"Sylvia Else"


The horizontal deflection output transistor measures 5.7 omhs from emitter
to base in either direction.

** Probably normal.

There is an inbuilt resistor from B to E in nearly all HOTs of 20 ohms or
less.

It would certainly show as a short on the SMPS output.

** ********.


..... Phil

On 13/03/2011 4:11 PM, Phil Allison wrote:
"Sylvia Else"


The horizontal deflection output transistor measures 5.7 omhs from emitter
to base in either direction.

** Probably normal.

Er, yes, I meant emitter to collector.


There is an inbuilt resistor from B to E in nearly all HOTs of 20 ohms or
less.

It would certainly show as a short on the SMPS output.

** ********.

Probably true, for the emitter to base.

I found what appears to be the correct schematic. The transistor's
collector emitter junction is in series with an EHT transformer primary
winding, and together they sit across the HT output from the SMPS, with
just a small inductor in the way. I must admit it doesn't look to me as
if it's performing a horizontal deflection output role - that's just how
the transistor is described in the data sheet.

Sylvia.

On 13/03/2011 4:29 PM, Sylvia Else wrote:
On 13/03/2011 4:11 PM, Phil Allison wrote:
"Sylvia Else"


The horizontal deflection output transistor measures 5.7 omhs from
emitter
to base in either direction.

** Probably normal.

Er, yes, I meant emitter to collector.


There is an inbuilt resistor from B to E in nearly all HOTs of 20 ohms or
less.

It would certainly show as a short on the SMPS output.

** ********.

Probably true, for the emitter to base.

I found what appears to be the correct schematic. The transistor's
collector emitter junction is in series with an EHT transformer primary
winding, and together they sit across the HT output from the SMPS, with
just a small inductor in the way. I must admit it doesn't look to me as
if it's performing a horizontal deflection output role - that's just how
the transistor is described in the data sheet.

Sylvia.

I've bitten the bullet, and bought a new television.

Still, I'm puzzled by the failure in the old one. The transistor has
clearly failed, as far as I can see. Removing the small inductor
mentioned above stops the clicking noise, which is consistent with there
no longer being a short across the SMPS.

I'd have expected the set to now turn on and produce sound. But it doesn't.

The SMPS uses a quasi-resonant circuit, and disconnecting the inductor
has a side effect of removing the feedback for the SMPS. But on my,
admittedly limited, understanding of such circuits, it should still work.

Sylvia.

It's been a long time since I dealt with CRT horiz output
sections/transistors, and the latter ones were in VGA monitors.

In the Repair FAQ there are safety, testing and troubleshooting procedures
for horiz section faults, including the lightbulb in series with the HOT B+
setup, IIRC.

The HOTs (transistors) are fairly rugged semis, but operating at 15+kHZ and
high peak/fast risetime conduction cycles.

FWIW section..

A few conditions wrt HOT failures that I can recall at the moment include
bad/cold/broken solder connections, loss of horiz drive and drifting
values/faults in the tuning capacitors (the small value 1 and 2kV caps).

Small low voltage/battery powered testers aren't very reliable, IMO, for
testing/evaluating HOTs, since reliable leakage testing at higher voltages
than most small testers are capable of, should be performed to determine the
junction's performance compared to the datasheet published specs.

The above point being that one rarely knows for sure if they're receiving
genuine exact replacement parts nowadays, and testing before installation is
likely the best way to find out if the part are bogus.

My recommendations (and many other archived repair recommendations) for Sony
TVs and monitors, is to research the failure and buy all the recommended
repair parts from a Sony authorized distributor, especially for PSU and H,V
sweep faults.

--
Cheers,
WB
..............


"Sylvia Else" wrote in message
...
On 13/03/2011 4:29 PM, Sylvia Else wrote:

I've bitten the bullet, and bought a new television.

Still, I'm puzzled by the failure in the old one. The transistor has
clearly failed, as far as I can see. Removing the small inductor mentioned
above stops the clicking noise, which is consistent with there no longer
being a short across the SMPS.

I'd have expected the set to now turn on and produce sound. But it
doesn't.

The SMPS uses a quasi-resonant circuit, and disconnecting the inductor has
a side effect of removing the feedback for the SMPS. But on my, admittedly
limited, understanding of such circuits, it should still work.

Sylvia.

"Wild_Bull"

FWIW section..

A few conditions wrt HOT failures that I can recall at the moment include
bad/cold/broken solder connections, loss of horiz drive and drifting
values/faults in the tuning capacitors (the small value 1 and 2kV caps).


