Toshiba TV29C90 problem; Image fades to black...

[Miketew]

Terry Wrote:

"John Bachman" johnREMOVE@anatek.REMOVEmv.REMOVEcom wrote in message
news:g3ii41hn8c7ij4sbbrr6rmhihug25722lu@4ax.com...-
On 29 Mar 2005 02:51:37 -0800, "Glynn R." kittyslave75080@yahoo.com
wrote:
-
Hey-- I've kinda wondered this too! In a circuit, I might choose a
16v
in a circuit I expect to have 5 volts running through. I have been
told
I could put a 63v there and it works just the same. BUT, would it last
better? Would the extra expense do anything at all for reliability?-

Reliability is generally improved by "derating" but only up to a
limit. Derating means operating the capacitor at a voltage less than
its rating, ie, a 25 volt capacitor operated at 15 volts is derated
15/25 = 60%. In other words, it is being operated at 60% of its
rated
voltage.

Capacitor voltage ratings can be derated 25% - 100% depending on the
type but going beyond that is a waste of money and space except in
the
most demanding applications.

John
-
Are there any other considerations; for electrolytic caps?
What I'm getting at is that an electrolytic capacitor rated at say 16
microfarads at say 450 volts DC, if operated at a very low voltage,
lets
assume, say 25 volts for sake of argument, may not have the stated
capacity
of 16 mfd. because of the manner of the electrochemical action of the
capacitor.
Or am I off track with this idea? Note this ? is only in reference to
electrolytic caps.

I have operated 2 mfd. 'paper' caps rated for 50v DC at 350v DC (with
ripple) knowing that they were tested to 2000v static DC when
manufactured!
Also have operated similar 0.5 mfd. cap at 115v RMS (60 HZ.) in a fan
circuit with only one failure in 30+ years.

TIA
Ripple current also has a bearing on size too and is sometimes listed

by the manufacturer


--
Miketew

 

[Bill Jeffrey]

Try www.primopdf.com. Dunno about the bookmarks ...

Bill
====================

Rifleman wrote:

Hi!

There is probably simplier ways to convert a word document to a PDF file
than this but here goes:
Download a software called openoffice which is for free and will be more
than enough for most users, I do like microsoft office but but the cost is
way beyond what I can afford.
I bought Staroffice which is similar to openoffice and microsoft office but
it didn't make my wallit to empty, anyway it can convert any document to PDF
in an easy way and the cost is arround 1/4 of microsoft office.
Here's the link http://www.openoffice.org/dev_docs/features/2.0/index.html

Bjorn


"Sadiq" <sathick@gmail.com> skrev i meddelandet
news:1111946634.724720.132520@o13g2000cwo.googlegroups.com...

hello? i like to create my word files all to PDF format with bookmarks.
anyone can help me to prepare pls. mention the free site to get the
software also.thanks.

 

[Isaac Wingfield]

In article <codj415nu64h69qu9fi7e0truecfl8ogkk@4ax.com>,
John Bachman <johnREMOVE@anatek.REMOVEmv.REMOVEcom> wrote:

On Tue, 29 Mar 2005 12:59:05 -0330, "Terry" <tsanford@nf.sympatico.ca
wrote:


"John Bachman" <johnREMOVE@anatek.REMOVEmv.REMOVEcom> wrote in message
news:g3ii41hn8c7ij4sbbrr6rmhihug25722lu@4ax.com...
On 29 Mar 2005 02:51:37 -0800, "Glynn R." <kittyslave75080@yahoo.com
wrote:

Hey-- I've kinda wondered this too! In a circuit, I might choose a 16v
in a circuit I expect to have 5 volts running through. I have been told
I could put a 63v there and it works just the same. BUT, would it last
better? Would the extra expense do anything at all for reliability?

Reliability is generally improved by "derating" but only up to a
limit. Derating means operating the capacitor at a voltage less than
its rating, ie, a 25 volt capacitor operated at 15 volts is derated
15/25 = 60%. In other words, it is being operated at 60% of its rated
voltage.

Capacitor voltage ratings can be derated 25% - 100% depending on the
type but going beyond that is a waste of money and space except in the
most demanding applications.

