Sony tv color reversal

Thanks for the great information! From a Google search I found the
information in this thread I needed to repair my Sony KV-20TS30 TV
which suddenly developed color gradients in an oval pattern. My
problem was just as described here: the THP601 thermistor (black
1/2x5/8 inch component next to where the degaussing coil plugs into the
main circuit board) had no solder left on the center pin. I could also
wiggle the lead. Turning the set upside down and applying solder got
the set working again.

Sony tv color reversal: SUCCESS!!!!
This MADE my week! I'm a hero in the extended family! Wednesday
night I finally brought home my soldering equipment (not too much call
for soldering DB25s in these days of the 100MBit office anyway!),
pulled the back cover, turned the whole set upside down and confirmed
all the hints from you guys:
The degauss wires were indeed covered with black tape. The circuit
traces went from those wires directly to one of the black boxes which
did indeed have 3 pins (I had to shine my bright light *through* the
circuit board to see this clearly - might be a good hint for beginners
in the future)...and LowAndBehold, one of the pins was NOT SOLDERED
ANYMORE (guess how excited I was) It was not burned looking in the
least, just no longer soldered and in fact I could gently wiggle it
and feel that it was not solidly connected. I then KNEW you were
right.

I fired up my iron, used the hot iron itself to clean up the pin and
hole and gave it a nice quick small flow of fresh solder. I kept
wanting this to be more difficult... but I just closed the tv back up,
plugged it in, turned it on and there to the shocked amazement of my
family was a PERFECT COLOR PICTURE! Total Cost: a few good
descriptions to this group and a speck of solder. You guys are Great!
I'm going to re-visit the crippled stereo equip in my lower room now!

Final Hindsight data: The component was marked "THP601" on the
circuit board (I decided this must mean "Positive" acting "THermistor"
or "Posister" as Sam mentioned and an electronics friend said meant
just the opposite direction for the voltage or the temperature.)

Terry

Terry:
Andy is quite correct about the cracked solder connectionslike he
says, usually the center pin. You may have to scrape the terminal with an
exacto knive or with emery cloth in order to get a good solder connection.
Almost never is the part bad, resoldering usually does the trick. Also if
you get the internal deguasser workingyou may still have to degauss
the set with an external device to clear up all of the impurities.
Dan Sofie
Electronics Supply & Repair

It will be on the main board or power supply board if it uses a seperate
power supply. It's a roughly 1/2" plastic cuble and will be near where
the power line connects to to board.

> I *did* attempt to guess at the degaussing wires you described but
> there were two choices: #1 a thin silver (braid?) of a wire hooked
> around two springs at bottom tube corners with fairly thin gray leads
> coming over to the "back-of-PicTube" card (per memory) ...or...
> #2 A pair of thick black (almost looked like thin coax) cables
> carefully draped around the top and bottom of the tube, joining
> together in center with Black and White leads, fairly thick, going to
> the corner of "motherboard" ending in a board plug right next to the
> incoming AC power source line.

The metal braid is the CRT dag grounding strap. The degaussing coil is
the think tube or tubes covererd in electrical tape or plastic. There
will be 2 wires going to the main board. Sounds like #2.

Just start looking at the board in this area. If the soldering is bad,
it will be very obvious. It's usually the center pin; the solder will
be overheated and cracked.

--
Andy Cuffe

OK guys: I finally pulled the 5 screws and looked inside...
ByTheWay: It's a Sony KV20TS30

Shock...there did *not* appear to be little lighted blinking arrows
pointing out the DeGaussing Thermistor to me!!! In fact, I was quite
rudely presented with tons of dust :-)
Seriously...I should have scribbled down the "TH601" in below message
so I could have looked for that component - 'cause I GOT LOST IN
THERE! Which is it? A) the "motherboard" B) the vertical card near
the rear panel plug-ins or C) the back of picTube vertical card?

I *did* attempt to guess at the degaussing wires you described but
there were two choices: #1 a thin silver (braid?) of a wire hooked
around two springs at bottom tube corners with fairly thin gray leads
coming over to the "back-of-PicTube" card (per memory) ...or...
#2 A pair of thick black (almost looked like thin coax) cables
carefully draped around the top and bottom of the tube, joining
together in center with Black and White leads, fairly thick, going to
the corner of "motherboard" ending in a board plug right next to the
incoming AC power source line.

Hey! Ray,Mike,"P",et.al. I've re-read your msgs and I already have
these hints: should be on main PC board near PSupply(so #2 above must
the the degauss wires, right?) should be a "black box with 3 legs" and
might be called "TH601." (plus now we know it's a KV20TS30 model)
Does all this sound right to everyone? 'cause I'm going to need it to
ID the thing tonight(there were *several* black boxes and blobs in
that area. I think I looked under the PC board at that corner near
power line and nothing looked burned, but we'll see.

TIA again, Terry

In article <>,
Terry_H (Terry) wrote:

Just fixed a garage sale special with these symptoms. Re-solder
component TH601. This is a three leg device in degauss circuit. One leg
had absolutely no solder. It's accessible without even removing the
board.
PShovestul

Sent via Deja.com #
Before you buy.

Not necesarily. With the set unplugged (it should be unplugged for the
entrie operation of course), clip a jumper across the main (largest) filter
capacitor.

Solder joint. This happens all the time with these sets.

It probably will still be there. It probably needs purity adjustments, but I
would recommend leaving that alone, or referring it to a pro. Otherwise you
might just make it worse.

It's a resistor that varies with temperature. It should look like a small
black square device with three leads on the bottom. Find the degaussing coil
around the picture tube, then locate the two-wires comming from it - going
to a plug plugged into the main chassis board. The thermistor won't be far.
One of the solder connections will be blackened, probably with virtually no
solder left on it at all.

Good luck! (and make sure the set is unplugged!)

-Woodie

OK guys, I immediately got about 4 diagnoses that
it's the degaussing thermistor via email & news
(this group is responsive!) so I plan to attempt
"usenet guided tv surgery."

Q1) If I unplug for 8hours will I be safe from the
caps shocking me? I'm going to let it sit during
a work day and then probably try to discharge the
tube (ms1125 gave me detailed instructions
-Thanks!)
Q2) further diagnosis attempt: now that you've
focused me on degaussing, I realized that I've
been seeing little symptoms (for a year?) where
I'll be watching tv and all of a sudden the tube
will do a brief halo degaussing and then get
normal again. It was fairly occasional so I
didn't worry about it much. Would this symptom
point us more toward a bad thermistor or is it
still just as likely to be the solder joint?
Q3) Also, my tube has had just a brush of a halo
wash up in one of the corners - I think only one
corner for most or all of it's life - in case that
might add something to the diagnosis.
Q4) What the heck is a thermistor, anyway? (I
already understand degaussing, I believe.)

OK, I'll ask more questions before I go in with
the screwdriver...
Terry
ps. posting via deja since my news server is down
this AM so hope you can read this..

Sent via Deja.com #
Before you buy.

If the picture was nice and sharp, and bright, no colors missing or weak by all
means have it repaired. It is almost impossible to get a new set built as well
as a middle of the road older set. This is true off all makes.

Some of the older 20" Sony's tubes went weak, but watchable. They got sorta
fuzzy and had no guts. Thet were watchable though, and if yours is affected it
probably happened a long time ago.

They picture quality is the bottom line, if it looks like the picture on a new
TV fix it.

It sounds like your degaussing thermistor is either burned out or has
cold/cracked solder joints.

It sounds as if the degaussing circuit is on all the time.

Tom