Toshiba TV29C90 problem; Image fades to black...

[Sam Goldwasser]

sck0006 writes:

On 18 Mar 2006 12:40:11 -0500, Sam Goldwasser <sam@saul.cis.upenn.edu
wrote:

Does anyone know of a free source for decent quality schematics? I have
several complete manuals downloaded from various places but the resolution
of the schematics tends to be terrible and only marginally useful.

I think we have the 465b manual at work, I'll have to check on Mon.
If we do, I'll only be able to copy a couple of pages so I'll just be
able to get the power supply and maybe a few others, but I'll give it
a shot.

Thanks. That would probably be adequate. There's no problem with the text
of the manuals, just the schematics. And this problem would seem to be
associated either with the power supplies or the CRT bias/intensity/Z
input circuits.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

 

[janek77]

I've looked into that allready, replaced them both.
No change.
Anybody knows of a way to check transformer windings for shorts?
Thanks

"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:%tYSf.4605$uT3.694@newsfe7-win.ntli.net...

"janek77" <alkaprim@hotmail.com> wrote in message
news:sNUSf.11933$ng.680103@news20.bellglobal.com...
Hi, that damn things overloads?
When powered up as is the output voltages are ~40% too low.
Then when I disconnect ie 12V or 55V load everything seems to run fine,
ie
voltages are right and adjustment works fine.
The only difference , it runs twice too fast (by checking waveform 1).
Could it be the transformer?(maybe primary winding has short?)
Here's the schematic:
http://img.photobucket.com/albums/v338/gamow/PS.gif




First place I'd be looking, is at the electrolytics. Either run an ESR
meter across them all, or look at each rail with another 'scope. Chances
are, you'll find one with shedload of hash on it. Particularly suspect any
that are near anything else that gets hot.

Arfa

 

Direct Components Inc. 4828 W. Gandy Blvd. Tampa, Fl 33611
Phone: 1-888-723-7279 or 813-835-3883 Fax: 813-831-0295 Email:
info@directics.com

They have them in stock

 

[JANA]

You cannot substitute the lamp. The original lamps have a specific
luminosity, shading characteristics, power and voltage rating, and colour
temperature.

In reality, these lamps are lasting about 800 to 1000 hours if you are
lucky. I know some people that are changing these lamps about once a year.

What I would recommend, is to sell the set, and get a new flat panel LCD TV.
You will pay a little more up front, but the LCD should give you about
40,000 to 60,000 hours of service before it needs a new set of lamps and
ballast transformer. By then, you will be more than due for an upgrade
always. Under normal use, the new models of the LCD screens should last
about 10 to 12 years if used for only about 10 hours per day. This would be
a much more cost effective way of watching TV.

--

JANA
_____


"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:aYVSf.8$0_4.3@fe06.lga...
had to replace my DLP lamp
on my RCA 61" HDTV.
what i got was a small lamp
mounted in a plastic carrier case
with interlock plug.
this cost me $448 bucks and
1.5 month wait by the time it got
to my house.
i noticed when removing the old
one the element in the center had
obviously blew apart from his base
in the center and was just hanging
by the side wire with some loose glass
floating around inside the envelope.
in my opinion i didn't get that much time
on the unit, maybe 1.5 years or moderate
usage? is this normal life expectancy or
did i have a dud ? when i purchase this
HDTV, the first one only lasted 8 hours and
the lamp went out, i made the store deliver
a whole new TV set.

now, i noticed on the lamp there is a
Philips number that seems to be the part number
of the lamp only and not the carrier ! is it
possible for me to simply get the lamp and rebuild
this extra carrier unit ?, the lamp is simply held in
with Robertson type screws.
i don't remember the part number but its a small
mercury lamp of 100W/30W level, the tv has a high and
low power setting for the lamp.

--
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5

 

[JANA]

What you are doing is causing an arc from the cathode to the control grid.
This will temporarily clean off the cathode. A CRT renouvinator does
basically the same thing, but in a more sophisticated fashion, where it can
also check the other grids for leaks, and also measure the tube's emission.

