Toshiba TV29C90 problem; Image fades to black...

Vertical circuit parts in Toshibas are usually numbered in the 3xx range.
Check these caps for ESR, capacitance, and leakage. Don't assume they are
all near the output.

Leonard

"Jerry Chanderpaul" <jerrych@simex.ca> wrote in message
news:5oX1e.939$w63.325707@news20.bellglobal.com...
Hi, I am reparing a Toshiba tv cx28600 with vertical a output
problem..white
horizontal bar across screen..I will have to change the vertical ic
AN5521....does anyone know which caps will also have to be changed with
this ic so the problem does not reoccur

Thank you

Jerry
Click to expand...
 
Right at the cathode and control grid of the blue tube, if you swapped it
with another colour channel, and the blue still stays bad, I would strongly
suggest that it is defective.

From my interpretation, I am convinced that you have a bad tube. This is not
uncommon.

How old is the set?

--

Jerry G.
======


"Dave Gostelow" <davegostelow@(nospam)yahoo.com> wrote in message
news:d29g3v$uhd$1@news6.svr.pol.co.uk...
Hi,
I have a JVC widescreen TV AV-28WR2EK which has a fault with the blue gun,
or its driver. I searched the NG and found some good posts about similar
problems which suggested it was probably a short in the tube (and to try
floating the heater).
Well, I tried a few diagnostics:
swapped the blue and red cathode drives at the final resistor, fault still
on the blue gun.
lifted the drive transistor collector on blue so that the cathode voltage
rises to the supply, fault still there on blue.
'floated' the heater using 3 turns of wire around the HT transformer core,
and fault is still there!

So I begin to think there isn't a heater to blue cathode short, but maybe a
blue to something else short.

Then I tried disconnecting the blue cathode completely, by lifting the final
resistor, and the blue gun turns off! So is it shorting to something or not?
If I stick my DVM on the blue cathode and ground to measure its 'floating'
voltage it turns on strongly, so its being pulled down by the DVM. If I
measure voltage between blue cathode and supply I get the blue gun very
faintly on and a voltage reading of about 15-20 volts (blue gun more
positive than supply).

The supply voltage is 201V and before I started fiddling I saw at all 3
cathodes I was seeing voltages of 150-170 volts depending on the picture.

I would have decided the tube had a short except for the behaviour when the
cathode is left floating, which suggests to me that the blue gun would
probably turn off if it was driven to a higher voltage than 201V.

Has anyone seen a similar problem? And if so, was there a fix? Or, does
anyone have any further ideas for things to try?

Dave.
 
MCM or Fulton
Do a search for those.

kip


<jwiggins@surfmore.net> wrote in message
news:1112046017.036892.137110@f14g2000cwb.googlegroups.com...
I am repairing a Sony STR DE-835 Home Entertainment unit and need to
find a source for replacement parts. All of my local parts houses are
unable to cross the numbers.


Looking for: Q606 MN 2488 OPY M Part# 8-749-010-25
Q607 MP 1620 OPY M Part# 8-749-010-26


Can someone point me in the right direction to purchase these parts?
Thank in advance for any help received.


Joe
Click to expand...
 
Rifleman Wrote:
"philo " "philo "@privacy.net skrev i meddelandet
news:3anrcgF6a5cntU1@individual.net...-
dennis702717@yahoo.com wrote:-
Noticed that old Fluke meters are selling for $50-$80 whereas
comparable Wavetek meters, same features, sell for $10-$30.

Any suggestions on whether the extra cost of a used Fluke is worth
it,
over Wavetek?

Also, is the Ideal multimeter really a Wavektek? (Buttons are in the
same position, same functions.) But, why cheaper?
-
although i've used fluke's for years...
the last time a got a meter it was a wavetek

it had more features than the fluke and cost less...
it's been running fine for many years and i use it in a very rough
industrial application


my guess is that if both a fluke and a wavetek were dropped from a
great
height...the fluke would prob hold up better...
but the wavetek is a good meter-

You are so right, there is lot's of good DMM,s on the market for less
price
than FLUKE but those FLUKE are good. I got 2 FLUKE 77 and I had them
for I
don't know how long maybe 15 years or more and they never seem to wear
out.
Even if you are a PRO you even try to measure high voltage with the
range
knob at ohm :)
I've done this and they are still ok.

