Toshiba TV29C90 problem; Image fades to black...

[James Sweet]

runderwo@mail.win.org wrote:

Yes, it appears to be an empty, broken fuse holder. When I first
unscrewed it, I was confused and thought it was similar to the mains
fuses that screw into the panel. A step in the right direction, thanks!

It doesn't even sound broken to me, often the fuse is all that holds the
bottom contact down away from the cap, with no fuse at all installed all
bets are off.

 

[PTV75230]

ZZactly@aol.com Wrote:

Hi Folks;



I found out how to get into the service menu but I can't seem to find
the convergence. Can someone point me the way here ? I can get into
the
rest of it, and I don't intend to touch anything there because without
a manual, I have no idea what's what. This thing ranks about dead last
in user friendliness IMO.

JURB

How did you get into the service mode?


--
PTV75230

 

[Tony Martinez]

Mark wrote:

Is there a mode switch on this model?

HOW THE FUCK SHOULD I KNOW?

 

[Leonard Caillouet]

I would strongly suggest getting the documentation. It is not at all easy
to figure out nor something that one could describe in a paragraph. You can
find the docs on the techdata site.

Leonard

"PTV75230" <PTV75230.24dh18@diybanter.com> wrote in message
newsTV75230.24dh18@diybanter.com...

ZZactly@aol.com Wrote:
Hi Folks;



I found out how to get into the service menu but I can't seem to find
the convergence. Can someone point me the way here ? I can get into
the
rest of it, and I don't intend to touch anything there because without
a manual, I have no idea what's what. This thing ranks about dead last
in user friendliness IMO.

JURB

How did you get into the service mode?


--
PTV75230

 

[Ross Herbert]

On 8 Mar 2006 10:54:13 -0800, runderwo@mail.win.org wrote:

because I mistook what is apparently a broken fuse holder
for the fuse itself.

So, are you now sure that the problem was caused by a broken fuse
holder in the first place?

 

[Bill Simpson]

Thanks again Arfa...I think we're done.

Bill

On Wed, 08 Mar 2006 11:12:10 GMT, "Arfa Daily"
<arfa.daily@ntlworld.com> wrote:

"Bill Simpson" <plusnetfiles@comcast.net.com> wrote in message
news:qids02pd1js4o7rlf6labhan24s755bq92@4ax.com...

Thanks for all the help. Since you introduced the concerns about
maintaining the proper polarity. Is there a simple way to verify
this? I recently pick up a new Greenlee DM-810 True RMS Digital
Multimeter at a garage sale for $5. Does this have a function that
would test polarity?


Bill, I'm assuming that this is a digital meter - yes ? OK. Making sure that
you have the red probe in the red socket, and the black in the black socket,
then just go ahead and measure the output. If you have your red lead
connected to the positive output wire, then the meter will just
read " 12.00 " or whatever. If you have your red lead connected to the
negative output wire, then the meter will read " - 12.00 " ie a minus sign
at the front of the number.

As additional confirmation, the original power supply may well have a little
picture of the output connector, indicating polarity, as might the monitor
by its input socket. Additionally, as any replacement you buy is likely just
a generic type, it will probably also have a picture of its plug, indicating
polarity. For what it's worth, you very likely will not have to do any
cutting and grafting. In general, there seems to be a loose " standard " on
the plug size and polarity sense, employed by the current crop of externally
powered LCD monitors and TVs. But that said, I emphasise, better to be safe
than sorry ...

Arfa

On Mon, 06 Mar 2006 14:06:46 GMT, "Arfa Daily"
arfa.daily@ntlworld.com> wrote:


"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

 

[Arfa Daily]

No probs, Bill. Glad we were able to help you.

Arfa

 

[PTV75230]

Leonard Caillouet Wrote:

I would strongly suggest getting the documentation. It is not at all
easy
to figure out nor something that one could describe in a paragraph.
You can
find the docs on the techdata site.

Leonard

PTV75230[/color]

What techdata site?


--
PTV75230

 

[427Cobraman]

Well, all switch matrices checked out as well as supply voltages and
oscillators. ESR'd all electrolytics. The only thing that was off is
the LED drive circuits 1,2, and 4 on IC102. On the good board, these
are all at 4.7v when unit is powered off, regardless of state when in
operation. On the bad board, all are at zero. I wouldn't think these
would affect general operation, but who knows. I've checked, and a
couple other eyes have checked for cracks, solder bridges and bent
pins...everything looks good. I'm at wit's end. I'm sure I'll get
motivated to dig around some more after a nice cold brew. Link to
diagram:
http://www.archive.org/download/Partial_diagram_of_a_display_board_schematic/de845.gif

 

[amaverik]

Thanks for he response!! Having been "under the weather" I haven't been
able to work on the problem again but thanks again!

