Toshiba TV29C90 problem; Image fades to black...

Homer J Simpson wrote:

helee4@hotmail.com> wrote in message
news:1166467960.828169.79030@n67g2000cwd.googlegroups.com...

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

 

[Steve]

The schematic is up on alt.binaries.schematics.electronics under
Schematic for xtal problem

Another thought, should I have the unit powered up and this particular
xtal switched on when I attempt to measure the circuit capacitance?
It has some diodes which switch the oscillators on one at a time, I
don't know how they would effect the measurement if they weren't
biased on.


On Sat, 16 Dec 2006 05:43:13 -0000, Jim Land
<RrrrFfffTttt(NO)@(SPAM)hotmail.com> wrote:

Steve <skamego@hotmaill.com> wrote in
news:9sb6o21mhn7toflq120bc0c13p8a78jepr@4ax.com:

I have a handheld meter, however, when I hook it up to the circuit, it
measures negative capacitance.

This circuit uses coils for the frequency adjustment.

This is getting interesting! How about if you scan the schematic and post
the oscillator circuit for us to see? (Somewhere on the web or in the
newsgroup alt.binaries.schematics.electronic)

 

[Homer J Simpson]

<helee4@hotmail.com> wrote in message
news:1166481170.125468.270750@48g2000cwx.googlegroups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

 

Homer J Simpson wrote:

helee4@hotmail.com> wrote in message
news:1166481170.125468.270750@48g2000cwx.googlegroups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?

 

[Dave Plowman (News)]

In article <1166468967.307428.139460@80g2000cwy.googlegroups.com>,
<kevin.pavin@gmail.com> wrote:

I have a small surface mount amplifer/filter chip on a packed PCB that
I need to replace. In order to solder in the new one I obviously need
to desolder the old one first being as careful as possible not to
damage anything else on the board. I've never desoldered before and
was wondering if someone could give me the basics or atleast point me
to a tutorial for desoldering in this type of application. Thanks so
much for any advice,

It's often worth crunching up the faulty chip with cutters to remove most
of it before applying heat. Sounds brutal but the important thing is not
to damage the PCB and prolonged desoldering is likely to. Once you've
reduced it to just the soldered 'tails', remove each one individually
using solder braid.

--
*If I throw a stick, will you leave?

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

 

[Arfa Daily]

<kevin.pavin@gmail.com> wrote in message
news:1166468967.307428.139460@80g2000cwy.googlegroups.com...

Hi all,

I have a small surface mount amplifer/filter chip on a packed PCB that
I need to replace. In order to solder in the new one I obviously need
to desolder the old one first being as careful as possible not to
damage anything else on the board. I've never desoldered before and
was wondering if someone could give me the basics or atleast point me
to a tutorial for desoldering in this type of application. Thanks so
much for any advice,

Kev

If you really have no experience of desoldering, then I would venture to

suggest that you are dicing with death to attempt successful removal of a
surface mount chip on a packed board, as a first project ...

You really will need to practice first on a scrap board. I usually start by
flooding the pins with new solder, then wicking off as much as possible.
This will remove much more solder than just going for it with the existing
solder, which will not melt and flow up into the solder wick very well. I
then slide a length of single strand rework wire under all the pins down one
side, and tack solder the end to any convenient solder pad. If you then
gently pull on the free end of the wire, away from the chip body, whilst
applying heat to each pin in turn, they will come up off the board cleanly,
as the wire passes below them.

When most of the pins are separated from the board, you may see the chip
body start to move. Be careful then that the removal of the last couple of
pins does not twist the IC and pull the last couple of pads off the board.
If you do not see the IC moving, it is likely glued to the board. The glue
bond is usually easily fractured by inserting a blunt scalpel blade under
the edge of the IC body, and twisting. When the IC is off the board, re-wick
the pads to make sure that they are very flat, and remove any traces of
glue.

Position the new IC very carefully, making sure that it is the right way
round, then tack two pins at opposite corners. Check the pin alignment again
with a strong magnifying glass. When you are satisfied that it is aligned
correctly, apply some liquid flux to one row of pins, then just go ahead and
solder with the smallest iron tip and finest gauge solder that you have.
Don't worry about solder-flooding bridging the pins at this point. If you
are using a good quality liquid flux, this should be minimal anyway, if you
are not going mad at applying solder. Repeat for the other one or three rows
of pins, depending on package type.

