Toshiba TV29C90 problem; Image fades to black...

[propman]

"pink" <dapinkie@gmail.com> wrote in news:1162141086.238180.174710
@i42g2000cwa.googlegroups.com:

22-303

I posted a copy to the alt.binaries.schematics.electronic newsgroup.....

 

[Randy]

Dani, not sure if you or anyone else here is aware of a great repair tip
database called www.repairworld.com it's a pay service but VERY reasonable.
Saved me many times.
And has payed for itself over and again.


"Dani" <greeben@gmail.com> wrote in message
news:1162142336.774551.219620@h48g2000cwc.googlegroups.com...

Has anyone got these 25, & 27" chassis to work, & stay working after
they blow up for the first time? The ones I have seen, keep blowing up,

even after replacing the flyback, diodes in the SMPS, & totally
rebuilding
the SMPS. Got any tips? Thanks, Dani.

 

[Colin Jones]

On Oct 28, 7:04 pm, David Naylor <dave1...@comcast.net> wrote:

Colin Jones wrote:
We have a JVC AV-28WT2EK which has been working perfectly until today.
For a few seconds before it died, the picture went squashed to the
bottom of the screen, there was a loud pop/bang then the screen went
blank.

If you switch it on now, it goes into standby, applying power via the
remote, there is a 'ping/hiss' noise from the tube, which then starts
to come through the speakers as well. This lasts a few seconds before
the TV puts itself back into standby. The screen stays steadfastly
black.

I did wonder with the pop if there would be anything visibly fried
inside, but cannot see any signs of 'explosions' or anything.

Having successfully repaired my VCR power supply after getting help
online (by replacing several capacitors), I wondered if I might be able
to do the same with the TV? Anyone any pointers - or ideas on what it
could be/what I should do first?

Cheers,
Colin.

PDF user manual
http://www.jvc.co.uk/files/instruction_manual/ib_av24wt2_28wt2.pdf-
don't seem to be able to find a service manual free online.This unit is well known for the 200. or 2220 m at 200 volts cap in the
power supply going back look at the largest electroletic cap towards
the right and see if the top looks puffed up. if not check the others
But I would bet that , that is the problem

Unfortunately none of the electrolytic capacitors (as far as I can
tell) have any *visible* problems with them - I have scrutinised the
whole board pretty carefully! I have a small analogue multimeter, and
was trying to follow the FAQ instructions for testing them here:
http://www.repairfaq.org/sam/captest.htm - it does appear to go over to
the right, then charge slowly up to infinite - I couldn't quite work
out from the FAQ what is supposed to happen if the polarity is reversed
- the multimeter just went over to the right but did not really move,
but I am only following the info - so may not be interpreting the
results correctly!

There is some power as when it is on, the red standby LED is on, and
you can use the remote and switch on the set. When you do this the
other LEDs on the front all come on as usual, and there is a purple
glow from the tube, but coupled with a nasty crackling noise, and the
set switches back to standby after a few seconds.

When it is in standby there is a very quiet 'tick-tick' sound from the
right-hand board. I've heard that this is a capacitor type noise as
well? However I don't know whether this is 'normal' when in standby or
whether it should be totally silent?

 

[Harmonitron]

OZ (O2micro) seem to be really holding their cards close to their chest.
They don't seem to release data sheets for their chips!

The only schematic I could find on the web was a Hitachi service manual.
See
http://opilased.rvg.edu.ee/riistvara/index.php?path=LCD_monitor_Hitachi_CML-176SXW%2F&download=LCD_monitor_Hitachi_CML-176SXW_manual.pdf.
It has the chip pinout.

I had a similar problem with a HP1702 monitor. It would light for a second
and then go dark. Sometimes it would stay on. See
http://www.fixitwiki.com/index.php?title=HP1702_LCD_monitor_repair for
details.

Jay, thanks very much for your details on your problem. It put me on the
right track.

 

[Charlie East]

Is this one that needs the H drive transformer and the coil in the base
circuit to H out resoldered?
"Randy" <flyback3@chartermi.net> wrote in message
news:Ak61h.405$sI6.149@newsfe03.lga...

Dani, not sure if you or anyone else here is aware of a great repair tip
database called www.repairworld.com it's a pay service but VERY
reasonable.
Saved me many times.
And has payed for itself over and again.


