1976 RCA picture problem
 

Anyone here want to take a shot at diagnosing a picture problem?

RCA solid state 17 inch black and white. Sound is ok. Picture seems small. Channel tuner seems very fickle.

Low voltage from power supply.

Tuner probably just needs cleaning.
Size problem probably power supply.
Post the CHASSIS number from inside its like KCS###
and maybe we can give some hints.

73 Zeno:smoke:
LFOD !

Inside it reads:
KCS202R
RWZ Li
2747622-0(?)
REV 005

I can remove the tuner, but I am not sure what to do with it.

OK I pulled the manual & its a simple set to deal with.:banana:
For the others its the B&W chassis with modules. A common & good set.
Before we go any further need to know what experience you have.
Also if you have a meter. You WILL need a meter for the size problem.
Let me look on Utube for a tuner cleaning video. You can use
WD40 but its best to use very little & put it in the best places........

73 Zeno:smoke:
LFOD !

Are you sure the size issue isn't the source (Video Game?) feeding it a cropped image? If you put it on a blank channel does the screen fill out?

THanks, everyone. I am consolidating responses from two different threads.

Yes, I can no longer get analog stations, so I connected an Atari VCS to the antenna screws via an Atari RF switch box.

The image is usually distorted when I first turn it on. I have to nudge or wiggle the channel knob a bit before the image comes in with snow. (pics below)


I bought and connected a digital tuner, and the image was still small (pic below).

Yes, please. I bought a meter (pic below), but I am new to using them. I've poked around arcade crt monitors, but I would need guidance.

I thought it was an LPTV you were tuned to. There's an LPTV in this market that looks like that (very snowy). There are still a few analog signals on the air.

Look around the main PCB for a crack. Especially where it is soldered
to the main frame. IIRC I had a few of the similar 12" sets with
cracks. Also be sure the modules are seated. Almost has to be moving
damage.

73 Zeno:smoke:
LFOD !

My thoughts based on the recent pics:

Seller pic shows some snow. The tuner was probably dirty then and has gotten worse.

Your snow picture shows that the raster almost completely fills the screen which points to two things: the small bit of wavy underscan on the side is probably one or more power supply lytics failing. And all your current signal sources are cropping the image...Your DTV box should have crop/zoom settings try playing with them...Also try different channels as some channels lock the zoom/crop settings such that a box can't fix it.

One more thought there is an analog channel 6 in the Chicago market (they are pretending to be an FM radio station, but have to keep their video carrier on to send audio) you may want to try tuning them.

Didn't know you had it shipped, check to see if the Yoke has slid back on the neck of the CRT.

The pictures is small but perfect, bad power supply will usually have some other symptoms.

Get rid of that Atari switch box, they were garbage when they were new.

As always, I have to jiggle the tuner a bit to get a signal. I was able to tune in channel 6. It was on 7 at first, so I had to fine tune for a bit. I get clear audio but no video, but this is the same on my working tvs.

I am including more interior images (excuse the quality). I can include links to youtube video if helpful.

... It's also worth noting that when it arrived, the lower left part of the screen was pushed into the frame. I snapped back pretty easily, but could be relevant. I'm including images of the packaging as well.

Loosen the yoke clamp and make sure it's pushed all the way up against the back of the tube. It looks okay but obviously the set took a hard hit if the tube was dislodged.

In this picture the screen is filled all the way out, except the right edge and that seems to be because the Horizontal hold is off and flopped to the left.


http://videokarma.org/attachment.php...6&d=1542525728

Complete newbie with these things. I am assuming that is the metal clamp wrapped around the glass. Should I take any safety precautions? I'm not sure what pushing back means: away from the screen or toward the screen.

For the yoke.......
Loosen the clamp.
Push all the way forward against the "bell" of the CRT.
Get a picture on & be sure its not tilted.
If its tilted rotate yoke a little bit. Use a glove or just be careful of
the wires. It wont kill you but you can get a surprise !
Slowly tighten clamp until you can JUST not move it. Done :banana:

For tuner.......
Pull tuner assy.
Remove the tuner shield. It has catches on both sides & slides off. It
is U shaped.
You will see 4 or 5 wafers that the shaft go through.
Spray a little contact cleaner or WD40 on the wafer part that moves.
Spin channel knob about 4 rotations each way.
Try it, should be clean now.

Other stuff.....
One pix shows hoz way off. Odds are the horz hold control is also dirty.
Spray cleaner into the gap where the 3 wires / pins enter.
Adjust back & forth a bunch then adjust to get a pix.

enuf fer now. I need an ale:D

73 Zeno:smoke:
LFOD !

It's not getting better...

Could be the set was connected to an outdoor antenna during a lightning storm and the 1st RF amp transistor got blasted.

Making progress... Got the yoke twisted back in place per zeno's instructions (Thank you!). But not yet brave enough to take the tuner apart. All of the wires are soldered.

I took some pictures of the inside and discovered one of the corners that anchored the screen in place was completely broken! It must have gotten pushed in during shipping. I took pics of one of the normal corners and the broken one after some efforts to put in back in place. Would this kind of damage seem connected to the small image?

No surprise there, most sets I've opened have the RF input cable soldered in place. In my experience those things need really good grounds. If the 1st RF amp transistor is blown it'll be a real dog to replace if even possible, it's pretty tight in there. Unless you have a schematic that identifies the transistors don't bother trying. Any tuner that uses approximately the same B+ voltage should work even if it doesn't physically fit. Fortunately for me a blown tuner was very much the same internally as one from my parts stash, the most important feature being a removable shaft. The hardest part will be swapping the front of the housing so it will mount properly.

The damage to the CRT anchoring point has nothing to do with the image size issue.

Cabinet damage means the set took a good lickin. Thats why I said
to give the main PCB a look for cracks. Especially at the mounting
lugs & the flyback.

73 Zeno:smoke:
LFOD !

His problem is probably a dirty tuner (easy fix) versus your transistor issue (not particularly easy).

First step on any noisy tuner issue should always be clean the contacts. You should not need to remove the whole tuner from the cabinet or any wires from the tuner. Most sets made it so that you could unclip and remove the tuner shield and clean the contacts with the tuner still mounted and connected. There is a front and back to the tuner that the shaft passes through and a "top" that the wires connect to(some tuners are mounted upside down or other wacky ways so "top" is not always pointing up)...The removable shield typically comprises the bottom and sides of the tuner. It usually clips into the top. To remove pinch the sides inwards near their centers at their upper edge where they meet the "top" and pull down after you've started to pinch while still pinching...The shield should slide off. After that identify the contacts and start spraying cleaner and spinning the knob...If there is lots of room around the contacts I like to stick a soft white pencil eraser in there and let the contacts brush against it...This alone will help but if you do it while they are wet with contact cleaner you will be impressed with how much tarnish it will remove.

I guessed that this reply would contain an argument against what I said. You've done it to me many times, please try to refrain from it from now on. I know I'm not stupid but it still kind of stings.

It may be true that his tuner is dirty, but it wasn't I who initially suggested that the RF amplifier transistor may be blown.

Not trying to sting nor to imply any kind of stupidity. The topic has drifted away from what he needs to do into speculation into highly unlikely causes. Your Post seemed to suggest replacing that transistor was the way to go and that it is very difficult (and it was the most recent bit of talk on it). That will scare an amateur off of touching the tuner. I simply pointed things back in the right direction. (we should make sure the easy common issues have actually been dealt with before going off into the weeds should we not?)

If what I see as bad advice is given I will attempt to correct it (or improve the advice given) no matter who gives it, starts it, or contributes to it...If you happen to be caught up in the giving of bad advice that is not my fault. And you have no right to tell me where and how I can put my two cents in on an issue as long as I am abiding by the rules of VK. I will try to sound more respectful going forward...But bear in mind we ALL get correct by other VK'ers from time to time, and unless someone explicitly calls you a big dummy that is likely NOT even a tiny part of their goal in offering what they see as the correct information to those reading.

If it was a dirty tuner, usually you can wiggle the shaft and they snow will come and go. Since it obviously took a spill I'd look for a broken resistor, wire or other component, (on top of the tuner or elsewhere).
You should have determined the location of the point of impact. Is that close to the tuner?
Did you check voltages at the tuner?
Might even be an IF problem.

...

Have you tried to hook it up to a DVD or VCR?

Yes. The last image I provided (of a football game) is from a digital converter box capable of playing video off a hard drive. Like the Atari, the image is just small.

Did you try using the crop/zoom function of your DTV box?

My DTV doesn't seem to have that feature. Neither would the old video game, of course. Are you saying I should ignore the problem and just adjust the video source?

1976 RCA picture problem
 

Not saying to ignore anything, just to be sure you identify the actual cause so you're not barking up the wrong tree. You really need to find some video source that outputs 4:3 format and connect that to your set. Then, you can tell with more certainty if your set is not displaying the signal correctly.

It would be ideal if you have another 4:3 TV so that you can use process of elimination to determine what the culprit is.


Incidentally, what is the make & model of your DTV converter box?

For gosh sake, three pages and no one has said how to determine if the small picture is the TV or the source? Just turn up the brightness control, and the whole raster will get bright. If the sides, top and bottom are still pure black, it's the TV raster being too small. If light appears in the black areas, then the problem is the source.

Thanks for your input, everyone. I took it to a skeptical repair shop for a diagnostic. He seemed more interested in getting the $20 fee, but we'll see if he has anything to say about the problem.

The game source is an Atari 2600. It's only capable of 4:3 ratio output. The maker of the digital convertor is Ematic. I assure you the source is not the problem.


I have adjusted the brightness and other settings. The image is simply small. Even the static screen. See some of the early pictures. Do you have any recommendations for adjustments?

Update: The electronics repair guy called me and said it appears to be a problem with the "flyback" ... this is not a part he can source. What steps should I take now? Is this a part for which I could just pull the parts number and order one on ebay? How would I know a good one from a bad one?

Your flyback is fine if you have a picture. It is about the same as saying the CRT is going on a set with a good CRT that you don't want to service...He just wants you to give up on it after paying the fee, without him doing any work.

Do you really need a B/W set?
You can drive 100 miles north and pick up 2 really nice 19 or 20" color table models that work perfect, free for the hauling.
Either that or check Craig's list for sets nearer to you. :thmbsp:

Earlier in the thread, people suggested the issues could be low B+, and a dirty tuner.

Both of those issues are consistent with the symptoms, and my experience repairing old TV sets. I would never say never, but it seems fairly/extremely unlikely that any of your issues are at all flyback related. Maybe post an ad in the classified section looking for a local tech or forum member to have a look at it? I think a decent tech or even hobbyist could have this diagnosed properly quite quickly.

My only wonder is why someone from Chicago would want an RCA, and not a Zenith or an Admiral :)

Almost impossible the FBT is bad. Did you check for cracks on
the main board ? This set is quite simple, dosnt even have a
regulator. if the board is OK I can give you a few voltages to
check & maybe find the problem.

Reason for diagnosis can be many. I could go into that if you wish.
Reason for the $20 is 95% of sets not worth repair are abandoned.
Then HE has to pay to recycle it. thats $10 - $30 around here.
Lastly how many $20 bills do you need to make $50 K a year after
15% SS tax plus state & fed taxes. You would have to gross at least
$70 K. And that dont cover shop expenses.

73 Zeno:smoke:
LFOD !