John

Are there any other considerations; for electrolytic caps?
What I'm getting at is that an electrolytic capacitor rated at say 16
microfarads at say 450 volts DC, if operated at a very low voltage, lets
assume, say 25 volts for sake of argument, may not have the stated capacity
of 16 mfd. because of the manner of the electrochemical action of the
capacitor.
Or am I off track with this idea? Note this ? is only in reference to
electrolytic caps.

No, the capacitance is not a function of applied voltage.

For aluminum electrolytics, it most certainly is. Operating such a cap
well *below* rated voltage can cause a loss of capacitance over time.

I have operated 2 mfd. 'paper' caps rated for 50v DC at 350v DC (with
ripple) knowing that they were tested to 2000v static DC when manufactured!
Also have operated similar 0.5 mfd. cap at 115v RMS (60 HZ.) in a fan
circuit with only one failure in 30+ years.

That is not the result I would expect.

For a capacitor, the "voltage rating" is the voltage the cap is
*guaranteed* to withstand, continuously, over the entire temperature
range specified, and for the entire design lifetime of the device.
Naturally, in order to accomplish that, *almost all* of the devices
manufactured will actually be able to handle stress well in excess of
the "rated" value, at more moderate temperatures, and/or for shorter
times.

But designers apply components beyond their ratings at their peril --
that may be the way to a courtroom.

Isaac

 

[Franc Zabkar]

On 29 Mar 2005 02:51:37 -0800, "Glynn R." <kittyslave75080@yahoo.com>
put finger to keyboard and composed:

Hey-- I've kinda wondered this too! In a circuit, I might choose a 16v
in a circuit I expect to have 5 volts running through. I have been told
I could put a 63v there and it works just the same. BUT, would it last
better? Would the extra expense do anything at all for reliability?

Looking closely at the legend on Bob Parker's ESR meter, a higher
voltage rating for a given capacitance equates to a lower ESR ... most
of the time. The 1uF and 2.2uF caps show the opposite trend, and the
100V and 250V caps also buck the trend on occasion. I've heard that
higher voltage electrolytic caps may also have higher leakage
currents.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

 

[NSM]

"cnctut" <cnctutwiler@wmconnect.com> wrote in message
news:1112066983.687552.220510@o13g2000cwo.googlegroups.com...

I've never seen wattage ratings on a capacitor--voltage yes. Is it
simply .5CV^2 and that's it? I can design a circuit for a particular
capacitance--but how is the physical size of the Cap determined--I've
seen big capacitors with same MF's as little caps? What am I missing?

The size is determined by the capacitance, the voltage, the ripple current
rating and the technology used.

N

 

[Asimov]

"Glynn R." bravely wrote to "All" (29 Mar 05 09:36:54)
--- on the heady topic of "Re: Capacitor Wattage Capability"

GR> From: "Glynn R." <kittyslave75080@yahoo.com>
GR> Xref: aeinews sci.electronics.repair:44431

GR> Yeah, "forming" caps... how important is this process, and isn't some
GR> "forming" done for us at the factory?

GR> I know it's whining, but: IMO electrolytics are almost always a weak
GR> link in equipment. If you were to build a device you wanted to last a
GR> hundred years, you could probably do it with the resistors, diodes,
GR> transistors, I.C.s, inductors, crystals etc. our industry uses all
GR> the time. But you have to worry about electrolytics-- they just "go
GR> bad". This, to me, is a sorry shame. I realize I have no data to
GR> substantiate my claim... its just my personal observation. Has anyone
GR> got data to prove/disprove that electrolytics are as good as the rest
GR> of the component chain?

If the electrolytic capacitor is built and used in a manner for which
it was designed, then it will last many decades. Circumstantial proof
is from operating equipment I own which dates back 40 years or more.
As long as the seal remains intact the electrolytic capacitor is
self-healing once the dielectric layer has been formed. Indeed, every
time power is applied to the equipment an electrolytic capacitor
undergoes this self-healing process. The worst possible use one can
put an electrolytic capacitor through is with zero volts applied.
Thus using an electrolytic capacitor at a much lower than its design
voltage is accordingly something to avoid. Naturally high heat is
another bad environmental ingredient to shorten life expectancy.
The capacitance varies only very slightly with voltage.

