Toshiba TV29C90 problem; Image fades to black...

[Ryan]

My expectations might have been higher with this monitor since
I spent so much on it. Also, I've never had a monitor go bad on
me before. But then, my employers probably never gave any
monitor enough time to go bad.

For ~$150, the KDS Visual Sensations VS-190IS (19'', 1600x1200, .25mm)
seems like another good candidate to look into.

Any other suggestions/comments out there?


"Larry Jaques" <jake@di\/ersify.com> wrote in message
news:iigtjv41qrubp7315t0sqrg92rl1n8udrt@4ax.com...

On Sat, 16 Aug 2003 22:46:31 GMT, "Ryan" <ryan@no_spam.com> pixelated:

I guess I could try playing with the ViewMatch Color (or RBG) settings a bit before
shelling out the $$$ for a new monitor. Any suggestions of a quality monitor (either
CRT or flat panel) without spending a fortune these days? Or, isn't there such a thing?

Robert's right in that most monitors seem to last only
3-4 years. I just upgraded to a 19" KDS for $269, about
half the price I paid for the cheapo ADI 17" or the 17"
CTX, the old monitor of my fondest memory. Since I'm no
longer building my own, I had fallen out of touch with
the brands. The man who built my current system said that
the KDS had a good, solid chassis and fewer problems than
any other monitor he had sold in the previous several years.
Combined with a 3 year warranty, that was good enough for me.


---------------------------------------------------
I drive way too fast to worry about my cholesterol.
---------------------------------------------------
http://www.diversify.com Refreshing Graphic Design

 

[Winfield Hill]

Winfield Hill wrote...

Winfield wrote...

Here's a sample circuit you could try.

C2 should probably be somewhat larger, say 1000pF 500V.

And R2 should be smaller, say 330 or 470 ohms. If R2 is
too high it slows the Q1 swtching speed, increasing the
supply current. The purpose of R2 is to minimize any
damaging currents when the 400V supply is turned on or
off. If it can't be assured that the square-wave output
will be on and have a low impedance when the 400V supply
goes on or off, etc., a 15V zener diode to ground can be
added across Q2's gate. And changing D1 to a 15V zener
would similarly protect Q1. If these zener diodes are
used the square-wave drive capability must be increased
(doubled) to handle the zener's capacitance.

.. +400V ----+----+----------,
.. R1 | _|_ D1 |
.. 100k /_\ 1N4148 | Q1
.. | | |--| VP0550
.. +----+------||->'
.. | |--,
.. _|_ C2 |
.. --- 1000pF |
.. | 500V +---o
.. R2 |
.. 8-volt 330 |
.. square- | |--' Q2
.. wave -----+-----------||<-, VN0550
.. |--|
.. |
.. gnd

Thanks,
- Win

 

[Ryan]

Since I've never had a monitor go bad on me before,
I went ahead and invested the big bucks on a really nice 21" monitor.
Now that I've learned my lesson, I don't think I'll be doing that again.
I'm going to buy mainstream hardware (not state-of-the-art).
BTW, I also built my own system and am usually very gentle with
my equipment. The only banging that this monitor might have
gone through is during shipping since I bought it online,
which people advise against. So, I may be paying a little more for
the monitor if I don't buy online. But, I'll be able to easily return/exchange it.

For now, I'm staying with a CRT since I don't believe that
LCD technology is mature enough yet. There's still too many
problems with faulty/defective pixels. And, the price is
a factor as well.


"Larry Jaques" <jake@di\/ersify.com> wrote in message
news:0r0vjv45r9rpuutimq1dcdoqd2se6a3gtm@4ax.com...

On Sun, 17 Aug 2003 06:52:52 GMT, "Ryan" <ryan@no_spam.com> pixelated:

My expectations might have been higher with this monitor since
I spent so much on it. Also, I've never had a monitor go bad on
me before. But then, my employers probably never gave any
monitor enough time to go bad.

I usually upgraded computers within that time and have gone
from 14 to 15 to 17 to 19" in that time. One 14-incher got
flaky and the ADI focus coil got loose, but I've been fairly
lucky with monitors, too. I probably smack them less than
other folks since I used to build systems and understand 'em
more.

For ~$150, the KDS Visual Sensations VS-190IS (19'', 1600x1200, .25mm)
seems like another good candidate to look into.

I see that prices have dropped again since January. Wow!

Any other suggestions/comments out there?

