Toshiba TV29C90 problem; Image fades to black...

[Barney]

"Lanzar" <christian.loo@netikka.fi> wrote in message
news:677fafc5.0503311238.6929d6cc@posting.google.com...

I have a television with a strange problem. When i start the tv it
takes about 10-15 seconds before the picure appears. And also the red
color is missing, so the piture is bluegreen (but no lines). And then
after about a half minute red fields starts flashing across the
screen, and then it turnes off. Any idea what cause this?

As a test try swapping the drives to the CRT over. If it's the CRT then it
will still flash red, if it's something else it will flash either green or
blue.

 

[Art]

Sounds like you need a better antennea with preamp installed professionally.
A deep fringe antenna should do a work.
<gcotterl@co.riverside.ca.us> wrote in message
news:1112331012.798812.136320@l41g2000cwc.googlegroups.com...

The antenna has a 300-ohm matching transformer to which is attached the
75-ohm round coax cable.

 

[Art]

Probably a defect within the controller, will need to have it professionally
serviced, if the appropriate parts are still available.
<gcotterl@co.riverside.ca.us> wrote in message
news:1112336383.288350.195040@f14g2000cwb.googlegroups.com...

Hey Lee,

Thanks loads for your #$@J)*Y*$#&^# response.

 

[Art]

Get is professionally repaired, if parts are still available.
<gcotterl@co.riverside.ca.us> wrote in message
news:1112330843.088707.245550@l41g2000cwc.googlegroups.com...

I have an old (late-1980's) RCA Colortrak 2000 TV operated by a
remote-control or by the buttons on the front panel of the TV set.
When I turn the TV on or change channels, the time is displayed on the
TV screen.

I set the TV-time to match the real-time (for example, 2 PM). But, as
time goes by, the TV-time progressively gets out-of-synch with the
real-time. For example, at 7 PM (real-time), the TV-time is 9 PM.

How can I get the TV-time to stay the same as the real-time?

Is the clock a part of the TV or is it in the remote-control?

Gary

 

[Art]

Check the drive voltages at each of the crt cathodes, compare the red with
the other two. do this with the socket attached and removed from the crt.
Trouble shoot the red video drive circuitry before totally condemning the
crt. If a projection set, try swapping the red drive pwb to one of the other
crts and see if the set functions, remove the red crt drive and see if the
set functions. ETC, Good Luck
"Barney" <barneyxyzNOSPAM@hotmail.com> wrote in message
news:EPWdnYqzaKATldDfRVnyvA@brightview.com...

"Lanzar" <christian.loo@netikka.fi> wrote in message
news:677fafc5.0503311238.6929d6cc@posting.google.com...
I have a television with a strange problem. When i start the tv it
takes about 10-15 seconds before the picure appears. And also the red
color is missing, so the piture is bluegreen (but no lines). And then
after about a half minute red fields starts flashing across the
screen, and then it turnes off. Any idea what cause this?

As a test try swapping the drives to the CRT over. If it's the CRT then it
will still flash red, if it's something else it will flash either green or
blue.

 

[Sam Goldwasser]

"Mr. Lee" <bubba@biff.com> writes:

TV is 20 years old get a new one or forget about the clock.

That's your best suggestion? I don't knoe where I got the idea this was
a *repair* group.

--- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
+Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
| Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

Note: These links are hopefully temporary until we can sort out the excessive
traffic on Repairfaq.org.

Important: Anything sent to the email address in the message header above is
ignored unless my full name is included in the subject line. Or, you can
contact me via the Feedback Form in the FAQs.

gcotterl@co.riverside.ca.us> wrote in message
news:1112322963.316093.327350@g14g2000cwa.googlegroups.com...
I have an old (mid-1980's) RCA Colortrak 2000 TV.

I operate the TV -- using a remote-control or using the buttons on the
front panel of the TV set -- the time is displayed on the TV screen.

When I set the TV-time to match the real-time (for example, 2 PM), five
hours later (at 7 PM real-time), the TV-time is 9 PM.