** Not to forget arcing inside the CRT or the horizontal transformer.


Small low voltage/battery powered testers aren't very reliable, IMO, for
testing/evaluating HOTs,

** 99 % of them cannot do any test on them at all.


since reliable leakage testing at higher voltages than most small testers
are capable of, should be performed to determine the junction's
performance compared to the datasheet published specs.

** Pure gobbledegook.


The above point being that one rarely knows for sure if they're receiving
genuine exact replacement parts nowadays,

** Instead of what - fakes ??

and testing before installation is likely the best way to find out if the
part are bogus.


** Absolute bull****.

No simple test will reveal a device that is merely sub-standard or of a
similar but cheaper type to the original.

The only way is to deal with reliable suppliers ONLY.


My recommendations (and many other archived repair recommendations) for
Sony TVs and monitors, is to research the failure and buy all the
recommended repair parts from a Sony authorized distributor, especially
for PSU and H,V sweep faults.

** Wear a belt and braces too - do you ??



..... Phil

On 14/03/2011 7:51 PM, Phil Allison wrote:
"Wild_Bull"

FWIW section..

A few conditions wrt HOT failures that I can recall at the moment include
bad/cold/broken solder connections, loss of horiz drive and drifting
values/faults in the tuning capacitors (the small value 1 and 2kV caps).


** Not to forget arcing inside the CRT

In a vacuum?

or the horizontal transformer.

Sylvia.

"Stupider than Anyone Else.


** Not to forget arcing inside the CRT

In a vacuum?


http://en.wikipedia.org/wiki/Vacuum_arc


** One of the most common causes of HOT failures.

Dumbass.



..... Phil

Arcing, shorts and HV leakage can all take place within a CRT.
I've seen several CRTs that had HV leakage to the Focus element (didn't
damage the HOT though).. there may be some examples in the Repair FAQ of
this type of fault and other CRT faults.

--
Cheers,
WB
..............


"Sylvia Else" wrote in message
...

In a vacuum?

or the horizontal transformer.

Sylvia.

On Mar 13, 1:11 am, "Phil Allison" wrote:


There is an inbuilt resistor from B to E in nearly all HOTs of 20 ohms or
less.

**************.

Most horiz output internal resistors are between 25 and 50 ohms.
Besides, 20 ohms isn't 5.7ohms. In circuit, E to B reads an ohm or
under as the secondary of the horiz driver transformer is directly
across it.. Out of circuit, a reading of 5.7 ohms E to B is a bad
transistor. It's not common in horizontal outputs, but an E to B
short does happen.


On Mar 13, 1:11 am, "Phil Allison" wrote:
** Probably normal.

**** More likely a stupid answer.

A common problem in Sonys is a bad solder connection on the secondary
of the horiz driver transformer, so instead of reading under an ohm,
the cold solder causes a reading of several ohms up to the internal
resistor value. Simply resoldering the horiz driver will restore
proper reading if the output is otherwise OK.


Twit.

Hey, this is fun!!!!!

Sony tvs are notorious for being picky about spares. I dislike them
for that reason, as they usually get repair estimates rejected due to
cost grounds.And that's assuming spares availability...

I recently dumped a 25" CRT set (FE2 chassis I think) - shorted
horizontal output stage. Common fault with the chassis - the
transformer fails, killing the line o/p transistor and damages the
micro. Unless you replace the lot in one go, with genuine sony bits,
you're back to square one... plus the uPc is NLA and an awkward smd
type. Set was BER, a shame considering it was barely 8 years old.
-B

"Stroonz is a ****head "

"Phil Allison"

There is an inbuilt resistor from B to E in nearly all HOTs of 20 ohms or
less.

**************.

Most horiz output internal resistors are between 25 and 50 ohms.

** I have seen them with 20 ohms and less.

You need to get out more.


Besides, 20 ohms isn't 5.7ohms.


** The OP corrected her error in the next post - which you have not
bothered to even read.

The 5.7 ohms was measured from C to B.

No clue was given about the use of in or out of circuit testing.


In circuit, E to B reads an ohm or
under as the secondary of the horiz driver transformer is directly
across it..

** Not all HOT drive circuits are like that.


** Probably normal.

**** More likely a stupid answer.


** Why don't you go and get ****ed ?


....... Phil

On Mar 14, 8:01*pm, "Phil Allison" wrote:

** I have seen them with 20 ohms and less.


******** Yes, but those are called shorted.



On Mar 14, 8:01 pm, "Phil Allison" wrote:
** Not all HOT drive circuits are like that.


