[sci.electronics] RCA TV question

ndp@aluxz.UUCP (Nimesh Parikh) (10/20/88)

I have an old RCA tv set (~8 years) which just went bad.

Here is what happened. The tv went out of focus one day
so I used the knob in the back to bring it back in focus.
This worked great for about 2-3 weeks. Suddenly one day,
while I was watching it, it just blurred right in front of
my eyes. Now the back knob has no effect.

Did the picture tube quit ? or would it be just some
component (R or C) inside which gave in after long time
of service ? Should I just throw the tv away or what ?

I will appreciate if some of you can shed some light.
Thanks

					Nimesh Parikh
					ihnp4!aluxz!ndp

john@anasaz.UUCP (John Moore) (10/20/88)

In article <952@aluxz.UUCP> ndp@aluxz.UUCP (Nimesh Parikh) writes:
>
]I have an old RCA tv set (~8 years) which just went bad.
]
]Here is what happened. The tv went out of focus one day
]so I used the knob in the back to bring it back in focus.
]This worked great for about 2-3 weeks. Suddenly one day,
]while I was watching it, it just blurred right in front of
]my eyes. Now the back knob has no effect.
]
]Did the picture tube quit ? or would it be just some
]component (R or C) inside which gave in after long time
]of service ? Should I just throw the tv away or what ?

I just had this same problem on a 15 year old Sears TV. The
problem was solved by replacing the focus divider.

The focus voltage is derived from the anode voltage using
a large and strangely built resistor called the focus divider.
On my set, it was about 3x4x1 inches, made of plastic and filled
with potting material, and mounted on the side of the high
voltage section. It had one wire to the neck of the picture tube
(to the focus electrodes), one to the high voltage, and one to
the top of the focus adjustment pot. Replacing this part (~$15)
will probably solve your problem.
-- 
John Moore (NJ7E)           {decvax, ncar, ihnp4}!noao!nud!anasaz!john
(602) 861-7607 (day or eve) {gatech, ames, rutgers}!ncar!...
The opinions expressed here are obviously not mine, so they must be
someone else's. :-)

tlm@hpsmtc1.HP.COM (Teri Miller) (10/20/88)

As I recall, Sam's Photofacts have troubleshooting guides, along with the
schematics and other data.  If it were my set, I'd invest in the Sam's for
it, and look at the recommended fix before making a decision.

gmg@hcx.uucp (Greg M. Garner) (10/21/88)

In article <952@aluxz.UUCP>, ndp@aluxz.UUCP (Nimesh Parikh) writes:
> 
> I have an old RCA tv set (~8 years) which just went bad.
> 
> Here is what happened. The tv went out of focus one day
> so I used the knob in the back to bring it back in focus.
> This worked great for about 2-3 weeks. Suddenly one day,
> while I was watching it, it just blurred right in front of
> my eyes. Now the back knob has no effect.
> 

 I also had this same _EXACT_ problem happen to me in my commercial defenders
arcade game.  The focus knob has no effect now. I tried shorting the pot, 
opening it, still no effect.  My focus knob is mounted on the high voltage
supply, so I assumed that the high voltage supply was trashed. I took the thing
outm and haven't gotten around to getting another one, so I will be interested
in hearing anyone elses comments on these strange happenings.  If no one else
answers you, try replacing the HV supply like I am, maybe it will work!

   Greg Garner
   gmg@hcx.uucp
   501-442-4847

/* Come on guys, lets get busy and build a FTL drive! */