By arcing the focus supply back across the CRT guns, I hope you don't one
day blow the hell out of the horizontal output stage. Then you will be
spending a lot of time and money on the set to fix it back.

--

JANA
_____


"Dani" <greeben@gmail.com> wrote in message
news:1142696464.033824.14310@i40g2000cwc.googlegroups.com...
I would like to share this great tip with all you great helpfull Tech's
out there! This is only for Technicians who really know there way
around the inside of a T.V.! Please don't just anyone try this!! If you
don't have a proper CRT rejuvinating set, this will be a great fix, for
an otherwise lost cause.

Sony 1 K problems, that is T.V.'s with the red, or green, or blue
having too low, or high of an emission to get a raster due to the
"blanking circuit", can be solved with an odd, & somewhat dangerous
technique! With the set off, unsolder each cathode on the CRT board,
then momentarily bridge the gap of each gun, one at a time, to see how
much emission there is. You will have to raise the G 2 pot to get a bit
of raster in a darkened room! Next solder the two good cathodes
(usually only one is out of gain specs), back, leaving the bad one. Now
this is where it gets dangerous!!! While the set is off remove the
focus line from the CRT socket ( 5000 volts), & while the set is
running, momentarily make contact with the unsoldered leg of the bad
gun. Do this with caution, & at least five times. It will try to arc,
but just keep a steady hand, & keep the wire with a good insulated tool
at the unsoldered leg only. Now, while the set is off, unhook the G 2
wire, & set it to about 200 volts DC unloaded, & charge a 100 uf
capacitor @ 250 volts. Do this two, or three times, then discharge it
to the unsoldered gun, while the set is runing. Do this charging, &
discharging to the gun at least five times! At this point, you should
see the bad gun get brighter, & brighter. I have done quite a lot of
experimenting, & this will save a lot of those Sony CRT's, that would
otherwise be toast. Grey scale comes back to within a close enough
spec, to make the customer happy. Just don't give a long warranty. Hope
this helps you all out. Take care, Dani.

 

[n cook]

spudnuty <spudnuty@lycos.com> wrote in message
news:1142724250.971008.319780@v46g2000cwv.googlegroups.com...

I would also be interested in a solution to this problem. I have a
Toshiba laptop in my "to be repaired pile" and the same thing has
happened to the LCD cable. It was glued to the LCD glass and the glue
has aged and become brittle so that the connection is completely off.
Richard

n cook wrote:
Ancient_Hacker <grg2@comcast.net> wrote in message
news:1142598154.121374.53040@i40g2000cwc.googlegroups.com...
Hi, I have a small LCD display where the edge has a 60-track ribbon
cable going to the motherboard. The cable is clear plastic with very
thin carbon tracks. The end going to the PC board has gone
intermittent, so I pulled it off. Apparently it was glued on with
some
gray goop.

The carbon tracks on the end of the cable have mostly pulled off the
plastic. I could cut off the bad end as there's about 1/4 inch of
slack in the cable BUT:

(1) There's some beige painted-on insulation over the carbon. It
comes off with acetone, but so do the carbon tracks! How do I get
the
beige insulation off without hurting the delicate carbon underneath?

(2) What do I use to glue the cable back on? Or should I fashion a
clamp?


Help!


How are the conductors of the ribbon connected to the conductive lands
on
the LCD glass ?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

As far as flexible ribbon replacement I usually plait up fine 40swg
enamelled/magnet copper wire into a braid, in this case 6,7,7 wires plaited,
cut into 3 and then those 3 plaited together . This is very flexible and
seems long lasting. Identify the order of conductors , bypass the ribbon
connector at the pcb end and solder direct to the pcb. The problem is the
LCD end. If it is proper metal in the ribbon it is possible to cut close to
the LCD it may be pssible then to grind back the covering to give some land
pads.
How to remove the glue without removing the conductive deposition lands on
the LCD edge. I would try squashing each stripped wire end in steel plates,
risking work hardening but as conductive glued/painted to each land and then
overall glued that should be ok, any inter-trace overpaint/shorts cut back
before total curing. It is the safe removal of existing LCD contacts that is
the problem. I've never tried the LCD part of such a repair but would very
localised heat like SM re-work hot air gun work to release without
destroying the conductive glass coating or crack the glass ?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[James Sweet]

