Toshiba TV29C90 problem; Image fades to black...

[Smitty Two]

In article <LPPNf.344324$c31.12099@fe08.news.easynews.com>,
no@spam.invalid (tvguy) wrote:

I Do respect some of the techs on this site when they use common since
on how they help someone out by trying to find out what type of
experience they have to do a curtain type of repair but when you got
guys like this Kip on here that really don`t give a crap and tells
them to go further than what they should then it is no good. There is
a proper way to help someone and then there is a sloppy way and I find
Kip and a few others use the sloppy way. Thats just my opinion.

What the hell is common since? And who's talking about fixing curtains?
Or doesn't sloppiness apply to the English language, IYHO?

 

[tvguy]

Are you an english techer ? If you are then fail me for my not writing
proper english .

 

[tvguy]

Is this how this forum is ran by doing quotes all the time instead of
making replies ? Thanks for filling me in. I thought it was like alot
of the other forums I belong to that we can just click on the reply
and make a reply to the post. I will remember this from now on and
hit the quote tab.

Leonard Caillouetwrote:
How do we know what you are responding to unless you include the

previous

post. I am not foing to go back and find the previous posts to try
to guess
which one you are commenting on. You will be largely ignored if you
don't
provide some context for your comments.

Leonard

"tvguy" <no@spam.invalid> wrote in message
newsy%Nf.65165$265.40306@fe09.news.easynews.com...
That was my point that I had put in his original post and you and
others didn`t get ther point that some of these guys don`t have a
clue to what to do or where to look even if you did put it in plain
english for them. I would also suggest to take this to your local
repairshop or atleast give them a call to see if they will come out
to have a look at before you go in there and do more damage than
what is already there.

 

[mistermaniac]

Bill Simpson Wrote:

I tried to post this yesterday, but it didn't seem to show up.
Apologies if it's duplicated. Probably a Comcast problem.

I have a very unusual problem with an LCD monitor. I will try and be
descriptive as possible without being confusing.

When the adapter for the monitor is plugged directly into a wall
outlet, and there is always current to the wall outlet, I can turn the
monitor on and off normally. There are no problems.

When the adapter for the monitor is connected to my UPS and the UPS is
turned off and then back on, or when the adapter is plugged into a
wall outlet and then unplugged from the wall outlet and plugged back
in, I begin to have problems.

Specifically, in the two situations above, when booting the computer,
the monitor will "buzz" briefly, the picture will come on, and then go
off. It will do this several times during the boot sequence. It will
do it once at the bios, once at the Windows splash and then again at
the login screen. Upon each of the three occurrences mentioned, the
monitor will "buzz", the picture will come on briefly and then go off.

However…if I reboot the system several times, or when I'm at the last
login screen, turn the monitor on and off several times with its
switch, it will eventually stay on.

I have tested this monitor with different video cards and on different
systems, so it's not the video card or one specific box.

From the way the LCD is reacting, the problem seems to be similar to a
bad ballast in a fluorescent light, is this possible?

Any suggestions (except leave it plugged in all the time? Is there any
way to test this LCD with minimum equipment and knowledge?

Thanks in advance.

When the screen goes "off" does it really goes off? It sounds like a
bad inverter or a bad ccfl.


--
mistermaniac

 

[Michael A. Terrell]

Peter Hofmann wrote:

I have a board here, which seems to be manufactured by Motorola in 1984/85.
ALL components on it have a special numbering i.e. 09M05-48M44-61L03-71K85
... It might be a modem board, because there is a RX-IN + TX-IN there are
optocouplers ... and thers is microprocessor with eprom, ram, i/o devices on
it. the eproms are Intel 2716 numbered 09M11 and 69N34-69N35 ... I think its
a 8-Bit cpu from motorola 6809/6802/6804 ??? ... may be there is someone in
the world, who can tell me which cpu it is or where I can find a
cross-reference list to the usual nomenclatur - thanks in advance

info appreciated to oe3pha@hotmail.com

SCxxxxx numbered parts from Motorola are proprietary, so you have to
get the information from the board's OEM, not ON semiconductor.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Arfa Daily]

"mistermaniac" <mistermaniac.2447p1@diybanter.com> wrote in message
news:mistermaniac.2447p1@diybanter.com...

Bill Simpson Wrote:
I tried to post this yesterday, but it didn't seem to show up.
Apologies if it's duplicated. Probably a Comcast problem.

I have a very unusual problem with an LCD monitor. I will try and be
descriptive as possible without being confusing.