"Dani" <greeben@gmail.com> wrote in message
news:1162142336.774551.219620@h48g2000cwc.googlegroups.com...
Has anyone got these 25, & 27" chassis to work, & stay working after
they blow up for the first time? The ones I have seen, keep blowing up,

even after replacing the flyback, diodes in the SMPS, & totally
rebuilding
the SMPS. Got any tips? Thanks, Dani.

 

[Oppie]

<meow2222@care2.com> wrote in message
news:1161904100.715631.74550@k70g2000cwa.googlegroups.com...

freecycle

It may come to that but I'm a hopeless optimist about trying to fix things
myself. Even an abject failure is a learning opportunity to understand how
these things work. I'm an engineer and any tidbit I can pick up in repairing
may serve well in the future.

 

[Jeff, WB8NHV]

Charlie East wrote:

Is this one that needs the H drive transformer and the coil in the base
circuit to H out resoldered?
"Randy" <flyback3@chartermi.net> wrote in message
news:Ak61h.405$sI6.149@newsfe03.lga...
Dani, not sure if you or anyone else here is aware of a great repair tip
database called www.repairworld.com it's a pay service but VERY
reasonable.
Saved me many times.
And has payed for itself over and again.


"Dani" <greeben@gmail.com> wrote in message
news:1162142336.774551.219620@h48g2000cwc.googlegroups.com...
Has anyone got these 25, & 27" chassis to work, & stay working after
they blow up for the first time? The ones I have seen, keep blowing up,

even after replacing the flyback, diodes in the SMPS, & totally
rebuilding
the SMPS. Got any tips? Thanks, Dani.

I have the 19" version of the CTC185. Only had one problem with it
since I purchased it new almost seven years ago--the RF port snapped
off the tuner PCB. The tech who repaired the set (in my home)
resoldered the ground points around the tuner as well, which were a
major source of trouble in all RCA (Thomson) televisions with on-board
tuners. After the repair, however, my set has worked flawlessly on
cable the last six years or so (I had the repair done only a couple of
months after purchasing the set).

Why would the large-screen sets (25-27") using the same chassis as my
19" TV have so much more trouble with other things besides the tuner,
such as the flyback and power supply? I have a friend who owns an RCA
TV with a 25" CRT; he has apparently had no problems with it in perhaps
five years, despite the TV having fallen off a table a couple of years
ago and having been moved some 15 miles about a year and a half ago. I
don't know, however, if his TV has the CTC 185 chassis or not. It may
not (probably doesn't), considering his has the Guide Plus+ on-screen
program guide; my CTC185 doesn't have it either.

The Guide Plus+ feature seemed to me at its introduction, and still
seems to me today, to have been a feature included only in high-end
RCA/Thomson TVs; I don't think it lasted all that long, however, as I
haven't seen it in any of RCA's new sets, either its SDTV models or any
of its remaining flat-tube CRT sets and certainly not in recent RCA
high-definition FPs. Was Guide Plus+ just a glitzy flash-in-the-pan
feature RCA included in their sets just as a selling point for a couple
of model years? I would think so, since most digital cable services
such as Time Warner, et al. now include an on-screen program guide and
a flip bar (in their cable boxes; I don't know if this is available
with the company's HD service which connects directly to a HD FP set)
that shows the name and channel number of the station you are watching,
and a listing of channels and programs by time, channel, etc. With a
feature like this already available in the cable box, there is no need
for an on-screen channel guide in the TV itself.


Jeff Strieble, WB8NHV (email addy not shown to deter spammers)
Fairport Harbor, Ohio USA

 

[Bill S.]

In article <Dartattack.2gecb7@diybanter.com>, Dartattack.2gecb7
@diybanter.com says...

Do you the values of R504 and R524? The markings are gone and C432
is bad. The circuit board looks overheated under all three components.

7.5K 2W. They are flameproof metal film resistors, and usually
continue to work fine even after burning off the marking ink.
Crystallized solder joints probably need re-done, though.

 

electronicsmart@gmail.com wrote:
: Hi, I am getting a few LCD TVs 32" and higher various brands with most
: of these having broken screens. I dont have experience fixing LCD
: monitors/TV so am going to attempt this. I have some experience with
: fixing other devices and electrical circuits. My question, how much
: does the LCD screen costs on average for 32" and higher TVs.

