Lost the Lower 1/2 of my Display ??

[Katmandu]

Yup. Lost the bottom 1/2 of my KDS -7's display.

Best I can decipher (with my limited electronic experience) is that the
"HOT" transistor "may" have some bad solder connections.

Where is the "HOT" transistor in these schematics ??

http://www.85merk.com/members/katmandu/Monitor/


ERIC

 

[john]

Thats the Vertical...Yikes !
kip

--
"Watch the return E-Mail addy its false"
"Katmandu" <NoSpam@woh.rr.com> wrote in message
news:xSG8b.55152$3b2.7033325@twister.neo.rr.com...

Yup. Lost the bottom 1/2 of my KDS -7's display.

Best I can decipher (with my limited electronic experience) is that the
"HOT" transistor "may" have some bad solder connections.

Where is the "HOT" transistor in these schematics ??

http://www.85merk.com/members/katmandu/Monitor/


ERIC

 

[Katmandu]

Real "Professional" John.


ERIC

"Katmandu" <NoSpam@woh.rr.com> wrote in message
news:xSG8b.55152$3b2.7033325@twister.neo.rr.com...

Yup. Lost the bottom 1/2 of my KDS -7's display.

Best I can decipher (with my limited electronic experience) is that the
"HOT" transistor "may" have some bad solder connections.

Where is the "HOT" transistor in these schematics ??

http://www.85merk.com/members/katmandu/Monitor/


ERIC

 

[Al Savage]

On Sat, 13 Sep 2003 15:39:09 UTC, "Katmandu" <NoSpam@woh.rr.com> wrote:

[Disqualifier: I no longer work in this field. I am not an EE, nor
really a proper tech, but I _have_ repaired several hundred monitors and
terminals in a professional repair environment, so I'm qualified to
generalize on this topic.]

Yup. Lost the bottom 1/2 of my KDS -7's display.

That's a *vertical* problem, Eric.

Where is the "HOT" transistor in these schematics ??

HOT = Horizontal Output Transistor.

You'll need to think in terms of the vertical deflection supply voltage,
the vertical deflecion amplifier IC, and the associated capacitors. Or,
in rare cases (for a monitor, not for a TV), the deflection yoke itself.

IOW, component ID IC301 (TDA8172) and everything around it. Especially
electrolytic caps. A 'scope helps, but you can do some things without.
For example, make sure that vertical IC is being fed correctly:

http://wwww.ges.cz/sheet/t/tda8172.pdf
shows that it desires no more than 35v on pin 2. That PDF will also
show you where pin 2 is, and what a TDA8172 looks like when it's
relaxing at home on the couch Your schematic is fortunately able to
tell you that a 15v feed is considered normal. Without a 'scope, you
can only measure pin 2 (with the unit running) and see if the voltage is
under 15v; if so, you can guess that a filter cap may not be doing its
job, and the resultant ripple is being averaged by your test instrument
into a lower voltage reading.

But I don't really think that you've got a supply voltage problem --
that would likely show up as a different symptom than top-half vertical
deflection only.

A 'scope or ESR meter (but not a DMM, without practice) can show you
some failure modes of associated electrolytics. C304, C303, C305 all
look to be likely candidates to me. Also D301 would be easy to check.

WAG: one of those caps and/or failed IC, based on past experience.
Sure, could be other things, but I'd start with those two if'n it was on
my bench.

While the vertical deflection circuit has a lot less potential for harm
that the HV or horizontal deflection circuit(s), you're elbow or
whatever isn't going to know that. On a set that will run, if it's
unplugged it's unlikely to be a cap that kills you, as a normally
operating set almost always "bleeds" most really harmful potentials when
it's unplugged, after a minute or two. The CRT can definitely kill you,
but again most modern rigs will bleed off after 30 seconds or so, if
they're operating more or less normally.

But you can't take any of that for granted, you always have to assume
that anything you touch -- purposefully or accidentally -- is
potentially lethal. And some diagnostic work *must* be done with the
unit operating in "lethal mode" -- all connectors exposed, usually
propped up out of the case sideways on bits of wood or cardboard prop
boxes, is the way I do it, and it's dangerous as hell. Easy to let a
probe slip, hard to see the board location with it on its side and under
a tangle of wires, the wire harnesses inevitably too short to really
move any one board out of the way enough to see, etc. It's really not
as easy as you might think.

