Toshiba TV29C90 problem; Image fades to black...

Ash posted:





<< speaking of fcc rules, what is the limitation of power you can operate
without having to be sneaky about it >>

--

I believe that is covered in CFR47, Part 15.

<A HREF="http://www.access.gpo.gov/nara/cfr/waisidx_03/47cfr15_03.html">2003
CFR Title 47, Volume 1</A>


For the FM broadcast band look at 47cfr15.239, but there is a bunch of sections
that may also apply.

Don
 
On 27 Dec 2004 13:41:05 -0800, "Zephy" &lt;zephinilium@yahoo.com&gt; put
finger to keyboard and composed:

I fixed both monitors. It was a bad solder joint. Was making big plans
to go buy parts, and got fed up and just started poking around
intuitively with my finger on the back of the circuit board. I touched
the jumper that goes between pins 8 &amp; 9 on the TDA1180P and instantly
it syncs up. A few minutes with the soldering iron and both units are
working. Sometimes it *is* simple.
Click to expand...
So why is the IC getting too hot to touch?


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
 
On Wed, 29 Dec 2004 00:42:55 GMT, "Fred" &lt;testing@testing1212mouse.com&gt; wrote:

Yes, sounds like it could be. One of these cold rainy weekends I'll take it
apart and check all the solder connections, etc. Thanks, Ken, for your
correspondence and help!
Click to expand...
Sounds very much like a Disaster Waiting To Happen.....

DS
 
This again!

I finally got the transistor &amp; replaced it.
Results same as before - OnScreenDisplay doesn't sync horizontally;
all else seems OK.

Since I now have the set apart, I checked the waveforms.
H pulses OK at base and emitter of Q4402 look just like what the manual
shows. Also waveform right at pin 23 of the micro is OK.

Micro pins 25 &amp;26 (the passive components of the PLL) don't look so
great, but there are no manual waveforms to compare them with.
Any ideas - anybody??
 
My vote is that the batteries are still bad, and there is nothing wrong with
the camera!

--

Jerry G.
=====

"Fred" &lt;testing@testing1212mouse.com&gt; wrote in message
news:BEoAd.5574$Y57.1499@trnddc08...
"David Springthorpe" &lt;david.springthorpe@idx.com.au&gt; wrote in message
news:ntv3t09lp3djjnd43gf129kntij8l8dm9o@4ax.com...
On Wed, 29 Dec 2004 00:42:55 GMT, "Fred" &lt;testing@testing1212mouse.com
wrote:

Yes, sounds like it could be. One of these cold rainy weekends I'll take
it
apart and check all the solder connections, etc. Thanks, Ken, for your
correspondence and help!

Sounds very much like a Disaster Waiting To Happen.....
Click to expand...
Well, we'll soon find out! I've already got the tools together -- let's
see.... duct tape, paper clips, sledge hammer, 24 ounce bottle of redskin
peanuts, TV Guide.... Yep! I'm all ready to go!

Now back to an update...

After using the AC adapter for awhile, I disconnected it and then ran it on
batteries only. This time I took 4 or 5 photos before the "battery low"
warning came back up. Then plugged back in with the adapter and it work
fully again. Probably not a revelation to the more advance folks, like
David, but I like to double check things before pulling out the chain saws.

Later,

Have a NICE DAY, David! Don't run out in front of any buses or anything.

Fred
 
"Tim R." &lt;tim87529@nospamcswebmail.com&gt; wrote in message
news:EspAd.43257$uM5.2849@bgtnsc05-news.ops.worldnet.att.net...
A friend claimed he was able to use a car battery as an arc welder. Is
this
possible? Would it damage the battery?


Any responses are appreciated!

Tim
Click to expand...
Yes it's possible, but only should be done in emergencies. It can cause the
battery to explode amoung other things.
 
I finally got the transistor for Q4402, &amp; replaced it.
Results same as before - OnScreenDisplay doesn't sync horizontally;
all else seems OK.

Since I now have the set apart, I checked the waveforms.
H pulses OK at base and emitter of Q4402 look just like what the manual
shows. Also waveform right at pin 23 of the micro is OK.

Micro pins 25 &amp;26 (the passive components of the PLL) don't look so
great, but there are no manual waveforms to compare them with.
Any ideas - anybody??