When the adapter for the monitor is plugged directly into a wall
outlet, and there is always current to the wall outlet, I can turn the
monitor on and off normally. There are no problems.

When the adapter for the monitor is connected to my UPS and the UPS is
turned off and then back on, or when the adapter is plugged into a
wall outlet and then unplugged from the wall outlet and plugged back
in, I begin to have problems.

Specifically, in the two situations above, when booting the computer,
the monitor will "buzz" briefly, the picture will come on, and then go
off. It will do this several times during the boot sequence. It will
do it once at the bios, once at the Windows splash and then again at
the login screen. Upon each of the three occurrences mentioned, the
monitor will "buzz", the picture will come on briefly and then go off.

However.if I reboot the system several times, or when I'm at the last
login screen, turn the monitor on and off several times with its
switch, it will eventually stay on.

I have tested this monitor with different video cards and on different
systems, so it's not the video card or one specific box.

From the way the LCD is reacting, the problem seems to be similar to a
bad ballast in a fluorescent light, is this possible?

Any suggestions (except leave it plugged in all the time? Is there any
way to test this LCD with minimum equipment and knowledge?

Thanks in advance.

When the screen goes "off" does it really goes off? It sounds like a
bad inverter or a bad ccfl.


--
mistermaniac

Yes, you need to establish this. It is very possible, if the monitor is
genuinely not starting after a period of being totally unpowered, that the
problem is actually the external power supply, which is pretty much certain
to be a switch mode type. I have had a number of these giving similar
symptoms to those you state, the cause being bad electrolytics, particularly
on the primary side. In general, when switchers have this sort of problem,
once you've persuaded them to come on, and the caps have warmed up a bit,
they will stay on. Try measuring the output voltage of the power supply,
after it's been off for a couple of hours. You may well find that there
isn't any, or what there is, is pulsing. You could also try hanging a low
wattage car bulb across the power supply output - say an interior light
bulb - if you can figure a way of getting a connection to the output plug.

Arfa

 

[Bert]

Fouten maken we allemaal een of andere tijd Gerard.
Groetjes
Bert.

 

[jw51]

The user manual indicated that the unit will switch off if there are
faulty speakers,.I checked the speaker wiring looking for shorts. By
investigating on the net I now assume that the unit will turn on for a
second or two before it turns off.

I have not gone further until I get some circuits, no sense probing
around in the dark and maybe causing a further problem.

 

[Bill Simpson]

On Mon, 06 Mar 2006 09:03:42 GMT, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

I see that my reply did get double posted. Thanks for the very
precise information. With my rather low level of technical knowledge,
do you think it more advisable that I just replace the power supply?

The power supply that I currently have is

Sunny
Input :100-240 - 1.6A Max, 50-60Hz, 70-80VA
Output: +12V - 4.0A

I contacted the manufacturer of the monitor and they want $75 for a
replacement power supply (More on that later). I've found some others,
more reasonably priced online. One is a 12V 5A (60W) and the other is
a 12V 4.16A (50W). Am I correct in assuming that both should work?
If the connector is different in these power supplies, would cutting
and soldering the original connector to the new power supply be
acceptable rather than the more complicated and dangerous course that
professionals with your expertise would take? I know it's a crude
solution, but it's something I would feel comfortable with.

The rest if off topic, but if you have some time, I would like your
opinion. I had mentioned earlier that I contacted the manufacturer
about a new power supply. I went to their home page and read the FAQ
ahead of time. I found this in the FAQ:

"My screen comes on for a second and then goes black. How do I resolve
this issue?

1. Please contact Customer Service for further assistance at
323-346-0888. There is a possible short in the ac adapter. "

It seems that the manufacturer knew about this problem for some time.
I had registered my monitor and asked the representative when I called
why they hadn't notified me of the problem (As the warranty on the
montitor had just run out). I also asked if this wasn't a potential
fire hazard. I got a typical rebuff. My question is: Could a short
in the power supply cause a fire? I this a dangerous situation or
would normal internal safeguards kept anything hazardous from
happening?

Thanks again for all of the expert help. You all went above and
beyond what I expected.

"tvguy" <no@spam.invalid> wrote in message
news:TvOOf.7298$Pu3.1234@fe12.news.easynews.com...
Arfa Dailywrote:
"tvguy" <no@spam.invalid> wrote in message
news:1A6Of.198994$H54.155366@fe03.news.easynews.com...
It don`t sound like a bad inverter if it is running good when
plugged
directly to the wall outlet. If it only does this when plugged into
the powersupply of the computer then this would be a problem of the
computers powersupply. Did you try to plug it into another computer
to see if you still have the same problem ? I would suggest to try
this first and see what happens.