That's why nobody here is really encouraging you. You haven't qualified
yourself as having a HV electronics background or experience, or having
stated that you've put the time in, reading repairfaq.org's safety
section/warning. Nobody wants to contribute to a future Darwin Award
winner.

--
Regards,
Al S.

 

[Tom MacIntyre]

On Sun, 14 Sep 2003 00:51:44 GMT, "Katmandu" <NoSpam@woh.rr.com>
wrote:

Yea, I'm aware of the Charged Caps.

A now former Co-worker of mine died after blowing a hole right thru the
middle of his heart. He was working on a Microwave oven and apparently
didn't discharge the Caps.

I was real sad cause he was a maintenance man in the Hospital I worked as
Medical Technologist there.

After he blew a hole in his heart, he survived a couple of days. The EMS
had coincidently brought him to our hospital.

It was sad for me to watch his Cardiac Enzymes (CK, CK-MB and Iso's) shoot
through the roof. Cardiac Enzymes measure damage to heart muscle BTW....

Nuff of that, believe you me, I'm not touching a darn thing inside the case
without knowing EXACTLY what it is.

Thanks for the info/concern Tom.


ERIC

You have at least eased my mind a bit, and microwave ovens are a lot
more dangerous than TV's and monitors, but...please read that FAQ!

Tom

"Tom MacIntyre" <tom__macintyre@hotmail.com> wrote in message
news:7957mv8rm5qkvklf8b3k7s0v1ot002k7av@4ax.com...
On Sat, 13 Sep 2003 16:53:55 GMT, "Katmandu" <NoSpam@woh.rr.com
wrote:

Real "Professional" John.


ERIC

Are you aware that you are possibly one step away from killing
yourself or that monitor. I hope you win that one...

Tom


"Katmandu" <NoSpam@woh.rr.com> wrote in message
news:xSG8b.55152$3b2.7033325@twister.neo.rr.com...
Yup. Lost the bottom 1/2 of my KDS -7's display.

Best I can decipher (with my limited electronic experience) is that
the
"HOT" transistor "may" have some bad solder connections.

Where is the "HOT" transistor in these schematics ??

http://www.85merk.com/members/katmandu/Monitor/


ERIC

 

[Tom MacIntyre]

On Sun, 14 Sep 2003 00:23:10 -0500, "Al Savage" <asavage@iname.com>
wrote:

On Sat, 13 Sep 2003 15:39:09 UTC, "Katmandu" <NoSpam@woh.rr.com> wrote:

[Disqualifier: I no longer work in this field. I am not an EE, nor
really a proper tech, but I _have_ repaired several hundred monitors and
terminals in a professional repair environment, so I'm qualified to
generalize on this topic.]

Al...did you retire? I also no longer work in this field, I work in
another field. I think our previous experience in this field is good
for awhile yet.

Tom

Yup. Lost the bottom 1/2 of my KDS -7's display.

That's a *vertical* problem, Eric.

Where is the "HOT" transistor in these schematics ??

HOT = Horizontal Output Transistor.

You'll need to think in terms of the vertical deflection supply voltage,
the vertical deflecion amplifier IC, and the associated capacitors. Or,
in rare cases (for a monitor, not for a TV), the deflection yoke itself.

IOW, component ID IC301 (TDA8172) and everything around it. Especially
electrolytic caps. A 'scope helps, but you can do some things without.
For example, make sure that vertical IC is being fed correctly:

http://wwww.ges.cz/sheet/t/tda8172.pdf
shows that it desires no more than 35v on pin 2. That PDF will also
show you where pin 2 is, and what a TDA8172 looks like when it's
relaxing at home on the couch Your schematic is fortunately able to
tell you that a 15v feed is considered normal. Without a 'scope, you
can only measure pin 2 (with the unit running) and see if the voltage is
under 15v; if so, you can guess that a filter cap may not be doing its
job, and the resultant ripple is being averaged by your test instrument
into a lower voltage reading.

But I don't really think that you've got a supply voltage problem --
that would likely show up as a different symptom than top-half vertical
deflection only.