A*s*i*m*o*v

.... Bad Beer Rots Our Young Guts But Vodka Goes Well.

 

[Jamie]

Terry wrote:

"John Bachman" <johnREMOVE@anatek.REMOVEmv.REMOVEcom> wrote in message
news:g3ii41hn8c7ij4sbbrr6rmhihug25722lu@4ax.com...

On 29 Mar 2005 02:51:37 -0800, "Glynn R." <kittyslave75080@yahoo.com
wrote:


Hey-- I've kinda wondered this too! In a circuit, I might choose a 16v
in a circuit I expect to have 5 volts running through. I have been told
I could put a 63v there and it works just the same. BUT, would it last
better? Would the extra expense do anything at all for reliability?

Reliability is generally improved by "derating" but only up to a
limit. Derating means operating the capacitor at a voltage less than
its rating, ie, a 25 volt capacitor operated at 15 volts is derated
15/25 = 60%. In other words, it is being operated at 60% of its rated
voltage.

Capacitor voltage ratings can be derated 25% - 100% depending on the
type but going beyond that is a waste of money and space except in the
most demanding applications.

John


Are there any other considerations; for electrolytic caps?
What I'm getting at is that an electrolytic capacitor rated at say 16
microfarads at say 450 volts DC, if operated at a very low voltage, lets
assume, say 25 volts for sake of argument, may not have the stated capacity
of 16 mfd. because of the manner of the electrochemical action of the
capacitor.
Or am I off track with this idea? Note this ? is only in reference to
electrolytic caps.

I have operated 2 mfd. 'paper' caps rated for 50v DC at 350v DC (with
ripple) knowing that they were tested to 2000v static DC when manufactured!
Also have operated similar 0.5 mfd. cap at 115v RMS (60 HZ.) in a fan
circuit with only one failure in 30+ years.

TIA


normally , there i a Temp rating on the cap.

calculate the ESR (effective Series R) and thus calculate
the wattage verses current.. to get your heating factor.
for those that don't denote the temp, i don't know.

 

[Shoreline Electronics]

Change these two caps : Look for the brown glue crud that causes strange
problems on these older models.


---------------------------------------------------------------
Text pasted from WinSTIPS 2.0
http://www.ServiceSoftware.com
---------------------------------------------------------------

MITSUBISHI CS3506R

Audio Buzz Or Whine In Audio

From Mitsubishi

Check C714 Off Pin #44 Of Ic701 For Glue, If Present Remove It ( The
glue...not the cap) And Resolder Connections. Pcb-Signal. (2.2uf 50v)

---------------------------------------------------------------

MITSUBISHI CS3506R

Bars Rolling Through Pix Vertically And Video Flashes

TV Doctor-T.O., Ca

Bad C232 - 10mf@ 50v

---------------------------------------------------------------

MITSUBISHI CS3506R

Video No Go

Sam Sieben Cet/Csm - Isf/Haa Trained

Replace C232 Off Of Pin 1 Of Ic202. Ic202 Is A Dynamic Black Level Ic And
Failure Of This Capacitor Causes A Symptom Of No Video.

---------------------------------------------------------------



--
==========================
Jeff Stielau
Shoreline Electronics Repair
344 East Main Street
Clinton,CT 06413
860-399-1861
860-664-3535 (fax)
jstielau@snet.net
========================

"Floyd Gilmour" <karlsaal@yahoo.com> wrote in message
news:1112058432.188883.243760@f14g2000cwb.googlegroups.com...