******** She didn't ask about all HOT drive circuits, she asked about
HERS.



** Why don't you go and get ****ed ?

...... *Phil

Now is that nice?

"Stroonz is a ****HEAD "


Most horiz output internal resistors are between 25 and 50 ohms.

** I have seen them with 20 ohms and less.

You need to get out more.


Besides, 20 ohms isn't 5.7ohms.


** The OP corrected her error in the next post - which like a total
****head you have not bothered to even read.

The 5.7 ohms was actually measured from C to B.

And the bitch gave no clue about the use of in or out of circuit testing.



In circuit, E to B reads an ohm or
under as the secondary of the horiz driver transformer is directly
across it..

** Not all HOT drive circuits are like that.

Many have a low value R in series with the base with a diode across it.


** Why don't you go **** a dead donkey ?



....... Phil

On Mar 15, 11:38*am, "Phil Allison" wrote:
"Stroonz is a ****HEAD *"



Most horiz output internal resistors are between 25 and 50 ohms.

** I have seen them with 20 ohms and less.

* * You need to get out more.

Besides, 20 ohms isn't 5.7ohms.

** The OP corrected her error in the next post *- *which like a total
****head you have not bothered to even read.

*The 5.7 ohms was actually measured from C to B.

*And the bitch gave no clue about the use of in or out of circuit testing.

In circuit, E to B reads an ohm or
under as the secondary of the horiz driver transformer is directly
across it..

** Not all HOT drive circuits are like that.

*Many have a low value R in series with the base with a diode across it..

** Why don't you go **** a dead donkey ?


Im very annoyed now, I was sipping coffee when I read that, and some
got sprayed from laughing



...... *Phil

On Mar 14, 9:38*pm, "Phil Allison" blathered:

** The OP corrected her error in the next post *- *which like a total
****head you have not bothered to even read.


******* Doesn't matter if she corrected it or not. You were INCORRECT
when you believed a 5.7 ohm E to B reading was normal in HER SONY.

On Mar 14, 9:38 pm, "Phil Allison" blathered:
** I have seen them with 20 ohms and less.

Yes, and they were shorted. OTOH, if you can cite a transistor that
was actually used as a horiz output that has an emitter-base resistor
of less than 20 ohms, I'll happily concede.

On Mar 14, 9:38 pm, "Phil Allison" droned:

*The 5.7 ohms was actually measured from C to B.


******** Read above ^


On Mar 14, 9:38 pm, "Phil Allison" wrote:
*And the bitch gave no clue about the use of in or out of circuit testing.

******** We don't know if she's a bitch or not. She might be quiet
pleasant.....


On Mar 14, 9:38 pm, "Phil Allison" wrote:
** Not all HOT drive circuits are like that.


No one said all HOT drive circuits are like that. But again, she
wasn't interested in every conceivable version of the drive circuit,
she was interested in HER Sony. Her Sony doesn't have a "low value
resistor in series with the base". If you don't know what you're
talking about or can't offer correct specific information, you really
should pipe down, or at least qualify your opinions as just that.


On Mar 14, 9:38 pm, "Phil Allison" wrote:
** Why don't you go **** a dead donkey ?

...... *Phil

Common Phil, where does one find a dead donkey, even if one was so
inclined to be intimate with it. You may not be the smartest guy on
the web, but you are a riot!!!

On Mar 14, 9:58*pm, Stroonz wrote:

Oh, and the quiet above is a typo: reverse the "e" and "t"

"Stroonz is a PSYCHOTIC ****HEAD "


Most horiz output internal resistors are between 25 and 50 ohms.

** I have seen them with 20 ohms and less.

You need to get out of that asylum more.


Besides, 20 ohms isn't 5.7ohms.


** The OP corrected her error in the next post - which like a total
****head you have not bothered to even read.

The 5.7 ohms was actually measured from C to B.

And the mad bitch gave no clue about the use of in or out of circuit
testing.


In circuit, E to B reads an ohm or
under as the secondary of the horiz driver transformer is directly
across it..

** Not all HOT drive circuits are like that.

Many have a low value R in series with the base with a diode across it.

The original exchange was:

" The horizontal deflection output transistor measures 5.7 omhs from
emitter to base in either direction.

** Probably normal. "

See - no reference is made to any particular set in my remark .


** Why don't you go **** two dead donkeys ?



....... Phil

On Mar 14, 10:08*pm, "Phil Allison" wrote:


** The OP corrected her error in the next post *- *which like a total
****head you have not bothered to even read.


****** Yes, the OP did correct her error, something you refuse to
do. You said a 5.7 ohm reading was "probably normal" for her Sony.
You were wrong and can't admit it. Nice character flaw Phil.