JANA wrote:

What you are doing is causing an arc from the cathode to the control grid.
This will temporarily clean off the cathode. A CRT renouvinator does
basically the same thing, but in a more sophisticated fashion, where it can
also check the other grids for leaks, and also measure the tube's emission.

By arcing the focus supply back across the CRT guns, I hope you don't one
day blow the hell out of the horizontal output stage. Then you will be
spending a lot of time and money on the set to fix it back.

Normally I'd agree, though if the CRT is otherwise shot, who cares?

 

[Mark D. Zacharias]

"OldSchool" <barrettgr@comcast.net> wrote in message
news:1142712001.625572.126810@i40g2000cwc.googlegroups.com...

They all work but sound like crap. If I just run my Kenwood amp and
tuner through the system (without any link to the yama) it sounds fine.
Sounds like my 25+ year old amp finally boosted it's last signal.

I'm thinking the controls on the Kenwood need cleaning.

But why drive the Kenwood with the Yamaha's pre-outs anyway? The RX-V995 has
more power and lower distortion, though I suppose the Kenwood might have
more perceived "punch", also IIRC it has meters for eye candy.

Mark Z.

 

[Mark D. Zacharias]

"Adam Funk" <a24061@yahoo.com> wrote in message
news:lccue3-v3g.ln1@news.ducksburg.com...

On 2006-03-18, Bill Jeffrey <wjeffreyAT@alum.DOTmit.edu> wrote:
Adam -

I would think that a CD label would be a GOOD thing, as long as you
don't pull it off (and why would you?). It would be a barrier against
the inadvertent scratches that happen during handling. Yes? No? It
would also tend to keep ambient light out of the disk - or at least the
side that is normally stored upward, facing the light.

I've been under the impression that the adhesives damage the coating.
(I could be wrong.)

Labels aren't permanent and can cause a variety of problems; among the ones
I've seen are causing jamming in slot-loading machines, and clamping
problems in regular tray or carousel models. On a regular machine, if any
adhesive migrates a bit, the disc can stick to the clamper and also cause
jamming problems.


Mark Z.

 

[Bill Jeffrey]

Dave D wrote:

"Bill Jeffrey" <wjeffreyAT@alum.DOTmit.edu> wrote in message
news:2CWSf.9131$z82.8920@fed1read07...

Adam -

I would think that a CD label would be a GOOD thing, as long as you don't
pull it off (and why would you?). It would be a barrier against the
inadvertent scratches that happen during handling. Yes? No? It would
also tend to keep ambient light out of the disk - or at least the side
that is normally stored upward, facing the light.



The adhesive on labels contains solvents which may compromise the CD's
coating over time, or even break it down altogether. I personally would
never attach anything sticky to my CDs or DVDs, least of all my most
precious and irreplaceable ones.

Dave

Thanks, Dave. Didn't know that.

Bill

 

[Anthony]

gijigeorge@hotmail.com wrote in news:1142346738.593712.115330
@z34g2000cwc.googlegroups.com:

I require a unwinding/winding machine. This machine will release paper
from a roll and it will go through a special scanner and have to wind
the paper back into a roll.

I am planning to make this machine.

Unwinding the paper roll is not a problem as the scanner can pull the
paper in.