Hi, I have read a bunch of posts about the capacitors on circa 1990s
Mits but this set is different from most of the posts I've read. This
one has the 930B436 PIP (no bypass?) which does NOT have the surface
mount caps and I've replaced just about all of the electrolytics in the
set, I think I only have a few BP I can still replace. I have been
battling the inverted video (no luma high chroma) on my set now for
about 6 months and it seems to get better for 30 days at a time. Since
the failures started I have also had another symptom which is a fairly
loud audible buzz not from the speakers, but from the neck of the
picture tube. I have found that if you swith the channel back and forth
several times you can get something to sync and the buzz goes away.
Reseting the power also seems to work sometimes. On my last round of
capacitors (about 30) I again have a great picture but I still get
that buzz intermittently. I have a few areas where the traces were
compromised by the acid and I've had to make repairs but everything
seems sound. I read on a couple of posts about the neck of the picture
tube actually cracking which concerns me. This set came to me used with
a vertical problem (fixed with 5 capacitors) and I only have about $50
in caps in it plus the picture is great when it works, so I definately
want to get it fixed. For anyone reading this take the time and check
ALL of the capacitors as in every section there have been many "fishy"
caps if not just plain gunk leakin'! The condition of some of these
caps was so bad, it's surprising that the crazy thing could run at all.
If anyone has any tips to get rid of this buzz for good I sure would
appreciate it. Thanks!

 

[Charles Schuler]

<tom_sawyer70@yahoo.com> wrote in message
news:1112221335.622270.247610@o13g2000cwo.googlegroups.com...

Hello,
I have a Dell-branded monitor, model D1728D-LS, that has an issue.
Yesterday, it was working fine until mid-afternoon when the viewing
area changed to an vertical 2"-wide rectagle. It did not crop the
image, rather the width of the monitor was compressed into this
rectangular area.

I've tried turning it off/on, disconnecting the cable (the "check
signal" message was squiggly and also appeared illegibly about 2 inches
wide), and I connected another monitor to the same machine...the other
monitor displayed the screen properly.

There seems to be a horizontal deflection problem. Could be a transistor,
IC, capacitor, power supply issue, and so on. I'd say replace it or, if in
warranty, notify Dell or the retailer.

 

[Jim Adney]

On Wed, 30 Mar 2005 16:51:04 +1000 Franc Zabkar
<fzabkar@optussnet.com.au> wrote:

I've heard that
higher voltage electrolytic caps may also have higher leakage
currents.

I suspect that's true only if you measure each cap at its rated
voltage. I believe that if you measure each cap at the same voltage,
while staying within both ratings, the higher voltage electrolytic
will show less leakage.

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

 

[Franc Zabkar]

On 30 Mar 2005 15:12:41 -0800, "b" <reverend_rogers@yahoo.com> put
finger to keyboard and composed:

Hi, set is SAIVOD 14C5N (=ANSONIC AN- 1400). 1998 ONWA CHASSIS
revision 06 11 98 .

set initially dead, had squeal from psu and shorted HOT (D2499)
...replaced HOT and snubber cap, plus two electrolytics in the psu c509
10uf and c508 47uf (which i suspect led to the well documented problem
of these chassis : rise in the HT line voltage ).

Problem now is that the set powers up and works but won't go into
standby. Audio and pic are muted but Heaters and HT still on.

There is no red LED action on the front panel. Remote commands are
obeyed, however.

I then replaced q506 and q507, both were shorted. q507 was c2335 and
c506 was 2n5401. I didn't have the latter so used A1013, which had a
very similar spec to 2n5401. Unfortunately there was no change, though
neither new transistor shorted.

any suggestions on where to go from here gratefully recieved!
regards, Ben

I'm not familiar with your set, but it seems that your uP *is*
switching to standby mode (muted audio and pic), but is unable to
control the B+ switching transistor(s). I'd troubleshoot the base
drive to Q507. In the worst case, your uP's power control pin may be
defective.

BTW, I'm assuming you know that the pinouts for the 2N5401 and 2SA1013
are different, ie EBC and ECB, when looking from the flat side, from L
to R.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

 

[James Sweet]

<tom_sawyer70@yahoo.com> wrote in message
news:1112221335.622270.247610@o13g2000cwo.googlegroups.com...

Hello,
I have a Dell-branded monitor, model D1728D-LS, that has an issue.
Yesterday, it was working fine until mid-afternoon when the viewing
area changed to an vertical 2"-wide rectagle. It did not crop the
image, rather the width of the monitor was compressed into this
rectangular area.

I've tried turning it off/on, disconnecting the cable (the "check
signal" message was squiggly and also appeared illegibly about 2 inches
wide), and I connected another monitor to the same machine...the other
monitor displayed the screen properly.

