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Crt A68EGD low emission of cathode. Is possible to increase the hitting

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Hello,

yes, it is possible. You can increase the hitting.

Good luck.

Posted on Jul 19, 2010

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My 99 alero has emission code P0452 how. Can I fix it


P0452 - Evaporative Emission Control System Pressure Sensor Low Input.
An excessively low voltage from the sensor is sent to ECM.

The EVAP control system pressure sensor detects pressure in the purge line. The sensor output voltage to the ECM increases as pressure increases. The EVAP control system pressure sensor is not used to control the engine system. It is used only for on board diagnosis.

Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)

Possible causes
- The EVAP control system pressure sensor circuit is open or shorted
- EVAP control system pressure sensor may be faulty

Possible solution
- Retight gas cap - Replaced EVAP Control System Pressure Sensor

Hope this helps.

Jun 02, 2011 | Oldsmobile Alero Cars & Trucks

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Audio OK but no Picture


NO PICTURE; SOUND OUTPUT OK; PICTURE TUBE BASED COLOR TELEVISIONS.

 

This is a common fault to most of the picture tube based televisions, irrespective of its brand and model number.  There are several reasons for this fault, and 90% of them are related with its video output card, usually located at the neck of the picture tube. Plugged on to its neck.  This card can be pulled out from the neck of the picture tube to repair.  Pull it strait back, no sideways movement should be done, while pulling it out, as it may cause damage to the connection pins of the picture tube.

 

 If you see a color predominant screen that is, if the screen shows excessive blue, red or green color with nice white lines all across the screen, lying parallel to each other and inch apart or so.

 

Check which color is predominant?  Just assume the blue color predominant screen with nice slanting line across the entire screen, about an inch apart to each other.

 

The first thing to do is to measure the voltage at the blue cathode of the picture tube.  You can do this check, while the set is On.  Set a multimeter to measure DC voltage range 500V or above.  Check the voltage at the blue cathode.  You can see markings on the card Bk, Rk & Gk.  All of these are the three cathode connection points.  Among the, Bk is now out discussion point now.

Understand that, the cathodes of a vacuum tube, is negatively biased, that is, if the voltage of the cathode will go down with respect to its screen voltage, the emission of that cathode will increase, and vice versa.  In our case, now, the voltage at the Bk will be less.  Check the voltage of the other two cathode points for reference.  A slight voltage difference, says about 3 volts or so, is Ok, but should never be too below to this.

 

Here one thing to note is, that the voltages of the other two cathodes are high, and the voltage to the blue cathode only is very low.  This is the reason you see a high intensity blue screen.  It were happened to one among other cathodes, say if the voltage at RK is low, you will see a high intensity red screen, and if voltage at Gk is very low, you will see a high intensity green screen.  Of course all this screen will have lines as said earlier [retrace lines] will be there.

 

Let us come to the reasons for this fault.

 

Take the case of blue predominant screen as stated earlier.  It is sure that the voltage at the blue cathode will be low in this case.  That is, the blue cathode pin of the picture tube does not get proper voltage to cut off.

Check the solder terminal of the picture tube base socket pin of blue cathode first.  It is advised to resolder all the crt base connecting socket, soldered on the CRt base board [video output board], by applying a little more solder, because, these solder terminals will heat up while TV works.  Repeated heating and cooling may make the solder terminals to get loose, and no proper connection.

If the solder terminals are OK, there is blue predominant screen, check this resistor connected to the blue video output transistor for value developed or loose soldered.  Check the voltage across the tow terminals of this resistor.  This is the collector current limiting resistor, and will be of a resistance value between 10 to 15Kohms/2W.  If the value of this resistor had developed high, the voltage at the Bk will be low.

If the resistor is found OK, and still the voltage at the Bk is less, than the other two cathodes, check the video output transistor [blue] for Collector to Emitter short.  Replace it is advised.


on Jun 09, 2012 | Sony Televison & Video

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Cathode emission check for colour picture tubes


<p>How to check the colour cathodes of a picture tube for emission<br /> <p> <br> <p>It is very easy to cehck the emission of the cathodes of a colour picture tube. Assuming all other circuit parts are working, including LOT [Line output Transformer] and video output section.<span> </SPAN>There is proper screen voltage; focus voltage and EHT [Extra High Tension]. Locate the three cathode points on the base card, usually marked as Gk, Bk and Rk.<span> </SPAN>Keep the brightness, contrast and colour control to zero position.<span> </SPAN>Take a wire of suitable length, say 50cms or so, tie its one end to TVs chasis [negative].<span> </SPAN>Take one resistor of value 100K 1W, tie its one end to the other end or the wire, thus one end of this resistor is now connected to negative chasis and the other end of it is free now.<span> </SPAN>Hold this resistor with with some electrically noncunductive material [using hand gloves will be better]; switch on the Tv, wait a minute or so to get it warm up.<span> </SPAN>Just make a touch at each cathode of the picture tube base card solderings.<span> </SPAN>Just one touch will give you a colour of the respecive cathode on the screen.<span> </SPAN>Never hold it for long time. This process can be used for checking cathode emission of any type of Cathode Ray Picture tubes. <br> <p>

on Apr 18, 2011 | Televison & Video

2 Answers

Color is all red


i dont know contact you service

Apr 08, 2011 | RCA F32645 32" TV

1 Answer

Sorry if this posts twice. I think I might have posted an ealier question in an improper area. I have a Sony Wega 32" Trinitron Model KV-32F S200 (Year 2003) Recently, I've been getting a Green...


