My new Zenith 14A9C50 - Videokarma.org TV - Video

static1701 · #1 03-26-2019, 05:52 PM

I picked up a Zenith TV from 1970 on Marketplace, after reading about it I decided to give it a try before replacing anything. I did bring up the power slowly and at around 90 volts I got a picture. Happy with the results, it did not pick up my analog channel from my BT transmitter but the tuner is very scratchy. I have the VHF knob but it needs to be glued. Overall the set is in nice condition. I use to have one like this in the metal cabinet years ago... wish I still had that one. Anything special to know about restoring one of these?

Electronic M · #2 03-26-2019, 06:09 PM

Ground solder joints can go open, HV reg thermistor can go bad (DRH4683 has a thread here on how to fix that), and I've seen a couple Zeniths from that time with unsoldered tuner power wiring (must have had a lazy assemblyline worker).

ESigma25 · #3 03-26-2019, 09:21 PM

Those are my favorite style of console sets, I have a 1978 RCA with similar layout. Beautiful set, shame the knobs are missing!

static1701 · #4 03-27-2019, 06:38 AM

I have the knobs, they just need to be glued. both the fine tuning ring and the channel selector are broken but I can fix them. It looks like they were broken long ago and glued before.

dieseljeep · #5 03-27-2019, 09:51 AM

Quote:

Originally Posted by static1701

I have the knobs, they just need to be glued. both the fine tuning ring and the channel selector are broken but I can fix them. It looks like they were broken long ago and glued before.

It doesn't look like much was done to it through the years.

static1701 · #6 03-27-2019, 03:52 PM

Once I get it working correctly I am going to look at removing the safety glass to get rid of the cataract. I have watched a bunch of videos on how to do it. Seems like a big job but if this turns out to work well it will be worth the effort.

Electronic M · #7 03-27-2019, 05:40 PM

Use the guitar string method. You don't need to heat the wire and it is safer than all the heat based methods...And on green cataracts like yours water is completely ineffective.

old_coot88 · #8 03-27-2019, 06:03 PM

Quote:

Originally Posted by static1701

Anything special to know about restoring one of these?

Back in the day, the biggest problem we ever saw with these was the HV regulator tube. In the intervening decades, other stuff may have cropped up like that thermistor etc.

static1701 · #9 03-27-2019, 06:40 PM

I started testing the tubes but ran into problems with my tube tester, the compactron socket is not working (Won't heat) I did find both tuner tubes are bad but not shorted. I attached some pictures using my pattern generator. Going to figure out the problem with my tester so I can continue testing the tubes.

Electronic M, thanks for the correct method to remove the cataract.

Electronic M · #10 03-27-2019, 08:48 PM

Seems like everything but the receive chain is functioning close to correct.

Your going to need to do purity (based on the second pic), greyscale (Pic is too red and blue on the monochrome patterns), and possibly focus adjustments.

Typically there are 2 standard heater pins for compactrons. If the solder lugs on that socket under the tester chassis have voltage, then the ends in the socket are probably dirty, bent such that they don't grip the pins, or have gone open (also possible for the pins of a tube to be too corroded to make contact, but that can be debunked by trying a different tube).
Try and clean the socket, if that don't work try desoldering the leads from the heater pin terminals and pushing them out the top from the bottom then tightening the pin grip or replacing the contacts with ones from a similar socket.

static1701 · #11 03-27-2019, 09:18 PM

I fixed my tube tester. 2 different wires were wrapped but not soldered. I could not believe it. Soldered them and tested the rest of the tubes. 6HA5 rf amp, 6GJ7 Ocs / Mixer, 6MN8 Color amp, 6HE5 Vert Output (Shorted), 6KT8 Sync Sound / Limiter are all bad. Surprised it works as well as it does.

dieseljeep · #12 03-28-2019, 09:50 AM

Quote:

Originally Posted by static1701

I fixed my tube tester. 2 different wires were wrapped but not soldered. I could not believe it. Soldered them and tested the rest of the tubes. 6HA5 rf amp, 6GJ7 Ocs / Mixer, 6MN8 Color amp, 6HE5 Vert Output (Shorted), 6KT8 Sync Sound / Limiter are all bad. Surprised it works as well as it does.

Was that a factory or a kit built tester?
ESRC in Florida has a few of those tubes for a buck each.
I don't remember the Zenith knobs breaking that easy. They seemed to be made of a better plastic.

static1701 · #13 03-28-2019, 02:32 PM

My tester is a Mercury 1100, factory built. I have large stock of tubes, I had to order a few of them (Did not feel like trying to get to all the boxes). The Lady I bought the TV from broke the knob when a dresser got pushed up against it, the fine tuning part looks like it had been glued before.

static1701 · #14 03-28-2019, 05:52 PM

I replaced the rest of the bad tubes (Turns out I had what I needed) It picked up Ch10 from my BT transmitter. The tuner needs to be cleaned, it is hard to get it to lock on to a channel. The brightness control needs to be cleaned, if I mess with it I can get a much brighter picture but it won't stay. I will get some de-ox this weekend. I turned all the screens down, someone had messed with them, also adjusted the focus a bit. And all this and I have not changed any capacitors yet. They really built this one well.

static1701 · #15 04-02-2019, 07:18 PM

I worked on the set today: Cleaned the tuner, cleaned the brightness pot, turned the max brightness pot all the way up but I don't get a very bright screen. I don't have a CRT tester or a high voltage probe. What Can I do before I invest money to start replacing parts to make sure that the set it worth fixing? I am thinking of replacing all the electrolytic caps in the power supply / high voltage to see what happens since it is not that many. Thoughts?