Toshiba TV29C90 problem; Image fades to black...

[James Sweet]

Arfa Daily wrote:

"Ron(UK)" <ron@lunevalleyaudio.com> wrote in message
news:GsGdnU8sWejcLTnYRVnytwA@bt.com...

Arfa Daily wrote:


In that case, go for it. I would be interested to know how you get on
with such transpants, and which presets you ultimately find most
suitable. Also, how quiet they are in actual practical usage.

Arfa

I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)


Hi Ron. That is a very good point, and one that I hadn't even considered
when thinking about his original plan to use these. If you look in the post
that started the thread, he says that he is intending using the presets that
you can get a 6mm shaft for that turns them into a ( semi ?? ) user
control - I'm sure you've seen the idea on stuff where there is an
adjustment that would be a good idea to have available to the user, but not
in a way that encourages him to *use* it. The shafts that I've seen usually
have a lightly splined finish so that they can be gripped, and a screwdriver
slot in the end. I think he intends to pass one of these through a panel
mount shaft bush, and then persuade the knob to fit.

Arfa

It's really a moot point though. One can still buy very high quality
pots from a reputable manufacture. That's the route to take rather than
trying to hack in something different. A good pot will last the life of
most equipment. I use Bournes pots in arcade game controllers, they seem
to hold up well to the abuse.

 

[Arfa Daily]

"James Sweet" <jamessweet@hotmail.com> wrote in message
news:tUgph.3163$Br.1752@trndny08...

Arfa Daily wrote:
"Ron(UK)" <ron@lunevalleyaudio.com> wrote in message
news:GsGdnU8sWejcLTnYRVnytwA@bt.com...

Arfa Daily wrote:


In that case, go for it. I would be interested to know how you get on
with such transpants, and which presets you ultimately find most
suitable. Also, how quiet they are in actual practical usage.

Arfa

I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)


Hi Ron. That is a very good point, and one that I hadn't even considered
when thinking about his original plan to use these. If you look in the
post that started the thread, he says that he is intending using the
presets that you can get a 6mm shaft for that turns them into a ( semi
?? ) user control - I'm sure you've seen the idea on stuff where there is
an adjustment that would be a good idea to have available to the user,
but not in a way that encourages him to *use* it. The shafts that I've
seen usually have a lightly splined finish so that they can be gripped,
and a screwdriver slot in the end. I think he intends to pass one of
these through a panel mount shaft bush, and then persuade the knob to
fit.

Arfa


It's really a moot point though. One can still buy very high quality pots
from a reputable manufacture. That's the route to take rather than trying
to hack in something different. A good pot will last the life of most
equipment. I use Bournes pots in arcade game controllers, they seem to
hold up well to the abuse.

Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.

Arfa

 

[Michael A. Terrell]

Arfa Daily wrote:

Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.

What do you mean by "Group equipment"?


BTW, http://potentiometer.com/ carries high end commercial & military
grade pots in the US.

--
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

 

[Eeyore]

"Michael A. Terrell" wrote:

Arfa Daily wrote:

Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.

What do you mean by "Group equipment"?

Musical Instrument amplifiers and the like.

Graham

 

[N Cook]

James Sweet <jamessweet@hotmail.com> wrote in message
news:tUgph.3163$Br.1752@trndny08...

Arfa Daily wrote:
"Ron(UK)" <ron@lunevalleyaudio.com> wrote in message
news:GsGdnU8sWejcLTnYRVnytwA@bt.com...

Arfa Daily wrote:


In that case, go for it. I would be interested to know how you get on
with such transpants, and which presets you ultimately find most
suitable. Also, how quiet they are in actual practical usage.

Arfa

I'm interested to know how the OP plans to reliably connect a standard
shaft to a preset, I`m presuming his idea of a preset and mine concur.

One other point, presents don`t normally come in log tapers, do they?