Hello

There are two causes for this problem. One is related with green output transistor, and the other is to chroma Ic. The most common cause is with the transistor said above. You just check the video output voltage points at picture tube base board. There are three cathodes may be marked as R,Gand B. In trinitron picture tubes, these pins are pin number [8 Blue KB], pin number [9 Green KG] and pin number [10 Red KR]; and the voltages must come approximately equal to KR=154, KB=155, and KG=163, and the main video output voltage goes to these transistors will come around 225VDC. These are not accurate voltages tor refer. It may vary by 2% to set by set. All the three transistors used will be identical in number, and usually found 2SC3271N. In your TVs case, green cathode voltage may be very low from the fault stated above I thinks. When cathode voltages goes low, emission of that cathode will increases, and colour of that cathode will be predominent. You just check these voltages, and check the main video input voltage said above too. There are three resistors of 2W fitted to the the main video voltage and collector of each transistor said above; and if any one,say the resistor fitted to green output transistor collector is faulty, or open or loose sodered, the voltage at the green cathode [pin-9] will be low causing this problem. If the transistor said above gor a leak with collector to emitter will also may the cause.
Just check it. Normally this base card of Sony TVs are marked C board. If all the transisors are found okl, and still the problem perisits, the fault must be in the Chroma Ic. It may need replacement.
In practice,I found this fault to be due to bad solderings in the base card. You just check it first and go forward.
If any doubts, contact me through Fixya. OK.

Nov 10, 2010 | Sony FD Trinitron WEGA KV-32FS100 32" TV

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White Raster with thin lines; Sound Ok.


White raster with retrace lines: No picture, Sound OK
(picture tube based telivisions.)

It is a common fault to occur in most of the CRT based telvisions, regardless of which brand it is. There will be sound OK, and a bright screen with thin white horizontal lines across; at about an inch space, all over the screen area. This fault may occur along with colur shades also, like blue screen with white retrace line, red screen with white retrace lines, green screen with white retrace lines. Let us take the first case. A white raster with white thin retrace line acorss the screen. These are call vertcial retrace lines technically. To make it mor understand, we have to go to some picture tube electrode details. There are three colour cathodes for a colour picture tube, Red, Blue and Green. Two girds are there called Focus and Screen. Focus grid is supplied with focus voltage which in turn determine the cocus of picture, and screen grid is supplied with screen volrage which determine the emission of the picture tube; in short. There is a final anode to all the picture tubes, which supplied with Extra High Tension voltage, can be located at the top side of the picture tube, to which the EHT voltage from LOT is connected with the help of rubber ****** and clip. Without these three voltages, EHT, Screen and Fcous, no raster will be produced. Therefore in our case, there is a raster, so, horizontal output section including Line Output Transformer [LOT] is functioning well, and as far as sound is there, tuner and video IF section are working well. In fact, all other section except, video output section is working properly.
There are three cathode points on the base card, marked as Bk, Rk and Gk. Check the voltages of these three cathodes. In our case, it will be very low or approximately equal to zero. When cathode voltages goes low, emission of the CRT increases, is the reason. There must be a voltage between 120 and 135VDC at these points. Find out the reason for this voltage drop is the next step. The video drive voltages in most TVs comes from LOT windings, after rectification and filtering. There will be one reisitor of low value, say one Ohms or so, will be connected series with this winding, in between diode and winding. Check the voltage at the cathode of this rectifier diode first. If found low replace the diode and the smoothin capcitor. The smoothing capacitor will be between 33 and 47MFD 250VDC rating. Replace both of them. If there is volatge, say 200VDC or so, check whether this voltage comes to the CRT base board or not, If not, check the conducting wire, serial resistors; if used for open. There is no chance of transistor shortage at this time as the raster we see is white. If raser we see have a specific colour predominent, that is green, blue or red, check the revalent video out transistors and replace it. It is best to replace all the three video output transisors at the same time with same batch and number.

