Toshiba TV29C90 problem; Image fades to black...

[John Del]

From: jurb6006@aol.com (JURB6006)
Date: 2/1/05 4:45 AM Eastern Standard Time
Message-id: <20050201044520.02052.00000336@mb-m14.aol.com

Re: STK 392-020 suspect lot# E418


I've run across this so many times, I only use OEM parts now. Zero callbacks.
Not only with conv ICs, but typical vert ICs, audio amps and transistors,
switch mode regulators (I had a dozen bad STR53041s and 10 bad 2SC4927 HOTs
from Tritronics)

HOWEVER, there is a company in Colorado called Electronica who sells only OEM
sourced semis. Of course, it's still possible for his sources to slip
forgeries to him as well, but he's very diligent in monitoring his parts.

John

 

[Jerry G.]

This sounds like a mother board failure. During service of any kind, the
manufacture replaces the complete mother board.

If you want to troubleshoot a mother board, I would wish you a lot of luck.
These are very sophisticated, and having just a DVM and a scope would be a
waist of time to really get in to it. Even if you were able to locate a bad
parts, other than a simple cap or resistor, you would have to be able to
source the parts, and have the soldering tools to change it.

Many of the semiconductors on these boards are proprietary to the
manufacture. A number of them contain firmware in which, even if you have
the programming equipment for, you would have to have a source for the
coding that goes in to them.

On a laptop, there are only several things to try when troubleshooting it.
You have the RAM modules, screen assembly and its back-lamp inverter supply,
and maybe a daughter board for some options. The rest, such as the IR ports,
are generally built on to the mother board, and are not changeable.

The only thing you can do without spare cards on hand, is look for an all
reset button, and try that. You can also use a DVM and verify that the
mother board battery and the power supply are good.

One thing I have seen in the odd laptop, is that if the main battery, or the
mother board battery is defective, the computer may not start or run. Check
these first.

--

Jerry G.
=====

"Lorene" <lwoomer@earthlink.net> wrote in message
news:uvfKd.2848$Eh5.585@trnddc04...
I have a Gateway M305CRV two weeks out of warrenty that simply stopped dead
in its tracks.
I wasn't doing any thing out of the ordinary and all of a sudden nothing
worked. The mouse froze up. The CTRL-ALT DEL would not bring the Task
Monitor up or allow me to reset. So I turned it off and back on again.
Now it only lights up the LEDs above and to the right of the on/off button.
In fact it circulates through the LEDs. The fan also comes on. That is all
it does. Nothing on the screen.
It seems as if the BIOS is in a loop waiting for something.

I have tried the following not necessarily in this order without success.
Plugged the monitor from the desktop into the back -- didn't help.
Took the battery out and let it set for an hour. Plugged the AC line in --
didn't help.
Reseated the RAM -- didn't help.
Reseated the HD -- didn't help.
I took what I assummed to be the CMOS battery out and turned it on without
the CMOS battery -- din't help.
Put the Diver CD in the drive and turned it on -- didn't help.

My questions are"
1. Does anyone know what order the BIOS does its work?. I would assume it
checked the RAM first. It knows when the battery is running low because I
let it set there circulating through the LEDs until the battery lite turned
a blinking red and finally shut down.
2. Does the BIOS normally, or can it, write to the display without RAM being
present. Nothing gets displayed at the moment.
3. Does anyone have a source for the Service Manual for the M305 laptop. Do
I really have to pay for it. IT would seem to me if Gateway won't help fix
it they should at least provide a source that tells you how to take the
thing apart correctly.

Please don't suggest talking to Gateway. I tried that and all my arguments
fell on deaf ears. I believe I have a case for the machine still being under
warranty since I had a months worth of trouble when I first got it. But I
get the distinct feeling from my conversations with their support people
that they really don't give a grunt.

Reading through the news groups and internet it seems like I'm not the only
one whose laptop ended up in this state. But so far I have found no
solutions.

Right now I purposely took out the CMOS battery and let the main battery run
completely down and am going to let it set for a day or two.

 

[Tim Schwartz]

Hello,

Please be more specific. What do you need cross reference help with?
Tim Schwartz
Bristol Electronics

marfalla wrote:

Hello Tim!
I have the same problem, do you get any more Information.
Please send me a mail
PLEASE MAIL TO autic@aon.at
Heinz
Austria

 

[Shoreline Electronics]

Your flyback may have an open winding. I had this exact same chassis with
this problem.. Looky here!


If this doesn't do it , can you post a photo of the fault on the web
somewhere?

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

RCA CTC169EJ5

Raster Squashed Vertically. Has Osd But No Audio Or Video.

