RCA TV Tuner

My RCA tv is a 32in crt type and is 11 years old. It started jumping off the station by itself and looks like it is tuned to a non working channel. It just buzzes like you are tuned to a channel that is not in your area.
When I tap on the plastic board in the back where the antenna is connected it will clear up. My question is what would tapping on it likely be affecting? Is it likely to be a bad solder connection, or would this be a defective component such as a diode or transistor? I suspect it is something involving the tuner. The controls are all pushbutton on this model and not a mechanical dial type tuner.
How can tapping on the chassis back cause the tuner to lock back onto the channel in other words???

my experiences with rca that sound like a plan solder is always a problem with this mfg.solder around tuner box remove the bottom R/F cover and solder metal sheild grounds.also check cable barrel where it attaches to sheild resolder if loose.use a magnifing glass look real close to tuner circuit you may fine crack solder in other areas.if problem presist you may need to change some devices.sounds like the OSC or VCO for signal search is not working.i have changed ICS in this circuit.

Post edited by: hobbist, at: 2008/05/02 13:43

ccrider, welcome to the forum. I hope you will like it here I have nothing to add to the excellent information Hobbist posted here above.

Thanks for the reply, you sound like just the person I was hoping would answer my post! Excuse my ignorance, but how can I identify the tuner box? Also the bottom RF cover? I see I will have to remove the chassis after unplugging all the wires going to it after discharging the high voltage circuit. I need help in identifying the tuner box, and RF cover too. Is the RF cover on the bottom of the chassis?
The darn thing works fine once you get it started after you tap on the rear of the chassis near where the antenna lead is attached.

tuner box is where you plug in coaxl cable its the metal skirt around that area..some are part of main board cover under neath no you do not unplug anything just loosen up wires from the restrainths should be enough slack to move chassic in to servive position.some r.c.a. tuners stand upright off chassic look on main board under side also for posible bad solder you discription tapping chassic is a classic loose solder discription. RCA is noted for this in almost all models i see it every day at tv shop.

Hi...Thanks to your description, I think I found the tuner. It is apparently a metal box about 4in by 2in and about 1/2 in high on top of the chassis directly in front of the antenna lead in. There is a small circuit board on top of it where some wires connect into.
I need to get up enough ambition to pull out the chassis to inspect it better. I appreciate your tip to relax the restraints and not disconnect other leads. You sound like you have been there before!
As you can see, I am not a tv technician! I am a retired mechanical engineer with only enough knowledge to get me in trouble probably!
Any more advice on inspection....do I just look around the outside of the tuner box and underneath the chassis for solder cracks? Or do I have to get inside the box itself?
This is a large console model and is very heavy. I am surprised at the small size of the chassis though!

rca is noted for solder problems solder tuner first then tap on it and see if thats what it was.if not picture flashes jumps than solder board.i am a tv station engineer i had tv appliance store for 28 years.i work in medical tv repair shop.45 percent hospital tvs are rca 20inch.i own a tv station in pa.




what is this ctc ??? look on main board behind tuner if its stands up right look for cracking of the board.consol tv have not been made for a least 20 years.is it a ctc176 or ctc 179 could be a ctc 70???

Post edited by: hobbist, at: 2008/05/06 18:20

Post edited by: hobbist, at: 2008/05/06 18:20

Hi....It is a ctc 186/7 purchased in 1996. It is a 32in console and I was surprised at how small the chassis is for such a large tv.
You definitely sound knowledgeable of these and your tips are appreciated. When you say solder the tuner, where on the tuner are you soldering? Where it is attached to the board? Would that be underneath, all I see is the metal box from above which is about 4in by 2in and 1/2 in high. There is a small circuit board mounted vertically on top of it and the antenna lead enters next to it.
I guess if you remove the restraints and pull the chassis out the rear and turn it upside down the solder joints would be visible.
As a tv expert, what make do you prefer now. I plan to replace this one with a 32in table model crt type if I cannot fix this one. I also plan to replace the kitchen tv with an lcd type because I need the light weight for a wall mount there. Actually I need to replace both of these with digital next year since I have an inside antenna and they are analog! So your preference on make would be a help. By the way, where are you located, I am in Union, Mo outside StL about 35miles.

in the metal box pop off cover on top and unsolder metal sheild on bottom i have shop manual for this set the circuit board stands uprigth is part of a sound circuit do not disturb this board.orginally chassic was designed for a 20 inch cabinet.some circuit changes were made so it can operate 32or36 inch.its a surface board mounted tuner its not removeable.part two question

i have two 20 inch sharps one is 12 yrs old and never had the back off for anything.the other sharp is 14 yrs old and never has been repaired.so that said. i prefere sharp,recommend jvc and panasonic ,samsung, sansaui advent,curtiss mathes sony is ok but they have had some q.c.problems.my wifes kitchen tv is a durbrand color 13 inch crt type 2.5 yrs old never had a problem its made by chiniese company name is funiua ??.i have one in my room 1yr old no problem 13 inch crt this tv is now sold as a dtv at w/m sizes just right for a kitchen counter.lcd tv i have a problem with them.i threw away 32 tvs 20inches philips lcd displays had a one to two year life spand the displays run 3200 to4000 dollars cheaper to replace tv thats what we do..the crystal cracks from the heat they run hot.i personally buy crt types i have dish network for 14yrs.my signal is ditigal to analog all ready.i own i small tv station low power these new rule does not apply to low power stations i my self 50,000 other has filled a class action law suit againist the transistion in feb.we do not have that kind of money for the new transmitter and we lost are viewers my station broadcast religions sermens its in pa. we are from pa originally. i live in smithville north carolina 20 mile east of raleigh nc.on rt70 and 301 long side of i95.

Post edited by: hobbist, at: 2008/05/07 13:38

Post edited by: hobbist, at: 2008/05/07 13:46

Post edited by: hobbist, at: 2008/05/07 15:56

I noticed something new! There is a tall vertically mounted board about 6in high just to the left of the tuner. It has a metal brace that is fastened to the main chassis board and extends to the top of the vertical board. It is intended to support this vertical board but is very loose and when I move it back and forth, the station tuned into goes on and off. Now I don't know if tapping on the back of the chassis near the tuner causes it to come and go, or if that was just causing this tall vertical board with the metal brace to wiggle and cause this! I wonder if wiggling the vertical board causes the printed circuit board to deform and cause the problem or if there is a bad solder connection there instead of the tuner! I wonder what the tall vertical board is intended to do?
Funny thing is, once the channel comes on after tapping or wiggling, it stays on nicely all evening! So I have just been starting it up and using it that way.
Thanks for your input on tv preferences. I guess some just last forever on each brand and some don't. I favor panasonic, jvc, toshiba, sony I guess.

know that you narrowed down the area you should try to fix it. if left that way it could cause another problem later on.just be careful do not crack the board.may be bad solder in both areas.just do a little soldering.do not splash solder on chassic.glad to be of help with problem.looking at the print that circuit board its part of the tuner seek and scan and afc (automatic frequency control) make long story short automatic fine tunning and station lock.

Post edited by: hobbist, at: 2008/05/09 20:04

I finally got around to tearing into it. Your advice was invaluable. I removed the circuit board and unsoldered the tuner bottom cover. I looked all around and found no obvious problems with a magnifying glass. I bent the tabs that supported the vertical board next to the tuner because it looked like one of them might hit a trace on the board. I resoldered the tuner bottom cover and did solder around where the antenna connects where it looked like it needed a better connection.
Miracle of miracles, it works fine now! I am a little surprised since I do not know exactly what I did that helped!
Regardless I appreciate all the help I got here. Many thanks.

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