The original exchange was:

" The horizontal deflection output transistor measures 5.7 omhs from
* *emitter to base in either direction.

** Probably normal. *"

See - *no reference is made to any particular set in my remark .

It's hard to explain this to someone who is unfamiliar with Sonys, but
I'll try again: If everything in her Sony is normal, the E to B
resistance reading will be under an ohm in circuit. If the secondary
of the horiz drive trans in her Sony is open or the connection is bad,
it will read the internal emitter to base resistor directly, if the
transistor is so equipped. (some Sonys of this era use no e to be
resistor). If the transistor is measured out of circuit, it will read
approx 35 ohms e to b if it's not shorted. Under NO CIRCUMSTANCES
will this TV show 5.7 ohms across the e to b junction. Such a reading
is ABNORMAL. Perhaps you left the "ab" out of your reply.

And I know you'll requote her correcting her reading, but it doesn't
change the fact that you believed and proclaimed as fact that an E to
B reading of 5.7 ohms in HER SONY was normal.


** Why don't you go **** two dead donkeys ?

...... *Phil

You know, vile, classless folk take all the fun out of a debate.

Enjoy your last word Phil......

"Stroonz is a LYING PSYCHOPATH "

You said a 5.7 ohm reading was "probably normal" for her Sony.

** Wrong.


The original exchange was:

" The horizontal deflection output transistor measures 5.7 omhs from
emitter to base in either direction.

** Probably normal. "

See - no reference is made to any particular set in my remark .


** Why don't you go **** two dead donkeys ?

On 15/03/2011 10:33 AM, b wrote:
Sony tvs are notorious for being picky about spares. I dislike them
for that reason, as they usually get repair estimates rejected due to
cost grounds.And that's assuming spares availability...

I recently dumped a 25" CRT set (FE2 chassis I think) - shorted
horizontal output stage. Common fault with the chassis - the
transformer fails, killing the line o/p transistor and damages the
micro. Unless you replace the lot in one go, with genuine sony bits,
you're back to square one... plus the uPc is NLA and an awkward smd
type. Set was BER, a shame considering it was barely 8 years old.
-B

That's the kind of scenario that's deterred me from replacing the
transistor. Your comment about the damage to the microprocessor is
particularly relevant given my inability to persuade the set to produce
sound with the transistor removed, or even to enter/leave standby mode.

Sylvia.

On Mar 15, 2:42*pm, Sylvia Else wrote:
On 15/03/2011 10:33 AM, b wrote:

Sony tvs are notorious for being picky about spares. I dislike them
for that reason, as they usually get repair estimates rejected due to
cost grounds.And that's assuming spares availability...

* I recently dumped a 25" CRT set (FE2 chassis I think) - shorted
horizontal output stage. Common fault with the chassis - the
transformer fails, killing the line o/p transistor and damages the
micro. Unless you replace the lot in one go, with genuine sony bits,
you're back to square one... plus the uPc is NLA and an awkward smd
type. Set was BER, a shame considering it was barely 8 years old.
-B

That's the kind of scenario that's deterred me from replacing the
transistor. Your comment about the damage to the microprocessor is
particularly relevant given my inability to persuade the set to produce
sound with the transistor removed, or even to enter/leave standby mode.

Sylvia.

Not familiar with the set so I don't know exactly - but functions
related to sound may
be powered from a rail generated from the EHT transformer.

Even if not, it is possible that it may be muted or disabled by the
CPU if the EHT circuit isn't working correctly.
Many other functions may be shut off for safety also.

In the past I have found that the majority of sets/monitors (note -
have not worked on many newer than the 1990's)
will work once the H out transistor is replaced, however this isn't
always the case. The tuning caps (usually across the transistor) can
fail or lose capacitance causing the voltage to go through the roof
(they often look normal),
yokes can burn out (Samsung, usually inside on the H section where you
can't see it without removing from tube, usually from corrosion), the
EHT transformer can short internally, or can develop an arc through
the plastic casing to chassis.

Arcing from out of the housing on some transformers that contains the
focus and screen pots. I have seen often

Some of these arcs can be particularly bad, in fact some seem to
manage to burn their way through silicon sealant and continue the arc
as before. (note -too close to the frame to allow a decent thickness)

In some cases, the only way I could stop this was to remove the
aluminium frame from around the transformer, and cut away a section of
it near the where the arc was so as to give the transformer nothing to
arc to. It also allowed more clearance for a thicker coat of silcone
sealant to prevent future problems.