How can I get the TV-time to stay the same as the real-time?
Is the clock a part of the TV or is it in the remote-control?

Gary

 

[Wouter van Ooijen (www.vo]

How do I check if a transistor is working using a multimeter - both
BJTs and FETs? How will I know if it's shorted etc? Also, for a BJT
how will I know the emitter, base and collector by using a multimeter?

dunno for fets. for BJTs first measure the diodes to distinguish PNP
and NPN. Now you should know which lead is the B. Choose E and C. Use
resistance measurement between E and C. Should be high. Put your
finger on B and E. Resistance should be lower. Exchange E and C choice
and repeat. Lowest resistance is the correct E and C.


Wouter van Ooijen

-- ------------------------------------
http://www.voti.nl
Webshop for PICs and other electronics
http://www.voti.nl/hvu
Teacher electronics and informatics

 

[Harry Dellamano]

<genenamg@yahoo.com> wrote in message
news:1112291657.595936.40770@z14g2000cwz.googlegroups.com...

How do I check if a transistor is working using a multimeter - both
BJTs and FETs? How will I know if it's shorted etc? Also, for a BJT
how will I know the emitter, base and collector by using a multimeter?


Thanks,
GN
I am surprised no one mentioned how easy it is to test a MOSFET with a

DVM.
First you must have a DVM that's open circuit voltage in diode mode is
greater than the Vgs(th) of the device you are testing. I have a Fluke DVM
that puts out 3.55 VDC which works for all MOSFETS that I have tested. Also
remember that the gate has large capacity to the other pins such that it
will store the last potential that was forced on it.

P to S + N to G open
P to S + N to D diode (0 .70V)
N to S + P to G open
N to S + P to D Ron

Harry

 

[John Bachman]

On Fri, 01 Apr 2005 14:46:47 GMT, wouter@voti.nl (Wouter van Ooijen
(www.voti.nl)) wrote:

How do I check if a transistor is working using a multimeter - both
BJTs and FETs? How will I know if it's shorted etc? Also, for a BJT
how will I know the emitter, base and collector by using a multimeter?

dunno for fets. for BJTs first measure the diodes to distinguish PNP
and NPN. Now you should know which lead is the B. Choose E and C. Use
resistance measurement between E and C. Should be high. Put your
finger on B and E. Resistance should be lower. Exchange E and C choice
and repeat. Lowest resistance is the correct E and C.


You might consider the nifty little component tester by Peak at

www.anatekcorp.com/testequipment/atlas.htm It tests all those
components, figures out the lead configuration for you and performs an
actual test of the device, not just continuity.

John

 

[krw]

In article <cooq41904pah2n60aiuah7ppov66pjrndo@4ax.com>,
johnREMOVE@anatek.REMOVEmv.REMOVEcom says...

On Fri, 01 Apr 2005 14:46:47 GMT, wouter@voti.nl (Wouter van Ooijen
(www.voti.nl)) wrote:

How do I check if a transistor is working using a multimeter - both
BJTs and FETs? How will I know if it's shorted etc? Also, for a BJT
how will I know the emitter, base and collector by using a multimeter?

dunno for fets. for BJTs first measure the diodes to distinguish PNP
and NPN. Now you should know which lead is the B. Choose E and C. Use
resistance measurement between E and C. Should be high. Put your
finger on B and E. Resistance should be lower. Exchange E and C choice
and repeat. Lowest resistance is the correct E and C.


You might consider the nifty little component tester by Peak at
www.anatekcorp.com/testequipment/atlas.htm It tests all those
components, figures out the lead configuration for you and performs an
actual test of the device, not just continuity.

There is also the el-cheapo multi-tester from Harbor Freight. I picked
up three (one for the brat, two to throw in various tool boxes) this
one for $2.99 each. I just got them last night, so I haven't tried the
transistor tester yet. They certainly aren't Flukes, but for $3 they
seem to work ok.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?function=Search
Search for 90899-1RGH. If you order it with the number 90899-1RGH from
their ex-tree catalog (rather than what shows up on the search above)
they're $2.99 each.