I suppose that digital LCDs would be OK for h/a
display but I don't like them for design work or
watching movies. My satellite system showed me
the limitations of removing too many colors. I'm
guessing that the dark backgrounds in scenes are
posterized from a combination of video compression
and color reduction. LCDs are still more costly,
too.


---------------------------------------------------
I drive way too fast to worry about my cholesterol.
---------------------------------------------------
http://www.diversify.com Refreshing Graphic Design

 

[John Del]

Subject: Questions about HV leads in CRT based sets...
From: "Steve Reinis" noemail@all.com
Date: 8/17/03 2:52 AM Eastern Daylight

Can I simply buy say, five feet of proper HV lead from an electronics
supplier and cut it to my own length, or do these leads need to be a
specific length? I have absolutely no intentions of splicing the leads...

I don't believe the length is important, but the shielding is. Make sure the
tubes are fully shielded. Also, when reinstalling the anode caps, make sure to
use RTV as the originals did. These babies love to spit.

John Del
Wolcott, CT

"Nothing is so opportune for tyrants as a people tired of its liberty."
Alan Keyes

(remove S for email reply)

 

[David]

The cost to repair is going to likely be very close to replacement cost of a
low end 17" monitor. I see many 17" monitors on sale new for under $90 all
the time.

$200-$300 will get you a top of the line flat screen (not LCD) 17" monitor.

David

Rob <rm1122333@yahoo.com> wrote in message
news:9d11b6b.0308170849.22517003@posting.google.com...

Just recently my 4-year-old 17" Relisys TE786 monitor has started
acting up. The picture would randomly just flicker off and on to a
black screen. It took me a while, but I think I've discovered that it
does this when the air conditioning is on. As the room and monitor get
colder, it flickers on and off more, finally it gets to a point where
it the pictures flicks off and doesn't come back on, even though the
monitor is still getting power. Eventually, the picture goes black,
then it clicks a few times and I get a white screen with vertical bars
which usually means the monitor isn't getting input. I wanted to
change the VGA cable, but it's soldered inside the monitor; it doesnt'
just simply unplug.

So I assume I either have a faulty cable, or a cold-sensitive part
inside my monitor. Is this going to be something expensive to repair?
People in another group told me it'd be cheaper to get a new monitor,
but I can't really afford two or three hundred dollars for a new
monitor at this point.

Thanks for any advice,
Rob

 

[David]

I clarify to make sure you use the HV rated silicone sealant.
Both Philips and Toshiba sell tube of the HV rated sealant, also it must
cure fully before HV gets applied, usually2 to 3 days.

David

John Del <ohger1s@aol.com> wrote in message
news:20030817122934.11588.00000115@mb-m11.aol.com...

Subject: Questions about HV leads in CRT based sets...
From: "Steve Reinis" noemail@all.com
Date: 8/17/03 2:52 AM Eastern Daylight

Can I simply buy say, five feet of proper HV lead from an electronics
supplier and cut it to my own length, or do these leads need to be a
specific length? I have absolutely no intentions of splicing the
leads...


I don't believe the length is important, but the shielding is. Make sure
the
tubes are fully shielded. Also, when reinstalling the anode caps, make
sure to
use RTV as the originals did. These babies love to spit.

John Del
Wolcott, CT

"Nothing is so opportune for tyrants as a people tired of its liberty."
Alan Keyes

(remove S for email reply)

 

[Jim Adney]

On Sun, 17 Aug 2003 00:20:51 GMT Robert Baer
<robertbaer@earthlink.net> wrote:

Jim Adney wrote:

Yes, it probably wasn't much of a "standard," but it was close enough,
and probably within 1%, which was better than almost anything else in
those days.

Cannot get 1% accuracy with (at best) 5% cathode resistors.....

For Dynaco, at least, I believe they used special 1% resistors here.
But I have to agree that even that would not assure 1% precision in
the idle current setting.

OTOH, I'm sure it was good enough for what they needed.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[Jim Adney]

On Sun, 17 Aug 2003 00:18:41 GMT Robert Baer
<robertbaer@earthlink.net> wrote:

Jim Adney wrote:

Now I've got an old Eppley standard cell sitting across the room, and
those could be held to a microvolt, but they DID age, and they DID
have a temp dependence. None of that affected the first 4 digits,
however. Those last 3 digits are a LOT tougher. ;-)

Ahhhh..... you speak of differences of primary and secondary
standards.

