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 Post subject: RCA Victor 17T172 Help Needed
PostPosted: Aug Thu 12, 2021 3:40 pm 
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Joined: Aug Thu 12, 2021 3:09 pm
Posts: 19
Hi Everyone!

New guy here...

I just picked up a 1951 RCA Victor 17T172 . I have a collection of 70's and 80's TV's and I have re-capped and done some minor work on along with arcade monitors from that era but I have never messed with a TV with vacuum tubes before.

I picked this RCA up for cheap and when I powered it on I actually got raster and static sound which surprised me!

A bit about my set-up: I have a Blonder Tongue Agile Modulator that I have set to broadcast on channel 12. I use this on my 70's and 80's TV's and it works great...

I connected some rabbit ears to the back of the RCA and powered it on. I couldn't get a picture but I actually picked up the sound from the broadcast (albeit VERY crackly and only at the top 20% or so of the volume knob travel). When I went to adjust the rabbit ears I got a hell of a shock when I touched them! I turned off the TV, disconnected the rabbit ears and reconnected the "built-in antenna".

I turned on the TV again and kinda messed with the knobs and didn't get an image that I could make out but I could see that it was absolutely receiving the broadcast! The image looked to be warped for lack of a better term. I tried adjusting the horizontal lock, drive and frequency on the back and couldn't really make it any better. Honestly, I probably made it a tad worse lol.

I moved around front and noticed something interesting - The image was trying to come through on channel 12 but the audio portion didn't work unless I switched it to channel 13. I could only get the scrambled image at the same time as the audio when carefully balanced the knob between channel 12 and 13. Basically like channel 12.5. Is it safe to assume that the RF tuner might be the culprit here? Perhaps that is tied to the reason I got a shock when I had the rabbit ears going into it?

Tonight I am going to change the channel on my Blonder Tongue to something like channel 5. Perhaps the tuner is all gunked up on the high-end?

Anyway. I am excited to get this thing going and I appreciate the help!

Since I'm new it won't let me post pics or the video yet. I will do that in the next post here...


Last edited by TVee on Aug Fri 13, 2021 1:34 am, edited 1 time in total.

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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 12:45 am 
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Joined: Aug Thu 12, 2021 3:09 pm
Posts: 19
Here's pics:

Image

Image

Image

Image


Last edited by TVee on Aug Fri 13, 2021 12:58 am, edited 1 time in total.

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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 12:45 am 
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Joined: Aug Thu 12, 2021 3:09 pm
Posts: 19
Ah jeez, everything came posted way too big. Sorry about that.


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 12:48 am 
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Joined: Aug Thu 12, 2021 3:09 pm
Posts: 19
Video attached.


Attachments:

[ Play Quicktime file ] IMG_5030-1.mov [ 2.54 MiB | Viewed 2305 times ]
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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 12:53 am 
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Joined: Aug Thu 12, 2021 3:09 pm
Posts: 19
Image


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 1:02 am 
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Joined: Aug Thu 12, 2021 3:09 pm
Posts: 19
I went down to channel 6 on the Blonder Tongue and now at least I do get sound and image on the same channel.


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 1:55 am 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 3509
Location: Dallas, TX
On a set this old it probably has many problems. The TV is from an entirely different era. It is highly recommended that
you replace the electrolytic and paper dielectric capacitors before you plug something this old in. Paper dielectric capacitors
were not used for the most part after about 1970. You're lucky you didn't smoke something.
This website has a lot of good info on restoring TVs (and radios). Many people recommend starting with a tube radio
or two before tackling a tube TV, just to get used to the different technology.
https://www.antiqueradio.org/begin.htm

Many times the antenna terminals have a path to connect to the chassis. Many times on sets with power transformers
there is a paper capacitor that connects the chassis to at least one side of the AC power cord. This cap is probably
leaky or shorted, that would explain the shock. That cap should be replaced with a safety rated capacitor (if they fail, they
fail open rather than short or catch on fire).

Photos that are less than 800 pixels wide will not cause a problem with the width of the post.

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 2:31 am 
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Joined: Apr Mon 16, 2012 5:31 am
Posts: 414
And the CRT has a metal bell which is,at about 12 kV. I would steer clear of the chassis while it is powered. The zap is not nice.


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 3:04 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 3509
Location: Dallas, TX
By the way, welcome to the forum!
That TV is a good example of an early RCA console. The cabinet is in good shape, replace the grill cloth and touch up the
woodwork and it would look great.

I found a link that you can download a RCA service manual from.
https://www.earlytelevision.org/tv_sche ... s_rca.html
The Early Television Museum website has lots of interesting info on TVs from the 1920s up into the mid 1950s on B/W sets.
The museum's interest in color sets runs from the mid 1950s into the early 1960s.
Broadcast equipment is also in the collection.

You might try to find a SAMS manual also.

Phil's old radio has a restoration story about a RCA console a couple of years newer.

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 3:51 pm 
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Joined: Aug Thu 12, 2021 3:09 pm
Posts: 19
Thanks for the replies. This should be a fun project for me! I got myself the service manual and I have been reading a ton.

So the move here is to pull the chassis and replace all of the caps and test/replace the tubes...

Oddly, I cannot seem to find a really solid answer on how to discharge the tube and chassis for chassis removal.

