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Vertical Deflection Output Circuit LA7840

I need equivalent for this IC

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6 Suggested Answers

6ya6ya
  • 2 Answers

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Posted on Jan 02, 2017

MikeNJ1964
  • 398 Answers

SOURCE: tv cuts off 10 seconds after switch on and destroying vertical output ic

If the main IC is not putting out a vertical drive signal then the vertical output will not do anything and therefore will not be damaged. What exactly do you mean by the set "literally eats deflection IC's"? What is the number on the vertical output IC? I will bet that your pump-up cap or pump-up diode is defective.

Posted on Jul 05, 2007

ttech
  • 139 Answers

SOURCE: Sanyo DS25390 Vertical problem

Jack,Did the Vert Ic have Broken conns around the legs?

Posted on Jul 19, 2007

  • 556 Answers

SOURCE: missing vertical deflection on philips TV

TDA 8362B IC which have vertical freq.output is at pin no.43. (vert.osc) caution for fixing this problem minimise brightness to avoid crt burn. proceed as follows 1 if you are getting sawtooth at output of ic tda 8362 pin 43 then check 1 supply at vertical output ic from eht. 2 yoke connector loose . 3 check vertical output ic parts. 4 finally vertical ic. please check for normal output from power supply even though fault gets rectified just for protection. good luck.

Posted on Sep 23, 2007

  • 556 Answers

SOURCE: Sanyo 25" Standard Tube Vertical Deflection Problem

you can proceed as follow to fix it.

  1. reduce brightness to minimum to avoid screen burn.
  2. check voltage on vertical uotput
  3. check yoke connector for loose.
  4. check v/yoke winding.
  5. check v/drive from signal processor to vertical output

now your problem how to find out whether drive is there or not it is very simple even you donot have scope.

you simply touch with screw driver or meter prob  at the poibt where vertical signal is input to vertical stage

if h/line is spreadindg or tries to spread then your output is ok &problem is in drive ckt.

for schematic try given site give model no &download it

http://www.eserviceinfo.com/index.php?what=search2

hope this will help

 

 

Posted on Oct 12, 2007

  • 1 Answer

SOURCE: Does the TOSHIBA TA8445K Vertical Deflection IC fails when the Deflection Yoke is Dirty?

hola tengo un tv onwua que no me habre el verticar ya revise los voltajes y estan bien pero en la pata 11 tengo solo 7 voltios en ves de 12 voltios cual puede ser el problema de mi parte muchas gracias.mi email es ruben_148_2@hotmail.com.

Posted on Aug 15, 2008

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1 Answer

On screen horazantal white line


May not be an easy fix:

A single horizontal line means that you have lost vertical deflection. High voltage is most likely fine since there is something on the screen.

This could be due to:


Dirty service switch contacts. There is often a small switch located inside on the main board or perhaps accessible from the back. This is used during setup to set the color background levels. (On some sets, this is located on the CRT neck board and may be a jumper plug or other means of selecting service mode - not an actual switch.)
When moved to the 'service' position, it kills vertical deflection and video to the CRT. If the switch somehow changed position or got dirty or corroded contacts, you will have this symptom. Flip the switch back and forth a couple of times. If there is some change, then replace, clean, resolder, or even bypass it as appropriate.


Bad connection to deflection yoke or other parts in vertical output circuit. Bad connections are common in TVs and monitors. Check around the pins of large components like transformers, power transistors and resistors, or connectors for hairline cracks in the solder. Reseat internal connectors. Check particularly around the connector to the deflection yoke on the CRT.

Bad vertical deflection IC or transistor. You will probably need the service manual for this and the following. However, if the vertical deflection is done with an IC, the ECG Semiconductor Master Substitution guide may have its pinout which may be enough to test it with a scope.

Other bad parts in vertical deflection circuit though there are not that many parts that would kill the deflection entirely.

Loss of power to vertical deflection circuits. Check for blown fusable resistors/fuses and bad connections.