In the case of the battery I was just thinking of this as a useful
reference, especially since the OP didn't specify any particular
tolerance.

The Eppley cell is probably a secondary standard at best. In this
context, I don't think I would be willing to call the carbon-zinc cell
even a tertiary standard.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[Jim Adney]

On Sat, 16 Aug 2003 04:35:44 -0700 Watson A.Name - 'Watt Sun'
<alondra101@hotmail.com> wrote:

In article <5wg%a.152046$o%2.65030@sccrnsc02>,
dobrien25NOSPAM@comcast.net mentioned...

Well, Dynaco tube amps used batteries as a reference in theiur biasing.
http://www.angelfire.com/ma2/AdamVon/dynaresto.html

Well, so did radar sets, they used the old Burgess batteries as 'C'
batteries.

I dont' think the Dynaco reference was made quite clear enough for
you. There was no battery in the device; the just told you to adjust
the tube bias until the voltage drop across the precision cathode
resistor was equal to that across a fresh carbon-zinc cell.

Thus it was actually used as a reference to remove the uncertainty in
the calibration of the voltmeter that the average kit builder might
have in those days.

I've never seen one, but grid bias cells are often mentioned in the
antique radio newsgroup. They must have been common at one time, maybe
the 30s and 40s.

-
-----------------------------------------------
Jim Adney jadney@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------

 

[Steve Reinis]

Yes, I will do that. I also have an older (1988) Magnavox 47" set that was
found on the roadside that came back to life after cleaning the dust and
goop out of it and applying HV rated silicone liberally around the flyback.
Until I cleaned it out, it would run, but put on a pretty good lightshow!

-Steve

David <dkuhajda@locl.net.spam> wrote in message
news:3f3fe114@news.greennet.net...

I clarify to make sure you use the HV rated silicone sealant.
Both Philips and Toshiba sell tube of the HV rated sealant, also it must
cure fully before HV gets applied, usually2 to 3 days.

David

John Del <ohger1s@aol.com> wrote in message
news:20030817122934.11588.00000115@mb-m11.aol.com...
Subject: Questions about HV leads in CRT based sets...
From: "Steve Reinis" noemail@all.com
Date: 8/17/03 2:52 AM Eastern Daylight

Can I simply buy say, five feet of proper HV lead from an electronics
supplier and cut it to my own length, or do these leads need to be a
specific length? I have absolutely no intentions of splicing the
leads...


I don't believe the length is important, but the shielding is. Make
sure
the
tubes are fully shielded. Also, when reinstalling the anode caps, make
sure to
use RTV as the originals did. These babies love to spit.

John Del
Wolcott, CT

"Nothing is so opportune for tyrants as a people tired of its liberty."
Alan Keyes

(remove S for email reply)

 

[Allodoxaphobia]

On 17 Aug 2003 09:49:12 -0700, Rob hath writ:

Just recently my 4-year-old 17" Relisys TE786 monitor has started
acting up. The picture would randomly just flicker off and on to a
black screen. It took me a while, but I think I've discovered that it
does this when the air conditioning is on. As the room and monitor get
colder, it flickers on and off more, finally it gets to a point where
it the pictures flicks off and doesn't come back on, even though the
monitor is still getting power. Eventually, the picture goes black,
then it clicks a few times and I get a white screen with vertical bars
which usually means the monitor isn't getting input. I wanted to
change the VGA cable, but it's soldered inside the monitor; it doesnt'
just simply unplug.

So I assume I either have a faulty cable, or a cold-sensitive part
inside my monitor. Is this going to be something expensive to repair?
People in another group told me it'd be cheaper to get a new monitor,
but I can't really afford two or three hundred dollars for a new
monitor at this point.

Nice diagnosing.
It could well be a cold solder joint. But, unless you really, Really,
REALLY, *REALLY* know in your heart-of-hearts that you're "qualified"
to open it up and attempt the repair -- _don't even try!_
Over the years I've located and repaired several cold solder joints
in (various brands of) monitors here on my own home lan.

Jonesy
--
| Marvin L Jones | jonz | W3DHJ | OS/2
| Gunnison, Colorado | @ | Jonesy | linux __
| 7,703' -- 2,345m | config.com | DM68mn SK

 

[GPE]

Yup --

Switch to be driven by standard 4000 series CMOS logic (4543 if I remember
correctly) operated at 5 volts. So we're talking IOH of upto 1mA.