When working on arcade monitors and whatnot, I always ground from under the rubber anode that's attached to the tube to discharge. This doesn't have a rubber anode. The HV appears to be attached to the frame on the front of the monitor. I found a guy on youtube who restored a 1952 RCA and it has the rubber anode I'm used to. I guess 1951 was the last year of this style?(whatever this style is)

How do I discharge a TV with this set up?

Here is a pic:
Image


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 8:11 pm 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 3509
Location: Dallas, TX
As Penthode has said that CRT has a metal bell.
The front of the CRT bell is made of steel and the whole piece is attached to the HV.
A bit of a gotcha for unknowing hands.
There should be insulating sheets between the bell and the CRT screen mount/surround.
Some early TV CRTs were made this way. There is a glass to metal joint between the bell and the glass neck
and another between the bell and the glass screen. The thin metal weighs less than than the thicker glass
that would be needed. The seal tends to leak over the years so many are not good.
Like I said this is technology from another era!

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 8:37 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 10002
Location: Redlands CA
TVee wrote:


How do I discharge a TV with this set up?

Here is a pic:
Image



You don't really need to discharge the tube on this type because it doesn't hold a charge, however there might be a small high voltage filter capacitor inside the high voltage cage. All you need to do is ground any area of the metal CRT bell to ground and that will take care of it.


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 9:52 pm 
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Joined: Aug Thu 12, 2021 3:09 pm
Posts: 19
Notimetolooz wrote:
As Penthode has said that CRT has a metal bell.
The front of the CRT bell is made of steel and the whole piece is attached to the HV.
A bit of a gotcha for unknowing hands.
There should be insulating sheets between the bell and the CRT screen mount/surround.
Some early TV CRTs were made this way. There is a glass to metal joint between the bell and the glass neck
and another between the bell and the glass screen. The thin metal weighs less than than the thicker glass
that would be needed. The seal tends to leak over the years so many are not good.
Like I said this is technology from another era!


Thanks for the info! Definitely a whole new experience for me.

So the process to remove the chassis would be to unscrew the rod at the HV cage?


Last edited by TVee on Aug Fri 13, 2021 9:54 pm, edited 1 time in total.

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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 9:53 pm 
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Joined: Aug Thu 12, 2021 3:09 pm
Posts: 19
Eric H wrote:
TVee wrote:


How do I discharge a TV with this set up?

Here is a pic:
Image



You don't really need to discharge the tube on this type because it doesn't hold a charge, however there might be a small high voltage filter capacitor inside the high voltage cage. All you need to do is ground any area of the metal CRT bell to ground and that will take care of it.


Great to know but man, it makes me nervous! lol


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Fri 13, 2021 11:24 pm 
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Posts: 10002
Location: Redlands CA
TVee wrote:


Great to know but man, it makes me nervous! lol


At worst it's like getting a Static Electricity shock, it won't usually hurt you but the recoil can be dangerous.


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Sat 14, 2021 12:32 am 
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Joined: Aug Thu 12, 2021 3:09 pm
Posts: 19
Eric H wrote:
TVee wrote:


Great to know but man, it makes me nervous! lol


At worst it's like getting a Static Electricity shock, it won't usually hurt you but the recoil can be dangerous.


So support that rod and unbolt it from the HV cage?

Also, I attached a video of the current state of the "picture". I'm so damn close!


Attachments:

[ Play Quicktime file ] IMG_5073.mov [ 3.11 MiB | Viewed 2225 times ]
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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Sat 14, 2021 2:08 am 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 3509
Location: Dallas, TX
Eric H wrote:
TVee wrote:


Great to know but man, it makes me nervous! lol


At worst it's like getting a Static Electricity shock, it won't usually hurt you but the recoil can be dangerous.

Either that or getting punched in the face!

Don't count your chickens before they are hatched.

Some TV have the CRT attached to the cabinet. The chassis comes out separately and does not support the CRT. That makes it a little tough to troubleshoot because you must return the chassis to the cabinet to test out any fixes.
Be careful with any force applied to the CRT neck, the glass is very thin there and if it breaks all is lost.

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Sat 14, 2021 2:55 am 
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Joined: May Sun 07, 2017 11:35 am
Posts: 1549
Location: Belrose, NSW, Australia
Just played your mov file.

There doesn't seem to be much wrong with that TV at all. My guess is it may have received at least a partial recap some time in its life. Forget about testing and replacing tubes too. Touch as little as possible!!

Adjust the Horizontal Hold so that the lines get broader. Keep going and your picture will lock in.

Once you have a locked picture on the screen, you /we will be able to see what else needs to be done.

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Wax, paper, bitumen, cotton, high voltages - what could possibly go wrong?


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Mon 16, 2021 7:34 am 
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Joined: Apr Sun 08, 2007 6:47 am
Posts: 4982
Location: British Columbia
Does this set have a series string chassis or is it a later version of a 630 style chassis? I can see a power transformer (just noticed it) but I also see a pair of selenium rectifiers, with a pair of condenser cans, suggesting a voltage doubler for the B+ supply. I must say that the cabinet looks in decent shape, though the top may have a problem, the faux wood grain on the doors is good, and even the skirt at the base isn't too banged up. It looks like it's been kept dry all of it's life. Even if the picture tube was shot, or had gone to air, I would see about a glass substutute, fortunately that is NOT the case.
Regards
Arran


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 Post subject: Re: RCA Victor 17T172 Help Needed
PostPosted: Aug Tue 17, 2021 12:42 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 896
Location: Rockaway , nj 07866
Selenium rectifiers ,
Probably the first set to use 1v2 for focus


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