Quote:Are we talking about horizontal lines that are slightly diagonal and span the length of the screen? If this is the case, they are known as retrace lines and are meant to be blanked by the video IC. This is normally caused by one of three things. First, it might be a heater-to-cathode short, but because they are white, I would say it is unlikely since shorts are unusual and usually only occur on one or two heaters (electron emitters), and it would require all three to form white retrace lines. The second issue is that the grid voltage on the CRT is too high (otherwise known as the G2 voltage). The third option is that your RGB cutoff voltages are much too high (they were reset), or that a resistor or other current-limiting component on the CRT neck board failed, causing a higher-than-normal voltage to appear across the filaments.
Vertical Retrace Lines in Restoration Have Been Removed Don Patterson provided the images. It should be noted that many sets stream video to the CRT's grid. The polarity of the vertical pulse will be incorrect in this scenario, and the circuit depicted above will not operate. Another place in the vertical scan circuit that gives a negative going pulse may be found. If this is the case, you will need to experiment with the values of R3 and C3. To format smartphones, use invisible text. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
In addition to these, you may see an N, which Sony employed for their low-cost PVM series with a reduced TVL count. What exactly is a TVL count? Try Wikipedia or andynumbers gaming blog for more information. To put it simply, it is a measure of resolution for CRTs. The greater the count, the sharper the scanlines. Sharpness also increases noticeable flicker on interlaced video since a lower count causes the image to be blurrier and the alternating scanlines of an interlaced video (more on that later). Furthermore, with larger TVL counts, the black area between scanlines would be more visible.
Copyright, Samuel M. Goldwasser, 1994-2007. Every right is reserved. This document may be reproduced in whole or in part if both of the following requirements are met: 1. This notice is presented in its full at the start. 2. There is no payment other than the cost of copying. I may be reached via the Email Links Page on the Sci.Electronics.Repair FAQ (www.repairfaq.org). White/gray retrace lines | Index | Retrace lines caused by a bad CRT..
Crt Retrace Lines Fix
I responded yesterday, but the email got lost during the Forum update. Assuming you don't have the manufacturer's IIC calibration unit, Ajex, try this: 1. Adjust R830 and R831 to produce the least amount of green and blue; the image will most likely have a red tinge. 2. Create a blank screen by plugging in an AV input with nothing hooked in. 3. Make the room as dark as possible while still being able to see the TV controls. The less light there is in the room, the better. 4. Reduce the brigtness control to the lowest setting. 5. Adjust the flyback transformer's'screen' control until you can *barely* see the first hints of something on the screen. It should be as dark as it can possibly be. 6. Change R830 and R831 to make the image gray. As you spin the controls, the colour will vary. If the screen becomes too bright, reduce the brightness again. The goal is to see the deepest gray possible. 7. Re-display the image and set the brightness to normal. All of this should line the red, green, and blue weapons' cut off locations. Please let us know if the lines are still visible. Brian.
After about a month of usage, the TV I just purchased began to acquire retrace lines. I returned it to the lab for warranty (special offer) and got it analyzed by genuine specialists. They discovered that even with the filament supply turned off and VG2 set to 0V, the screen would still light up. They could even tell the electrons weren't coming from the cathode. That was in a test setup with merely the image tube. So the obvious conclusion in this situation has to be that the tube was defective, and it was replaced (32" 16:9 SF, extremely expensive). It had something to do with processing issues during the electron gun's production. Even though this was an uncommon occurrence, retrace lines CAN occur as a result of a faulty picture tube. It's more common to suspect the VG2 (screen voltage) or a flaw in the RGB video channel.
When the beam reaches the right-hand side of the screen in raster scan, it experiences a process known as horizontal flyback, in which its intensity is diminished and it causes the beam to "fly back" across the screen (the top-most mauve line). While the beam is returning, it is also being pushed down the screen. The horizontal/vertical retrace time is caused by the inductive inertia of the magnetic coils that deflect the electron beam.
Is it worthwhile to restore an old television?
When your flat screen TV's warranty expires and it develops a malfunction, most experts will advise you to replace it. A damaged screen on a television should only cost a few hundred pounds to fix. However, with new TV costs falling every year, it's definitely best to simply get a new TV.