I am leaving out things like dry joints and obviously damaged
components as I assume most people on this group would look for these
before posting.

On 15/03/2011 4:12 PM, kreed wrote:
On Mar 15, 2:42 pm, Sylvia wrote:
On 15/03/2011 10:33 AM, b wrote:

Sony tvs are notorious for being picky about spares. I dislike them
for that reason, as they usually get repair estimates rejected due to
cost grounds.And that's assuming spares availability...

I recently dumped a 25" CRT set (FE2 chassis I think) - shorted
horizontal output stage. Common fault with the chassis - the
transformer fails, killing the line o/p transistor and damages the
micro. Unless you replace the lot in one go, with genuine sony bits,
you're back to square one... plus the uPc is NLA and an awkward smd
type. Set was BER, a shame considering it was barely 8 years old.
-B

That's the kind of scenario that's deterred me from replacing the
transistor. Your comment about the damage to the microprocessor is
particularly relevant given my inability to persuade the set to produce
sound with the transistor removed, or even to enter/leave standby mode.

Sylvia.

Not familiar with the set so I don't know exactly - but functions
related to sound may
be powered from a rail generated from the EHT transformer.

Even if not, it is possible that it may be muted or disabled by the
CPU if the EHT circuit isn't working correctly.

Or just to make the damned thing difficult to diagnose, thus increasing
the chance it'll be tossed and a new one bought.

Many other functions may be shut off for safety also.

In the past I have found that the majority of sets/monitors (note -
have not worked on many newer than the 1990's)
will work once the H out transistor is replaced, however this isn't
always the case. The tuning caps (usually across the transistor) can
fail or lose capacitance causing the voltage to go through the roof
(they often look normal),
yokes can burn out (Samsung, usually inside on the H section where you
can't see it without removing from tube, usually from corrosion), the
EHT transformer can short internally, or can develop an arc through
the plastic casing to chassis.

Arcing from out of the housing on some transformers that contains the
focus and screen pots. I have seen often

Some of these arcs can be particularly bad, in fact some seem to
manage to burn their way through silicon sealant and continue the arc
as before. (note -too close to the frame to allow a decent thickness)

In some cases, the only way I could stop this was to remove the
aluminium frame from around the transformer, and cut away a section of
it near the where the arc was so as to give the transformer nothing to
arc to. It also allowed more clearance for a thicker coat of silcone
sealant to prevent future problems.



I am leaving out things like dry joints and obviously damaged
components as I assume most people on this group would look for these
before posting.

At one point, I saw some of the smoke escape, but unfortunately was on
the wrong side of the set to see where it came from

Sylvia.

On Mar 15, 6:23*pm, Sylvia Else wrote:
On 15/03/2011 4:12 PM, kreed wrote:



On Mar 15, 2:42 pm, Sylvia *wrote:
On 15/03/2011 10:33 AM, b wrote:

Sony tvs are notorious for being picky about spares. I dislike them
for that reason, as they usually get repair estimates rejected due to
cost grounds.And that's assuming spares availability...

* *I recently dumped a 25" CRT set (FE2 chassis I think) - shorted
horizontal output stage. Common fault with the chassis - the
transformer fails, killing the line o/p transistor and damages the
micro. Unless you replace the lot in one go, with genuine sony bits,
you're back to square one... plus the uPc is NLA and an awkward smd
type. Set was BER, a shame considering it was barely 8 years old.
-B

That's the kind of scenario that's deterred me from replacing the
transistor. Your comment about the damage to the microprocessor is
particularly relevant given my inability to persuade the set to produce
sound with the transistor removed, or even to enter/leave standby mode..

Sylvia.

Not familiar with the set so I don't know exactly - but functions
related to sound may
be powered from a rail generated from the EHT transformer.

Even if not, it is possible that it may be muted or disabled by the
CPU if the EHT circuit isn't working correctly.

Or just to make the damned thing difficult to diagnose, thus increasing
the chance it'll be tossed and a new one bought.


Years ago they probably realised that the sets were likely to last x
number of years, and by that time, few would bother fixing. Once you
start using tiny surface mount parts (including those QFP chips) the
odds of people not bothering with a repair increase exponentially
along with the cost if they do pay a serviceman to do it. Robot
assembly also allows things to be packed tighter than manual
assembly ?

At the same time the costs of these sets have plummeted. Can remember
around 2000 buying a new 25" set, and was over $1000. Within 3 years
or so, they were down around $5-600, and now if you can still buy 25"
CRT sets, I would be surprised if they were even $150-$200 in discount
stores or similar. I doubt you would get a repair done for a fault
like yours for less than this at a TV service shop. We have 2 nice
Sharp 26" ones in the Garage, that work fine and wont get used by me.
Cant even give them away.