A 'scope or ESR meter (but not a DMM, without practice) can show you
some failure modes of associated electrolytics. C304, C303, C305 all
look to be likely candidates to me. Also D301 would be easy to check.

WAG: one of those caps and/or failed IC, based on past experience.
Sure, could be other things, but I'd start with those two if'n it was on
my bench.

While the vertical deflection circuit has a lot less potential for harm
that the HV or horizontal deflection circuit(s), you're elbow or
whatever isn't going to know that. On a set that will run, if it's
unplugged it's unlikely to be a cap that kills you, as a normally
operating set almost always "bleeds" most really harmful potentials when
it's unplugged, after a minute or two. The CRT can definitely kill you,
but again most modern rigs will bleed off after 30 seconds or so, if
they're operating more or less normally.

But you can't take any of that for granted, you always have to assume
that anything you touch -- purposefully or accidentally -- is
potentially lethal. And some diagnostic work *must* be done with the
unit operating in "lethal mode" -- all connectors exposed, usually
propped up out of the case sideways on bits of wood or cardboard prop
boxes, is the way I do it, and it's dangerous as hell. Easy to let a
probe slip, hard to see the board location with it on its side and under
a tangle of wires, the wire harnesses inevitably too short to really
move any one board out of the way enough to see, etc. It's really not
as easy as you might think.

That's why nobody here is really encouraging you. You haven't qualified
yourself as having a HV electronics background or experience, or having
stated that you've put the time in, reading repairfaq.org's safety
section/warning. Nobody wants to contribute to a future Darwin Award
winner.

 

[Katmandu]

please read that FAQ!

Done.

I shoulda said earlier, it was especially sad for me (in the case of my
friend), that I was the Technologist on duty and was the one who had to run
his initial blood workup. I saw the results before the Dr.


ERIC


"Tom MacIntyre" <tom__macintyre@hotmail.com> wrote in message
news:i119mvcmon8a0k820lqrlk9sksfmi4d6fk@4ax.com...

On Sun, 14 Sep 2003 00:51:44 GMT, "Katmandu" <NoSpam@woh.rr.com
wrote:

Yea, I'm aware of the Charged Caps.

A now former Co-worker of mine died after blowing a hole right thru the
middle of his heart. He was working on a Microwave oven and apparently
didn't discharge the Caps.

I was real sad cause he was a maintenance man in the Hospital I worked
as
Medical Technologist there.

After he blew a hole in his heart, he survived a couple of days. The EMS
had coincidently brought him to our hospital.

It was sad for me to watch his Cardiac Enzymes (CK, CK-MB and Iso's)
shoot
through the roof. Cardiac Enzymes measure damage to heart muscle BTW....

Nuff of that, believe you me, I'm not touching a darn thing inside the
case
without knowing EXACTLY what it is.

Thanks for the info/concern Tom.


ERIC

You have at least eased my mind a bit, and microwave ovens are a lot
more dangerous than TV's and monitors, but...please read that FAQ!

Tom


"Tom MacIntyre" <tom__macintyre@hotmail.com> wrote in message
news:7957mv8rm5qkvklf8b3k7s0v1ot002k7av@4ax.com...
On Sat, 13 Sep 2003 16:53:55 GMT, "Katmandu" <NoSpam@woh.rr.com
wrote:

Real "Professional" John.


ERIC

Are you aware that you are possibly one step away from killing
yourself or that monitor. I hope you win that one...

Tom


"Katmandu" <NoSpam@woh.rr.com> wrote in message
news:xSG8b.55152$3b2.7033325@twister.neo.rr.com...
Yup. Lost the bottom 1/2 of my KDS -7's display.

Best I can decipher (with my limited electronic experience) is that
the
"HOT" transistor "may" have some bad solder connections.

Where is the "HOT" transistor in these schematics ??

http://www.85merk.com/members/katmandu/Monitor/


ERIC

 

[Katmandu]

Also worth mentioning here. ESPECIALLY in an Electronics Repair Forum.

The grim results of blowing a hole through one's heart (through Electrical
Shock) are this....

Consider that a person's "Normal" serum CK (Creatine Kinase - Heart muscle
enzyme) are around 35 - 75 mg/dl.

A person who has suffered a recent Heart Attack may have CK levels reaching
1,000 - 2,000 mg/dl.