When you have finished, examine your work with your magnifying glass again -
a jeweller's loupe is ideal for this - and then go back to any pins that
have bridged, and apply your solder wick with your iron tip to the vertical
faces of the affected pins. This will remove the excess solder causing the
bridge, without compromising the joint. Clean down with flux remover and an
old toothbrush, and recheck the work with the magnifier. You should find
that the job you have done is nearly as good as the original flow soldered
product.

Arfa

 

[Don Bowey]

On 12/18/06 5:17 PM, in article
1166491077.756410.110270@80g2000cwy.googlegroups.com, "helee4@hotmail.com"
<helee4@hotmail.com> wrote:

Homer J Simpson wrote:
helee4@hotmail.com> wrote in message
news:1166481170.125468.270750@48g2000cwx.googlegroups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?

What type of receiver is it? Regen, single or dual conversion?

Don

 

[Homer J Simpson]

<helee4@hotmail.com> wrote in message
news:1166491077.756410.110270@80g2000cwy.googlegroups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?

Without a service manual, I would need an oscilloscope with an RF probe for
starters.

 

Don Bowey wrote:

On 12/18/06 5:17 PM, in article
1166491077.756410.110270@80g2000cwy.googlegroups.com, "helee4@hotmail.com"
helee4@hotmail.com> wrote:


Homer J Simpson wrote:
helee4@hotmail.com> wrote in message
news:1166481170.125468.270750@48g2000cwx.googlegroups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?




What type of receiver is it? Regen, single or dual conversion?

Don

Hi Don, I wish I can answer your question. All I know is this is a 27
Mhz AM receiver for R/C car. Do you think it will be too much for a
beginer to fix? I mean the circuit looks pretty simple, so I figured I
want to give it try.

 

[Don Bowey]

On 12/18/06 6:44 PM, in article
1166496242.976455.167670@f1g2000cwa.googlegroups.com, "helee4@hotmail.com"
<helee4@hotmail.com> wrote:

Don Bowey wrote:
On 12/18/06 5:17 PM, in article
1166491077.756410.110270@80g2000cwy.googlegroups.com, "helee4@hotmail.com"
helee4@hotmail.com> wrote:


Homer J Simpson wrote:
helee4@hotmail.com> wrote in message
news:1166481170.125468.270750@48g2000cwx.googlegroups.com...

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?




What type of receiver is it? Regen, single or dual conversion?

Don

Hi Don, I wish I can answer your question. All I know is this is a 27
Mhz AM receiver for R/C car. Do you think it will be too much for a
beginer to fix? I mean the circuit looks pretty simple, so I figured I
want to give it try.

If the receiver does NOT have a crystal, it is probably a regen receiver and
you might be able to retune it to the transmitter. If there is no crystal,
look over the receiver to see if it has small adjustable capacitors and/or
coils that have a slug inside that can be adjusted. You will need plastic
tools to make any adjustments. Let me know what you find.

If the receiver has a crystal, be sure it is seated in its holder.

If it is not a regen, then it needs tools such as a scope and signal
generator in the hands of someone who can trouble shoot without having a
schematic.

Post the name of the city where you live and maybe someone will volunteer to
help.

Don

 

[Hugh Prescott]

Where are you located?

I repair radio systems for a large hobby shop in the MidWest, just north
of St. Louis, MO.

Have been doing R/C repairs since the 1960's

Will help if I can.

Make and model of car and radio?

Hugh




Don Bowey wrote:

On 12/18/06 6:44 PM, in article
1166496242.976455.167670@f1g2000cwa.googlegroups.com, "helee4@hotmail.com"
helee4@hotmail.com> wrote:


Don Bowey wrote:

On 12/18/06 5:17 PM, in article
1166491077.756410.110270@80g2000cwy.googlegroups.com, "helee4@hotmail.com"
helee4@hotmail.com> wrote:


Homer J Simpson wrote:

helee4@hotmail.com> wrote in message
news:1166481170.125468.270750@48g2000cwx.googlegroups.com...


What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

Looks like it is having problems round the detector / decoder areas. You
probably need more then a DMM to fix this.

How should I go about to start troubleshooting? And what kind of test
tool I would need?




What type of receiver is it? Regen, single or dual conversion?