Jeff Stielau : 8/2/99 : Shoreline Electronics

Check -12v Supply Off Pin 7 Of Flyback. If It Measures +4vdc Or Something
Odd, Check For Open Pin 7 On Flyback

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



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

"DHT112A" <kenlg@mindspring.com> wrote in message
news:1106508406.019494.248010@z14g2000cwz.googlegroups.com...

"I have a 35" Proscan 35123 direct view TV with a CTC169EJ5 board.
Manufactured in March of 96. I have replaced all the recommended parts
in the power supply and all voltages during idle and run are right on.
The original problem was a shorted HOT which was replaced along with
Q4302, Q2906, C4401, C4402 and C4403. I have had the flyback out and
it's resistances seem OK. A couple of times during the power supply
rebuild I put the board in the TV to put it in run and check some
voltages. When I turned it on it only had a bright narrow band across
the screen. Sound has always been fine. I tapped the flyback and it
came back to full screen. I have replaced Q4201 and Q4202 seems OK.

When the power supply rebuild was finished and I thought all was well
and we sat down to watch it, the thing suddenly popped through the
speakers and shut down. It does not try to restart but can be turned
back on by remote or power button on front panel only to pop and shut
down again. There is no certain time for shut down. It may be a
minute or two or just seconds. I see no burned, bulged or obviously
bad parts. The voltages don't appear to jump before shut down so I
don't think it is over voltage. The 143 volts at CR4116 drops then
comes back up in standby.

Now the picture has gone to a bright narrow band all the time with the
antenna hooked up and a dim thin rainbow colored football shape without
antenna. I have replaced U4501, CR4504, SCR501, Q4507, and Q4505. I
have checked the voltages in this area. All are good except pin 6 and 1
on U4501 are dead. All voltage around Q4801 are dead and there is no
voltage at the B and E on Q4803. The only thing I could find was a
cold solder joint where the yoke wire was hooked to the board causing a
resistance between the yoke connector and connection on the board. The
yoke resistance checks good.

The funny thing is it will stay on indefinitely while no antenna is
hooked to it but put the antenna on so it would have sound and picture
it pops and shuts down.

I plan on doing what I can but I have no scope. I have experience
building tube audio amps and understand tubes well but don't know much
about sand(transistors).
Any advice anyone can give will very much appreciated.

 

[jesusL77]

Pretty new to this Proscan repair stuff... sorry about not being able
to help on the repair, i trust you have an answer by now....

i however have a question for you...i need to
replace the vertical damper diode CR4504(as indicated on the parts
list) and possibly
the horizontal yoke capacitors.. i have searched the board and the best
i can
do is find a CR504?... any help as to the location of the CR4504 would
be appreciated... thanks

 

[DHT112A]

The CR504 is the CR4504. They leave off the first number on the board.

 

[iamnathanhudson]

i have my front right channel going bad.....it distorts and barely gets any
signal.....but then last night it worked fine........now today it won't
work......i know it is the front right because i hooked my left speaker to
it and it isn't the speaker it is the output........is there anyway you
could take a picture or something to show me some of the things to look
out....i have it here sitting open so knowing the more important things to
look at and kind of where they are would help greatly. thanks
-Nate

 

[Allodoxaphobia]

On 01 Feb 2005 05:53:34 GMT, JURB6006 wrote:

When you want to distribute a file like this, please put it in your webspace
and post a link. We seem to constantly have bandwidth etc. type problems. There
is too much traffic here.
Actually I'd like to see it, but I'll get it somewhere else.

I'm suprised binaries are even allowed here.
They can put a total stop to it.

There is no "they".
There is no "control".
Anyone who thinks this is a moderated ng
sure hasn't been reading here long.

Videos are out of the question. I'm suprised it made it.

It didn't -- not here. I never saw the OP, because my newsserver
deletes binaries posted to text-only ng's (such as ser.)

Absent that, most of the _real_ newsgroup readers can filter by size.
I use slrn here, and its 'score' file (killfile) can kill posts by size.

It must be a bitch for dial-up users to be at the mercy of such postings.

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

 

[JURB6006]

Hi;

"Jeff,
Look for a 2SD1276A regulator for the Horizontal Deflection ­to be leaky. "

Bill, I had to get your reply off of Google, that's why this is a new post.
I'll have my NG access fixed soon and I won't have these problems.

The way I see it is that is only if the convergence is tapping a waveform off
that stage, it may well be. Of course anything is possible.

I will look into it, and thanks again for your time and all your help. I'll
find a way to reciprocate someday, I just hope it isn't 20 years from now and I
gotta kill somebody or something (joking, err,,,,,yeh, joking).

JURB

 

[Mark D. Zacharias]

The first thing I would look for in this situation is bad solder
connections, at the speaker terminals, and maybe at the output IC and
protection relay. Also the relay could be cutting out, though this is less
common on receivers of this type.
Most Pioneer models of recent (the last 15 years or so) have little to no
direct access to the main board - even just to look at it will require a
major disassembly.


