it in & see what happens. The "Byron". Yours is the first 19-incher I've seen that uses the angled 6AU6 IF strip, might be an early set. Curious to see if it uses an integrator or a diode. That set should have a 24H21 chassis in it.

John, According to the sticker inside the cabinet, it is in fact a 24H20. I don't see that little 3 legged vertical integrator module on this chassis, if that's what you're talking about.

Also, looks like we now have a pair of the same exact TVs! Here is a quick series on the other one I'm restoring, just had the cabinet finished:

wa2ise · #7 10-01-2013, 03:42 PM

Hard to imagine this setup doing anything other than going into oscillation. Especially at 45MHz.

John Marinello · #8 10-01-2013, 10:37 PM

[QUOTE=StellarTV;3083898]

John, According to the sticker inside the cabinet, it is in fact a 24H20.

The sticker in your cabinet will say "TV Chassis 24H20 & 24H21".

The sticker will say "16GP4A or 19AP4A" for the CRT.

See attached.

Username1 · #9 09-19-2013, 10:22 AM

Is that double-decker tube thing stock ? or some kinda thing to get ya tv signals from the past somehow.....

Electronic M · #10 09-19-2013, 04:55 PM

I think the 6AU6 stack is an aftermarket device to boost fringe area reception. I believe one is on display at the ETF.
I thought they were for the tuner stage tubes but I might not be remembering properly.

cwmoser · #11 10-01-2013, 04:24 PM

Justin, I have a Porthole TV exactly like your 16"er that you had the cabinet
restored. Its called the "Lincoln" model.

BTW, that looks like a really nice cabinet refinish.

Did yours have a 16EP4 or a 16GP4 CRT?
My chassis was so rusted that I had to paint it.
But, it looks good now and plays decently.

Carl

StellarTV · #12 10-01-2013, 05:03 PM

Quote:

Originally Posted by wa2ise

Hard to imagine this setup doing anything other than going into oscillation. Especially at 45MHz.

Right?

Quote:

Originally Posted by cwmoser

Justin, I have a Porthole TV exactly like your 16"er that you had the cabinet
restored. Its called the "Lincoln" model.

BTW, that looks like a really nice cabinet refinish.

Did yours have a 16EP4 or a 16GP4 CRT?
My chassis was so rusted that I had to paint it.
But, it looks good now and plays decently.

The guy who did the work is a miracle worker with wood refinishing. His work is top notch and pricing would be considered affordable even 25 years ago. This cabinet had paint, gouges and a cigarette burn on the top and now it looks brand new. That is also a considerably poorly lit photo. I give him a hard time because when he brings something back he's very modest about it... "okay now, I wasn't quite able to get this or that right"...then he unwraps it and it's gorgeous. He runs a full time business from home out here in Sacramento.

I polished the bezel out on a buffing wheel with some tripoli. High polished the brass and nickel and used some gold touch up paint to shoot the outside, then covered everything over with a clear lacquer.

My 16" set has a 16EP4 in it. Emissions are a little sad on it but still useable. It usually takes about 10 minutes to come up to the good range on the tester after sitting unused for over a week. At first light it always seems like it's completely dead. I think it's gassy.

Here's another so-so pic of that cabinet

StellarTV · #13 10-02-2013, 04:50 PM

You're absolutely right! I went back when I got into the shop this morning to see where the heck I saw 24H20.. I was so sure I remember a rubber stamp label somewhere but can't seem to find it. Crazy Justin seeing aliens around the bed again... I must have seen that sticker and not read it thoroughly, or I'm remembering the 16" chassis I'm also working on simultaneously at home which is more likely.