Maybe I read it wrong, but I don't think that this is what the guy
was
saying. I read it as he was always using the external power unit, that
came
with the LCD monitor, and if he left it plugged in the wall, ie with
power
always available to this power supply, but with the monitor turned
off, when
he came to switch the monitor on, it came on ok. If, however, he
plugged in
to any power source that was turned off for periods of time eg his
UPS, or
unplugged from the wall for any length of time, then when he came to
put
power back on the PSU, and then tried immediately to switch on the
monitor,
he got the buzzing, spitting failure to start up, which is typical of
a
defective switching PSU, with bad electrolytics. Perhaps the OP can
confirm
??

If this is actually the case, then all the stuff about Windows and
rebooting
etc is probably a red herring. It just relates to the length of time
all
this takes, which gives the power supply time to struggle to a
startup.

Arfa

If that was what he was stating. I may have read his post wrong to
what he was trying to say. Then I would have to say yes that he has
something wrong with the external powersupply.


Yeah, I think that's what he's saying, tvguy - see his additional post
above.

Bill.

I think me and tvguy are now both in agreement. Yes, go for power supply
trouble. I had a FAX machine on my bench last week, which was powered from
an external 24v 1500mA switch mode supply. If left on, it would work for
ever. However, if left unpowered for a few hours, when put back on, the
power supply would struggle for about a minute, to start up.

Once I got inside it, it was fairly obvious that the two series-connected
82k startup resistors were pretty distressed and high. I replaced both these
( they use two in series to double the voltage rating of these small film
resistors ). Also, there was a single 220uF cap on the primary side. When
checked on my ESR meter, this went 38 ohms, which is way, way too high, so
this item was replaced as well. The supply then started up first time, every
time, no matter how long it had been off. Both of the mentioned components
are very common for causing startup trouble in any switcher.

Just a word of warning. If you are not used to switchers, be very very
mindful of your personal safety. This type of supply is VERY dangerous, and
could be lethal. Remember also, that the main smoothing cap will charge to
almost one and a half times your local input voltage. If the supply doesn't
start up, this cap will likely stay charged to very close on this figure for
hours, as most switchers do not employ a leak resistor across it. I would
always recommend having these supplies connected to a bench isolation
transformer, when they are opened to be worked on.

Arfa
[/QUOTE]

 

[Shoreline Electronics]

Definitely worth repairing! Good sets!


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

"Kath" <kathg5@netzero.net> wrote in message
news:1141600031.190675.162360@u72g2000cwu.googlegroups.com...

Hello, I don't know if I should just buy a new TV or have this one
fixed. I realize it is 9 years old. May I have some advice?
Everything works but then the picture starts moving up vertically until
it just disappears altogether and the screen is dark. This happens
gradually as if something is squeezing the picture upwards but the
sound is just fine. Shall I have it repaired? I would appreciate some
opinions on this. Many thanks!

Kath

PS Wouldn't you know it, it is working right now but I'll bet it goes
by Oscar time.

 

[Sam Goldwasser]

Ryan Underwood <nemesis@icequake.net> writes:

Hi,
I just acquired a Lab-Volt model 189 bench supply, 1966 vintage. It has a
passthrough AC output, a variac output, and a variable DC output.
Unfortunately, the variable outputs do not work (0 voltage independent of
knob setting). The pass through output does work though.

The fuse is a screw-in type, black thumb screw reads "Fuse" and when it pulls
out, there is a loose metal cylinder around the end of the fuse. I have no
idea how to test this type of fuse or even what it is called.

Anyone have pointers where to get started on this thing? The construction
appears to be nothing more than a bunch of transformers and a knob. I'm not
familiar with these variable type supplies.

Agreed with the other postings, especially on the SAFETY issues.

Most likely problme is a blown fuse (there might be nother one inside),
next most likely would be a bad connection or short somewhere, next most likely
might be a bad carbon brush on the Variac. There really isn't much
else to go wrong, though a shorted rectifier might be the cause of the
blown fuse.

--- 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.

 

[Arfa Daily]

"Bill Simpson" <plusnetfiles@comcast.net.com> wrote in message
news:aj9o02dm6d2n47hu4qlusena3qnlvf3o1d@4ax.com...