: Assuming all other boards are ok and only broken screen, is it worth
: fixing these to resell ? Are service manual available for these ? and
: is replacing LCD screen simple procedure of just removing the old one
: with a new/used one and only connecting a few cables to the new screen
: ?


The lcd screen is 80 to 90% of the cost, so unless you find a really cheap
source, you will probably loose on this deal.


: thanks.

 

[Homer J Simpson]

<electronicsmart@gmail.com> wrote in message
news:1162234434.662274.224450@i42g2000cwa.googlegroups.com...

Assuming all other boards are ok and only broken screen, is it worth
fixing these to resell ?

You will wind up with a unit that costs more than a new one, and way more
when they are on sale, and the warranty won't be as good. Not a good deal
for all. What happens when a customer refuses to claim the unit(s)?

 

[Harmonitron]

Jay, my repair didn't last.

I pulled down the OVP pin (2) to ground while I powered up the screen,
held it for two seconds and let go. The backlight stayed on.

I added 1.5M in parallel with the 1M pull-down resistor on pin 2 and that
seemed to work.

Every time I get the whole thing screwed together it fails again. It seems
to be temperature dependent a bit though and will stay lit sometimes.

I presume the whole problem is due to changes in the tubes as they age.
The designer hasn't quite got this figured out properly.

Anyone know what the correct thing to do is with the OVP signal? Should I
use a capacitive divider since the lamp voltage is capacitively coupled?

See
http://www.fixitwiki.com/index.php?title=OZ960_LCD_backlight_inverter_control_problems
for a typical OZ960 schematic.

 

[Dartattack]

Bill S. Wrote:

In article Dartattack.2gecb7@diybanter.com, Dartattack.2gecb7
@diybanter.com says...-
Do you the values of R504 and R524? The markings are gone and C432
is bad. The circuit board looks overheated under all three
components.-

7.5K 2W. They are flameproof metal film resistors, and usually
continue to work fine even after burning off the marking ink.
Crystallized solder joints probably need re-done, though.

Is that same 7.5K used in the Model CS4727? If so thanks.




--
Dartattack

 

[tomh]

electronicsmart@gmail.com wrote:

Hi, I am getting a few LCD TVs 32" and higher various brands with most
of these having broken screens. I dont have experience fixing LCD
monitors/TV so am going to attempt this. I have some experience with
fixing other devices and electrical circuits. My question, how much
does the LCD screen costs on average for 32" and higher TVs.

Assuming all other boards are ok and only broken screen, is it worth
fixing these to resell ? Are service manual available for these ? and
is replacing LCD screen simple procedure of just removing the old one
with a new/used one and only connecting a few cables to the new screen
?

thanks.

You say broken? If there is physical damage to the screen, it's trash,
dispose of properly please. As has been pointed out, not economical to
fix unless you have the exact model as a spare you got for free. However
if by broken you mean, does not work, that's a little different.
If the power lt is on but it's a dark screen, you may have just bad
backlighting. This is definitely worth the try, there have been several
threads here and elsewhere on the web on fixing the cold cathode inverters.
If the backlighting is OK but the screen doesn't show proper data or
it's all messed up that gets very iffy. There's typically one or more
FPGA's between the video in and the LCD itself. If they're bad, your
chances of finding a replacement part or a manual are slim to none. Toss
it or save for parts.
If you collect enough of them as unrepairables/freebie's you may be
able to build up an inventory of replacement parts. But there's nothing
really standard about them. Same model from the same "manufacturer" can
have different innards.

tomh

"I asked him what his name was and how 'come he didn't drive a truck,
he said his name was Columbus and I just said good luck"

 

[Homer J Simpson]

<chianghee@gmail.com> wrote in message
news:1162255166.598883.178550@i42g2000cwa.googlegroups.com...

I got my hands on a unit of car voltage stabilizer. This thing is
suppose to regulate the 12V fluctations when the engine is running. I
have opend up the unit to see the circuitry.

For what purpose would you use this?

 

[Dave]

"kell" <kellrobinson@billburg.com> wrote in message
news:1162398857.068903.66420@m73g2000cwd.googlegroups.com...

You spent more effort typing your post than typing "computer power supply
pinout" into google...

