I have a CRT type SONY 27 inch TV Model KV27T530. It's between 10 to
15 years old and still shows a great sharp picture in excellent color.
I have Cable TV for the basic channels (2 to 13) plus the first tier
of extra channels. A month or so ago it could show only the first
tier channels and would not even display the Channel number for the
second tier. So I took off the back cover to reseat all the
connectors. After that the ON switch wouldn't latch. It comes on and
switches itself off after a few seconds. What should I be looking for
to fix it?

I used to be an electronics tech and had fixed minor TV problems
before. This TV set isn't worth fixing at a shop. I am sure its
basically working OK and I don't like dumping equipment that can be
fixed. I'd be happy if it can just receive the first tier channels.
I've bought a large flat panel TV to watch the coming Olympics. So
fixing the SONY is something I can take my time on to troubleshoot.

Thanks in advance.

"PaPaPeng" wrote in message
...


I have a CRT type SONY 27 inch TV Model KV27T530. It's between 10 to
15 years old and still shows a great sharp picture in excellent color.
I have Cable TV for the basic channels (2 to 13) plus the first tier
of extra channels. A month or so ago it could show only the first
tier channels and would not even display the Channel number for the
second tier. So I took off the back cover to reseat all the
connectors. After that the ON switch wouldn't latch. It comes on and
switches itself off after a few seconds. What should I be looking for
to fix it?

I used to be an electronics tech and had fixed minor TV problems
before. This TV set isn't worth fixing at a shop. I am sure its
basically working OK and I don't like dumping equipment that can be
fixed. I'd be happy if it can just receive the first tier channels.
I've bought a large flat panel TV to watch the coming Olympics. So
fixing the SONY is something I can take my time on to troubleshoot.

Thanks in advance.


So are you saying that there is a mechanical problem with the switch? If so,
just replace the switch.

Or are you saying that the TV shuts down after a few seconds?

Mike

I took off the back cover to reseat all the connectors.
After that the ON switch wouldn't latch.

Does this not suggest that in dismantling the set, you moved something, or
put something back the wrong way?

On Fri, 13 Jun 2008 03:26:12 -0400, "Michael Kennedy"
wrote:


"PaPaPeng" wrote in message
.. .


I have a CRT type SONY 27 inch TV Model KV27T530. It's between 10 to
15 years old and still shows a great sharp picture in excellent color.
I have Cable TV for the basic channels (2 to 13) plus the first tier
of extra channels. A month or so ago it could show only the first
tier channels and would not even display the Channel number for the
second tier. So I took off the back cover to reseat all the
connectors. After that the ON switch wouldn't latch. It comes on and
switches itself off after a few seconds. What should I be looking for
to fix it?

I used to be an electronics tech and had fixed minor TV problems
before. This TV set isn't worth fixing at a shop. I am sure its
basically working OK and I don't like dumping equipment that can be
fixed. I'd be happy if it can just receive the first tier channels.
I've bought a large flat panel TV to watch the coming Olympics. So
fixing the SONY is something I can take my time on to troubleshoot.

Thanks in advance.


So are you saying that there is a mechanical problem with the switch? If so,
just replace the switch.

Or are you saying that the TV shuts down after a few seconds?

Mike



Its not the front panel mechanical switch. I can switch on the TV
with the front panel switch or the remote. There is a distinct click
coming on. Then there is a slight crackle as the static or whatever
fires up (to warm up the CRT?). After around five seconds the TV
clicks itself off (as if there is a safety cutoff.) I looked around
for a solenoid like item and of course there is none. It is something
solid state on another part of the motherboard. The cable runs are so
tight I cannot pull the MB out far enough to see or hear exactly which
component is making that noise. If it is solid state why is there a
distinct 'click' then. The question here is what kind of component
makes a click when you use the remote to turn the TV ON or OFF?

As for mis-reconnecting the cable all the cables have keyed connectors
and each of them is unique in size and shape. The cable runs are too
tight to make a mistake running the connector to another pin socket.
When I get around to it I will probably undo all the connectors and
reseat them again.

The other question is, is there such a thing as a hardware problem
that would kill the second tier of cable TV stations? The screen
wouldn't display any channel numbers or programs beyond Ch 13. Just a
black screen and not even the "snow" of a dead station. This condition
lasted for a week. I thought I'd be clever and reseat the connectors
to see if that will fix it. The old 27 inch CRT type TVs are hernia
boxes. I am no longer that young where I can move this thing around
easily to fix things.

On 13 jun, 18:40, PaPaPeng wrote:

As for mis-reconnecting the cable all the cables have keyed connectors
and each of them is unique in size and shape. The cable runs are too
tight to make a mistake running the connector to another pin socket.
When I get around to it I will probably undo all the connectors and
reseat them again.

The other question is, is there such a thing as a hardware problem
that would kill the second tier of cable TV stations?

1. you may have, whilst moving things, exacerbated a bad solder joint.
you'll need to pull out the pcb, taking photos on a digital camera
along the way, so as not to have trouble later, to get to the botom of
this.

2. re.cable channels - check tuning settings, do a channel search and
ensure they are enabled in the menu ('air' or 'cable' option set
right)
maybe the tuner is duff, but they don't often fail this way.

-B

On Sat, 14 Jun 2008 00:49:57 -0400, Meat Plow
wrote:

The question here is
what kind of component makes a click when you use the remote to turn the
TV ON or OFF?

A relay.