On Mon, 06 Mar 2006 09:03:42 GMT, "Arfa Daily"
arfa.daily@ntlworld.com> wrote:

I see that my reply did get double posted. Thanks for the very
precise information. With my rather low level of technical knowledge,
do you think it more advisable that I just replace the power supply?

The power supply that I currently have is

Sunny
Input :100-240 - 1.6A Max, 50-60Hz, 70-80VA
Output: +12V - 4.0A

I contacted the manufacturer of the monitor and they want $75 for a
replacement power supply (More on that later). I've found some others,
more reasonably priced online. One is a 12V 5A (60W) and the other is
a 12V 4.16A (50W). Am I correct in assuming that both should work?
If the connector is different in these power supplies, would cutting
and soldering the original connector to the new power supply be
acceptable rather than the more complicated and dangerous course that
professionals with your expertise would take? I know it's a crude
solution, but it's something I would feel comfortable with.

The rest if off topic, but if you have some time, I would like your
opinion. I had mentioned earlier that I contacted the manufacturer
about a new power supply. I went to their home page and read the FAQ
ahead of time. I found this in the FAQ:

"My screen comes on for a second and then goes black. How do I resolve
this issue?

1. Please contact Customer Service for further assistance at
323-346-0888. There is a possible short in the ac adapter. "

It seems that the manufacturer knew about this problem for some time.
I had registered my monitor and asked the representative when I called
why they hadn't notified me of the problem (As the warranty on the
montitor had just run out). I also asked if this wasn't a potential
fire hazard. I got a typical rebuff. My question is: Could a short
in the power supply cause a fire? I this a dangerous situation or
would normal internal safeguards kept anything hazardous from
happening?

Thanks again for all of the expert help. You all went above and
beyond what I expected.


Bill

If you don't feel qualified to go inside the supply, then I would not be
comfortable advising you to do so. The fault almost certainly will be one of
the things I suggested, but it's not worth risking injury to try to repair
it, if you're not absolutely confident of what you're doing.

Either of the two power supplies should be ok rating-wise. Any power supply
with a rating of 4 amps, will be a switch mode type, so by very nature will
be regulated to its declared 12v output.
Cutting and joining on the output lead is fine, BUT make absolutely sure
that you get the polarity the same as original. The monitor will not like
having reverse polarity DC shoved up it ...

If ever I join wires in this way, I always use heatshrink sleeving, which
you could probably get from your local Radio Shack. It shrinks easily with a
small paint stripper gun on 'low', and does a nice neat job of re-insulating
the cable, and reinforcing the join.

As far as the manufacturer's statement about a " short in the power supply "
goes, it's probably a bit of generic techno-babble that means nothing more
than ' a faulty power supply '. Joe public can equate with a " short ". It
sounds just technical enough to be describing something real, but is
basically meaningless in this context. It is unlikely that any fire would
ensue from any of the typical ( and much more likely ) faults that the power
supply would really be suffering from. It's probably just a typical switch
mode power supply design issue, where whover laid out the board, decided, as
they always seem to, to place an important cap right next to a resistor that
gets hot. It probably just happens that the fallout from this has been
particularly bad for this manufacturer, using this ( almost certainly
bought-in ) power supply on his particular product.

Arfa

 

[bigdaddy]

On Mon, 06 Mar 2006 02:02:39 GMT, no@spam.invalid (tvguy) wrote:

If you are sure that there are no more bad solding joints then I would
suspect a crack some wheres on the mainbord. I would look close to the
vertical section for this.

Could you please be more precise as I haven't got the schematics for
this TV and do not know much about TV circuitry either.

 

[Mike Berger]

I think Harmon Kardon pulled their schematics from their website one or
two years ago. I'm sorry that I didn't download them all first, but
it's rare for things to disappear from the Internet.


Boiler_81 wrote:

Free download and you don't have to prove you know what you are doing.

http://manuals.harman.com/hk/Service%20Manual/hk380i%20sm.pdf

 

[trm54321]

Thanks!

On Mon, 06 Mar 2006 02:10:39 GMT, "Mark D. Zacharias"
<spammenot@nonsense.net> wrote:

"trm54321" <trm54321@hotmail.com> wrote in message
news:6dam0219h5vbn43bk9qf3ri83ehepog1bp@4ax.com...
Thanks, I contacted four suppliers today with two replying and no luck
so far...
This machine is pretty old...
I've added a search on eBay also and may have to wait until one shows
up also...
Cheers Dave

On Sun, 05 Mar 2006 09:53:37 -0800, JR North <jasonrnorth@bigfoot.com
wrote:

There are 3 machines on Ebay, but no manuals- now. I have found several
service manuals for my vintage Technics audio equipment on Ebay for a
few bucks each. Most of the service manuals are sold by volume sellers,
who list many different ones. You could try contacting some of them, and
see if they have one laying around. For instance:

http://stores.ebay.com/jchas555

JR

trm54321 wrote:

This is an older Beta machine I'm trying to repair that doesn't rewind
anymore.
Any suggestions and does anyone have a service manual for this vintage
deck?
Cheers Dave
*** Free account sponsored by SecureIX.com ***
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The reel belt and idler tire(s) need to be replaced.

