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 Post subject: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 12:32 am 
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Joined: Jun Sat 27, 2020 12:08 am
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Location: Chicago, IL
Hey guys, I’m new to this forum and television collecting in general. I picked up my first set the other day, a ‘59 blonde Zenith model C2247E. Apparently, the set was used up until the mid 1960s when it was stored away for the past 50+ years. The owner said it was last powered up about a decade ago. All it did was display a horizontal line across the screen.
The inside was coated in half a centuries worth of filth. The set was serviced at one point (evident by a sticker on the back and a shotty filter cap replacement job). Besides that, everything under the 16c21 chassis seems to be completely original. None of the components look damaged, the resistors all tested good, and none of the caps displayed a resistance (though I know this method of capacitor testing isn’t considered to be very reliable). The tubes look fine, though I don’t have a tube tester to know for sure. The vertical pot was nearly frozen in place, so I’m thinking it’s possible that the issue may have been a bad pot rather than a bad cap in the vertical deflection.
I’m wondering what you guys think would be the best route to go when it comes time to work on this thing. Is it fine to power it up with a variac and dim bulb tester the way it is, or should I really give it a full recap before doing anything with it? The only issue I have with the later is the fact that the CRT is banded to the chassis and would need to come out if all the caps were to be replaced. There are grates on the bottom of the set which allow for some access to the underside of the chassis, but not much. I’ve read horror stories of these pre-implosion band B&W picture tubes going boom for no apparent reason, though if it has to be done then I’m up for the risk.


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Last edited by Tarkus01 on Jul Sat 25, 2020 6:03 am, edited 1 time in total.
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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 1:07 am 
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Location: Arvada, CO
Its a real neat looking set. Its OK to turn on the set without a variac/dim bulb for a short amount of time, after you variac/dim bulb it. A high-wattage dim bulb is my choice, as a slow variac power up may cause the Horizontal Oscillator not to start, and destroy the Horizontal output tube. The capacitors would be the most suspected reason for the vertical line. However a bad pot would also cause it. Nevertheless change all the wax capacitors and bumble bee capacitors out. Also test the pots before you change them out. If limited access is available from the bottom, as Zenith sometimes does, and taking out the chassis and picture tube is a must, then just do as the label on the picture tube says to do. Just put on safety glasses and be careful if your worried about it. I have never heard of a picture tube spontaneously combusting, but there is always the possibility.

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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 1:34 am 
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Location: Chicago, IL
Mr. Highlander wrote:
A high-wattage dim bulb is my choice, as a slow variac power up may cause the Horizontal Oscillator not to start, and destroy the Horizontal output tube.


Never knew! The set draws 210 watts, so if I go with the dim bulb test and use a 250 watt bulb, would that suffice?


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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 2:43 am 
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Location: Belrose, NSW, Australia
250 watt bulb may suffice. The option I use is one of those heatlamp bulbs you see in bathroom heaters in the ceiling. They are usually about 350 watts.

If there is a real fault this lamp will still light.

Keep the screen brightness low if there is no vertical deflection, otherwise you could end up with a permanent burn line. Assuming the CRT is OK, that is, I think I see a brightener hacked into the wiring.

My usual practice is this:

1. Pull all tubes (mark them for location!) except for the rectifier if it has a tube rectifier.
2. Power chassis up on a 60 watt dim bulb. Leave running for at least a day until the bulb fades to a red/orange glow. This gives the electros a chance to re-form and you may not need to change them.
3. Get the circuit out and replace all grid coupling caps (audio, vertical, sync separator, hor OP) and the B+Boost cap UNLESS they already have polyester caps in place.
4. Replace all tubes and power chassis up with a high power dim bulb (just in case).
5. You should now work on getting a raster on your set.
6. Once you have the TV running (however badly) start replacing paper caps A FEW AT A TIME, checking operation in between in case you have made a mistake. Doing it this way avoids creating a fault that wasn't there before and which may be VERY hard to find.
7. All paper caps replaced? Now fix remaining faults, there probably won't be many left.

I DO NOT test tubes, except in the chassis. A big waste of time IMHO. Having said that, a tube with a faded, dull getter flash should be replaced.

If you need to test the CRT and you don't have a CRT tester, search this forum for my post on the subject.

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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 5:10 am 
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If the set has not been powered for a couple of decades, powering it up with a variac or series light bulb will strain the electrolytics. Further, without routing out the paper capacitors most likely to fail before powering will lead to further trouble.

I make a habit of first reforming the electrolytics slowly overnight and then ensuring the leakage is low. Then I look at the schematic for capacitors with a high DC across them and choose a most likely candidate to fail, lift one leg and measure leakage. If less than 20Mohm, you can be sure as soon as the capacitor warms a little, the resistance will drop. I recommend heating the capacitor with a heat gun while measuring DC resistance and watch the resistance decrease.