My co-worker friend had a CK level in the 18,000 mg/dl range! This
indicated MASSIVE Heart Tissue damage!

Maybe this story can be added to the FAQs......



--
ERIC

"Katmandu" <NoSpam@woh.rr.com> wrote in message
news:NP%8b.59718$3b2.7780243@twister.neo.rr.com...

please read that FAQ!

Done.

I shoulda said earlier, it was especially sad for me (in the case of my
friend), that I was the Technologist on duty and was the one who had to
run
his initial blood workup. I saw the results before the Dr.


ERIC


"Tom MacIntyre" <tom__macintyre@hotmail.com> wrote in message
news:i119mvcmon8a0k820lqrlk9sksfmi4d6fk@4ax.com...
On Sun, 14 Sep 2003 00:51:44 GMT, "Katmandu" <NoSpam@woh.rr.com
wrote:

Yea, I'm aware of the Charged Caps.

A now former Co-worker of mine died after blowing a hole right thru the
middle of his heart. He was working on a Microwave oven and apparently
didn't discharge the Caps.

I was real sad cause he was a maintenance man in the Hospital I worked
as
Medical Technologist there.

After he blew a hole in his heart, he survived a couple of days. The
EMS
had coincidently brought him to our hospital.

It was sad for me to watch his Cardiac Enzymes (CK, CK-MB and Iso's)
shoot
through the roof. Cardiac Enzymes measure damage to heart muscle
BTW....

Nuff of that, believe you me, I'm not touching a darn thing inside the
case
without knowing EXACTLY what it is.

Thanks for the info/concern Tom.


ERIC

You have at least eased my mind a bit, and microwave ovens are a lot
more dangerous than TV's and monitors, but...please read that FAQ!

Tom


"Tom MacIntyre" <tom__macintyre@hotmail.com> wrote in message
news:7957mv8rm5qkvklf8b3k7s0v1ot002k7av@4ax.com...
On Sat, 13 Sep 2003 16:53:55 GMT, "Katmandu" <NoSpam@woh.rr.com
wrote:

Real "Professional" John.


ERIC

Are you aware that you are possibly one step away from killing
yourself or that monitor. I hope you win that one...

Tom


"Katmandu" <NoSpam@woh.rr.com> wrote in message
news:xSG8b.55152$3b2.7033325@twister.neo.rr.com...
Yup. Lost the bottom 1/2 of my KDS -7's display.

Best I can decipher (with my limited electronic experience) is
that
the
"HOT" transistor "may" have some bad solder connections.

Where is the "HOT" transistor in these schematics ??

http://www.85merk.com/members/katmandu/Monitor/


ERIC

 

[Al Savage]

On Sun, 14 Sep 2003 15:09:29 UTC, Tom MacIntyre
<tom__macintyre@hotmail.com> wrote:

[Disqualifier: I no longer work in this field. I am not an EE, nor
really a proper tech, but I _have_ repaired several hundred monitors and
terminals in a professional repair environment, so I'm qualified to
generalize on this topic.]

Al...did you retire?

Yup -- till I ran out of funds! I now make a lot less doing other
things -- my expectations have been suitably reduced.

I also no longer work in this field, I work in
another field. I think our previous experience in this field is good
for awhile yet.

Reading here, I haven't seen a sea change in the types of repairs in
tubed units, only a further reduction in serviceability and net profit.
I really enjoyed CRT repair, but could no longer make a living at it --
only folks with decades of experience and training can do that now, and
they're making far less than they should for that much investment.

Me, I didn't have decades to spend, and because I wasn't really all that
qualified in terms of education (I cherry picked, and took very good
notes), I can't easily transfer CRT skills to another field. But I
enjoyed it while it lasted.

--
Regards,
Al S.

 

[Tom MacIntyre]

On Sun, 14 Sep 2003 15:39:13 GMT, "Katmandu" <NoSpam@woh.rr.com>
wrote:

Also worth mentioning here. ESPECIALLY in an Electronics Repair Forum.

The grim results of blowing a hole through one's heart (through Electrical
Shock) are this....

Consider that a person's "Normal" serum CK (Creatine Kinase - Heart muscle
enzyme) are around 35 - 75 mg/dl.