 

[Meat Plow]

On Wed, 01 Nov 2006 11:21:35 -0600, Joe Has Frothed:

Thanks for the prompt reply. That sounds like a reasonable explanation.
Do you know of any easy fix for this? I am fairly mechanically inclined.

Upon further research the 1025 has multiple U4 codes.

U4-1 Open thermistor
U4-2 Low temp
U4-4 Temp
U4-5 Main pwb.

If it's a problem with the fuser itself which often it is the easy fix
would be to replace it. However without my hands, ears, eyes and even nose
there with your copier, I can't offer you any more advice.

On Tue, 31 Oct 2006 19:16:05 -0500, Meat Plow <meat@meatplow.local> wrote:

On Tue, 31 Oct 2006 17:58:20 -0600, Joe Has Frothed:

Does anyone know what status code U4 signify? I turn the machine on,
it says "wait" while warming up and then shuts down with status code
U4.

It has been working fine up until today. It would go into status code
U4 whenever there was a delay in copying something. Is it a "sleep"
function? I would turn off the machine and turn it on again and it
would work just fine until today.

Thanks in advance

Joe

In the 1012 the U4 code is a "heat problem" in general, fuser overheat or
heat stays on after it has reached operating temperature. Probably the
same in the 1025.
--

Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794

 

[Meat Plow]

On Wed, 01 Nov 2006 14:43:55 -0600, Joe Has Frothed:

Once again, thanks for the response. Sounds like my machine is ready for
the scrap hear. I don't think even Xerox supports it anymore. I Googled
and tried the Xerox website to no avail. Xerox no longer has support
data, manuals, etc for this model even though it is listed.

You wouldn't still have the URL where you found the codes, would you? I'm
looking for whatever info I can find.

Thanks
Joe

Sure:

http://www.snami.by/index.php/.116.677...0.0.0.html

--
Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794

 

[Jason D.]

On 2 Nov 2006 06:22:55 -0800, "Kev" <kkrie616@hotmail.com> wrote:

I got this set from a client and the H-OUT Q522 was missing so it was
quite oblivious someone had been into it before me. I ordered and
installed a new Q522 and also replaced T501 and both STK394-220 ICs.
Now when I press the power button I can hear the relays click
repeatedly and after about 30 seconds or so they stop and the set seems
to go into some sort of protection mode. Does anyone have any tech
tips that could save me some troubleshooting time? The self check
display LED does not blink to give any indication of a problem.

JVC AV56WP84 Rear Projection Television

Thanks,

Kevin

Kevin,

There are 2 ICP fuses in parallel on the power supply for convergence
power also for somewhere else as well and remember to put jumper on
the DVI or HDMI module next time you plug in without back panel off.

There is very rare few that needed HV leads to the suction cups
sleeved with silicone sleeves & HV RTV sealed all over each suction
cups and both ends of sleeves, this usually shows up as repeat blowing
HOT.

Get the bulletin kit along with HV RTV from JVC.

Cheers, Wizard

 

stickyfox@gmail.com wrote:

I've got a JR 72 MHz transmitter module that was transmitting a very
weak signal on the correct frequency. I replaced the power transistor
and the module worked for a few minutes, but now it transmits a very
strong signal on 144 MHz. There is no signal being transmitted on 72
any more. I imagine I've got to get the crystal back into its
fundamental mode but I could use some hints. Does anyone have a service
manual or schematic for the module?

A 2m RC system would be really neat but I don't think it'll be easy to
find a receiver.

2nd harmonic, 1st is the base frequency! IIRC 144 is ambulance service
band, here at least, so maybe not so neat. Need to show us the
oscillator circuit, otherwise can only say the osc cct needs to be
tweaked so it prefers the lower frequency. Can probably be done with a
little capacitance added to reduce closed loop gain at 144.


NT

 

[robotron -x-]

Meat Plow wrote:

On Thu, 02 Nov 2006 11:22:06 -0500, robotron -x- Has Frothed:


I need a 10Meg , 1 watt resistor, colors are brown black blue

This came out of a bose wave radio and they dont carry it at radio shack,
so
i just need an online store where i can order one

Any suggestions appreciated, thanx

www.mcmelectronics.com

NTE part # 1W610

i copy and pasted that part number but i got

"There were no matches found for your search."