--
Keith

 

[John Woodgate]

I read in sci.electronics.design that "Wouter van Ooijen (www.voti.nl)"
<wouter@voti.nl> wrote (in <424d5e4d.1215840596@news.xs4all.nl&gt about
'Transistors Checking Troubleshooting - BJTs, FETs', on Fri, 1 Apr
2005:

dunno for fets. for BJTs first measure the diodes to distinguish PNP
and NPN. Now you should know which lead is the B. Choose E and C. Use
resistance measurement between E and C. Should be high. Put your finger
on B and E.

Shouldn't that be 'B and C'?

Resistance should be lower. Exchange E and C choice and repeat. Lowest
resistance is the correct E and C.

--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[JANA]

The time of day in most of the TV sets is in part of the main controller.
This is not a simple thing for the end user to service. You would have to
have the set properly serviced by an experienced tech. It is very possible
however, that the parts may no longer be available.

Considering the age of the set, the cost of the repair may not be worth the
investment. This is something you would have to decide for yourself. The
newer sets are superior to the one that you have.

--

JANA
_____


<gcotterl@co.riverside.ca.us> wrote in message
news:1112322963.316093.327350@g14g2000cwa.googlegroups.com...
I have an old (mid-1980's) RCA Colortrak 2000 TV.

I operate the TV -- using a remote-control or using the buttons on the
front panel of the TV set -- the time is displayed on the TV screen.

When I set the TV-time to match the real-time (for example, 2 PM), five
hours later (at 7 PM real-time), the TV-time is 9 PM.

How can I get the TV-time to stay the same as the real-time?
Is the clock a part of the TV or is it in the remote-control?

Gary

 

[sofie]

"JANA" <jana@ca.inter.net> wrote in message
news:3b5r9iF6fm6cpU1@uni-berlin.de...
.. The

newer sets are superior to the one that you have.
- - - - - - - - - - - - - -

HOWEVER, they probably will not last as long.... the CHEAP "build quality"
is getting more prevalent.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

 

[Rono]

Iv' changed a couple of the LA7610 IC's,
& they have never come back! Tube may
not be arcing! Rono.

 

[Tom MacIntyre]

On Fri, 1 Apr 2005 18:43:34 -0330, "Rono" <rono@nl.rogers.com> wrote:

Iv' changed a couple of the LA7610 IC's,
& they have never come back! Tube may
not be arcing! Rono.

Not to be impertinent, but perhaps they are being taken somewhere else
for susequent follow-up care? I have seen many jungle IC's fail in
this way due to the CRT arcing, and one technique to prevent it is to
clamp the CRT drive outputs.

Tom

 

[Deke]

<gcotterl@co.riverside.ca.us> wrote in message
news:1112331012.798812.136320@l41g2000cwc.googlegroups.com...

The antenna has a 300-ohm matching transformer to which is attached the
75-ohm round coax cable.

First, replace the 300-ohm transformer. Half of the baluns that come in
antenna kits these days are bad (Channel Master, Jerrold, Winegard...rotten
quality baluns)
Second, bypass the amp. If signal/picture improves, the amp is toast. You
can get 75 0hm barrels at Rat Shack, or any electropnics store.
Third, if you wired the cabling up, make sure you havent shorted out the
coax connector. Check all coax connectors. LOOK CLOSELY! One tiny strand
of wire, between the center (copper) conductor, and the wire mesh shield,
and its toast, and everything goes to hell. If someone else wired it up, or
you bought it refab, check the connectors anyway.
Fourth, if you have a small, portable television, and a long extension cord,
take it up and hook it directly to the antenna, and see how much snow you
have.
Fifth, how is the cabling run? Has some moron put a staple thru it?
Staples will not only kill your signal, but they could short out the power
to the amp, and blow up the power supply.
Sixth, is the amp a two piece unit? If so, is the power supply, usually
down in the house, plugged in?
Seventh, take the Terk back, and buy a real antenna.