Is there any other troubleshooting to do (I have a basic/moderate
understanding of electronics) or anything else to check or attempt to
configure?

Thank you,
Dave

I would start by checking or replacing the horizontal output transistor, it
could also be as simple as solder joints.

 

[James Sweet]

"luch" <sluchini@hotmail.com> wrote in message
news:1112250678.949404.236590@g14g2000cwa.googlegroups.com...

I'm going to be putting a tv in a room where the viewing area will be
across the room, with a lot of ambient noise. I'd like to hook up my
tv to speakers in the viewing area, but the tv has not audio output,
just a headphone jack. Is there an adaptor that will allow me to
convert from the headphone jack to a speaker connection? These
speakers would not be powered, just in-wall speakers.

After reading some of the posts in this forum, I'm starting to get
concerned about creating a shock hazard or about blowing a component on
the tv? If this will work, what are the specs of the speakers I should
look a getting? If this will not work, will wireless speakers give me
what I want (I don't want the added wrinkle of having to remember to
power on/off the speakers, and there is not an electrical outlet in the
viewing area.) Thanks for any help.

Adding a headphone jack creates a shock hazard, but you already have one so
you'll have no problems. To connect the speakers you'll need an amplifier of
some sort, doesn't have to be anything fancy. You may need a couple
resistors to match the impedance but that may not be nessesary.

Another possibly neater option is to get a VCR with stereo audio out and use
that as the tuner.

 

[René]

On 30 Mar 2005 22:31:18 -0800, "luch" <sluchini@hotmail.com> wrote:

I'm going to be putting a tv in a room where the viewing area will be
across the room, with a lot of ambient noise. I'd like to hook up my
tv to speakers in the viewing area, but the tv has not audio output,
just a headphone jack. Is there an adaptor that will allow me to
convert from the headphone jack to a speaker connection? These
speakers would not be powered, just in-wall speakers.

After reading some of the posts in this forum, I'm starting to get
concerned about creating a shock hazard or about blowing a component on
the tv? If this will work, what are the specs of the speakers I should
look a getting? If this will not work, will wireless speakers give me
what I want (I don't want the added wrinkle of having to remember to
power on/off the speakers, and there is not an electrical outlet in the
viewing area.) Thanks for any help.

Easy way out: buy PC speakers (intended for connection to PC -
soundcard) - they usually have a 3.5mm input jack that can be plugged
into the headphone output (use converter if this output is 6 mm).
Headphone jack should be isolated from hazardous voltages.


--
- René

 

[Ross Herbert]

On 30 Mar 2005 22:31:18 -0800, "luch" <sluchini@hotmail.com> wrote:

I'm going to be putting a tv in a room where the viewing area will be
across the room, with a lot of ambient noise. I'd like to hook up my
tv to speakers in the viewing area, but the tv has not audio output,
just a headphone jack. Is there an adaptor that will allow me to
convert from the headphone jack to a speaker connection? These
speakers would not be powered, just in-wall speakers.

After reading some of the posts in this forum, I'm starting to get
concerned about creating a shock hazard or about blowing a component on
the tv? If this will work, what are the specs of the speakers I should
look a getting? If this will not work, will wireless speakers give me
what I want (I don't want the added wrinkle of having to remember to
power on/off the speakers, and there is not an electrical outlet in the
viewing area.) Thanks for any help.

Since you cannot use powered speakers due to lack of power outlets
where the new speakers are required you cannot use a wireless
transmitter receiver setup. This means that you will be limited to
directly connecting your new speakers to the TV, and this may be a
problem depending upon your technical ability and the TV audio stage
capability/wiring. It is technically fairly simple to do but it
requires a fair bit of effort and appropriate knowledge.

I suspect that because the TV set only has a headphone jack you will
not be able to connect external speakers directly. It is probable that
the existing headphone output jack isolates the internal TV speakers
when the headphones are plugged in (it should be wired like this), AND
there will be series limiting resistors to reduce the maximum level
being fed to the headphones. These resistors will need to be bypassed
in order to drive external speakers so this would mean delving into
the innards of your TV set. Unless you are familiar with TV servicing
then don't do it yourself.