Ron(UK)


Hi Ron. That is a very good point, and one that I hadn't even considered
when thinking about his original plan to use these. If you look in the
post
that started the thread, he says that he is intending using the presets
that
you can get a 6mm shaft for that turns them into a ( semi ?? ) user
control - I'm sure you've seen the idea on stuff where there is an
adjustment that would be a good idea to have available to the user, but
not
in a way that encourages him to *use* it. The shafts that I've seen
usually
have a lightly splined finish so that they can be gripped, and a
screwdriver
slot in the end. I think he intends to pass one of these through a panel
mount shaft bush, and then persuade the knob to fit.

Arfa




It's really a moot point though. One can still buy very high quality
pots from a reputable manufacture. That's the route to take rather than
trying to hack in something different. A good pot will last the life of
most equipment. I use Bournes pots in arcade game controllers, they seem
to hold up well to the abuse.

The thread concerns 12/13 mm footprint pots (sub miniature), no problem with
17mm miniature or 21mm standard size ones. I doubt game controllers use
subminiature ones.

 

[Ron(UK)]

N Cook wrote:

The thread concerns 12/13 mm footprint pots (sub miniature), no problem with
17mm miniature or 21mm standard size ones. I doubt game controllers use
subminiature ones.

One thing that concerns me about using a preset as a user control is the
'end stop' arrangement. Is the mechanism that prevents a user from
turning the control past it`s fully on or fully off position rugged
enough on a preset to to the job considering what heavy handed users
there sometimes are in the music business.

Also, if the end stop IS strong enough, is the mounting arrangement of a
preset strong enough to withstand the turning force of a typical death
metal guitarist after several pints of Krugermeister?



Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com

 

[Arfa Daily]

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:45A5AB91.8E2BBDD2@earthlink.net...

Arfa Daily wrote:

Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.


What do you mean by "Group equipment"?

Er, equipment used by groups ? Like bands ? Beatles, Rolling Stones ? Do you
not call them "groups" your side of the pond ? Never heard the term
"groupies" for the girls that follow them around ? In terms of this thread,
we have been talking specifically amplifiers for musical instruments, but in
general, at least over here, "group equipment" covers anything that a group
or band may be using on stage ( or off-stage ) to make their sound or image,
so amps, mixer desks, effects units / pedals, wireless mics, lighting
effects and so on. I know from our past
- errr ... 'conversations' shall we say - that you have been involved in the
repair of this equipment, so I'm sure that you probably have a valid opinion
on the substituting of panel-type pots with presets made into panel mounting
types ?? Back to you, friend ...

Arfa

 

[N Cook]

Ron(UK) <ron@lunevalleyaudio.com> wrote in message
news:HYWdnYJHnfw8YjjYRVnyvAA@bt.com...

N Cook wrote:

The thread concerns 12/13 mm footprint pots (sub miniature), no problem
with
17mm miniature or 21mm standard size ones. I doubt game controllers use
subminiature ones.

One thing that concerns me about using a preset as a user control is the
'end stop' arrangement. Is the mechanism that prevents a user from
turning the control past it`s fully on or fully off position rugged
enough on a preset to to the job considering what heavy handed users
there sometimes are in the music business.

Also, if the end stop IS strong enough, is the mounting arrangement of a
preset strong enough to withstand the turning force of a typical death
metal guitarist after several pints of Krugermeister?



Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com

Thanks for that, I had not considered the end stops.
The original one, with the flimsey wiper, had quite manly endstop nib on the
shaft and housing moulding.
These presets have similar sized physical end stops, the weakest point would
be the two plastic pauls on the shaft that engage with the slot, about 3 x
1.5mm each in cross section.
I would mount the body to pcb with hot melt glue.
Guitarists and pot problems is usually the guitar controls where the fascia
is plastic so no reliable mounting, so the nuts loosen and pots are then
twisted round and round , windlassing the wires into a broken mess.
That problem I cure by heavy-soldering a thick copper strip between all the
pots, replacing the wire grounds between the pots

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Zachary Burns]

Reposted in (214 KB)

Zack

"Zachary Burns" <zacharyburns@shotmail.com> wrote in message
news:45a6394f$0$503$815e3792@news.qwest.net...