Loss of vertical oscillator or vertical drive signals.
The most likely possibilities are in the deflection output stage or bad connections to the yoke

May 27, 2014 | Samsung Televison & Video

1 Answer

Igo 20"tv using la7840 verticl line


Check all the solder terminals at the vertical output IC. Re-solder all of it by applying a little more solder to each solder terminals. If it do not help you, desolder out the vertical output IC, and check all the related components. Check and replace damaged one/s. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy. Surf the site with patience. Pull up older posts. Surf the site with patience.
http://electronicshelponline.blogspot.com/

Apr 10, 2014 | Televison & Video

1 Answer

Onida tv


Horizontal line on screen denotes the absensce of vertical sweep itself. Check the vertical output section circuit to LA7840. Check for any loose solder terminals. It will be best to measure the input voltage to that IC from the LOT secondary supply. Try by replace the IC. If these do not help you, measure the frequency from the main IC. It should be at 50Hz. If this frequency is not present, the main IC is faulty. If you wish to get some more details about the circuit, check this link. http://electronicshelponline.blogspot.com/ Pull up older posts there, either by its left side bar, or see it in Timslide option. Schematic diagrams, that show vertical IC LA7840 is given. You can compare it.

Jun 23, 2013 | Televison & Video

1 Answer

Vertical line


Hello,

Most probably the vertical deflection amplifier is failing. The most common part that fails is the vertical output transistor.
The set is too old to find documentation on part numbers and descriptions. Probably the part is no longer available and you will need the assistance of someone who can help you find an equivalent transistor that will do the job.
Of course, without testing we cannot be certain the failure is the output transistor. It could be from something else such as the voltage regulator that feeds the dc line to the vertical section. Could be the vertical synchronous level that goes too low to trigger the vertical sweep generator.

Other bad parts in vertical deflection circuit though there are not that many parts that would kill the deflection entirely.

Loss of power to vertical deflection circuits. Check for blown fusable resistors/fuses and bad connections.

Loss of vertical oscillator or vertical drive signals
Good luck.

Jun 01, 2010 | Sony BRAVIA KDL-52W4100 52 in. LCD HDTV

1 Answer

Flat line in center on tv


You have lost the vertical deflection circuit. Replace the vertical output ic and all the capacitors in the vertical circuit.

Oct 20, 2009 | Toshiba CF32G50 32" TV

1 Answer

I HAVE GOOD AUDIO BUT A THIN LINE IN THE MIDDLE OF THE SCREEN THAT HAS VIDEO. ALSO THE SCREEN IS BLACK ON THE TOP AND BOTTOM WITH THE THIN LINE OF VIDEO IN THE MIDDLE.


Have you vertical deflection circuit checked for bad Vertical IC, and or Bad vertical Capacitors in the vert output section for the deflection board. Also have Vertical output Pump up Capacitor replaced, also have B+ voltage check coming from flyback transformer, for any open fusible resistors

Oct 12, 2009 | JVC AV-20120 TV

3 Answers

I have a three year old model pvc2542 tv/vcr combo the picture is just a line in the center of the screen


Bad vertical deflection circuit, unless you have a bad connection (bang on set to set it it fills out for a second) . you will need components replaced such as the IC, capacitors possibly a fuse from the power source to the vertical IC.
If its a bad connection soldering the IC pins is not to hard if you are OK with taking it apart yourself.
gd lk
Eric

Aug 21, 2009 | Televison & Video

1 Answer

Vertical line in center have replaced vertical output ic


If the line is vertical then the problem is no horizontal deflection. The vertical chip is probably fine.

Check connections around yoke (thats the connector with at least four wires that goes up to the coils around the neck of the tube)

Maybe that TV has two horizontal output transistors. One for deflection and one for high voltage? Check both of them. Look for bad solder joints!!!

May 21, 2009 | Sanyo DS31520 31" TV

2 Answers

Tv cuts off 10 seconds after switch on and destroying vertical output ic


If the main IC is not putting out a vertical drive signal then the vertical output will not do anything and therefore will not be damaged. What exactly do you mean by the set "literally eats deflection IC's"? What is the number on the vertical output IC? I will bet that your pump-up cap or pump-up diode is defective.

Jul 03, 2007 | Sharp 27K-S100 TV

2 Answers

20 inch T.V.


You have a bad vertical output IC, or the sweep power supply that drives the IC is bad. Your going to need the service schematic diagram and the know how to fix solid state electronics.

Sep 01, 2006 | Durabrand DWT1905 TV

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