When comes to winding, I have the following problems:
A simple mechanism to hold the 15mm paper core (eg. Axial chuck)
A simple mechanism to provide tension to the paper that is wound
A simple mechanism to keep the paper aligned, prevent crumbling

Conditions:
The paper width can be from 10 - 30 cm
The paper length can be from 10m - 100m
The paper quality can vary
The scanning speed can be 10cm per sec (max)

As it is quiet difficult to synchronise the scanner with the motor
connected to the winding part, I decided to let the paper coming out
the scanner to drop and a sensor will detect the paper lag and activate
the winding motor.

A simple ASCI diagram is as below:
1 = unwinding section
2 = scanner
3 = tension rollers
4 = winding section
5 = gap in the table for paper to drop

@ o @
| _____________ o |
| |____________| | |
---+-------------------------- -+-----+--
1 2 5 3 4

Any ideas, suggestions are welcome. You can contact me @
gijigeorge@hot......com

Thank you in advance.

Regards
Giji George

Having several years of experience in the printing industry, having slack
anywhere in the system is an absolute no-no. Tension must be critically
controlled throughout the system.
Tension is normally controlled via a 'dancer roller' and tension drive
stand between the unwind roll and the printing (scanning, in your case)
feeder. The same mechanism is used between the scanning device and your
take-up reel.

A dancer roller works by having a roller on an offset pivot. The roller
would be approximately 8-10" from the pivot point, and in operation,
would reside at a horizontal position. This dancer roller is attached to
an encoder, which feeds information to either the brake control mechanism
or drive, or to the take-up drive. The dancer roller is pre-tensioned,
typically via pneumatic cylinders, to determine your web tension. Using
the feedback from the dancer rollers, the drive or brake attempts to
maintain a horizontal position of the roller, thus creating a constant
tension on the web.

This type of thing is down to a science, and plenty of machinery exists
to do this. Do a search for 'paper rewinders' or 'paper rewinding
inspection machines'. Bobst-Champlain is but one of many manufacturers of
this type equipment, provided they are still in business.

--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email

 

[Adam Funk]

On 2006-03-18, Dave D <dave_d@dave_d.com> wrote:

The adhesive on labels contains solvents which may compromise the CD's
coating over time, or even break it down altogether. I personally would
never attach anything sticky to my CDs or DVDs, least of all my most
precious and irreplaceable ones.

Thanks. I'll keep using the CD pens.

 

[Joust]

DONT get a thompson.
spend a little extra for a Samsung or a Philips.
I'll bet you have a Thompson and that is your problem.
There is also a newer LG drive.
all can be used seamlessly.
there are PC versions of Samsung and LG drives that can be modded but it'll
cost you about the same and is not for beginners and honestly not worth the
effort. Lots of real drives are out there.
"Ken G." <goodguyy@webtv.net> wrote in message
news:25085-44197551-2139@storefull-3238.bay.webtv.net...

Thanks ! i will start at ebay

 

[Bob]

Smitty Two <prestwhich@earthlink.net> wrote in
newsrestwhich-F3ADE4.21450316032006@news.west.cox.net:

In article <dvcvp2$htd$1@news.doit.wisc.edu>, Bob <no@spam.org> wrote:



Thanks to all who replied. I think I found the problem: a 3-pin
component (transistor?) soldered to the main board and screwed to
copper channel (heat sink) that stands upright. Wiggling or tapping
the unit makes the whole gizmo click in and out. I guess the thing
to do is re-solder it.

don't forget to use a little liquid flux.

It worked! I'm listening to it right now. Thanks again everyone.

 

[Leonard Caillouet]

"JANA" <jana@ca.inter.net> wrote in message
news:4846b1Fic30cU3@uni-berlin.de...

You cannot substitute the lamp. The original lamps have a specific
luminosity, shading characteristics, power and voltage rating, and colour
temperature.

In reality, these lamps are lasting about 800 to 1000 hours if you are
lucky. I know some people that are changing these lamps about once a year.

What I would recommend, is to sell the set, and get a new flat panel LCD
TV.
You will pay a little more up front, but the LCD should give you about
40,000 to 60,000 hours of service before it needs a new set of lamps and
ballast transformer. By then, you will be more than due for an upgrade
always. Under normal use, the new models of the LCD screens should last
about 10 to 12 years if used for only about 10 hours per day. This would
be
a much more cost effective way of watching TV.