Posted a picture of it to: alt.binaries.schematics.electronic.

Also a picture at: http://www.geocities.com/zacharyburns/

Zack

"Homer J Simpson" <nobody@nowhere.com> wrote in message
news:sq9ph.131138$YV4.89995@edtnps89...

"Zachary Burns" <zacharyburns@shotmail.com> wrote in message
news:45a51501$0$91106$815e3792@news.qwest.net...

If I took a picture could you tell?

Post it in ABSE







--

 

[Michael A. Terrell]

Arfa Daily wrote:

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:45A5AB91.8E2BBDD2@earthlink.net...
Arfa Daily wrote:

Hi James. That was my original feeling also, but as I said further up, I
repair lots of group equipment, and really don't seem to suffer that much
from bad as opposed to broken pots, anyway.


What do you mean by "Group equipment"?



Er, equipment used by groups ? Like bands ? Beatles, Rolling Stones ? Do you
not call them "groups" your side of the pond ? Never heard the term
"groupies" for the girls that follow them around?

Groupie is a group of enthusiastic fans of any type, in the US.

In terms of this thread,
we have been talking specifically amplifiers for musical instruments, but in
general, at least over here, "group equipment" covers anything that a group
or band may be using on stage ( or off-stage ) to make their sound or image,
so amps, mixer desks, effects units / pedals, wireless mics, lighting
effects and so on.

They referred to them as bands, and their electronics as "Band Amps",
"Musical equipment" or "Guitar amps" when I was doing that work in the
'70s & '80s. Most repairs were done by part time techs at music stores,
but there was usually a
shop that specialized in amp repair in bigger cities. I even saw a few
british amps, back in the '70s when some clueless wanabes were trying to
copy one band or another, right down to the brand of wire and connectors
for their cables. The only thing they forgot was to learn how to play
music, sing, and perform in front of people who want good music. ;-)

I know from our past
- errr ... 'conversations' shall we say - that you have been involved in the
repair of this equipment, so I'm sure that you probably have a valid opinion
on the substituting of panel-type pots with presets made into panel mounting
types ?? Back to you, friend ...

As far as I am concerned, panel mounted controls are the only way to
go for any application that involves rugged service. PC mounted are ok
for internal adjustment, but nothing beats a mil spec made to last for
25 years of daily use.

--
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

 

[Meat Plow]

On Thu, 11 Jan 2007 09:28:04 -0500, Zachary Burns Has Frothed:

Reposted in (214 KB)

Zack

"Zachary Burns" <zacharyburns@shotmail.com> wrote in message
news:45a6394f$0$503$815e3792@news.qwest.net...
Posted a picture of it to: alt.binaries.schematics.electronic.

Also a picture at: http://www.geocities.com/zacharyburns/

Looks like a resistor.

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

COOSN-266-06-25794

 

[Homer J Simpson]

"Zachary Burns" <zacharyburns@shotmail.com> wrote in message
news:45a6394f$0$503$815e3792@news.qwest.net...

Also a picture at: http://www.geocities.com/zacharyburns/

3.9 Meg. 10%

 

[James Sweet]

The thread concerns 12/13 mm footprint pots (sub miniature), no problem with
17mm miniature or 21mm standard size ones. I doubt game controllers use
subminiature ones.

What difference does it make? Cheap pots are cheap pots. I was
originally using ones from Radio Shack, but those were not holding up
even to home use.

 

Hi David, sorry if the last post was a but confusing. What i was trying to
say was that the circuitry seems to be very sensitve to an im-balance in any
1 channel.

When i was doing some comparitive resistance checks on the 2 channels the
other day i noticed about 700k difference in resistance around the area of
the 2 transistors, this was traced to having different transistor types in 1
channel. I think the PWM detects this difference in current flow in 1
channel and shuts down.