 

[amaverik]

Thank you very much for responding!! Having been "under the weather" I
haven't been able to work on it yet but hopefully will be able to soon.
Thanks again!

 

[Peter Hofmann]

Thanks for the infos. The customer specified product number equates in many
cases to a standard chip number (74LS/74ALS/ ... 6809/6805/ ...) and I hope
that someone can identify the numbering system and can help with a
cross-reference list or can tell me the product/model description or the
company name ???

Many thanks
peter

"Peter Hofmann" <peter.hofmann@teleweb.at> schrieb im Newsbeitrag
news:bec6b$4408473b$506d651c$19505@news.chello.at...

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

 

[Tux]

Hi

I have the exact same problem with a Yamaha RX-V1400. Unit shuts-off after a
few minutes even with no sources or ouputs connected. I did post about it
here awhile ago but received no reply, so in the meantime I sent it to the
local Yamaha Service and it has been there for 4 months. They now say the
EPROM has lost configuration and they are waiting for a new one. I suspect
they have stuffed it up as I don't think the EPROM could have been the cause
of this problem. If you or anyone finds the cause of cause please let me
know. And IF mine ever gets repaired I will let you know.

Regards

Ampless :-(


"jw51" <western@webace.com.au> wrote in message
news:1141539005.552320.191660@i39g2000cwa.googlegroups.com...

No power on function, started becoming difficult to turn on over a
couple of days.

Checked speakers(Bose lifestyle) could find no problem.

Am trying to source a service manual for it.

Any ideas?

 

[James Sweet]

Ross Herbert wrote:

On 8 Mar 2006 10:54:13 -0800, runderwo@mail.win.org wrote:


because I mistook what is apparently a broken fuse holder
for the fuse itself.


So, are you now sure that the problem was caused by a broken fuse
holder in the first place?

Well there's no sense in arguing about it or belittling one another, I
would however strongly recommend doing some research on the subject
before mucking around with it too much. I do agree that a person should
be able to clearly identify just about any type of fuse or fuse holder
they come across before poking around in anything mains powered.

 

[Arfa Daily]

"427Cobraman" <quartermiler1320@yahoo.com> wrote in message
news:1141923038.156963.121560@u72g2000cwu.googlegroups.com...

Well, all switch matrices checked out as well as supply voltages and
oscillators. ESR'd all electrolytics. The only thing that was off is
the LED drive circuits 1,2, and 4 on IC102. On the good board, these
are all at 4.7v when unit is powered off, regardless of state when in
operation. On the bad board, all are at zero. I wouldn't think these
would affect general operation, but who knows. I've checked, and a
couple other eyes have checked for cracks, solder bridges and bent
pins...everything looks good. I'm at wit's end. I'm sure I'll get
motivated to dig around some more after a nice cold brew. Link to
diagram:
http://www.archive.org/download/Partial_diagram_of_a_display_board_schematic/de845.gif

Hmmm. That's interesting. The anodes of the LEDs are connected to B+ via

their 150R limiter resistors. The cathodes are connected back to pins 1,2,4
on the micro. On the good board, in standby, the pins - ie the LED
cathodes - are all at very nearly B+, which is exactly as you would expect.
In standby, the LEDs will want to be off, so the driver transistors,
internal to those pins, will be turned off. Now look at the situation with
the bad board. The voltage at the three IC pins can only be low as a result
of two conditions. First, the internal driver transistors are on. BUT, if
this is the case, then the LEDs must be alight, as we know that there should
be B+ on their anodes, even when the unit is in standby. The second
condition which would lead to there being no voltage on the IC pins, AND the
LEDs not alight, is B+ missing at the back side of the 150R limiter
resistors.

It's hard to see how this could be the case, if all of the other voltages on
the micro are correct. Never-the-less, it would be my best guess, as being
the case. Although you can be pretty sure from your measurements so far,
that B+ itself is established and correct, I'd give reasonable odds that
it's not everywhere it should be. I think that the missing voltages at the
LED drive pins are a big clue. My next move would be to check that B+ is
present at the junction point of the three limiter resistors and C120 and
pin 1 of IC105. Keep us posted on your findings.

Arfa

 

I got a service diagram from Lab-Volt after much consternation. Looks
like the holder is supposed to be like that, when the holder screws in
it both tightens up the "link" to the fuse as well as completes the
connection. So the holder may not be broken, I'll just see if it blows
another fuse before proceeding. Thanks for the helpful replies.