Interesting that that link to a manual that was posted really only
shows how to change the tube, yoke chassis, front plastic push button
assembly - but no schematic or details on board level repair. Maybe
they would just send exchange boards during the warranty period.

One big thing that would bother me, is paying for and replacing the
transistor, and then finding the problem still there or other faults.
You could change the CPU and god knows what else in between and still
have a problem.




Many other functions may be shut off for safety also.

In the past I have found that the majority of sets/monitors (note -
have not worked on many newer than the 1990's)
will work once the H out transistor is replaced, however this isn't
always the case. *The tuning caps (usually across the transistor) can
fail or lose capacitance causing the voltage to go through the roof
(they often look normal),
yokes can burn out (Samsung, usually inside on the H section where you
can't see it without removing from tube, usually from corrosion), the
EHT transformer can short internally, or can develop an arc through
the plastic casing to chassis.

Arcing from out of the housing on some transformers that contains the
focus and screen pots. I have seen often

Some of these arcs can be particularly bad, in fact some seem to
manage to burn their way through silicon sealant and continue the arc
as before. (note -too close to the frame to allow a decent thickness)

In some cases, the only way I could stop this was to remove the
aluminium frame from around the transformer, and cut away a section of
it near the where the arc was so as to give the transformer nothing to
arc to. It also allowed more clearance for a thicker coat of silcone
sealant to prevent future problems.

I am leaving out things like dry joints and obviously damaged
components as I assume most people on this group would look for these
before posting.

At one point, I saw some of the smoke escape, but unfortunately was on
the wrong side of the set to see where it came from



And short of going over everything with a magnifier and strong light
you have buckleys chance
of finding it - even that probably wouldnt work.

Had the same recently with a Eaton Powerware UPS. Smoke came out, the
thing still "sort of worked" .

Couldnt find the smoke source but found a number of burnt tracks,
shorted out 5404 3A diodes, and a FET that was shorted on all 3 legs,
the part was unobtainable from regular sources. TO make matters
worse, it looked as though the FET was designed to put a dead short
across the batteries under some circumstance. The battery was also
practically dead.

Getting another unit for about $110 ended up being the best fix.

Sylvia.

On 15/03/2011 10:46 PM, kreed wrote:
One big thing that would bother me, is paying for and replacing the
transistor, and then finding the problem still there or other faults.
You could change the CPU and god knows what else in between and still
have a problem.

And indeed discover that the still existing fault destroys them again.

TO make matters
worse, it looked as though the FET was designed to put a dead short
across the batteries under some circumstance.

No fuse protecting the battery? Sounds like a serious safety issue -
shorting out lead-acid batteries would have to be good way of starting
fires.

Sylvia.

On Mar 15, 12:46*pm, kreed wrote:

One big thing that would bother me, is paying for and replacing the
transistor, and then finding the problem still there or other faults.
You could change the CPU and god knows what else in between and still
have a problem.

This brings us back to the Sony problem. On many sets you can use
standard transistors and other semiconductors, at least for test
purposes, so it is usually worth a punt for a few quid to see if it
fixes the set. But an expensive chain failure which necessitates the
use of genuine parts (a typical sony scenario!) means that these sets
are not often worth bothering with. In this case I had no idea of the
set's history, for all I know the tube could have been wasted too -
another reason not to put serious time and money into such an item.

It is ironic that latterday CRT 'supermarket sets' tend to have a
better chance of getting fixed than some of those costing several
times as much!
-B

On Mar 15, 9:56*pm, Sylvia Else wrote:
On 15/03/2011 10:46 PM, kreed wrote:

One big thing that would bother me, is paying for and replacing the
transistor, and then finding the problem still there or other faults.
You could change the CPU and god knows what else in between and still
have a problem.

And indeed discover that the still existing fault destroys them again.

* TO make matters

worse, it looked as though the FET was designed to put a dead short
across the batteries under some circumstance.

No fuse protecting the battery? Sounds like a serious safety issue -
shorting out lead-acid batteries would have to be good way of starting
fires.

Sylvia.


From memory, and I may be wrong - It was not protected by the fuse,
only by the blown PCB tracks. (and there was current limiting from
there being a relatively thin wire leading from the battery + to this
part of the circuit.)

The circuit was not easy to trace out, and parts like this seemed
illogical.

The thing that probably killed it was that I was using it to charge up
about 5 SLA batteries, one after the other, and it might not have been
designed to be charging for this length of time continuously. once the
5th battery was connected - smoke time.

