Riddled TV Repair Forum

tbirdjkc · Joined: 19 Jan 2009 Posts: 9

Hi, i'm pretty sure the CRT is going out the tv. The screen takes about 5 minuets to warm up and then i get a flicker. i would like to see if i can turn the voltage up, but i cant find the knob, the only thing on the fly back is the dynamic focus knob and there is only a knob labeled H-sync on the board mounted on the neck of the tube. Any help is greatly appreciated. It is a 32" cabnet tv manufactured in 1991, if that helps. Also if their is a way could i bypass the IK circuitry to stop the flickering?

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Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

I guess you need to define flickering!! The IK line does not cause a flicker as such. What it does is blank the video and give you a no picture condition. This can cycle back and forth causing the picture to come and go at varying intervals. Consider this. If you are watching a black and white broadcast like the history channel many times does, is your picture tinted a color or is it a true grey scale like a black and white picture is supposed to be. If the picture is tinted and it is coming and going you have a bad CRT and no amount of fiddling will change that fact. If you can find the G2 control (may be mounted on the CRT pcb. Not on the neck but the board that plugs into the end of the CRT) you might make the picture stable but the problem WILL come back.

You cannot defeat the IK line as this will cause a no picture condition. The Micro has to have this information or it will blank the picture. This is not a Voltage as such but a series of 3 pulses so defeat is not possible. The original intent of the IK line was so that the set would automatically adjust the CRT bias and keep a good picture as the set ages. When the CRT can no longer produce the IK pulse the micro will blank the picture out causing a repair to be effected. Nice of them wasn't it.

Hope this helps

Jesse

tbirdjkc · Joined: 19 Jan 2009 Posts: 9

Thanks Jesse,
The picture does blank out at various intervals (on for 1-2 sec of for 1-3 sec) but when it comes back on the picture is bright and crystal clear, grayscale is very clear and sharp as well, so i am at a loss. the tube also seems to howl a bit when you listen with the rear cover off. I also noticed that the tv used to make a distinct loud buzz when turned on cold, it now only makes this noise when plugged in. Another weird thing is the fact that it hasn't been in use and un plugged for a few years and still retains all chanel presets color brightness audio and etc. settings Any ideas? i have a donor tv of the exact same model produced 2 years earlyer and it doesnt retain any settings as soon as its unplugged. im puzzled to say the least. the donor tv hardware is in perfect shape, so i think i'll try discharging them both and swapping innerds and see if i get the same issue.

Jesse Mack · Joined: 22 May 2008 Posts: 600 Location: The Last Frontier

ivtec · Joined: 19 Nov 2008 Posts: 10 Location: ma

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JTS1957 · Joined: 21 Jan 2009 Posts: 1387 Location: Far, Far Away

What does the doner set do? It might be easier to fix. :)
What's CRT tube number in each set? If same number AND doner set's tube is Good AND all plug-ins have SAME connectors/connections/ # of wires/ None "missing" / No "extras"... it should be possible to swap - in either direction.
By the way - Is there anything going on with any leds on front of set?

tbirdjkc · Joined: 19 Jan 2009 Posts: 9

Donor TV is the exact same set, same model #'s, everything is identicle, but is in worse shape cosmeticly and has a convergence issue, so i would have to figure that out, leds do nothing out of the ordinary. sleep led lights up for about 10 secs when turned on as it always has since the set was new. i always assumed it was a self diagnostic.