Bjorn
Click to expand...

Buy a Fluke....if your serious about reliability....


--
melosenoway
 
The user manual is copyright 1997 and I guess the TV is probably that old.
I've only had it a few days. I don't want to believe the tube is bad, but
I'm probably going to have to accept that it is, and its not going to be
worth replacing it. I'm going to try one more thing tomorrow before I give
it up: try adjusting the G2 (screen) setting to see if that makes any
difference. I found something about that adjustment on another posting which
was about fixing single colour visible flyback faults.

"Jerry G." <jerryg50@hotmail.com> wrote in message
news:3ar7jdF6c3riiU1@uni-berlin.de...
Right at the cathode and control grid of the blue tube, if you swapped it
with another colour channel, and the blue still stays bad, I would
strongly
suggest that it is defective.

From my interpretation, I am convinced that you have a bad tube. This is
not
uncommon.

How old is the set?

--

Jerry G.
======


"Dave Gostelow" <davegostelow@(nospam)yahoo.com> wrote in message
news:d29g3v$uhd$1@news6.svr.pol.co.uk...
Hi,
I have a JVC widescreen TV AV-28WR2EK which has a fault with the blue gun,
or its driver. I searched the NG and found some good posts about similar
problems which suggested it was probably a short in the tube (and to try
floating the heater).
Well, I tried a few diagnostics:
swapped the blue and red cathode drives at the final resistor, fault still
on the blue gun.
lifted the drive transistor collector on blue so that the cathode voltage
rises to the supply, fault still there on blue.
'floated' the heater using 3 turns of wire around the HT transformer core,
and fault is still there!

So I begin to think there isn't a heater to blue cathode short, but maybe
a
blue to something else short.

Then I tried disconnecting the blue cathode completely, by lifting the
final
resistor, and the blue gun turns off! So is it shorting to something or
not?
If I stick my DVM on the blue cathode and ground to measure its 'floating'
voltage it turns on strongly, so its being pulled down by the DVM. If I
measure voltage between blue cathode and supply I get the blue gun very
faintly on and a voltage reading of about 15-20 volts (blue gun more
positive than supply).

The supply voltage is 201V and before I started fiddling I saw at all 3
cathodes I was seeing voltages of 150-170 volts depending on the picture.

I would have decided the tube had a short except for the behaviour when
the
cathode is left floating, which suggests to me that the blue gun would
probably turn off if it was driven to a higher voltage than 201V.

Has anyone seen a similar problem? And if so, was there a fix? Or, does
anyone have any further ideas for things to try?

Dave.
Click to expand...
 
"Barney" <barneyxyzNOSPAM@hotmail.com> wrote in message
news:1IWdnXVz-dOqVNrfRVnyiA@brightview.com...
tariq.1.rahim@spamgourmet.com> wrote in message
news:1111971868.909144.22420@l41g2000cwc.googlegroups.com...
what's a scart socket?

will using the audio and video jacks instead of the single coax jack
bypass this problem too? thanks.


A Scart connector (also called a Euroconnector, so you may not have them
in
the US) is a 21 pin audio and video connector for connecting signals - via
a
suitable lead - between various AV equipment. Yes, using the audio and
video
should also work and bypass the problem as well.
Click to expand...
No US TV's have SCART connectors so it's understandable that someone from
here or Canada has never heard of them.
 