Mark Z.


"iamnathanhudson" <iamnathanhudson@protected> wrote in message
news:452491def371e3fb985da993868bd46c@localhost.talkaboutelectronicequipment.com...

i have my front right channel going bad.....it distorts and barely gets any
signal.....but then last night it worked fine........now today it won't
work......i know it is the front right because i hooked my left speaker to
it and it isn't the speaker it is the output........is there anyway you
could take a picture or something to show me some of the things to look
out....i have it here sitting open so knowing the more important things to
look at and kind of where they are would help greatly. thanks
-Nate

 

[Warren Post]

Thank you, Fred. The base unit now works fine with a simple TX whip
antenna made for 49.74 MHz. I´m not getting the 1 km range I need, but
externally mounting the base´s antennas up high ought to fix that.

--
Warren Post
Santa Rosa de CopĂĄn, Honduras
http://srcopan.vze.com/

 

[Stan]

"Scott McDonnell" <NetSamurai@comcast.net> wrote:

}Hello,
}
}...
}So far, I have tried:
}replacing a few speakers...amplifier...settings at the speakers
}...volumes on both amp and source...balanced bass and treble
}
}None of this seems to work.

Talk about the source...have you replaced it with a verified source,
like a portable cd player?

Stan.

 

[Doug]

Try Mouser Electronics. Catalog 617,page 612, "DGS DC Power Jacks".
www.mouser.com

 

[True american Zero]

Hi !

are these craks coming completely randomly ?

Isn't there fridge, a noise source some how ?

Can you swao the amp with another one from another restaurant, even on
closing days (if there any) just to give a try ?

Cheers

Georges

 

[David Montgomery]

Hi Doug,

Thanks for the response.

I looked through the current catalog (#620), but didn't see a direct
match.

Should I unsolder the part to see if there is a part number hidden on
the bottom? (I suppose it couldn't hurt anything at this point...)
Best,

David

 

[Jerry G.]

I don't know this model in detail, to give a detailed answer. Generally
speaking, I would be looking to see if there is proper standby supply going
to the uPC section.

--

Jerry G.
======


"Chris F." <zappymanREMOVETHIS@hotmail.com> wrote in message
news:zTdMd.224583$Np3.9364145@ursa-nb00s0.nbnet.nb.ca...
Got this '91 Magnavox 26" stereo TV, it's been for sale in my shop for
some time, but I've noticed something that might be a minor annoyance. Every
time the set is powered, it goes back to channel 3 and the display language
changes to Spanish. Doesn't matter if the set is left plugged in or not. Any
ideas?

 

[wpointer@gmail.com]

True american Zero wrote:

Hi !

are these craks coming completely randomly ?

Isn't there fridge, a noise source some how ?

Can you swao the amp with another one from another restaurant, even
on
closing days (if there any) just to give a try ?

Cheers

Georges

 

[Bill Jr]

Yeah, I understand....

Bill Jr


"JURB6006" <jurb6006@aol.com> wrote in message
news:20050202020319.13716.00000244@mb-m23.aol.com...

Hi;

"Jeff,
Look for a 2SD1276A regulator for the Horizontal Deflection ­to be leaky.
"

Bill, I had to get your reply off of Google, that's why this is a new
post.
I'll have my NG access fixed soon and I won't have these problems.

The way I see it is that is only if the convergence is tapping a waveform
off
that stage, it may well be. Of course anything is possible.

I will look into it, and thanks again for your time and all your help.
I'll
find a way to reciprocate someday, I just hope it isn't 20 years from now
and I
gotta kill somebody or something (joking, err,,,,,yeh, joking).

JURB

 

[Bill Jr]

Sounds like a bad eprom. Or maybe backup battery, if that old.

Good Luck,
Bill Jr


"Jerry G." <jerryg50@hotmail.com> wrote in message
news:36dckvF4v7r3lU1@uni-berlin.de...

I don't know this model in detail, to give a detailed answer. Generally
speaking, I would be looking to see if there is proper standby supply
going
to the uPC section.

--

Jerry G.
======


"Chris F." <zappymanREMOVETHIS@hotmail.com> wrote in message
news:zTdMd.224583$Np3.9364145@ursa-nb00s0.nbnet.nb.ca...
Got this '91 Magnavox 26" stereo TV, it's been for sale in my shop for
some time, but I've noticed something that might be a minor annoyance.
Every
time the set is powered, it goes back to channel 3 and the display
language
changes to Spanish. Doesn't matter if the set is left plugged in or not.
Any
ideas?

 

[Doug]

Hi David,

Probably no number there. You could try to match it up with something
close from the catalog. Or you could try Cyberhome (510-353-6099). They
might have a parts or service dept. By the way, is the part actually
broken or is it possibly just cracked loose from the board?

Doug