Speed is another factor. Must be quick turnon and turnoff. Unit turned on
every 16mS with a 1mS 'on' duration.
I tried using some quite small high voltage SMT NEC high voltage darlington
opto's. Worked great except the turnon and turnoff speeds were far too
slow. Couldn't get enough current on a non-darlington version.

I've got a few workable ideas including dual transistor config -- but all
are too big.

Any ideas would be appreciated.

TIA,
Ed


"Winfield Hill" <whill@picovolt.com> wrote in message
news:bhme4202tjp@drn.newsguy.com...

Ed, GPE wrote...

I'm also looking to switch high voltage controlled by a CMOS
gate. But this one's a tad harder. Need to be as small as
possible and needs to switch a load to ground. The load is
operated at -150 volts DC at 25mA.

Can you spell out your switch-driving voltages, etc,?
For example, are these from a positive logic level, so
that you need a level-shift function, as well as the
-150V switching?

Thanks,
- Win

 

[JURB6006]

You should not have to move the CRTs away from each other, all you need to do
is to shim the red and blue to aim them properly. I assume this is nessecary
because you want to use a larger than original screen size.

I don't see any reason why simply shimming the inner mounting screws of the red
and blue CRTs would not suffice. I also believe this method will cause less
convergence problems.

JURB

 

[AB]

On Sun, 17 Aug 2003 20:06:33 GMT, "GPE" <GPE@Cox.net> wrote:

Yup --

Switch to be driven by standard 4000 series CMOS logic (4543 if I remember
correctly) operated at 5 volts. So we're talking IOH of upto 1mA.

Speed is another factor. Must be quick turnon and turnoff. Unit turned on
every 16mS with a 1mS 'on' duration.
I tried using some quite small high voltage SMT NEC high voltage darlington
opto's. Worked great except the turnon and turnoff speeds were far too
slow. Couldn't get enough current on a non-darlington version.

Hey Ed,

I can't model this one because Circuitmaker does not have a spice
model for a photodiode.

But, I was wondering about a photodiode supplying current to the base
of a high speed transistor for HV. If the emitter and the photodiode
were bonded together so that the LED shined on the photodiode, it
should switch fast.

The transistor could be biased so that it was just short of conduction
and the LED could be pulsed easily to supply larger current on the
transition.

An smt led with a photodiode glued so the photodiode is close to the
emitter should give a hefty jolt to the base of the transistor.

Has anyone ever tried this before????

Smile, it can always get worse:>:

Art

 

[JURB6006]

I've had this before. It was a Sony and was so evenly magnetized that the
colors were interpolated, but the purity was actually good. The degausssing
coil couldn't handle it, nor could an external one. What I wound up doing was
wiring a variac right to the DG coil and cranking it all the way up and
bringing it down slowly.

I have read warnings about using to strong of a degausser on a Sony, but it
seems that might apply more to the magnets rather than the CRT itself, plus in
this case there was really no other choice but to rotate the color drives. That
would be ridiculous.

Basically the variac trick worked just fine.

JURB

 

[u1061771156]

In article <Xns93D8E9CDD4E91jyanikkuanet@204.117.192.21>, Jim Yanik wrote:

u1061771156@csi.com (u1061771156) wrote in
news:slrnbjqkrc.f5.u1061771156@csi.com:

While Tek 2430's are being discussed in the group, I'll add my problem
to the list:

Used to work fine. Then it intermittently didn't seem to want to
trigger, and could usually be encouraged to start triggering by
fiddling with controls (such as pressing SAVE and then ACQUIRE a few
times).

Next it intermittently failed the self-test on the trigger, IIRC it
failed both A and B timebase tests from all trigger sources. Rerunning
the test would sometimes pass.

These days it just hangs in the self-test, saying:


CH1 10mV~ A 5ms 59.4mV? EXT1
Ch2 200mV~

RUNNING SELF TEST

Anyone seen behaviour like this before?
I tried reseating some connectors and socketed chips where I could see
them but that's had no visible effect.

Is the service manual available somewhere at a sensible price?
Regards,
Mike.

It may just need a complete calibration.Recommended once a year.
They do not stay calibrated indefinitely.
Jim Yanik

Thanks Jim. I admit I'm surprised it would hang as a result of being a
bit out of cal (failing the test would be fair game).