All i would say is replace all 4 2sc5707 transistors (2 per channel) plug in
the ccfl's and see what happens. If it works , then, as a test unplug 1 of
the ccfl tubes and you will see it shuts down again.

Also, if you replace the trannies and you get the same symptoms try plugging
in a different pair of ccfl's , you might have a duff tube which is causing
the imbalance.

Let me know how you get on

Graham






"David Farber" <farberbear.unspam@aol.com> wrote in message
news:12qd45sia0uucd4@corp.supernews.com...

So are you saying that it works fine if you replace all four of the
transistors with the BD911's?

--
David Farber
David Farber's Service Center
L.A., CA

grobinso@lycos.co.uk> wrote in message
news:ztqph.55514$HV6.45054@newsfe1-gui.ntli.net...
Just made another interesting observation on this board.

When the board has 2 BD911's fitted in place of the 2sc5707 in 1of the
channels and has 2sc5707's in the other channel then plugging in a pair
of
ccfl tubes gives the same symtoms (works for 3 seconds or so then goes
off).
The 2sc5707 transistors have been removed and metered and appear to be
ok.

If i put BD911's in both channels then the unit works (stays on). If i
unplug one of the CCFL tubes then i get the original fault and the unit
goes
off after 3 secs or so.

I am wondering if the Pulse Width Drive chip that drives the ccfl tubes
is
detecting an im-bablance in the 2 channels and is shutting down.either
that
or the 2 2sc5707 transistors are still defective despite reading ok on
cold
test.

Tricky one this !!

Graham


grobinso@lycos.co.uk> wrote in message
news:b92ph.48049$Qa6.42218@newsfe6-gui.ntli.net...
Thanks David, will be interesting to see what happens after you get the
replacement transistors in. Perhaps my continuing problems are due to
having tried BD911 transistors in place of the 2sc5707.

Let me know how you get on please.

Graham


"David Farber" <farberbear.unspam@aol.com> wrote in message
news:12q87m840j8scdb@corp.supernews.com...
"David Farber" <farberbear.unspam@aol.com> wrote in message
news:enmdu4$e8m$1@aioe.org...
This 17" Dell monitor, model number CN-0M1609-4633-3AG-2DTL, will
power
on
when AC is first applied. In the middle of the screen appears,
"Dell
Genesis
Display Perfection." Then it disappears after a second. When you
press
the
power button with no input signal, the Dell self test feature check
illuminates in the bottom left corner of the display. You can see
the
red,
green, blue, and white bars within the self test box. Then, it
starts
to
scroll diagonally up to the right for about a second and then the
display
turns off. The power light remains on. If you hook it up to a PC,
you
do
not
get any display. The boards are in good condition and I reflowed
the
solder
over many of the components with no improvement. Any ideas what
might
be
going on here?

Thanks for your reply.
--
David Farber
David Farber's Service Center
L.A., CA





grobinso@lycos.co.uk> wrote in message
news:txUoh.61045$n36.43746@newsfe7-gui.ntli.net...
Hi David, i believe it should be ok with the trannies out, it just
means
that one channel will not be driven.

Would be interested to know if you still have the same symptom (on
for
2-3
secs and then off) with the trannies out.

I think what is happening is that the PWM chip is detecting
overcurrent
and
shutting down. I found that with BD911 transistors in in place of the
2sc5707 i am still getting the same problem but i cant find any more
s/c
devices. As i understand it , with these monitors this is a real
common
problem, even if you manage to get the thing working its likely to
break
down again, with the same devices s/c a day/week/or even months
later.
It
seems its always the same channel (the top lamp) that goes but no-one
really
knows why. I also understand that the transformers are suspect and go
s/c
or
arc internally. Dry solder joints are also a major problem as are
poor
quality electrolytic caps.

I am coming to the conclusion that this monitor suffers from a major
design
fault from new, they seem to just make it out of warranty and then
fail


Apparently many service shops now refuse to handle them, they are a
warranty
claim waiting to happen.