Reply
 
As the subject suggests, how easy is it to replace a p-channel mosfet
with a n-channel moset?

P-channels are very hard to find, and i cant get a replacement for one
that burnt out on a car stereo. Lots of n-channels around though. is it
easy just to plonk them in, and use a bit of trickery to make them go?

Maybe in reverse or something.. i guess theres certain procedures laid
out for this now. I dont wanna rip the whole circuit to bits, but the
stero (cd/mp3 player) is worth repairing if its gonna work.

It was a D15P05 that burnt out.
15A, 50V, 0.150 Ohm, P-Channel Power MOSFET.

Closest i could find to buy locally was a 2sj16012, half the power, and
bloody expsensive.
 
On Wed, 29 Dec 2004 02:29:53 GMT, "Fred" &lt;testing@testing1212mouse.com&gt; wrote:

Have a NICE DAY, David! Don't run out in front of any buses or anything.
Click to expand...
Well, put it this way, if I ever try to "fix" things they usually end up
completely stuffed.....

DS
 
On Tue, 28 Dec 2004 22:26:40 -0500, "Jerry G." &lt;jerryg50@hotmail.com&gt;
wrote:

I would still think you should have the set properly checked by a tech who
is experienced with the model series of Sony set that you have.

Things like the power supply, scans, and power supply should be properly
checked. There is a procedure for setting up the G2 voltage. The details
should be in the service manual for your set. If it a little low, it is not
going to be bad for the CRT, but if it is high, it will accelerate its
deteriation, due to excessive beam current.

You may still have an intermittant solder connection in the set, or
something that is mechanicaly not right, going by how you described that it
came back to life, and is reacting now. This should be properly checked.

Take care about the safety issues when working on TV sets. This is most
important for yourself.
Hi Jerry,
Click to expand...
thanks for the feedback. I do have the service manual,
but I don't have, nor am I versed in the operation of,
an oscilloscope. Must admit, it would be good to have
it and know how to use it.
There's another setting, sub-contrast (SPIX), that also
requires a scope to set it.

I *did* have a tech repair the powersupply 4 months ago,
but he did not check the alignment. I believe this is the
source of many of the problems I've experienced since.
Such as excesively high brighness and contrast.



Dave
 
My new Sony vcr was being used by a 13-inch Mitsubishi tv.

I have a 27-inch Sony tv in the house. We don't use it because the sound has
deteriorated. However, the picture is still good.

Anyway, I connected the 27-inch Sony tv to the Sony vcr, and the graininess
that occurred on channels 5 and 7 on the vcr tuner was gone.

The three-second static also was absent.


So, the original graininess was probably caused by one of the following:

1) The small size of the Mitsubishi tv.

2) The incomplete compatibility between the Mitsubishi tv and the Sony vcr.


So, the vcr is probably not the problem.

Thanks to all for your suggestions.

Regards,

Alex K.
 
This is a very dangerous way to do welding! The battery is seeing a short
circuit, and can explode. I have heard of some serious accidents doing this
practice. Tell your friend to get himself a proper welding supply that is
designed for this type of work, and is safe.

The battery will be making high internal heat between the plates, and
releasing hydrogen at the same time. This is a bid combination! The state of
this is very unstable, and not safe.

--

Jerry G.
======


"Tim R." &lt;tim87529@nospamcswebmail.com&gt; wrote in message
news:EspAd.43257$uM5.2849@bgtnsc05-news.ops.worldnet.att.net...
A friend claimed he was able to use a car battery as an arc welder. Is this
possible? Would it damage the battery?


Any responses are appreciated!

Tim
 
Just curious..... what is, or was, the milli/amp rating of the batteries
that seemed to fail ? The AC adapter you found puts out a lot more
amps than a same voltage AC transformer for a phone or whatever. Glad
you're gaining on the problem......

Fred wrote:
Looks like we're making progress -- thanks to that real nice feller who
posted and suggested I try using the camera with an AC adapter.

[Note to the "try a new battery" crowd: No, it wasn't the batteries.]
Click to expand...
 
Yowsa, what a gold mine of useful information!!!! Many thanks, everyone!!!

Dad found the manual but it doesn't include the entire model number (the
oven was made by Roper), so he'll pull out the oven to see if he can find
the sticker with the whole model number on it and we can go from there.