on Apr 18, 2011 | Televison & Video

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SONY TRINITRON ONE COLOUR PREDOMINANT SCREEN


Sony Trinitron sets are of CRT [Caothde Ray Tube] types. The common fault seen in these type of TVs are any one colour predominant on screen wih sound OK. Either red, blue or green colour with some thin horizontal lines at about an inch apart will be seen on the entire screen. This is totally a display card problem, which can be seen pluged onto the picutre tube neck. There are three electron guns for every picture tube, which emits red, blue, and green beams, which in turn illuminates the phosphor on the screen to get that colour. If no emission from all guns, results in a blank screen, ie black screen without any disply at all. The three colour beams together produces proper coloured picture what we see on screen. These three gun's terminals are brought out by pins of the picture tube outside to which video signals are given in appropriate proportion to produce a TV picture. Normally, all these three pins are biased with a voltage of about 170 to160VDC+ve. Take one colour gun, as an example and and let me describe the problem.
Let it be a green gun. These guns are called cathodes of the picture tube. If it gets a voltage with respect to its grid, it will emit electrons according to the voltage applied to it. This is a negative process, that is, as the voltage at this pin drops, its emisson incresses and vice versa. If the emission increase, the colour with respect to that gun also will increase and gets predominant at the screen. So when we see a green predominant screen, there will be less voltage at the green cathode with resepect to the other two. If red colour is predominant, the voltage at red cathode will be less than the other two. If blue colour is predominat, the voltage at the blue cathode will be less than the other two.
We must find out the reason for this fault first. Assume that your Tv has a red predominant screen with some thin lines across it, at about one inch apart of the entire screen, it is clear that the the red cathode voltage is very lower than the other two. the main reason for this fault, normally seen in most of the Sony Trinitron, are loose soldering points either to the picture tube base socket or the resistor connected between the red drive transistor's collector point. Resoldering the most of these points on the base card by applying a little more solder will rectify this probelm. Other possibility is shorted video output transistor of that cathode. A direct short [collector to emitter] of these transistors will drop volatge to very low at that respective cathode of the picture tube, and that colour will be pridominant along with lines. Replacing the transistor will solve the problem. In some cases, the resistor connected to that transistor may have blown out. If so, it should alo be replaced. Whatever the case may be, voltage at the respective cathode that emits colour will be very low with respect to the other two. Find out the reason and rectify it. You can compare the voltages of the other two cathodes with respect to the faulty colur cathode. Cathode pins will be marked on the base card, and can be identified. It is best to pull out the base card from the picture tube neck and place it somewhere a safe place without shorting it with other parts of the TV. You can measure the voltages of these points very easly, without fearing the damge to the picture tube. After all are found Ok, replug the base card and switch on the TV. The set will be alright. In rare cases, chroma IC also can be a reason for this fault. if it is faulty, after a short period after switch on the TV, the IC will overheat and shutdown the entire system.

on Mar 21, 2011 | Televison & Video

1 Answer

Retrace green, relay on/off..when turn on the screen is green and after a few seconds it turns off by itself


Oh dear ! I fear my answer may not be what you want hear but my advise is free. Bright green raster with Flyback (retrace) lines may indicate a heater cathode short in the tube (crt) this causes a sharp increase in beam current and the power supply shuts down into standby mode. To prove the point isolate the red and green cathode pins on the tube base and cross couple the red video output stage to the green cathode pin and the green output to red cathode pin using wire links. If set now comes on with bright red raster the fault is in the green video output stage and not the tube. If still bright green then tube is most likely cause. Gently tapping the tube neck may prove the point, but take care the tube neck is thin glass and if hit too hard will break compounding your problems. WARNING if you do not feel totaly confident to attempt this level of repair there is no shame in seeking the advice of your local service technician. Safety first always

Mar 04, 2010 | Sanyo 21MT4 21" TV

1 Answer

Have 46 samsung dlp that has green lines all over the screen . menu still works but doesnt go away on the menu mode. the green is so thick that you cant see any picture in the background.


Red, green, or blue retrace lines ( a quote from "Notes on the Troubleshooting and Repair of Television Sets", found at http://www.repairfaq.org/sam/tvfaq.htm#tvrgbrlin )

Where only one color is showing, suspect an incorrectly adjusted individual background/bias control or bad part on the CRT neck board for that color.
  • Individual brightness/background/bias control(s) - mark setting of pot for the problem color and then see if a slight adjustment removes the retrace lines. See the chapter: "TV Adjustments". Of course, if this happened suddenly, the problem is not due to a misadjusted control though a dirty pot is possible - turn it back and forth - this might clean it and restore normal operation.
  • Component or connection on CRT neck board - insufficient voltage to or incorrect biasing of the video driver for this color can result in the CRT never totally blanking. Compare voltages and signals, and swap components between good and bad channels to confirm.
  • Blanking circuit - this may be a part of the video/chroma chip or separate. Check and compare waveforms of good and bad colors to determine if the blanking pulses are making it to the video output.
There is a slight possibility that a bad CRT may result in visible retrace lines. To eliminate this possibility:
  • Disconnect the filament - all evidence of a picture, raster, and retrace lines should disappear once the filaments/cathodes have cooled (15 seconds or so. If there are still visible retrace lines, the CRT is suffering from cold or field emission from someplace (may not even be the cathode).
  • Turn down the screen (G2) control on the flyback (usually). If one color remains no matter how you set the control, again there is some kind of weird emission from the CRT. However, if white/gray retrace lines remain, the problem may be in the screen supply.
(quote ends)
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You will be greatly helped if you have a schematic for your TV set, and you may need to change some parts, clean some connector contacts and/or tweak settings inside the set, so remember the original settings before you tweak them...

Good luck

3rq8 (Triarcuate)

Jul 23, 2009 | Televison & Video

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