You will need to select external speakers having the same impedance as
the internal ones (this data may be stamped on the internal speakers
or it is in the TV user guide spec - possibly 8 ohms). You also need
to select external speakers which will be as efficient as possible
given the limited power output of the usual audio output amplifier in
most TV's, but this rating should also be in the spec - say speakers
rated at 5 - 7W RMS.

Now if the headphone output jack is a 3.5mm unit, as I suspect, then
you won't be able to wire your new speaker cables into a 3.5mm plug,
since this type of plug just isn't designed to take other than the
small diameter cable as used on headphones. Your new speaker cables,
being much longer, will most likely be stranded figure eight flex cord
so you will need to make a suitable adapter box to expand the 3.5mm
plug connections out to two sets of connectors suitable for stereo
speaker cables. There aren't any off-the-shelf items to do this that I
know of so you will need to be handy with electronics construction
techniques and components.

If all this seems too hard for you then you won't be able to achieve
your aim of connecting external speakers to your TV unless you use
powered speaker units and an A/V transmitter setup.

 

[Steven]

If my news provider had dropped what you'd just replied to, I'd surely be
confused but I'd try to recover...
"Ken G." <goodguyy@webtv.net> wrote in message
news:10094-4241F9C7-135@storefull-3254.bay.webtv.net...

I hate all of it , if your paying attention you dont need anything but
an answer to the question . If the whole darn first topic is included at
the top where i have to keep scrolling to read the next post i soon give
up and quit reading .

Old vcr`s will be worth fixing till no one wants to pay for it anymore

Of course you have answered the question with your typical uncanny wisdom.
Thanks, Ken

 

[Steven]

<Kim_Jong_Il@volcanomail.com> wrote in message
news:1111685125.401201.57760@o13g2000cwo.googlegroups.com...

"The only time I can think of that pot-toasting is acceptable is if
you're replying to the subject."

Allow me to express my support for pot-toasting. Got a light?

They used to toast Luckies. I can't see how that could hurt?

 

[Steven]

"beerismygas" <beerismygas@yahoo.com> wrote in message
news:d8f90366.0503252339.3460218a@posting.google.com...

"Mark" <makolber@yahoo.com> wrote in message
news:<1111774739.364511.55730@f14g2000cwb.googlegroups.com>...
the usual problem is that the take up reel which is driven by a
friction drive, starts slipping too much and no longer takes up the
tape so the tape bunches up and gets tangled.

Mark

oh.ill try changing the belt then.thanks

Cleaning the capstan and pinch rollers couldn't hurt

 

[Ivor Floppy]

<sdchew@ieee.org> wrote in message
news:1112287400.782184.52730@o13g2000cwo.googlegroups.com...

Hi Everyone,

I was wondering what do you call the kind of rubber/foam type heat sink
you typically find attached on a IC in a small non/poorly ventilated
casing (e.g. pager, cell phone)? Its typically gray in colour and feels
soft and rubbery. I think some of the old Apple Powerbooks also use
them to vent heat to the casing.

Anyone also knows where I can buy them?

thermal interface pads.
http://www.warth.co.uk/site2003/blue_site/Introductions/products_fast.html
do quite a range of different types

The one called "Kool-PadsŽ HeatPath GTQ 2100 " looks like the same stuff
I've seen inside CDROMs etc.

 

[Keith Williams]

In article <1112291657.595936.40770@z14g2000cwz.googlegroups.com>,
genenamg@yahoo.com says...

How do I check if a transistor is working using a multimeter - both
BJTs and FETs? How will I know if it's shorted etc? Also, for a BJT
how will I know the emitter, base and collector by using a multimeter?

BJTs are easy: A BJT will look like two diodes (Base-Emitter and Base -
collector). Find the common lead. That's your base. If the
transistor conducts ('+' to '-') from the base to the other two, it's
an NPN. If it conducts the other way it's a PNP. If it conducts both
ways or neither, pitch it. Telling the difference between the emitter
and collector is a tad harder. If your multimeter has a "transistor
tester" the direction with the largest beta is correct.

MOSFETs are harder. ;-)

--
Keith