Crt Tv Retrace Lines Problem
After about a month of usage, the TV I just purchased began to acquire retrace lines. I returned it to the lab for warranty (special offer) and got it analyzed by genuine specialists. They discovered that even with the filament supply turned off and VG2 set to 0V, the screen would still light up. They could even tell the electrons weren't coming from the cathode. That was in a test setup with merely the image tube. So the obvious conclusion in this situation has to be that the tube was defective, and it was replaced (32" 16:9 SF, extremely expensive). It had something to do with processing issues during the electron gun's production. Even though this was an uncommon occurrence, retrace lines CAN occur as a result of a faulty picture tube. It's more common to suspect the VG2 (screen voltage) or a flaw in the RGB video channel.
The first is the degaussing circuit, and the second is the CRT Tube itself. First, I opened the TV to inspect the degaussing circuit. It consists of just two components: a degaussing coil and a posistor (PTC). I unplugged the degaussing coil from the connection and measured its resistance using an Ohmmeter. I received 18 Ohm, which implies there is no open circuit. The posistor was the subject of the following test (A Posistor is a resistor that connects in series with the degaussing coil around the picture tube). Because the posistor couldn't be verified with a multimeter, I had to replace it and retest it. I purchased the component from an electronics store.
I believe the most likely cause is a failure of either the EEPROM that controls your RGB cutoff voltage or G2 or "Screen" voltage to rise significantly, or a failure of a component on the CRT neck board that either allows the G2 voltage to rise significantly or the component on the video IC that blanks the screen during retrace has failed. My hunch is that the EEPROM or static-dynamic memory within the monitor and TV (which regulates many of these voltages on contemporary TVs and monitors) has either been partly damaged or reset to some type of standard value, leading you to see the retrace lines. Then then, if they aren't retrace lines at all, this is all irrelevant. Anyway, good luck with this; truly, diagnosing and repairing CRT issues these days may be difficult and costly.
I soldered the new e-cap and tested the surrounding components for dry joints; all of the solder connections seem to be in good condition. I then switched on the television, and a regular image emerged (see photo below): Assuming that I did not identify the bulged e-cap in the previous scenario, I will begin to investigate the DC supply voltage to the vertical output IC. If the DC supply voltage is satisfactory, I will replace the vertical output IC and retest. If you want to be an expert at diagnosing and fixing CRT TVs, I suggest Humphreys Ebook. Check out his Ebook by clicking here.
Sharp Crt Tv Retrace Lines Problem
TV Maintenance Suggestions Symptom Problem Description APEX Size Model Chassis Fix 20 AT2008 Power Dead replace rectifier in SMPS secondary 20 AT2008 Video Retrace lines on a white screen G1 should be resoldered on flyback transformer 21 AT2002. There is no audio. RF565 (10 ohm/2 watt) 21.08.2008 There is no picture in the video, but the sound is OK. 220uF/160V C561 GB5108 51 Vertical vertical issue; changing the vertical IC did not help. LB01 51 GB51HD09 Resolder Video Green is missing from Video RG17 (on the green CRT board), as well as RB17 and RR17 52 GB51HD09. No blue color in the video RB17 (on blue CRT board, 330ohm, .25W) Isn't your model listed? Look for it on our Forums. Caution: Do not commit suicide. Don't blame us if you do... We completely warned you. These guidelines are meant for skilled service professionals who are well-versed in their craft. Individuals who are not qualified should never service their own equipment. Televisions carry very high voltage, which may kill you.
For measuring reasons, the visual signal is commonly referred to one volt. Black is represented by 0.3 volts, whereas white is represented by 1 volt. At the conclusion of each line, the video is disconnected or blanked, and a pulse ranging from 0.3 to 0 volts is introduced. This is the synchronization signal for the line. These pulses are split at the receiver and sent into a PLL, which generates the line scan. The frame synchronsing signal, which occupies a few lines, is also a collection of pulses applied at the conclusion of each frame.
Is there anybody who knows where I should start looking? I didn't notice anything about brightness or contrast in the diagram, so I'm not sure where to begin. I have a 19" CELERA CL2002 Chasis CN-12C model from 2002. I discovered a schematic for an APEX model AT1302 Chasis CN-12C that looks to be close.
There's also the phosphor itself. As the beam contacts the phosphor, there must be some dispersion to the surrounding phosphor, which reduces dot sharpness. Photographic film contained some light scattering inside the emulsion, which restricted resolution. A specific thickness of the phosphor may generate a comparable phenomonon.
