I need a replacement part # and location for the "BAD-Blue Signal Video Output Transistor"???
I am a retired A/V technician and I have the ability to replace this component if someone can locate a shematic and get the infor mation that I need...thanx, Franklin -
My Zenith 32A33 screen goes blue after it warms up and then it turns itself off and after it is back on, it looks like the picture has a translucent blue veil over it and there are darker blue slanted lines across the screen.
Best Solutionposted on Jul 26, 2006
Rating: 76.38%, 304 votes
Pravin indicated that his solution for
32A33 32" TV Problem
is valid for all Standard Televisions
90 % probability, looks like the Blue Signal Video Output Transistor has become faulty. This is a very simple "fixable' problem for a Professional Technician. Should not take more than 15-20 minutes.
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Re: I need a replacement part # and location for the...
Actually, your description indicates that the blue gun in the tube itself is shorting out. This happens when the set has been on for a while and the metal parts in the CRT guns have heated up and actually contact each other. If the video output transistor is bad then your screen would be blue right from the start. An easy way to prove it is to monitor the voltage of the blue pin on the picture tube socket. It should measure around 150 - 175 volts. When the screen starts going blue you will see that voltage drop dramatically. Quickly pull the CRT board off the picture tube while watching the voltage on the blue pin. If the voltage jumps back up the instant the socket is removed, your picture tube is bad. There are CRT rejuvinators that have the "remove short" function, but that has about a 50% chance of success and I usually find that the short will return a few months down the road.
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If the color tone is just a bit more blue, check the video output section circuit for any fault. If there is no fault, and still you see blueish tone, replace the blue output transistor. The video output stage circuit card can be located at the back of the CRT itself, will be directly plugged on to its back. If nothing helps, you have to enter its service mode option, to check the blue drive, and blue cutoff settings. If this si the case, it will be best to contact any service technician, since the adjustment is somewhat critical one. To get some details, http://electronicshelponline.blogspot.com/ Pull up older posts.
Hello Check the Blue video output transistor for loose solder. This transistor can be located at its video output card, usually pluged on to the neck of the picture tube. There is no blue output is now, only Red and green are there. The mixing of Red and Blue color, and absensce of blue color, causes the raster to appear as yellow. The fault is purlely with blue output transistor at the video output state of your tV. If there is no loose solder, just replace this transistor with same number. If loose solderings are found, resolder that points by applying a little more solder, without making any solder bridge short in between adjecent solder terminals.
Blue video output section of your Soney tv has failed. It may be due to a open video output transistor or a resistor. Video output section can be located at the picture tube base card itself. in some models, Sony used transistors, and on others they uses IC for this section. Just open your tV, and measure the voltages at the Red, Green and Blue cathode voltages. It should be almost the same to each other. In your tVs case, the voltage at the Blue cathode will be high. Normally it should be due to an open resistor or loose or bad solderings. I advise you to resolder most of the suspected solder points with applying a little more solder, without making any solder bridge shorts in between. Check it out. If this does not help, check Blue output transistor, or if it is an Ic; whatever may be used, for open. If found faulty, replace it with same type and number. OK.
You have a bad ground on a color output transistor or a bad ground on a color output resistor. These are located on a board that is attached to the CRT. Also check the diodes on this same board, these may be bad as well. In worst cases the color output transistor and a diode will be bad. Thanks for asking!
Hi, quiescent current is set with a diode string located far away from the output transistor high miller compensation cap values used, quasi-complementary (of course), lots of non-linear, single-transistor gain stages here and there.
That's all i can remember about it...
This is most likely because it is not driven(no signal coming to its base) , you`ll have to follow it`s signal path all the way to the chroma demodulator or jungle i.c .There might be a few drivers transistors in between the processor and the output.
An oscilloscope is handy in tracing the signal but you might have luck by testing all the components along the way.
Otherwise it might be the processor that has a bad output. Hope this will help
Replace 120k resistor on the blue
video output module. Resistor is located next to the blue video
output transistor (has heat sink). If you replace it with a 1/2 watt
carbon type, it will probably never happen again. I recomend the
same resistor on the red and green video boards at the same time.
if it is white brightlines along with blue back ground please check
1 sypply to blue video output transformer.
2 crt base or connector loose.
3 check components related to blue video ckt & blue video output transistor.
4 blue signal reaching to blue video section
5 verv very rare case if set is old set then there is a possibility of crt.
hope this will help.
I will not bore you with advice which you cannot follow. (90 % probability, looks like the Blue Signal Video Output Transistor has become faulty). This is a very simple "fixable' problem for a Professional Technician. Should not take more than 15-20 minutes.Nothing you can do. Call for Professional help.