A person who has suffered a recent Heart Attack may have CK levels reaching
1,000 - 2,000 mg/dl.

My co-worker friend had a CK level in the 18,000 mg/dl range! This
indicated MASSIVE Heart Tissue damage!

Maybe this story can be added to the FAQs......

Interesting...

http://www.mdausa.org/publications/Quest/q71ss-cktest.html

Tom

 

[Cher]

1st Rule of working around high voltage is to keep one hand in your
pocket - at least till you are sure all voltage has been discharged.


On Sun, 14 Sep 2003 00:23:10 -0500, "Al Savage" <asavage@iname.com>
wrote:

On Sat, 13 Sep 2003 15:39:09 UTC, "Katmandu" <NoSpam@woh.rr.com> wrote:

[Disqualifier: I no longer work in this field. I am not an EE, nor
really a proper tech, but I _have_ repaired several hundred monitors and
terminals in a professional repair environment, so I'm qualified to
generalize on this topic.]

Yup. Lost the bottom 1/2 of my KDS -7's display.

That's a *vertical* problem, Eric.

Where is the "HOT" transistor in these schematics ??

HOT = Horizontal Output Transistor.

You'll need to think in terms of the vertical deflection supply voltage,
the vertical deflecion amplifier IC, and the associated capacitors. Or,
in rare cases (for a monitor, not for a TV), the deflection yoke itself.

IOW, component ID IC301 (TDA8172) and everything around it. Especially
electrolytic caps. A 'scope helps, but you can do some things without.
For example, make sure that vertical IC is being fed correctly:

http://wwww.ges.cz/sheet/t/tda8172.pdf
shows that it desires no more than 35v on pin 2. That PDF will also
show you where pin 2 is, and what a TDA8172 looks like when it's
relaxing at home on the couch Your schematic is fortunately able to
tell you that a 15v feed is considered normal. Without a 'scope, you
can only measure pin 2 (with the unit running) and see if the voltage is
under 15v; if so, you can guess that a filter cap may not be doing its
job, and the resultant ripple is being averaged by your test instrument
into a lower voltage reading.

But I don't really think that you've got a supply voltage problem --
that would likely show up as a different symptom than top-half vertical
deflection only.

A 'scope or ESR meter (but not a DMM, without practice) can show you
some failure modes of associated electrolytics. C304, C303, C305 all
look to be likely candidates to me. Also D301 would be easy to check.

WAG: one of those caps and/or failed IC, based on past experience.
Sure, could be other things, but I'd start with those two if'n it was on
my bench.

While the vertical deflection circuit has a lot less potential for harm
that the HV or horizontal deflection circuit(s), you're elbow or
whatever isn't going to know that. On a set that will run, if it's
unplugged it's unlikely to be a cap that kills you, as a normally
operating set almost always "bleeds" most really harmful potentials when
it's unplugged, after a minute or two. The CRT can definitely kill you,
but again most modern rigs will bleed off after 30 seconds or so, if
they're operating more or less normally.

But you can't take any of that for granted, you always have to assume
that anything you touch -- purposefully or accidentally -- is
potentially lethal. And some diagnostic work *must* be done with the
unit operating in "lethal mode" -- all connectors exposed, usually
propped up out of the case sideways on bits of wood or cardboard prop
boxes, is the way I do it, and it's dangerous as hell. Easy to let a
probe slip, hard to see the board location with it on its side and under
a tangle of wires, the wire harnesses inevitably too short to really
move any one board out of the way enough to see, etc. It's really not
as easy as you might think.

That's why nobody here is really encouraging you. You haven't qualified
yourself as having a HV electronics background or experience, or having
stated that you've put the time in, reading repairfaq.org's safety
section/warning. Nobody wants to contribute to a future Darwin Award
winner.

 

[Katmandu]

Good article.

I noticed my range was a bit off and it's U/L not mg/dl. Tired when I wrote
it.....


--
ERIC


"Tom MacIntyre" <tom__macintyre@hotmail.com> wrote in message
newsc39mvkllht0vf77jp2ti3uemd741tlrt7@4ax.com...

On Sun, 14 Sep 2003 15:39:13 GMT, "Katmandu" <NoSpam@woh.rr.com
wrote:

Also worth mentioning here. ESPECIALLY in an Electronics Repair Forum.