 

[Leonard Caillouet]

Who did you send it to? Yamaha would have likely take some action by now if
there was that kind of delay for parts. You need to call Yamaha customer
service. Where is your dealer in all of this?

Leonard


"Tux" <tux@netmadeira.com> wrote in message
news:44108da2$0$15553$a729d347@news.telepac.pt...

Hi

I have the exact same problem with a Yamaha RX-V1400. Unit shuts-off after
a few minutes even with no sources or ouputs connected. I did post about
it here awhile ago but received no reply, so in the meantime I sent it to
the local Yamaha Service and it has been there for 4 months. They now say
the EPROM has lost configuration and they are waiting for a new one. I
suspect they have stuffed it up as I don't think the EPROM could have been
the cause of this problem. If you or anyone finds the cause of cause
please let me know. And IF mine ever gets repaired I will let you know.

Regards

Ampless :-(


"jw51" <western@webace.com.au> wrote in message
news:1141539005.552320.191660@i39g2000cwa.googlegroups.com...
No power on function, started becoming difficult to turn on over a
couple of days.

Checked speakers(Bose lifestyle) could find no problem.

Am trying to source a service manual for it.

Any ideas?

 

[Leonard Caillouet]

http://www.techdata-kicksass.net/

It requires a subscription, but with dozens of gigbytes of manuals it is a
good value for most shops.

Leonard

"PTV75230" <PTV75230.24ev1d@diybanter.com> wrote in message
newsTV75230.24ev1d@diybanter.com...

Leonard Caillouet Wrote:
I would strongly suggest getting the documentation. It is not at all
easy
to figure out nor something that one could describe in a paragraph.
You can
find the docs on the techdata site.

Leonard

PTV75230[/color]

What techdata site?


--
PTV75230

 

[Ross Herbert]

On 9 Mar 2006 15:07:37 -0800, runderwo@mail.win.org wrote:

I got a service diagram from Lab-Volt after much consternation. Looks
like the holder is supposed to be like that, when the holder screws in
it both tightens up the "link" to the fuse as well as completes the
connection. So the holder may not be broken, I'll just see if it blows
another fuse before proceeding. Thanks for the helpful replies.

You are a worry... this is the first time you have even mentioned that
the unit is "blowing fuses". Your previous posts inferred that the
problem was with continuity related to this fuse, but this new
information puts a whole new complexion on things. The very fact that
the fuse is blowing infers there is nothing wrong with the fuse holder
or the fuse. Assuming that you are using a properly rated delay fuse
(slo-blo, or time delay fuse usually with a 'T' marking), and it is
still 'blowing', then the fuse and holder are fine. The most likely
problem is that there is some component following the fuse which is
overloading it and causing it to do its intended job.

Have you even opened the case to see if there is any obvious sign of a
short circuit anywhere? Perhaps I shouldn't ask that if your attempt
to repair the unit up till now is an indication of your knowledge.

 

[Smitty Two]

In article <hup1121r3itefphn1t846p67jlal4bt0rh@4ax.com>,
Ross Herbert <rherber1@bigpond.net.au> wrote:

On 9 Mar 2006 15:07:37 -0800, runderwo@mail.win.org wrote:

I got a service diagram from Lab-Volt after much consternation. Looks
like the holder is supposed to be like that, when the holder screws in
it both tightens up the "link" to the fuse as well as completes the
connection. So the holder may not be broken, I'll just see if it blows
another fuse before proceeding. Thanks for the helpful replies.


You are a worry... this is the first time you have even mentioned that
the unit is "blowing fuses". Your previous posts inferred that the
problem was with continuity related to this fuse, but this new
information puts a whole new complexion on things. The very fact that
the fuse is blowing infers there is nothing wrong with the fuse holder
or the fuse. Assuming that you are using a properly rated delay fuse
(slo-blo, or time delay fuse usually with a 'T' marking), and it is
still 'blowing', then the fuse and holder are fine. The most likely
problem is that there is some component following the fuse which is
overloading it and causing it to do its intended job.

Have you even opened the case to see if there is any obvious sign of a
short circuit anywhere? Perhaps I shouldn't ask that if your attempt
to repair the unit up till now is an indication of your knowledge.

The OP's claims to the contrary, it seems to me that he doesn't know a
fuse from a fuse holder. Fine, ignorance is OK, and if he's a novice, I
have no problem with that. But, his complete inability to see what he
sees and communicate it clearly is exceptionally frustrating. One
picture link would help us help him.