To generalize that the lamps are lasting 800 to 1000 hours is overly
pessimistic. Most are lasting much better than that. It is likely that
the RCA had the same problems that Sony and others did with Philips lamps
for a while. Those problems seem to have improved quite a bit. The Osram
lamps used by other vendors still seem to last longer, but recent Philips
lamps seem to be much improved over those of a couple of years ago. The
life of this type of lamp has a great deal of variability. Some don't last
long and some do. I know lots of people that have thousands of hours on
their DLP lamps.

LCD panels have their advantages, but even the best still have artifacts
that are likely to be noticed by many more people than would find problems
viewing a DLP unit. The picture on the better DLP products is stunning.
Even the RCA DLP is far more watchable than even the best LCDs IMO. You
also won't get the size out of a flat panel LCD that you will from DLP
products.

Leonard

 

[OldSchool]

I'm driving 6 rooms of speakers with it. Low volume (lots of small
kids) but the Yamaha is having a hard time driving them alone.

 

[webpa]

Radio could be defective, but it is more likely that the "white noise"
is an actual RF signal...possibly from something recently introduced in
your area: Broadcast radio transmitter (AM, FM, TV), cellular telephone
base station, broadcast TV or radio station adding a digital
transmitter; etc. Investigate. You didn't say whether your location or
time of day affected the noise....

 

[Do Little2]

<suchi_84@yahoo.com> wrote in message
news:1142255760.595794.75160@z34g2000cwc.googlegroups.com...

Hi folks,
I need a help. As I am basically an electrical engineer I have
succeeded in micro-stepping a stepper motor by 128 micro steps of step
angle 1.8degrees which mean it can at one instance move by as small as
0.014degrees. Well the problem now is that I need to convert this
angular motion into its equivalent linear motion(i micron) so that I
get a micron level motion.

Use a spline gear with shaft connected to an anvil.

See link below for a possible <0.1 micro m resolution.
M-168 High-Resolution Stepper-Mike Actuators

10, 25 & 50 mm Travel Ranges
Resolution <0.1 ľm
2- and 5-Phase Stepper Motor
Manual Positioning Knob
Sub-nm Resolution with Optional PZT Actuator

5,000 Hours MTBF
http://www.physikinstrumente.com/en/products/prdetail.php?sortnr=703800

 

[Scott Ehrlich]

In article <1142802268.799162.290170@u72g2000cwu.googlegroups.com>,
webpa <webpa@aol.com> wrote:

Radio could be defective, but it is more likely that the "white noise"
is an actual RF signal...possibly from something recently introduced in
your area: Broadcast radio transmitter (AM, FM, TV), cellular telephone
base station, broadcast TV or radio station adding a digital
transmitter; etc. Investigate. You didn't say whether your location or
time of day affected the noise....

Day or night. Doesn't matter. With or without antenna. Whether in the
car driving through area towns or on my desk at home.

It is something in/with the radio.

Would be _REALLY_ nice is the Optoelectronics Digital Scout had a built-in
speaker. I'd dream about that in my car... Though next best thing to no
built-in speaker would be to get the cheapest scanner it can control...

Scott

 

[Frank S.]

It is either a GSM (Cingular, Tmobile Suncom etc.) the amplifier if
detecting the rf signal which is a pulsed signal. It is the phone
"checking in" with the base station,
There is no "usable" information being transmited (other then to the phone"
Frank

Mike Muderick wrote:

If I leave my cell phone near my computer speakers I will hear occasional
buzzing, clicking, etc. Before the phone begins to ring, I hear a
dah..dah.daahhhhh. I know this is RF interference being picked up by the
amplifier in the speaker. If one were to record this sound with a
microphone at 11 or 22Khz, would it be possible to obtain any information
(usable signal) from the recorded audio?
Thanks,
Michael@muderick.com