Anyway, much to my surprise, several hours later (after posting) the
display came up with a screen of randomish trace. Still no response to any
controls, however powering it off and on again has made it come back normal.
Weird. It passed all tests (and an internal cal) and seems fully OK.

As you'd mentioned the battery, I did check that (it's on the underside
one of the two PCBs on the top) and got 3.6V. I guess it's a rechargable
lithium one (it lists mAh on the top of it), maybe it had just completely
run down? I only use this scope intermittently so it's had months off.
I notice there is also a 1F Gold Cap in there (a much classier
one than the cheap ones I've seen dead in VCRs!) and that seemed OK too
(about 4.5V on it). Why both a battery and a cap? Do you know what is
retained by each?

Regards,
Mike.

 

[Winfield Hill]

GPE wrote...

Yup -- Switch to be driven by standard 4000 series CMOS logic
(4543 if I remember correctly) operated at 5 volts. So we're
talking IOH of upto 1mA.

Speed is another factor. Must be quick turnon and turnoff.
Unit turned on every 16mS with a 1mS 'on' duration.

Ed, GPE wrote...

I'm also looking to switch high voltage controlled by a CMOS
gate. But this one's a tad harder. Need to be as small as
possible and needs to switch a load to ground. The load is
operated at -150 volts DC at 25mA.

The Supertex VN0550N3 that I suggested before is well suited
for your HV switch task, but in a different circuit of course.
It's a 550-volt N-channel FET in a TO-92 package, in stock at
Mouser for $0.98. You can use a PNP transistor in common-base
mode acting as a level shifter to drive the NMOS FET.

If I understand your problem, a circuit like this should work,

.. 5V logic
.. in --- R1 ----, gnd
.. 4.3k | |
.. |/V Q1 LOAD
.. ,----| MPSA92 |
.. | |\ ,--o --'
.. gnd | |
.. | |
.. | |--' Q2
.. +----||<-, VN0550
.. | |--|
.. R2 |
.. 8.2k |
.. | |
.. -180V -------+--------+-----

Assuming 5V logic drive, R1 creates a 1mA current in Q1, which
then appears across R2. This creates an 8V drive for Q2's gate
that turns Q2 on and drives the load with -180V, or any other
negative voltage, up to the rating of the MPSA92, which is 300V.
These are in stock at Mouser for just $0.17 each. Actually, you
could use a MPSA42 in place of a VN0550, they're only $0.14 each.
In this circuit the 'A92 can switch over 40mA, compared to 100mA
or so for the '550. Of course, much larger MOSFETs could also be
used, for example an IRF740 would allow switching -300V and 10A
on and off. Naturally the higher capacitance of the '740 would
slow down the switching speed (to about 30us or so).

Thanks,
- Win

 

[Dan]

If you could post model/chassis numbers it would greatly increase the
chances of receving a response.

Dan
"max" <maxg70@cwnet.com> wrote in message
news:vj6h0ajtq9cmf3@corp.supernews.com...

Is somebody can help me to find out datasheet for IC IX3395CEN2 for Sharp
TV.Picture black and white and no color.

 

[TV Fixer1]

Most of the doming I saw was in the very late 80's and early 90's; Saw JVC,
RCA, Zenith, and Mitsubishi, nearly all 27" sets

 

[Andy Cuffe]

William R. Walsh wrote:

Hello group...

I picked up a Sony Watchman TV (model FD-230) at a garage sale a short while
back. It is a nice little set that works excellently, apart from the volume
level being a bit low for my liking...

One thing I do wonder about is how it works. I figured that the set used one
of the small CRTs not unlike that which is found in some older video camera
viewfinders. This does not seem to be the case. I see that the "screen" (set
below some clear plastic for protection) is slightly slanted and it appears
that something in the "bottom" of the set projects on to that screen. The
picture comes up almost instantly, which I am sure rules out any sort of a
CRT display...

Does anyone know how this set works and if any color display models were
made using similar technology?

William

It is a CRT, but it must have a small cathode that heats up quickly.
It's hard to describe, but should be obvious if you decide to open it.
The electron gun is mounted horizontally in the set and scans the screen
which is angled at roughly 45 deg. You're looking at the same side of
the screen that the electron gun scans. I've read there was a color
version of this CRT that used something called beam indexing, but I
don't think it was ever used in a TV. If you're curious how this works,
there are some good posts explaining it. Do a google groups search and
you should find something.
--
Andy Cuffe
baltimora@psu.edu