GO7 too bright

mrsodapop

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Hi All,
I have a GO7 that was DOA, I installed Bob's deluxe kit(Fly,HOT,cap kit). Now it powers up and colors are good, but picture is way too bright. I did try turning it down at flyback, but as in the pics, it still is too bright. I looked on Randy's chart, and replaced X303, but no change.
Thanks for any help
Aaron M.
 
Did you replace the cap on the neckboard? Is it in properly? Proper value (10uF 250v)? Usually if it is bad, it can cause the screen to be over-bright and you won't be able to turn it down all the way...
 
I had the same issue when i changed the VR and it wasnt soldered in properly.

Check your B+ and see if its 120v
 
Hi All,
I have a GO7 that was DOA, I installed Bob's deluxe kit(Fly,HOT,cap kit). Now it powers up and colors are good, but picture is way too bright. I did try turning it down at flyback, but as in the pics, it still is too bright. I looked on Randy's chart, and replaced X303, but no change.
Thanks for any help
Aaron M.

When you turned the brightness knob, did it make any difference whatsoever? If not, bad pot?
 
OK, My B+ is 124.3vdc, I did check the cap on neck board- It was replaced, is in the correct orientation( - pointing to the inside, not toward edge), and is 10uf/250v. If I turn brightness on flyback, it gets so bright you can't see the image, turn it the other way, and I get what you see in the photos.
ARM123, what is the VR?
Thanks for any ideas
Aaron
 
I have seen the SCREEN/FOCUS block go bad on these before. (not often, but happens)
If you have another around I'd swap just that block and see what you get.
 
I'll just throw this out there as a possibility...
If the aquadag coating has been rubbed/washed/flaked off a large portion of the tube, it can cause the screen to be overly bright and show retrace lines.
 
Hi all,
I swapped the whole chassis out in to a known good tube, picture is still way too bright. I than swapped out the screen/focus board with a known good one, still no change, too bright.
Keep the good ideas coming!
Thanks
Aaron
 
Check R125 on the neckboard. It should be a 470k-ohm 1/4-watt resistor. It is in direct line between the brightness pot and the tube. If it is shorted or very low value, that could be your problem.

Otherwise, you could send it out to one of repair guys to look at it for you...
 
Oh, and bump your B+ down to 120. Sometimes a little high on the B+ causes the picture to get a little brighter...
 
I finally got time to get back to this POS monitor. I replaced X303 first, no change.
Modessitt, I looked on the neckboard and found the location of R125, but no resistor was there. I checked 3 other GO7s and they also do not have a resistor at R125. It looks like this part was not used on the actual boards??.
Thanks guys for the ideas, but I recently picked up over 35 monitor chassis that I'm trying to test/repair so I'll just throw this on the "big issues pile".
Aaron
 
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