On 15/03/2011 11:35 PM, kreed wrote:


The thing that probably killed it was that I was using it to charge up
about 5 SLA batteries, one after the other, and it might not have been
designed to be charging for this length of time continuously. once the
5th battery was connected - smoke time.

Still, I'd have expected it to have reached thermal equilibrium long
before even the first battery was fully charged. It shouldn't get any
hotter from subsequent chargings.

Sylvia.

The set's inability to show any signs of working circuits, with the HOT
(transistor) removed (or failed), is normal for most TVs made within about
the last 25 years.

Other than a Standby voltage supply, most TVs won't operate (even partially)
without a functioning horiz scan/sweep circuit, as in general, several
voltage supplies are derived from the IHVT integrated high voltage
transformer (some refer to as flyback or other terms).

--
Cheers,
WB
..............


"Sylvia Else" wrote in message
...

That's the kind of scenario that's deterred me from replacing the
transistor. Your comment about the damage to the microprocessor is
particularly relevant given my inability to persuade the set to produce
sound with the transistor removed, or even to enter/leave standby mode.

Sylvia.

The set's inability to show any signs of working circuits, with
the HOT removed (or failed), is normal for most TVs made
within about the last 25 years.

Other than a Standby voltage supply, most TVs won't operate
(even partially) without a functioning horiz scan/sweep circuit,
as in general, several voltage supplies are derived from the IHVT
integrated high voltage transformer (some refer to as flyback or
other terms).

My Sony KV-1920, purchased ca. 1974, was one of the first TVs with a
switching power supply. When the supply failed in the early 80s, a guy from
Sony warned me not to try to fix it myself. "If you don't catch all the bad
parts the first time, some of the replacement parts might fail. It's best to
have a trained tech look at it." It cost me around $75 (which seemed a lot,
then) but the set was properly repaired and worked another 15 years.

On Mon, 14 Mar 2011 18:29:09 -0700, Stroonz wrote:

On Mar 14, 8:01Â*pm, "Phil Allison" wrote:

** I have seen them with 20 ohms and less.


******** Yes, but those are called shorted.



On Mar 14, 8:01 pm, "Phil Allison" wrote:
** Not all HOT drive circuits are like that.


******** She didn't ask about all HOT drive circuits, she asked about
HERS.



** Why don't you go and get ****ed ?

...... Â*Phil

Now is that nice?

You can safely ignore Phil's posts. Most do because of his extreme mood
swings and personality disorder.



--
Live Fast Die Young, Leave A Pretty Corpse

On Mar 15, 11:00*pm, Sylvia Else wrote:
On 15/03/2011 11:35 PM, kreed wrote:



The thing that probably killed it was that I was using it to charge up
about 5 SLA batteries, one after the other, and it might not have been
designed to be charging for this length of time continuously. once the
5th battery was connected - smoke time.

Still, I'd have expected it to have reached thermal equilibrium long
before even the first battery was fully charged. It shouldn't get any
hotter from subsequent chargings.

Sylvia.

You are probably right, but this was the only change to "normal" usage
I can think of before it failed

On Mar 15, 11:47*am, Meat Plow wrote:


You can safely ignore Phil's posts. Most do because of his extreme mood
swings and personality disorder.

--

On a hunch, I checked the garbage AOL email addy that I use to
register for public forums, and there (amongst the ton of spam emails)
were more than a couple of emails offering the same advice. But I'm
not completely convinced he has mood swings or a personality disorder;
I suspect he's a typical internet bully who can only demonstrate
bravery from behind the security of a keyboard. If someone were to
act like that in real life, you go up to them, grab them by the
throat, and watch them fill their Pampers. Still, I've often gotten a
good laugh from his posts.

"Stroonz is a **** "


I suspect he's a typical internet bully ..


** Hey - pal.

Blind Freddy can see that YOU are bullying me.

Cos you are a psychotic control freak.



..... Phil

On 16/03/2011 8:55 AM, kreed wrote:
On Mar 15, 11:00 pm, Sylvia wrote:
On 15/03/2011 11:35 PM, kreed wrote:



The thing that probably killed it was that I was using it to charge up
about 5 SLA batteries, one after the other, and it might not have been
designed to be charging for this length of time continuously. once the
5th battery was connected - smoke time.

Still, I'd have expected it to have reached thermal equilibrium long
before even the first battery was fully charged. It shouldn't get any
hotter from subsequent chargings.

Sylvia.