As eager as I generally am to power the thing up, a few minutes spent examining a few components can save hours.


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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 7:09 am 
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Location: Belrose, NSW, Australia
I guess everyone has their own way of doing things, we're not far apart on the methods we use though. My method of reforming the electros using a LOW POWER dim bulb is gentle and lets them come up at their own pace. It allows you to put the chassis aside (for a week if necessary) while you are doing something else. It works. It has done so consistently.

A caveat about reforming chassis mount electros: check their backsides for white crusty material around the terminals. If you see this, that electro is not long for this world. Replace it. But use a modern CAN type, forget all the rubbish about restuffing them with modern much smaller electros. The originals are big for a good reason - ripple current. You don't have to match the original capacitance rating closely, electros have a VERY wide tolerance. For example, a modern low ESR can of 50uF will replace an original 100uF - or the other way around if that's what you have.

The point about checking caps that have a voltage across them first is not lost. If it's a paper cap you replace it anyway, if it's not bad now it soon will be. But after 50 years mica caps that have a voltage across them have become suspect due to "silver mica disease", that is, silver migration across the insulator due to an applied DC electric field. This causes some long term intermittent faults.

Having spent lots of time in person, on the phone, through forums and via email trying to help those who have got into trouble trying to get TVs going by "shotgunning" (replacing all the caps at once) I am very aware just how easy it is to make a mistake (or in your case break a track on a PCB) when doing this.

I am an electronics design engineer with over 40 years experience and prior to that I was a TV service tech during the era where everyone wanted to keep their old B&W TVs running long enough for color to arrive. I now do lots of TV restos for collectors, as a hobby, mostly around the vintage of your Zenith and mostly very similar in design.

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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 4:37 pm 
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Location: Pewaukee, WI
Another thing to eventually change is the .001uF and higher caps with white tubular ceramic shells I've found a number of leakers and suspect they are just another incarnation of paper cap.

irob2345 wrote:
I) I am very aware just how easy it is to make a mistake (or in your case break a track on a PCB) when doing this.
.

Zenith TVs were %100 hand wired sets until around 1970 when some color and monochrome sets started getting a single plug-in PCB (which Zenith called duramodules)...So no PCBs in a Zenith that old. Some Zeniths just before the duramodule had a chassis mounted DIP color demod IC, discreet socketed transistors and tubes on the same chassis. My 20CC50 is an example of that.


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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 7:06 pm 
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Location: Dallas, TX
Welcome to the forum Tarkus01.
Obviously there are differences in opinion and ways of doing things on the forum.
If one of the electrolytics has been replaced by someone before there is a good likelihood that others
are bad.
Do be careful not to burn a line in the picture tube (CRT) when you get it powered up.
That CRT probably isn't "banded" in the way it could be an implosion hazard. The term refers to metal bands that were applied under tension to CRTs during manufacturing. In some cases the bands have mounting brackets welded to them. People wanting to replace the CRT with another type would want to save the mounting brackets and would cut the bands, relieving the tension that keep the tube from imploding.
If there is a metal band around the wide part of the CRT that has a screw clamping it then it isn't the banding you are afraid of. However that doesn't mean there is no danger. The glass on the bell (cone shape) and the screen are thick glass, if you somehow broke the tube there it would implode. Lots of little glass shards everywhere (hopefully not in you eyes). The glass on the neck of the CRT is very much thinner (about like a wine glass) and easier to crack. A crack there might not implode but it would totally ruin the tube in an instant.
No one makes CRTs like this anymore, if you can find an old one they are expensive. A CRT like yours is is supported around the screen and by the yoke ( cylindrical part that the CRT passes through) most likely. Some sets have the CRT mounting clamp on the front attached to the cabinet, in that case it is better to leave the CRT in the cabinet. If your CRT is just mounted to the chassis I would leave it attached. Be careful taking the socket off the CRT, sometimes the black plastic tube base is loose and you could pull it off and break the fine wires connecting the tube to the base pins.
Here are some pictures of an Admiral chassis and CRT. I did remove the CRT after I slid the assembly out.
Attachment:
AdmC2236AE02.jpg
AdmC2236AE02.jpg [ 161.76 KiB | Viewed 2116 times ]

Attachment:
AdmC2236AE06.jpg
AdmC2236AE06.jpg [ 192.7 KiB | Viewed 2116 times ]

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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 9:15 pm 
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Joined: Apr Sat 06, 2013 2:18 pm
Posts: 555
Location: New Hampshire
Very nice set & the best starter to work with.
The CRT stays on the chassis. To pull chassis remove 4 bolts from bottom,
4 1/4" bolts one at each corner of the CRT. Pull tuner & vol control.
Sometimes also the front knobs then it all comes out. At least change out the can
that was moused. Easiest to mount a terminal strip right near the old can & leave the
old can in for looks. Take it from there ONE repair at a time. Only change
caps one or 2 at a time then recheck as you go !