The grim results of blowing a hole through one's heart (through
Electrical
Shock) are this....

Consider that a person's "Normal" serum CK (Creatine Kinase - Heart
muscle
enzyme) are around 35 - 75 mg/dl.

A person who has suffered a recent Heart Attack may have CK levels
reaching
1,000 - 2,000 mg/dl.

My co-worker friend had a CK level in the 18,000 mg/dl range! This
indicated MASSIVE Heart Tissue damage!

Maybe this story can be added to the FAQs......

Interesting...

http://www.mdausa.org/publications/Quest/q71ss-cktest.html

Tom

 

[Tom MacIntyre]

On Sun, 14 Sep 2003 16:43:19 GMT, Cher <ccher@your.place> wrote:

1st Rule of working around high voltage is to keep one hand in your
pocket - at least till you are sure all voltage has been discharged.

But...doesn't that direct the high voltage to your...?

I know...just kidding.

Tom

On Sun, 14 Sep 2003 00:23:10 -0500, "Al Savage" <asavage@iname.com
wrote:

On Sat, 13 Sep 2003 15:39:09 UTC, "Katmandu" <NoSpam@woh.rr.com> wrote:

[Disqualifier: I no longer work in this field. I am not an EE, nor
really a proper tech, but I _have_ repaired several hundred monitors and
terminals in a professional repair environment, so I'm qualified to
generalize on this topic.]

Yup. Lost the bottom 1/2 of my KDS -7's display.

That's a *vertical* problem, Eric.

Where is the "HOT" transistor in these schematics ??

HOT = Horizontal Output Transistor.

You'll need to think in terms of the vertical deflection supply voltage,
the vertical deflecion amplifier IC, and the associated capacitors. Or,
in rare cases (for a monitor, not for a TV), the deflection yoke itself.

IOW, component ID IC301 (TDA8172) and everything around it. Especially
electrolytic caps. A 'scope helps, but you can do some things without.
For example, make sure that vertical IC is being fed correctly:

http://wwww.ges.cz/sheet/t/tda8172.pdf
shows that it desires no more than 35v on pin 2. That PDF will also
show you where pin 2 is, and what a TDA8172 looks like when it's
relaxing at home on the couch Your schematic is fortunately able to
tell you that a 15v feed is considered normal. Without a 'scope, you
can only measure pin 2 (with the unit running) and see if the voltage is
under 15v; if so, you can guess that a filter cap may not be doing its
job, and the resultant ripple is being averaged by your test instrument
into a lower voltage reading.

But I don't really think that you've got a supply voltage problem --
that would likely show up as a different symptom than top-half vertical
deflection only.

A 'scope or ESR meter (but not a DMM, without practice) can show you
some failure modes of associated electrolytics. C304, C303, C305 all
look to be likely candidates to me. Also D301 would be easy to check.

WAG: one of those caps and/or failed IC, based on past experience.
Sure, could be other things, but I'd start with those two if'n it was on
my bench.

While the vertical deflection circuit has a lot less potential for harm
that the HV or horizontal deflection circuit(s), you're elbow or
whatever isn't going to know that. On a set that will run, if it's
unplugged it's unlikely to be a cap that kills you, as a normally
operating set almost always "bleeds" most really harmful potentials when
it's unplugged, after a minute or two. The CRT can definitely kill you,
but again most modern rigs will bleed off after 30 seconds or so, if
they're operating more or less normally.

But you can't take any of that for granted, you always have to assume
that anything you touch -- purposefully or accidentally -- is
potentially lethal. And some diagnostic work *must* be done with the
unit operating in "lethal mode" -- all connectors exposed, usually
propped up out of the case sideways on bits of wood or cardboard prop
boxes, is the way I do it, and it's dangerous as hell. Easy to let a
probe slip, hard to see the board location with it on its side and under
a tangle of wires, the wire harnesses inevitably too short to really
move any one board out of the way enough to see, etc. It's really not
as easy as you might think.

That's why nobody here is really encouraging you. You haven't qualified
yourself as having a HV electronics background or experience, or having
stated that you've put the time in, reading repairfaq.org's safety
section/warning. Nobody wants to contribute to a future Darwin Award
winner.