There isn't one. That would have been the first component to suspect.

Meat Plow wrote:
On Sat, 14 Jun 2008 05:49:42 +0000, PaPaPeng wrote:

On Sat, 14 Jun 2008 00:49:57 -0400, Meat Plow wrote:

The question here is
what kind of component makes a click when you use the remote to turn
the TV ON or OFF?
A relay.
There isn't one. That would have been the first component to suspect.

Well then you're hearing something snap, possible in the high voltage.


There are a lot of sets with various relays. It's certainly not out of
reason to hear a click. Some don't click, but at least one of the ones
I have does.

jak

On Sat, 14 Jun 2008 11:58:40 -0400, Meat Plow
wrote:

On Sat, 14 Jun 2008 02:57:35 -0500, jakdedert wrote:

Meat Plow wrote:
On Sat, 14 Jun 2008 05:49:42 +0000, PaPaPeng wrote:

On Sat, 14 Jun 2008 00:49:57 -0400, Meat Plow
wrote:

The question here is
what kind of component makes a click when you use the remote to turn
the TV ON or OFF?
A relay.
There isn't one. That would have been the first component to suspect.

Well then you're hearing something snap, possible in the high voltage.


There are a lot of sets with various relays. It's certainly not out of
reason to hear a click. Some don't click, but at least one of the ones I
have does.


The OP claims there are no relays. I have my doubts.


Okay. Let us assume there is a relay. It clicks ON and it Clicks
OFF. This would indicate that the relay works. The question then is
which part of the circuitry causes it to click ON or OFF and why? How
does such a circuit work? It must be connected to the front panel
switch and the front panel IR remote singal detector and pass through
some circuitry before it connects to the relay.

The next question is a relay can only close a contact, that is
complete a conductor path, presumably to turn ON a circuit which
should then latch ON. That ON status lasts 5 seconds, a lifetime in
electronics. Then the relay clicks to OFF, an unlatch action. At
this point I can't figure out what is happening and why. Is there
such a thing as an undervoltage or overvoltage protection circuitry
that turns off the TV if the voltage (or some other condition) is not
met?

Everything in on a 12 inches by 14 inches motherboard. Thus there is a
high degree of IC integration that does not lend itself to component
repairs. The TV set worked great for something like 15 years. The
last time 5 years ago,there was an intermittent yet persistent
problem, was the spreading of scan lines on the top of the screen.
After many tries over a period of a few years I eventually got lucky
when a tool accidentally brushed a cable and I was able to reproduce
the problem. This allowed me to locate a practically invisible
separation of a pin donut on the MB. Reflowed that and the TV worked
even better then before. SONY PCBs do have a reputation for cold
solder separations with age.

Now back to the original problem of loss of second tier cable channels
that is blamed on the channel tuner. The TV set has an electronic
tuner. It doesn't have a bank of mechanical contacts to fail
selectively as in missing certain channels let alone a block of
channels. Is there such a thing as an electronic tuner that has
circuitry for blocks of channels, first tier, second tier, third tier
and so on. I would think access to those tier blocks are controlled
by the cable company. If the cable company cut off the second tier
channels, I should at least still have the channel number displayed on
the screen and maybe some "snow" not a totally blank black screen. I
don't have a conceptual tehcnical explanation for that either.

On 14 jun, 19:12, PaPaPeng wrote:


Now back to the original problem of loss of second tier cable channels
that is blamed on the channel tuner.

did you try the menu idea I mentioned before? what happened?
B.

On Sat, 14 Jun 2008 11:14:08 -0700 (PDT), b
wrote:

On 14 jun, 19:12, PaPaPeng wrote:


Now back to the original problem of loss of second tier cable channels
that is blamed on the channel tuner.

did you try the menu idea I mentioned before? what happened?
B.


Sorry, missed that. I have only a generic remote without that option.
My house was broken into and the crooks took my stereo, etc. consoles
the TV being too big to carry.

I forgot about the controls hidden behind the front panel. But now
that I can't even get the TV set to fire up I won't be able to check
out the menu options.

On Jun 14, 4:17*pm, PaPaPeng wrote:
On Sat, 14 Jun 2008 11:14:08 -0700 (PDT), b

wrote:
On 14 jun, 19:12, PaPaPeng wrote:

Now back to the original problem of loss of second tier cable channels
that is blamed on the channel tuner.

did you try the menu idea I mentioned before? what happened?
B.

Sorry, missed that. *I have only a generic remote without that option.
My house was broken into and the crooks took my stereo, etc. consoles
the TV being too big to carry.

I forgot about the controls hidden behind the front panel. *But now
that I can't even get the TV set to fire up I won't be able to check
out the menu options.

As I remember, there is a high-voltage shutdown in those sets that
probably takes about 5 seconds from turn-on to turn off. If the OP
hears or feels a static sound just before the shutoff click, it is
probably an overvoltage problem.

It could also be a failure of the horizontal stage to turn on, the
initial power to the relay depends on the horizontal output stage to
fire up, and one of the turns on the transformer is connected to a
rectifier which then provides a holding voltage to the power relay to
keep it turned on. Without an oscilloscope, it is impossible to be
sure which of these scenarios is the case.

If the OP can feel the hairs on his arm react when the set is first
turned on and his arm is near the face of the CRT, there is probably
high voilatage being developed and it is an overvoltage shutdown. If
he doesn't feel any static build-up, then it is probably lack of
power to the holding relay that is the problem.

Bob Hofmann