73 Zeno 8)
LFOD !


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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 10:57 pm 
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Joined: May Sun 07, 2017 11:35 am
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Location: Belrose, NSW, Australia
Yes a good first set to restore.

I just zoomed in on the pics and what I thought was a PCB, isn't. My mistake, being from Oz I don't have the model familiarity many of you have.
Makes it an easier resto though.

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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Wed 22, 2020 11:41 pm 
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If I were to remove all of the tubes, run the set with a dim bulb tester and slowly replace each bulb with one of a higher wattage over a period of time, would I be causing any significant damage to the chassis?


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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Thu 23, 2020 1:19 am 
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Joined: May Sun 07, 2017 11:35 am
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Location: Belrose, NSW, Australia
No you won't do any damage. That's the raison d'etre of the Dim Bulb. If something shorts out, it draws more current, the filament of the lamp heats up, increases its resistance and limits the current to a safe level, even if you are not there. It acts faster than a fuse if something breaks down and it's self-resetting. A filament lamp is a very effective PTC thermistor.

You can check this by deliberately shorting out the heater winding on the transformer with a clip lead. The lamp will light up and there will be no drama.
Do this without the dim bulb and there will be a blue flash, clouds of acrid smoke and your clip lead might even catch fire!

For re-forming the electros a 60 watt lamp should be sufficient. As the electros form up they will draw less current and the voltage applied to them will rise. This all happens automatically. While it's happening, the electros may get slightly warm. This is normal.

Oh, if you set has a tube rectifier (5U4?) leave that in.

By the way this method can be used to safely bring up any gear, not just tube stuff, that has been dormant for a long time.

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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Thu 23, 2020 3:52 pm 
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Location: Dallas, TX
Here is a link to a very good website about restoring radios and TVs. Phil is a member of this forum and has been been adding to his website over the years as he does projects. His articles are well written and is photos are great. This is to the beginner's page but also go to his main page and check out the many restoration stories. I don't see one that is very near your set however.
https://www.antiqueradio.org/FirstSteps ... ration.htm

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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Thu 23, 2020 7:46 pm 
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Location: Lexington, NC
I think it's great you're trying to save that nice old TV. Has anyone noticed the similarity between this white Zenith and the Douglas' bedroom TV on Green Acres? They look like cousins. Arnold would approve. :D
Attachment:
green acres TV.jpg
green acres TV.jpg [ 157.08 KiB | Viewed 1917 times ]


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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Sat 25, 2020 3:42 pm 
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Location: Beaver Falls, PA. USA
Zenith did supply a lot of radios and TV sets to Hollywood. Watch enough old movies, and you'll see everything from the Stratosphere to the 6D029; Transoceanics too. Other brands do show up, but not as often.

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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Sat 25, 2020 4:26 pm 
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Joined: Apr Sat 06, 2013 2:18 pm
Posts: 555
Location: New Hampshire
irob2345 wrote:
Yes a good first set to restore.

I just zoomed in on the pics and what I thought was a PCB, isn't. My mistake, being from Oz I don't have the model familiarity many of you have.
Makes it an easier resto though.


Irob
All Zenith TV's were hand wired til abt 1970. Slowly they started using small
modules but they plugged into a hand wired chassis. This is why you see so
many plus the fact that 20-25% of sets sold in the US were Zeniths. They
didnt dry up & blow away like tube-PCB chassii.
This same basic chassis was used from the late 50's till this mid 70's. The last
ones were produced for 7 yrs without changes they were so good.

73 Zeno 8)


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 Post subject: Re: 1959 Blonde Zenith
PostPosted: Jul Sun 26, 2020 8:48 am 
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Joined: May Sun 07, 2017 11:35 am
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Location: Belrose, NSW, Australia
Quote:
This same basic chassis was used from the late 50's till this mid 70's. The last
ones were produced for 7 yrs without changes they were so good.


Yep, same in Oz with the AWA "cabinet" B&W TVs. The 50 series was all tube, hand wired, based on earlier designs that originated in 1959 and ran pretty much unchanged from the mid 60s until about '73. By this time it was a dinosaur, most other makers ran all SS designs. For the final year or so of B&W production they ran a Thorn hybrid design that was a step backwards in performance.

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