Sony Trinitron lost green & a homemade CRT test jig. (kv-27t

W

Wdyorchid

Guest
Trinitron (kv-27ts20) appears to have lost it's green because I can see only
purple, pale pictures. The problem occurred during a hot scorching day when it
became intermittent then permanent. Is it the tube or the circuit board? I
like to use a test jig tube to find out. I have two 17" Trinitron in the
basement and I'm trying to hook them as a test jig.

The problems are simple. Can this be done if the subject tube does not appear
to be an exact connection match? If so, how many wires jump from one tube to
the other? Four? (Red, Green, Blue and Ground.) Or do I just plug em all in to
the other tube as close to on the labeling as possible. What are possible side
effects?

Example:
Tube one (kv-27ts20) contains about nine pins.
Tube two (kv-xxxx) contains about seven pins.
Tube three (kv-xxx) contains about seven pins.
 
Forget trying to swap tubes with a different model - unless you want to see
how much equipment you can wreck in one day.

You didn't give enough information for a diagnosis. It could be something as
simple as a purity error due to a magnetic field from something like a
speaker, or if you relocated the set. It could be an electronic fault in
the colour decoding or display circuitry, or a tuner fault.

Also, if it's an older set, the high value resistors on the tube base PCBs
of Sony TVs tend to drift off value and cause lousy pictures - replace them
with metal film ones instead of carbon.

Let's hear more about the fault and the diagnostic tests done thus far.


"Wdyorchid" <wdyorchid@aol.com> wrote in message
news:20030806055137.02307.00001054@mb-m21.aol.com...
Trinitron (kv-27ts20) appears to have lost it's green because I can see
only
purple, pale pictures. The problem occurred during a hot scorching day when
it
became intermittent then permanent. Is it the tube or the circuit board? I
like to use a test jig tube to find out. I have two 17" Trinitron in the
basement and I'm trying to hook them as a test jig.

The problems are simple. Can this be done if the subject tube does not
appear
to be an exact connection match? If so, how many wires jump from one tube to
the other? Four? (Red, Green, Blue and Ground.) Or do I just plug em all in
to
the other tube as close to on the labeling as possible. What are possible
side
effects?

Example:
Tube one (kv-27ts20) contains about nine pins.
Tube two (kv-xxxx) contains about seven pins.
Tube three (kv-xxx) contains about seven pins.
 
When I was working in warranty service for Sony, this is one of the
models we were handling. On the back of the CRT socket there are marked
R G and B cathodes if I remember correctly. Use a DVM and measure the
voltages. I cannot remember the exact voltage range, but they should
be within about 15% of each other. The voltages are okay, then this is
a very strong indication of the tube being defective. If the tube is
shorted, it can also bring down some voltages. Disconnect the socket of
the tube, and take the readings on these points again. If the are
within specs, the tube is shorted. Component failure on this board is
very rare unless the tube when short, and did some damage.

In your case, I strongly believe the tube went defective on the green
section inside of it. This is common on these sets, after many hours of
tube use, and considering the age of the set.

You cannot jumper in the wrong tube. The electron-gun configuration,
voltage drives, and video drives must match exactly. The same goes for
the HV specs. If you mess with this, you are doing something that is
considered very dangerous for your safety, and also for the components
in the set!

--

Greetings,

Jerry Greenberg GLG Technologies GLG
==============================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
Instruments http://www.zoom-one.com/glgtech.htm
==============================================
"Wdyorchid" <wdyorchid@aol.com> wrote in message
news:20030806055137.02307.00001054@mb-m21.aol.com...
Trinitron (kv-27ts20) appears to have lost it's green because I can see
only
purple, pale pictures. The problem occurred during a hot scorching day
when it
became intermittent then permanent. Is it the tube or the circuit
board? I
like to use a test jig tube to find out. I have two 17" Trinitron in the
basement and I'm trying to hook them as a test jig.

The problems are simple. Can this be done if the subject tube does not
appear
to be an exact connection match? If so, how many wires jump from one
tube to
the other? Four? (Red, Green, Blue and Ground.) Or do I just plug em all
in to
the other tube as close to on the labeling as possible. What are
possible side
effects?

Example:
Tube one (kv-27ts20) contains about nine pins.
Tube two (kv-xxxx) contains about seven pins.
Tube three (kv-xxx) contains about seven pins.
 
I'm sorry to dissapoint you but their were no diagnostic done so far except a
bang here and there on the components with a wooden spatula. The TV weren't
transported before the failure. I'd decided not to buy a service manual. I'd
also felt the temperature on each heat sink and they appear to run warm as
normal. The Tv has been repaired twice by a friend and probably replaced the
tube and the resistor(s) you pointed out. My idea of the test jig is probably a
bad one.
-Wd


Forget trying to swap tubes with a different model - unless you want to see
how much equipment you can wreck in one day.

You didn't give enough information for a diagnosis. It could be something as
simple as a purity error due to a magnetic field from something like a
speaker, or if you relocated the set. It could be an electronic fault in
the colour decoding or display circuitry, or a tuner fault.

Also, if it's an older set, the high value resistors on the tube base PCBs
of Sony TVs tend to drift off value and cause lousy pictures - replace them
with metal film ones instead of carbon.

Let's hear more about the fault and the diagnostic tests done thus far.
Click to expand...
 
I think you have a very creative idea. Something I can do in a day. I'd never
thought of this. Had been tying to determine wether the tube has passed thru
all the good time for weeks and needed to find a way out. I'd been eyeing a
new 27" Trinitron on the market for $700. Anything below this price seem to
have un-crystal clear pictures. I use it to watch PBS or documentaries, wich
requires a TV as clear as Plasma TVs. Thanks for your and everyon'e else's
advices. Especially yours.
-Wdy


When I was working in warranty service for Sony, this is one of the
models we were handling. On the back of the CRT socket there are marked
R G and B cathodes if I remember correctly. Use a DVM and measure the
voltages. I cannot remember the exact voltage range, but they should
be within about 15% of each other. The voltages are okay, then this is
a very strong indication of the tube being defective. If the tube is
shorted, it can also bring down some voltages. Disconnect the socket of
the tube, and take the readings on these points again. If the are
within specs, the tube is shorted. Component failure on this board is
very rare unless the tube when short, and did some damage.

In your case, I strongly believe the tube went defective on the green
section inside of it. This is common on these sets, after many hours of
tube use, and considering the age of the set.

You cannot jumper in the wrong tube. The electron-gun configuration,
voltage drives, and video drives must match exactly. The same goes for
the HV specs. If you mess with this, you are doing something that is
considered very dangerous for your safety, and also for the components
in the set!

--

Greetings,

Jerry Greenberg
Click to expand...
 
I'd just completed the test in 5 minutes and here are the results:
Blue: 195 volt
Green: 194 volts
Red: 200 volts

The city charge ten dollars to throw away TVs here.
 
These are the parts you need to check/replace:
replace open r587& shorted d518 on "A" board
replace leaky C508 0.047MFD
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top