This set has a weak CRT and blinks on and off. I jumped the two
parallel resistors on the CRT board which are in series with the heater
and the pix came on. The same thing happens if I tweek the screen up
slightly. I decided to do both and the picture seems to be holding. I
realize this is a "deadman walking" however I would like to give the
customer some rough idea as to life expectancy. Does anyone have any
information, after returning a set like this, (with an explanation of
course), perhaps feedback from customers on this? Also, it occurred to
me that jumping the series heater resistor will increase the heater
current through the flyback. Should I be overly concerned about this on
a set whos' days are numbered anyway? Thanks, Lenny Stein, Barlen
Electronics

Jumping the resistors will certainly raise the heater current. This will
hasten the life in the CRT that is left. But, considering that it is almost
gone anyways, there is not much difference here.

As the CRT is going weak, the auto controlled bias circuits keep biasing the
CRT more and more to maintain its performance as best as possible.
Eventually they run out of range, and cannot maintain the proper current.
This also means less anode current, and thus the set is designed to go in to
protection when the anode current is below a certain amount.

Raising the heater current allows for a greater amount of emission. I have
seen tubes last anywhere from a few days to a few months like this. There is
no accurate way to predict anything with this type of affair.

The greater heater current may also cause the flyback to run a bit warmer,
and it may also put a bit more of a load on the horizontal output
transistor. This area is a bit robust, and should normally be able to take
the added load. After running the set for about an hour with some type of a
cover over it, if you can, take a temperature reading of the horizontal
output transistor. It should not exceed about 60 to 70 degrees Celsius. At
about 80 to 90 degrees Celsius, the transistor would be working at near its
maximum temperature range for long duration operation.

--

Jerry G.
======


wrote in message
oups.com...
This set has a weak CRT and blinks on and off. I jumped the two
parallel resistors on the CRT board which are in series with the heater
and the pix came on. The same thing happens if I tweek the screen up
slightly. I decided to do both and the picture seems to be holding. I
realize this is a "deadman walking" however I would like to give the
customer some rough idea as to life expectancy. Does anyone have any
information, after returning a set like this, (with an explanation of
course), perhaps feedback from customers on this? Also, it occurred to
me that jumping the series heater resistor will increase the heater
current through the flyback. Should I be overly concerned about this on
a set whos' days are numbered anyway? Thanks, Lenny Stein, Barlen
Electronics

I did the same but jumped with a .5 ohm to limit the inrush somewhat
(KV2786R)
Been 2 years, no effect on the flyback but I was still unsatisfied with the
picture.
The back of the tube was still clear with no signs of "silvering"
I took a chance with an old BW Rejuvenator. I wired it to a color CRT socket
and gave the guns a "shot" one at a time. It paid off, I was lucky.

-Joe


wrote in message
oups.com...
This set has a weak CRT and blinks on and off. I jumped the two
parallel resistors on the CRT board which are in series with the heater
and the pix came on. The same thing happens if I tweek the screen up
slightly. I decided to do both and the picture seems to be holding. I
realize this is a "deadman walking" however I would like to give the
customer some rough idea as to life expectancy. Does anyone have any
information, after returning a set like this, (with an explanation of
course), perhaps feedback from customers on this? Also, it occurred to
me that jumping the series heater resistor will increase the heater
current through the flyback. Should I be overly concerned about this on
a set whos' days are numbered anyway? Thanks, Lenny Stein, Barlen
Electronics

Jumping the heater resistor on that set can cause immediate failure of the
heater on startup due to the excessive inrush of current.
Perhaps simply taking its value down by 1/2 would not be so bad as the
resistor will still limit the inrush current somewhat.

The G2 increase is usually the best bet. If you know exactly what you are
doing and have the schematic on hand, you can 'fiddle' with the akb
feedback resistors on a weak gun to make the akb levels closer. What them
on start up on the oscope.

Less than 1 year is typical. I usually tell people to start looking and
shop around for the lowest price on the best tv set they are willing to
buy. With the impending transition to digital, might not be a bad time to
start shopping.

David

"dkuhajda" bravely wrote to "All" (09 Dec 04 19:20:11)
--- on the heady topic of " Sony KV27S15 weak CRT"

dk Subject: Sony KV27S15 weak CRT
dk From: dkuhajda

dk Jumping the heater resistor on that set can cause immediate failure of
dk the heater on startup due to the excessive inrush of current.

The heater filaments are rather tough. In fact the CRT is evacuated by
running the filament white hot and igniting the "getter" which removes
any remaining gas the vacuum pump didn't. For example a 6 volt crt
filament is designed to be run at well over 10 volts for that purpose.
The resistors are there to protect the flyback output from the surge
not the filament.


dk Perhaps simply taking its value down by 1/2 would not be so bad as the
dk resistor will still limit the inrush current somewhat.

Okay, it is wise but as explained it may not be needed.


dk The G2 increase is usually the best bet. If you know exactly what you

Increasing G2 won't help if the emission is too low. The picture will
be brighter but it will "posterize" due to the video limiting. It's
okay if all you watch are cartoons, though. ;-)

A*s*i*m*o*v

.... I ran Doublespace on my monitor & get 2 more TV channels.

"Joe" bravely wrote to "All" (10 Dec 04 01:53:02)
--- on the heady topic of " Sony KV27S15 weak CRT"

Jo From: "Joe"

Jo I did the same but jumped with a .5 ohm to limit the inrush somewhat
Jo (KV2786R)
Jo Been 2 years, no effect on the flyback but I was still unsatisfied
Jo with the picture.
Jo The back of the tube was still clear with no signs of "silvering"
Jo I took a chance with an old BW Rejuvenator. I wired it to a color CRT
Jo socket and gave the guns a "shot" one at a time. It paid off, I was
Jo lucky.
Jo -Joe

Sometimes the cathode gets dusty and this hinders the emission. The
rejuv clears away the film and restores emission. Sometimes all the
grids get dirty and no amount of rejuv will clear that.

A*s*i*m*o*v

.... I know flyback, ultor, and 47 other dangerous words.

"Ultor" now thats one I haven't heard in awhile....
Lenny.

Oh BTW, thanks for everyones opinions and advice. It is very much
appreciated. Lenny.

"Ultor" now thats one I haven't heard in awhile....
Lenny.

Heheheh.

"The ultor zapped me!"

"What? I think you've been watching too much 'Flash Gordon.'"

"No. I forgot to arc it to the DAG first!" - Reinhart

"LASERandDVDfan" bravely wrote to "All" (13 Dec 04 03:53:10)
--- on the heady topic of " Sony KV27S15 weak CRT"

LA From: (LASERandDVDfan)

"Ultor" now thats one I haven't heard in awhile....
Lenny.

LA Heheheh.

LA "The ultor zapped me!"

LA "What? I think you've been watching too much 'Flash Gordon.'"

LA "No. I forgot to arc it to the DAG first!" - Reinhart

What is the origin of the word ULTOR...?
I'm venturing a guess the letter U represents voltage...
Maybe then followed by Line Transformer Output Regulated?
The dictionary describes it as:

Ultor - An adjective used to identify the picture-tube anode or
element furthest from the cathode, the anode to which the highest
voltage is applied, or the voltage itself (e.g. the ultor anode is the
second anode of the picture tube, and the ultor voltage is the voltage
applied to it).

How can I use the word Ultor as an adjective? The 2nd anode is so very
ultor? More ultor? Most ultor? Or rather: ultor, ultorer, ultorest?

A*s*i*m*o*v

.... Man, that lightning sounds clos;3F_k6AW? NO CARRIER