I am going to continue working on it though as i hate to give up on
things
like this, its my own monitor so cost isnt an issue but for repair
shops
it
well cold be.

Anyway, let me know what you find with the voltages, should be
interesting.

Regards

Graham

Hi Graham,

I checked the voltage at pin 9 of the TL1451A chip and have come up
with
the
same results that you found in your monitor. The voltage swings from
14
to
18 volts after shutdown.
--
David Farber
David Farber's Service Center
L.A., CA

 

On Thu, 11 Jan 2007 08:19:10 -0500, "Zachary Burns"
<zacharyburns@shotmail.com> wrote:

Posted a picture of it to: alt.binaries.schematics.electronic.

Also a picture at: http://www.geocities.com/zacharyburns/

It's a 1/4 watt resister. It's exact value is probably not critical to
the circuit. Anything around 3.9 meg will work.

 

[Adrian C]

Meat Plow wrote:

On Thu, 11 Jan 2007 09:28:04 -0500, Zachary Burns Has Frothed:

Reposted in (214 KB)

Zack

"Zachary Burns" <zacharyburns@shotmail.com> wrote in message
news:45a6394f$0$503$815e3792@news.qwest.net...
Posted a picture of it to: alt.binaries.schematics.electronic.

Also a picture at: http://www.geocities.com/zacharyburns/

Looks like a resistor.

Looking at the rather large picture (scroll bars on the above website),
could be a molded inductor ...

--
Adrian C

 

[Bret Ludwig]

ACME wrote:

http://www.acme-sales.net
Toll free 1-800-575-9833

We accept VISA, MasterCard, American Express, Discover, PayPal,
and check-by-phone.

No minimum order. We ship anywhere. Most orders shipped same day.
Free shipping and handling on orders over $50. Why pay more?

I want to pay less. These are some expensive semi's. In many cases
regular DigiKey parts work as well or better at much less cost.

 

[Ancient_Hacker]

Zachary Burns wrote:

Some cable technician cut this off of my friends television

??? So he opened up the TV
??? And somehow during a new years eve party
??? probably without any tools
??? diagnosed the problem was this in this part


!!! sounds mighty fishy !!!

From the picture it's hard to tell-- it could be a resistor.

then again it could be a molded inductor.


in any case it's kinda unlikely a guy with no tools could pinpoint the
problem to one component that looks perfectly fine from the outside.

 

[Zachary Burns]

Oh, it could be a molded inductor.

Is there a way I can test this? If I hook up to an Ohm meter, I should get
what?

Zack


"Ancient_Hacker" <grg2@comcast.net> wrote in message
news:1168593911.983729.4480@s34g2000cwa.googlegroups.com...

Zachary Burns wrote:
Some cable technician cut this off of my friends television

??? So he opened up the TV
??? And somehow during a new years eve party
??? probably without any tools
??? diagnosed the problem was this in this part


!!! sounds mighty fishy !!!

From the picture it's hard to tell-- it could be a resistor.

then again it could be a molded inductor.


in any case it's kinda unlikely a guy with no tools could pinpoint the
problem to one component that looks perfectly fine from the outside.

 

[Michael Black]

"Ancient_Hacker" (grg2@comcast.net) writes:

Zachary Burns wrote:
Some cable technician cut this off of my friends television

??? So he opened up the TV
??? And somehow during a new years eve party
??? probably without any tools
??? diagnosed the problem was this in this part


!!! sounds mighty fishy !!!

From the picture it's hard to tell-- it could be a resistor.

then again it could be a molded inductor.


in any case it's kinda unlikely a guy with no tools could pinpoint the
problem to one component that looks perfectly fine from the outside.

ANd of course, likely the tv set itself supplies information on whether

it's a resistor or inductor, since the board itself would likely have
a marking to indicate the part number for the schematic.

But, as you and I have said, that information has been lost since
"the guy" who "diagnosed" this problem isn't sticking with the "repair".

Michael