Don

Hi Don, I wish I can answer your question. All I know is this is a 27
Mhz AM receiver for R/C car. Do you think it will be too much for a
beginer to fix? I mean the circuit looks pretty simple, so I figured I
want to give it try.



If the receiver does NOT have a crystal, it is probably a regen receiver and
you might be able to retune it to the transmitter. If there is no crystal,
look over the receiver to see if it has small adjustable capacitors and/or
coils that have a slug inside that can be adjusted. You will need plastic
tools to make any adjustments. Let me know what you find.

If the receiver has a crystal, be sure it is seated in its holder.

If it is not a regen, then it needs tools such as a scope and signal
generator in the hands of someone who can trouble shoot without having a
schematic.

Post the name of the city where you live and maybe someone will volunteer to
help.

Don

 

[Franc Zabkar]

On 18 Dec 2006 14:32:50 -0800, helee4@hotmail.com put finger to
keyboard and composed:

Homer J Simpson wrote:
helee4@hotmail.com> wrote in message
news:1166467960.828169.79030@n67g2000cwd.googlegroups.com...

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

This makes no sense. AFAIK the transmitter should not transmit
anything until you move the joystick, otherwise its 9V (?) battery
would quickly go flat.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[N Cook]

<kevin.pavin@gmail.com> wrote in message
news:1166468967.307428.139460@80g2000cwy.googlegroups.com...

Hi all,

I have a small surface mount amplifer/filter chip on a packed PCB that
I need to replace. In order to solder in the new one I obviously need
to desolder the old one first being as careful as possible not to
damage anything else on the board. I've never desoldered before and
was wondering if someone could give me the basics or atleast point me
to a tutorial for desoldering in this type of application. Thanks so
much for any advice,

Kev

Hint for de-soldering surface mount ICs.
Use a hot-air paint-stripper,1400W,500 degree centigrade,with 2 level heat
control to prolong element life.
Form a ring of silicone covered wire around the IC{to isolate the remaing
components on the pcb.Push a thin piece of wire
under one side of the IC and form a loop around the IC,repeat on the other
side;this is to remove the IC when the solder melts, tug on these wires
while heating up to ensure minimum heating contact time.
Place a slab of PTFE with right size hole cut into and
clip pcb and slab together with clothes pegs/Bulldog clips etc.
If the IC is for re-use then cover body of IC with heat insulating material
or blast IC with freezer spray.Allow the hot-air gun to get up to heat{say 1
minute}before applying to IC.
For more crowded boards make "conical" shrouds to surround the IC. I used
some PTFE strip that i had but thin paxolin or similar but drilled and wired
together would probably do. Cut 4 small trapezoids from the PTFE strip.
Fixed together with all long edges one side and short edges adjascent on the
other side. Fixed together with paper staples but for the smallest shroud
for 8 pin SM had to wire together the final join. Forms a sort of truncated
cone, frustrum, in shape. Tie to the PTFE cone (to stop the blower blowing
it off) with
copper wire or temporarily solder to distant points.
When practised the heated contact time should be less than
2 seconds - no board distortion or collateral damage surprisingly.
If you can't get the tugging wires under the IC then pass
under a few pins at each corner.
Because this tugging frees the IC at the earliest moment, the solder
on the board is not fully melted and leaves a profile for localising
the new IC in place and then solder pin by pin.
SAFETY NOTE:- ensure good ventilation, use safety goggles,and beware of very
slight risk of combustion.

other hints and tips on

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

 

[N Cook]

Meat Plow <meat@meatplow.local> wrote in message
newsan.2006.12.18.19.17.33.561000@nntp.sun-meatplow.local...

On Mon, 18 Dec 2006 11:09:27 -0800, kevin.pavin Has Frothed:

Hi all,

I have a small surface mount amplifer/filter chip on a packed PCB that
I need to replace. In order to solder in the new one I obviously need
to desolder the old one first being as careful as possible not to
damage anything else on the board. I've never desoldered before and
was wondering if someone could give me the basics or atleast point me
to a tutorial for desoldering in this type of application. Thanks so
much for any advice,

Kev

google

http://www.scienceprog.com/ease-way-to-desolder-smd/
--
Pierre Salinger Memorial Hook, Line & Sinker, June 2004

COOSN-266-06-25794

And for those of us without broadband, an outline of that method is ?

