RCA F20536EH CTC146L/LA Not tuning in channel
 

Hi
i have a RCA Model F20536EH that uses
chassis CTC146L/LA
from 1992
it was my Grandmothers TV

tv was pretty dirty inside

it had not been powered on in about 12 yrs and worked last time it was unhooked
it had a bunch of Y's on the screen when i first turned it on not sure what that was all about but they went away

it will not tune in ch3 or4 for use with a vcr, converter box ect.
the picture will come on for a second then turn to static.

one way i was able to get a picture was to flip the ch3-4 switch on the back of the vcr when the vcr was on ch4 and the tv on ch3 it has a picture but no sound. but it as sound on a blank fuzzy channel.

i tried re soldering the grounds on the tuner board on the bottom of the main board. maybe i could have missed a few connections?

maybe someone has a whole mainboard for this tv or a tuner
or would there be a way to mod it to use an rca input instead of the tuner?
let me know thanks

A few things to try.
Try random accessing either ch3 or 4 with a remote.
Go into the menus & be sure the tuners are set to normal off the
air stations.
Try auto program, if it has it, with VCR on.
The YYYYY is strange !
Modding it is too much trouble. Its a hot chassis so not so simple.
There are tons of free sets with a nice jack pack out there.

73 Zeno:smoke:
LFOD !

Yeah you can't add a composite input to that set. EEPROM may be going out on it or the 12 years of discharged caps freaked it out.

i took of the metal shield on the left side of it
if i leave it off the tv will tune in to ch 3 but there is still really no sound if i turn the volume all the way up sometimes i could hear distorted faint sound
and if i put the shield back on it will not tune the channel

could i try getting a uhf modulator and maybe see if the tuner works on a higher channel?

would something like this work?
https://www.ebay.com/itm/35361708014...AAAOSwvwphElvm

May grandma had that same tv and then she gave it to me in 2007. The tv was used as the main set in living room and was hooked to a cheap funi DVD/VCR. When the DVD/VCR borke the tv was gotten ride do to it being rf only and the new DVD player had composite out and my mom wouldn't buy an rf modulator. The tv was replaced by an early 90s Sylvania tv that had composite in. That Sylvania broke years ago and if I now what I now I could have fixed.

Your tuning voltage may be missing.
Write down all the pin markings & the DC voltage for each one
& post them. May spot something easy.

73 Zeno

do i just test the pins on the tuner for the voltages?
can i hook my millimeter to the tuner shield for the ground?

The TNR shield is a great COLD ground so use that. Measure on ch 3 or 4
PCB markings will vary by set but typically be marked:

IF
AGC
5V
Data
cont
enable
TV
B+
clock
+32.......................

Looking at the basic numbers may show a problem.

rca tuner voltage readings
 

Hi
i did not see the board marked the same way but maybe it's a little different
there were 10 pins on the tuner. let me know if i need to do anything else

AGC 8.01
BV/U 9.65
BS1 13.12
Tune Volt 4.69
BS2 13.08
12vDC 9.84
IFout - No reading
5vdc 4.97
PSC5v 0.05
FLO/K 3.51

can anyone tell me what the readings mean?
are they good or bad

I will admit to having no familiarity with this model, but the 12 volts reading 9 would tend to indicate bad capacitors in the power supply. If this voltage is also unstable it could be making the tuner drift off the channel.

that makes sense i wonder what cap it would be on the board?
i guess without an esr meter i would have to pull out every cap to test it
i have a tester that's similar to this
https://www.ebay.com/itm/38371850505...AAAOSw8vZXNJCK
and one like this
https://www.ebay.com/itm/15358195295...YAAOSwvA5dO7Cp
i was thinking of getting an esr tester but not sure what one to buy
they are kind of expensive

The 12 V for tuner comes from Q4106 12 V regulator
Voltages on it should be +- apx
Col 18V
Base 13.4
Em 12.7

You may want to measure the bandswitch / tuning voltage IC.
It is U3600

Also see if either Q4106 or U3600 get hot after a few minutes.
Should be just warm.

73 Zeno:smoke:
LFOD !

Oh BTW try unsoldering the 12V pin on the tuner. If it comes back to 12V
measured on the chassis side its almost sure to be a shorted tuner. If its
still 9V there is a problem on the chassis.

Zeno:smoke: