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Author Topic: Wells Gardner 25" k7000A zenith flyback version CAP questions  (Read 648 times)

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arcadepcnut

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I have the dreaded Wells Gardner 25" k7000A zenith flyback version of this monitor. have had for sometime. Years....15 years? yeah probably.
I have been using this in my vertical mame cabinet since i was a teenager, Built this machine in the late 90s.

Well it needs some love.
But im not sure what love it needs exactly.

The picture is very dim even on highest brightness setting. I have it adjusted to highest now just to get a playable picture. Over the years have to turn it higher and higher.
I dont know what to replace to get it back going optimally so it will last other 10-15 years.

I have a entire spare board
I have a spare  zenith flyback
I dont have a cap kit for this board.

what is needed to be done by a layman that will return the brightness back to a good normal nice bright crisp look?
I dont want to use my spare board yet because its a used spare and i dont know what issues it might have as my current works fine just dim.

thank you in advance for your help

grantspain

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Re: Wells Gardner 25" k7000A zenith flyback version CAP questions
« Reply #1 on: July 05, 2019, 12:50:13 am »
i would suggest testing your spare board to prove its not weak guns on the tube
caps are pretty important though

arcadepcnut

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Re: Wells Gardner 25" k7000A zenith flyback version CAP questions
« Reply #2 on: July 05, 2019, 10:20:38 am »
ok. i watched a video on weak guns and mine isnt doing those symptoms. i will pull the current board to put a cap kit on it and swap in the spare board while that one is out. if the spare board looks good ill keep the current board with new caps as a spare :)
« Last Edit: July 05, 2019, 10:34:42 am by arcadepcnut »

arcadepcnut

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Re: Wells Gardner 25" k7000A zenith flyback version CAP questions
« Reply #3 on: July 24, 2019, 08:30:26 am »
I thought i had a spare board but its for a 19" :(
So I replaced ALL caps with a cap kit and still had weak brightness and contrast and colors. basically no difference than before the cap kit.
 I emailed the seller and after some back and forth he determined it to be a bad voltage regulator. As my B+ on well gardner k7000a is at 143v and he determined its unsafe to use (been using it for 10+ years...whoops?!)

So i have pulled the board out again to replace that piece and noticed on the bottom of the board that the existing regulator repair is all sorts of jacked and im wondering even if i get a new regulator if i can even fix it.
Regulator is the 5 pins in the lower right next to the hole in the board.
I have attached picture to see if anyone can offer advice.
the pin 4 on the regulator the solder pad is missing and someone jumped it over.
pin 5 isnt even connected as the pad is gone and i have no idea where an alternate point might be?
« Last Edit: July 24, 2019, 08:32:00 am by arcadepcnut »

grantspain

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Re: Wells Gardner 25" k7000A zenith flyback version CAP questions
« Reply #4 on: July 25, 2019, 12:42:53 pm »
your chassis would shutdown with 143vdc b+, you must reading wrong point

arcadepcnut

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Re: Wells Gardner 25" k7000A zenith flyback version CAP questions
« Reply #5 on: August 09, 2019, 05:43:07 pm »
Update:
no thats wrong.
i promise it was 143v and was working just fine and actually BETTER than it is now.

what i have done:
put in a new cap kit. for the entire board.
change out the voltage regulator transistor with a new one and now it reads 130v exactly

Now i have a monitor with weak brightness (same as it was before all this work) and now no RED color at all. even when shorting the red transistor on the yoke no red.
So now this monitor is basically useless. i have troubleshot the red best i can took the tube to the only TV repair guy left alive in town.
He could not get his rejuvinator to work on my Zenith Tube and says from his experience tube is bad.

I think the moral is here: sometime with old tech its better to leave well enough alone alone than spend a bunch of time effort and money to make things worse.
These CRTs are dying and with so few people left with equipment and knowhow to repair them we will all be using LCDs in our cabs in 5 more years. :(
« Last Edit: August 09, 2019, 05:48:43 pm by arcadepcnut »