"Dave Gostelow" <davegostelow@(nospam)yahoo.com> wrote in message
news:d2a1kq$tqp$1@newsg3.svr.pol.co.uk...
The user manual is copyright 1997 and I guess the TV is probably that old.
I've only had it a few days. I don't want to believe the tube is bad, but
I'm probably going to have to accept that it is, and its not going to be
worth replacing it. I'm going to try one more thing tomorrow before I give
it up: try adjusting the G2 (screen) setting to see if that makes any
difference. I found something about that adjustment on another posting
which
was about fixing single colour visible flyback faults.
Click to expand...

If disconnecting the pin turns the blue off there's still hope. Are you
*sure* you swapped the blue with something else right at the tube socket?
 
"Tyrone Park" <tyrone_park@hotmail.com> wrote in message
news:9fbf6787.0503280609.6a3ed57e@posting.google.com...
Is there a way to remove the "heat run" from the display without the
service remote? If so, please be kind and reply with the info.
Thanks@!

TeePee
Click to expand...

What's heat run?
 
"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?


Thanks
Click to expand...
There's no such thing as a wattage rating for a capacitor, just voltage and
capacitance. Some newer ones are smaller than older ones, some brands are
different, non-polar ones are much larger and venting temperature or ESR can
also have an effect on size.
 
On 28 Mar 2005 13:40:17 -0800, jwiggins@surfmore.net put finger to
keyboard and composed:

I am repairing a Sony STR DE-835 Home Entertainment unit and need to
find a source for replacement parts. All of my local parts houses are
unable to cross the numbers.


Looking for: Q606 MN 2488 OPY M Part# 8-749-010-25
Q607 MP 1620 OPY M Part# 8-749-010-26
Click to expand...
MN2488 = 2SD2488 and MP1620 = 2SB1620.

See http://www.nteinc.com/specs/2600to2699/pdf/nte2649_50.pdf


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
 
"James Sweet" <jamessweet@hotmail.com> wrote in message
news:m842e.54874$hA3.20021@trnddc09...
"Barney" <barneyxyzNOSPAM@hotmail.com> wrote in message
news:1IWdnXVz-dOqVNrfRVnyiA@brightview.com...

tariq.1.rahim@spamgourmet.com> wrote in message
news:1111971868.909144.22420@l41g2000cwc.googlegroups.com...
what's a scart socket?

will using the audio and video jacks instead of the single coax jack
bypass this problem too? thanks.


A Scart connector (also called a Euroconnector, so you may not have them
in
the US) is a 21 pin audio and video connector for connecting signals -
via
a
suitable lead - between various AV equipment. Yes, using the audio and
video
should also work and bypass the problem as well.



No US TV's have SCART connectors so it's understandable that someone from
here or Canada has never heard of them.
Click to expand...
Has anybody considered a fluctuation in voltage to the tuner or video amp
bringing signal level sporadically low (say by a component fluctuating
erratically such as a capacitor being drawn by a bad diode)? Not that I'm an
engineer, but humor me, as nobody else has addressed the question well yet
IMO.
 
"Franc Zabkar" <fzabkar@optussnet.com.au> wrote in message
news:cdkh415herr0srmber56kbp1o0nnnme1sc@4ax.com...
On 28 Mar 2005 13:40:17 -0800, jwiggins@surfmore.net put finger to
keyboard and composed:


I am repairing a Sony STR DE-835 Home Entertainment unit and need to
find a source for replacement parts. All of my local parts houses are
unable to cross the numbers.


Looking for: Q606 MN 2488 OPY M Part# 8-749-010-25
Q607 MP 1620 OPY M Part# 8-749-010-26

MN2488 = 2SD2488 and MP1620 = 2SB1620.

See http://www.nteinc.com/specs/2600to2699/pdf/nte2649_50.pdf


- Franc Zabkar
--
Click to expand...
We have seen fakes on these, and NTE has had their share.

I recommend B&D Enterprises, (Bdent.com) or East Coast Transistor Parts
800-645-3516

Mark Z.
 
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?
Click to expand...
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
 
"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?
Click to expand...
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
 
I definately swapped the right connections.