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

 

[Scrim]

"Andy Cuffe" <acuffe@gmail.com> wrote in message
news:777bo2tijmp45obk3vii87r0a0p7gmc6no@4ax.com...

On Sat, 16 Dec 2006 12:55:22 GMT, "Scrim" <nospam@nospam.com> wrote:


First it blurred: I started prodding around in the back with a long glass
rod. I tried tapping the tube, tube end pcb, focus leads and the focus
adjust side of flyback transformer unit, to no avail.
The blurred focus cleared itself after a while, but later there were a
series of pops from the back accompanied by momentary collapses of the
screens image. I have no idea where the pops came from. If I knew this was
an insoluble tube problem I'd just give up, but, at best, this is such a
good monitor I'm still holding out for the chance it's reparable.
Any ideas how I could pin down the problem or eliminate any suspects?
Thanks

Scrim

The only real other possibility is the flyback. Unfortunately, that's
a pretty expensive part to replace on a long shot. It's also worth
checking for signs of arcing in the CRT socket.

Andy Cuffe

acuffe@gmail.com

OK, Thanks Andy and everyone else for the help,

Scrim

 

[Mark D. Zacharias]

jrgreene1968@suddenlink.net wrote:

Hello, i have a problem with a 3801 denon receiver, ..I bought this
receiver from a guy on the internet, said to be in exellent shape,
when it arrived, i plugged it in and it will not do anything, no
display, no standby light, no click when you hit power switch
nothing. I have checked all 7 fuses on the receiver with an ohm
meter, they are all ok. checked voltage where power cord plugs into
board, shows 120 volts, if you unplug receiver and checked switched
outlet on back of receiver, the outles show open with ohm meter,
unplug yellow and white wire on transformer to board and now switched
outlets are no longer reading open....does this sound like a power
transformer, any way to test?

Sorry - forgot all about you yesterday. I'll try to get you that manual.

mz

 

Franc Zabkar wrote:

On 18 Dec 2006 14:32:50 -0800, helee4@hotmail.com put finger to
keyboard and composed:


Homer J Simpson wrote:
helee4@hotmail.com> wrote in message
news:1166467960.828169.79030@n67g2000cwd.googlegroups.com...

I have a R/C car reciever (Kyosho Mini-z) which has become very poor
range recently. I have checked battery both on the transmitter and at
the car, crystal, and wiring, they all seems to be fine. The symptom
is if I have both the transmitter and the car switched on, the car will
twitch (the servo) badly, and the motor is start to running on its own
without me pressing anything.

What happens if the transmitter is switched off?

The car will totally stop twitching. So, I thougt it could be
transmitter that was bad, but I tried with 3 different transmitter and
still the same... Looks as if the receiver has problem treating the
incoming signal?

This makes no sense. AFAIK the transmitter should not transmit
anything until you move the joystick, otherwise its 9V (?) battery
would quickly go flat.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Hugh, It is one of those ESC receiver combo for micro size R/C car.
May I ask you how much it would be to fix?

Franc, the transmitter for radio control car would start transmitting
immediately after you turned on, that's why it is a MUST for hobbist to
switch on transmitter before turning on the car.

 

[N Cook]

Dave <dspear99ca@yahoo.delete.com> wrote in message
news:LfUhh.71438$YV4.51840@edtnps89...

"N Cook" <diverse8@gazeta.pl> wrote in message
news:em89v1$s4e$1@inews.gazeta.pl...

And for those of us without broadband, an outline of that method is ?

--

Hope you've got a single-sided, single layer PCB, put the flat side on an
upside-down hot iron, remove SMD's (all of them 'cuz they all melt) from
board. Doesn't go into replacement of said parts.

so a no-no , i take it

 

[David Naylor]

ChrisCoaster wrote:

In our area, channels above the teens are considered "cable", as they
would be in most places. The service is Family(sans box), with
channels 2 - 80 provided.

The issues are herringbones and ghosting that appear on ch 15 and up,
nonexistent on some, horrible on others. However, when viewing the
same channels via the Insignia home theater one-piece(DVD-VCR-amp) all
channels are crystal clear - 3D clear to be exact.

Is the issue the TV?

Thanks,

ChrisCoaster

yup bad tuner common on sharps

 

[William R. Walsh]

Hi!

so a no-no , i take it

Probably a site of questionable reputation...I see a sign of the video and
then get redirected promptly to a "DMV lemon law" page or something.

William