Mark Z.

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[trm54321]

Excellent...thanks!

On 5 Mar 2006 19:57:18 -0800, "VCR Gymnast" <alan.segal@uvm.edu>
wrote:

Although a service manual is always good to have, what you need is at:

http://www.studiosoundelectronics.com/mbk-56.htm

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[Bert]

In article <EqCdnZYSPdiogpbZRVn-ug@is.co.za>,
Bert <lijbertv_at_xsinet_dot_co_dot_za> wrote:

----- Original Message -----
From: "Gerard Bok" <bok118@zonnet.nl
Newsgroups: sci.electronics.repair
Sent: Sunday, March 05, 2006 1:44 PM
Subject: Re: Alkaline charging followup


On Sat, 4 Mar 2006 21:50:42 +0200, "Bert"
lijbertv_at_xsinet_dot_co_dot_za> wrote:

December around the 21st last year I did have a question on charging a
rechargeable alkaline AA battery.
Using those 2 in my wireless optical mouse.
Normal battery did last 1 month
Alkaline battery did last 5 month,
Alkaline recharge battery 2.5 month, empty reading is 1 volt.
Started charging both batteries on 1.68 volt, the charging current was
110
mA per battery.
Charging current after 10 hour is 95 mA for both batteries, constant
voltage
1.689 volt.
Hope this will help someone sometime.

And the number of spontaneous exploding charging cells is still
zero, I guess ?

--
Kind regards,
Gerard Bok

No exploding cells, do check every hour or so that the voltage on the
battery stays below 1.7 volt and the battery is still cool to touch.
Remember it is a rechargeable AA alkaline cell.
Greetings
Bert.

Seems like a lot of babysitting effort just to recharge a battery. Are you
doing this as an intellectual exercise, or do you really plan to keep this
going? This is why the commercial chargers used for RAM cells are controlled
by dedicated circuitry. The batteries are pulse-charged, and the duty cycle
is
controlled by the voltage of each individual cell as read in between
charging
pulses. As the voltage of the cell approaches 1.65V, which is the defined
terminal voltage for a RAM cell, the duty cycle of the charging pulses
approaches zero. Trying to replicate this, over several hours, by manual
checking against a constant-voltage source sure seems like a lot of work.


Mike S.
You are right about the babysitting, just wanted to see how many hours are
needed to a full charge, it is around 24 hours.
I will make sometime a pulse charger, keeps me busy.
Greetings
Bert.

 

Thanks Charles,
I checked the voltages(DC) on all pins on both hybrid power amps and
they are the same. I swapped the input to the hybrid power amps (left
and right channels) and I still have the same power amp getting very
hot. Not sure what to check next.






On Sun, 5 Mar 2006 20:07:34 -0500, "Charles Schuler"
<charleschuler@comcast.net> wrote:

trousky1@videotron.ca> wrote in message
news:7h2n02p9tp55ea4untpl25odspkp4as056@4ax.com...
Hi all,
I am trying to fix this receiver, I replaced the hybrid STK080G
power amp for the right channel, after having checked the voltages on
the pins. Now this power amp goes red hot when powered on.
Any ideas what/how to check ?

The driver ... the circuit that feeds the hybrid.

 

[lgmurillo]

There's a device that has the same functions as a cellular phone, but
doesn´t have a screen. It´s clasified like a GSM modem, but i think
it´s better. Basically it's a Java programable mc, with A/D channels,
digital inputs....
Your java IMLET can have GPRS, SMS, MMS... management.
Look for Aplicom 12-12i on google.

 

[Damir]

On Mon, 06 Mar 2006 13:12:54 -0500, trousky1@videotron.ca wrote:

Thanks Charles,
I checked the voltages(DC) on all pins on both hybrid power amps and
they are the same. I swapped the input to the hybrid power amps (left
and right channels) and I still have the same power amp getting very
hot. Not sure what to check next.

Without speakers connected,of course?