Much appreciate the help!!! Dad says thanks very much, too!

Matt J. McCullar
Arlington, TX
 
"Tim R." &lt;tim87529@nospamcswebmail.com&gt; wrote in message
news:EspAd.43257$uM5.2849@bgtnsc05-news.ops.worldnet.att.net...
| A friend claimed he was able to use a car battery as an arc welder. Is
this
| possible? Would it damage the battery?

ISTR there was some sort of odd spot welder that used carbon rods that might
do that.

N
 
"ArgGrr" &lt;arggrr@softhome.net&gt; wrote in message
news:cqtbh5$iji$1@lust.ihug.co.nz...
As the subject suggests, how easy is it to replace a p-channel mosfet
with a n-channel moset?

P-channels are very hard to find, and i cant get a replacement for one
that burnt out on a car stereo. Lots of n-channels around though. is it
easy just to plonk them in, and use a bit of trickery to make them go?

Maybe in reverse or something.. i guess theres certain procedures laid
out for this now. I dont wanna rip the whole circuit to bits, but the
stero (cd/mp3 player) is worth repairing if its gonna work.

It was a D15P05 that burnt out.
15A, 50V, 0.150 Ohm, P-Channel Power MOSFET.

Closest i could find to buy locally was a 2sj16012, half the power, and
bloody expsensive.
Click to expand...

You'd have to redesign the whole circuit, they use a more expensive P
channel part for a reason, an N channel is not suitable.
 
That neatly clears up a puzzle: a late model television set my neighbours
had placed out for the garbage seemed to have a shape roughly like that
on the Union Jack's cross scratched off the phosphor dot layer on the
INSIDE of the screen.

Had they been watching the set at the time, it would have given them
a wakeup.
Click to expand...
They probably knocked the thing off the stand, seen it happen a few times,
the yoke is heavy enough to snap the neck off. People get a big new set and
stick it teetering on the stand from their smaller old TV and sooner or
later it falls over.
 
"Rod Speed" &lt;rod_speed@yahoo.com&gt; writes:
And the reality is that its normally the neck that gets broken and the
worst that normally happens is that the cathode ends up hitting the
inside of the front surface and leaves a rather interesting pattern there.
Click to expand...
That neatly clears up a puzzle: a late model television set my neighbours
had placed out for the garbage seemed to have a shape roughly like that
on the Union Jack's cross scratched off the phosphor dot layer on the
INSIDE of the screen.

Had they been watching the set at the time, it would have given them
a wakeup.
--
John Savage (my news address is not valid for email)
 
cueball@www.com writes:

Our 20 year old (1984) JC Penney microwave, model 5919-00-40, ceased to
work last night. It acted like the fuse had blown, which it had, but
that didn't cure the problem. Further investigation revaled that the
problem lies in the control pad, not the actual part that does the
cooking and can kill you. I took out the circuit board, which contains
the display, keypad, etc. and controls the microwave, and looked it
over to see if there were any obvious problems, such as another blown
fuse, which there weren't. I saw some little strips of wire on the
board in various places marked 9V, 12V, etc. and when I connected a
meter between them and the ground wire I got no reading. I verified
that the transformer was providing electricity to the board, and the
output frpm the connectors matched the values printed on the circuit
board.

By accident I shorted out part of the transformer for the board, the
10v section, and to my surprise the display lit up and the buzzer
beeped, like it would after a power failure. Then it would sort of
slowly fade out. I didn't repeat this too many times because I didn't
want to ruin the power transformer or anything.

From this, can anyone figure out what might've happened? I really don't
want to scrap this as it is so simple to repair, as far as the layout
goes.
Click to expand...
You say you measured the outputs of the transformer? So, the 10 V output
measured 10 VAC

Also, you said a fuse actually did blow?

The circuitry between the transformer and the DC outputs should be quite
simple. If you aren't getting any DC voltages at, something is likely
open - a bad solder joint or fusable resistor.

The effect you describe of shorting the 10 VAC output from the transformer
sounds strange. Possibly you were pushing on something in the vicinity
and the act of shorting having an effect was just a coincidence.

I could speculate but better to just trace the circuit for one of the DC
outputs and check each component and the wiring. It shouldn't be too hard
to find the problem now that you know the rest of the circuit probably works.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
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