I'm very happy tonight because just over 1/4 turn of the 'screen' trimmer
has solved the problem. It has got the blue to turn off properly in black
parts of the picture, but the blue gun is still extremely strong compared to
the other two. I have been able to get a reasonable colour balance by
changing the engineer settings with the remote.

My conclusion: the tube is not dead yet, but how long it lasts is anyones
guess.

Thanks for the replies, and also to those whose archived posts I found via
google which gave me the hints that fixed the problem!

"James Sweet" <jamessweet@hotmail.com> wrote in message
news:db42e.54875$hA3.37942@trnddc09...
If disconnecting the pin turns the blue off there's still hope. Are you
*sure* you swapped the blue with something else right at the tube socket?
Click to expand...
 
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.
Click to expand...
No, the capacitance is not a function of applied voltage.

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.
Click to expand...
That is not the result I would expect.
 
On 29 Mar 2005 09:36:54 -0800, "Glynn R." <kittyslave75080@yahoo.com>
wrote:

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

I know it's whining, but: IMO electrolytics are almost always a weak
link in equipment. If you were to build a device you wanted to last a
hundred years, you could probably do it with the resistors, diodes,
transistors, I.C.s, inductors, crystals etc. our industry uses all the
time. But you have to worry about electrolytics-- they just "go bad".
This, to me, is a sorry shame. I realize I have no data to substantiate
my claim... its just my personal observation. Has anyone got data to
prove/disprove that electrolytics are as good as the rest of the
component chain?
Click to expand...
Older electrolytics were certainly unreliable components. That is no
longer the case assuming good electrical and thermal design. Poor
thermal design is responsible for the failure of many electrolytics as
elevated temperatures significantly degrade their reliability.

Designers must adhere to all of the limitations specified by the
manufacturer to achieve a solid reliable design.

John
 
On 28 Mar 2005 19:29:43 -0800, "cnctut" <cnctutwiler@wmconnect.com>
put finger to keyboard and composed:

I've never seen wattage ratings on a capacitor--voltage yes. Is it
simply .5CV^2 and that's it?
Click to expand...
That's the energy stored by a capacitor. An ideal capacitor dissipates
no power, so the concept of wattage makes no sense.

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?
Click to expand...
The size of a capacitor is determined at least partly by its voltage
rating. AFAIK, larger voltages require a greater distance between the
plates to avert dielectric breakdown. All other things being equal, to
maintain the same capacitance at this greater distance also requires a
larger plate area.

I believe the other important factor determining the size of a cap is
the type of dielectric used.

Thanks
Click to expand...
Another important consideration for caps is their equivalent series
resistance (ESR) and their ripple current rating. The ripple current
causes ohmic heating of the ESR, which then causes the temperature of
the electrolyte to rise. AFAIK, every 10 degC rise in operating
temperature reduces the life of the cap by half.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
 
An electrolytic capacitor is most likely over heating due to a failure. DO
NOT use the set this way. Using it, may cause more damage, and also present
a safety issue. Get it properly serviced!

--

JANA
_____


"Sm704" <sm7040@hotmail.com> wrote in message
news:1112123375.570089.75000@f14g2000cwb.googlegroups.com...
I have a 14" JVC TV which I purchased new about 2 and a half years ago.
Ever since I bought this TV, I've noticed a very strange problem with
it. When the TV has been on for about a half hour or longer, it starts
to give off an odor that is similar to a skunk or a latex glove. It's
awful. It's only when the TV is on, not off. I thought over time, the
smell would eventually disappear, but it doesn't seem to be...

What could possibly be wrong? What could be causing the TV to smell
like this?

Thanks.
 
It could be High voltage discharge, this causes an ozone smell, this
can occur from any high voltage point (20kv 30kv) especially if a
connection has a sharp point or termination wire spike. If the back
has vents, look through them in a darkened room and see if an arc is
visible. Also underneath vents if possible.
Al

What could possibly be wrong? What could be causing the TV to smell
like this?

Thanks.
Click to expand...
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top