You are probably right, but this was the only change to "normal" usage
I can think of before it failed

Coincidence - there's probably a yet to be discovered perverse law of
nature that says that a machine is most likely to fail shortly after a
totally irrelevant change in the way it is used.

Sylvia.

On 16/03/2011 2:19 AM, Wild_Bill wrote:
The set's inability to show any signs of working circuits, with the HOT
(transistor) removed (or failed), is normal for most TVs made within
about the last 25 years.

Other than a Standby voltage supply, most TVs won't operate (even
partially) without a functioning horiz scan/sweep circuit, as in
general, several voltage supplies are derived from the IHVT integrated
high voltage transformer (some refer to as flyback or other terms).

Well, that's possible, though as I've indicated, my TV wouldn't even
enter standby mode.

I suppose it's conceivable that since it failed in operation, it always
tries to power up in that mode, and that the processor won't allow entry
to standby mode unless everything's working. That would seem a bit
perverse, but who knows?

Sylvia.

Coincidence - there's probably a yet to be discovered
perverse law of nature that says that a machine is most
likely to fail shortly after a totally irrelevant change in the
way it is used.

Here's another one... "A machine is most likely to irreversibly fail shortly
after you've gone to a great deal of trouble to fix it."

These types of failures are the kinds of problems that TV techs have seen
regularly for a lot of years.. a relatively simple fault is capable of
causing the "smart chassis" type designs to be completely dead, in many
cases.

In sets that develop a fault, and also have some other components that have
changed values due to age, the chassis essentially has compound faults,
which were commonly referred to as Tough Dogs, among other names.
Shut-down circuits have been implemented for many years, to prevent the TV
from operating at all, if the CRT's HV potential exceeded a limit, as a
safety shutdown.

Some minor faults are often complicated by poor soldering during the circuit
board manufacturing process/build, which creates new faults as the boards
age and go thru many thermal cycles.

Many of the electronic equipment designs presently manufactured are similar
designs of smart chassis design, in that one fault will disable every
function.. maybe with the exception of a blinking LED.
In many of these designs, either everything operates within normal limits,
or the units just shut down and won't restart without experienced technical
intervention.

--
Cheers,
WB
..............


"Sylvia Else" wrote in message
...

I suppose it's conceivable that since it failed in operation, it always
tries to power up in that mode, and that the processor won't allow entry
to standby mode unless everything's working. That would seem a bit
perverse, but who knows?

Sylvia.

In sets that develop a fault, and also have some other
components that have changed values due to age, the
chassis essentially has compound faults, which were
commonly referred to as Tough Dogs, among other names.

The term probably dates back to at least the 30s. It refers to a problem
that refuses to yield to common-sense analysis or trouble-shooting.

On Tue, 15 Mar 2011 15:20:51 -0700, Stroonz wrote:

On Mar 15, 11:47Â*am, Meat Plow wrote:


You can safely ignore Phil's posts. Most do because of his extreme mood
swings and personality disorder.

--

On a hunch, I checked the garbage AOL email addy that I use to register
for public forums, and there (amongst the ton of spam emails) were more
than a couple of emails offering the same advice. But I'm not
completely convinced he has mood swings or a personality disorder; I
suspect he's a typical internet bully who can only demonstrate bravery
from behind the security of a keyboard. If someone were to act like
that in real life, you go up to them, grab them by the throat, and watch
them fill their Pampers. Still, I've often gotten a good laugh from his
posts.


I've had dialog with Phil that was very helpful and he's even apologized
to me (in his own way) once. On other occasions he's tore into me for no
reason whatsoever. And it's not just me but others that don't do things
the Phil Allison Way. I have no official proof but this behavior smacks
of a sever mental disorder.


--
Live Fast Die Young, Leave A Pretty Corpse

"William Sommerwerck" wrote in
:

Coincidence - there's probably a yet to be discovered
perverse law of nature that says that a machine is most
likely to fail shortly after a totally irrelevant change in the
way it is used.

Here's another one... "A machine is most likely to irreversibly fail
shortly after you've gone to a great deal of trouble to fix it."




It is called "the innate perversity of inanimate matter".
There was an article on it published MANY years ago in CQ magzine.

It have some ways to use ipoim to do things around the ham shack.
1) in order to prevent stretching from detuning your antenna, cut the wire
short to allow for stretch.
2) to fix a complex electronic device:
a) go through the parts list and contact all the parts suppliers. You
will find one or two parts that can not be found anywhere; it is one of
those.
b) examine the layout and locate the part that is most difficult to
remove and replace. You just found your defective component.

I don't remember the rest of the article but it has proven to be quite
useful to me, over the years.

73 de N5bz