 

[James Sweet]

"Barney" <barneyxyzNOSPAM@hotmail.com> wrote in message
news:EPWdnYqzaKATldDfRVnyvA@brightview.com...

"Lanzar" <christian.loo@netikka.fi> wrote in message
news:677fafc5.0503311238.6929d6cc@posting.google.com...
I have a television with a strange problem. When i start the tv it
takes about 10-15 seconds before the picure appears. And also the red
color is missing, so the piture is bluegreen (but no lines). And then
after about a half minute red fields starts flashing across the
screen, and then it turnes off. Any idea what cause this?

If it's a Zenith you probably have a short in the picture tube, otherwise
who knows, you have to post the brand and model for anyone to help you.

 

[Franc Zabkar]

On 31 Mar 2005 19:38:05 -0800, "Thomas" <cordless89@hotmail.com> put
finger to keyboard and composed:

I am trying to activate a relay when the vehicle is in anything other
than Park. The transmission module sends out 5V @ 120hz with varying
pulse widths. In Park, I read 0.71V with the meter and looks to be
apprx 1/7th of the pulse on the scope (square wave). In Reverse, the
pulse is measured at 1.6V of 1/3 of the pulse with higher voltages and
pulse widths in N,D,2. I've tried using this to enable a small dc
relay, but only get chatter (even in Park). I've been told I could do
the following...


RC Integrator - Unity-Gain OpAmp Buffer - Comparator

I think you would also need a sample-and-hold.

How would this work? Any help is greatly appreciated.

I'd prefer a one-chip solution involving a PIC micro, eg a $3 PICAXE
with on-chip BASIC. An intelligent chip could open up additional
possibilities.

Otherwise I'd opt for a discrete digital solution involving a 74LS123
retriggerable monostable multivibrator and a 74LS74 flip-flop.

Here's my hand drawn attempt:

http://members.optusnet.com.au/~fzabkar/PRNDL2.gif (7KB)

I've assumed a period of 8.3 msec (=120Hz), and pulse widths of 1.2ms
(1/7 x 8.3) and 2.8ms (1/3 x 8.3) for Park and Reverse signalling.
I've also assumed the pulses to be positive going.

The 74123 is triggered by the transmission pulse (P) and produces a
negative reference pulse, P1 (2.0ms). P1 clocks the 7474 flip-flop on
its rising edge, ie after 2.0ms. If pulse P is shorter than P1, then
the input to the FF will be low, otherwise it will be high. The Q or
Q* outputs can then be used to control a relay via a transistor.

Cext and Rext are chosen so that ...

2.0ms = 0.45 x Cext x Rext.
Rext >= 5Kohm.

I've selected a pulse width of 2.0ms because it falls half way between
Park and Reverse. Values of Rext = 10K and Cext = 0.47uF would give an
acceptable pulse width of 2.1ms.


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

 

[Franc Zabkar]

On Sat, 02 Apr 2005 13:19:42 +1000, Franc Zabkar
<fzabkar@optussnet.com.au> put finger to keyboard and composed:

On 31 Mar 2005 19:38:05 -0800, "Thomas" <cordless89@hotmail.com> put
finger to keyboard and composed:

I am trying to activate a relay when the vehicle is in anything other
than Park.

Oops, the relay driver transistor in my circuit should connect to the
Q output of the 7474, not its Q* output. I would also add clamping
diodes to the P input of the 74123:

+5V
___
|
_|_
/_\ 1N4148
|
|
P ---|--> 74123
|
_|_
/_\ 1N4148
|
_|_

Ground


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

 

[Franc Zabkar]

On 1 Apr 2005 07:43:18 -0800, gcotterl@co.riverside.ca.us put finger
to keyboard and composed:

Hi, Art:

According to the support-people at Terk (the manufacturer of the
antenna) "The TV38 is more than enough antenna for where you are".

The coax cable runs from the antenna to an antenna amplifier (about 20'
away) then out to the TV.

Gary

The best location for a masthead amp is on the mast. ;-)


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