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Author Topic: Wells-Gardner 19-K7901  (Read 4778 times)

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doatopgun

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Wells-Gardner 19-K7901
« on: August 16, 2015, 06:22:38 pm »
I have a Wells-Gardner 19-K7901 that I bought and it run for about a minute and it would click off.  I discharged it and re-flowed the solder for the trouble areas.  The monitor actually runs now but it's really redish.  The monitor appears to have already had the caps replaced and a new flyback, even though it is hissing.  I am going to order the new flyback.  My question is, what else might I need to order due to redness issues?  Thanks for any guidance you can give me!

« Last Edit: August 16, 2015, 06:24:45 pm by doatopgun »

Paradroid

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Re: Wells-Gardner 19-K7901
« Reply #1 on: August 16, 2015, 06:59:03 pm »
Take a look at this Arcade Otaku guide: How to Correctly Set Up Monitor Colours and Brightness.
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CraftyMech

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Re: Wells-Gardner 19-K7901
« Reply #2 on: August 16, 2015, 08:50:23 pm »
First try adjusting the red drive pot on the neckboard. If you don't see any significant change, reflow the pins for the pot & nearby red drive transistor. Make sure the pot isn't cracked.

Still no change, then you can swap one of the other drive transistors for red. If the red tint is still constant and none of the above helps, the tube might have a short in the red gun.
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doatopgun

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Re: Wells-Gardner 19-K7901
« Reply #3 on: August 16, 2015, 11:50:10 pm »
Thanks for the info.  I will give it a shot tomorrow!

baritonomarchetto

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Re: Wells-Gardner 19-K7901
« Reply #4 on: August 17, 2015, 04:53:22 am »
Your flyback is ok so there's no need to replace it.
Your black is there so you have no color output transistors bad or carhodes shorted.
Check the solders on the neckboard and toy with the colors pots in that small pcb
« Last Edit: August 17, 2015, 04:56:36 am by baritonomarchetto »

CraftyMech

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Re: Wells-Gardner 19-K7901
« Reply #5 on: August 17, 2015, 03:00:48 pm »
Your flyback is ok so there's no need to replace it.
Your black is there so you have no color output transistors bad or carhodes shorted.
Check the solders on the neckboard and toy with the colors pots in that small pcb

The entire raster area is filled with red and there are retrace lines visible, so "your black is there" doesn't make sense.

The symptom is a prime candidate for a cathode short, or cold solder joint/bad color transistor on the neckboard.
« Last Edit: August 17, 2015, 03:04:00 pm by CraftyMech »
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baritonomarchetto

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Re: Wells-Gardner 19-K7901
« Reply #6 on: August 17, 2015, 04:11:29 pm »
Take a look to the start flag on the ground: i can see a good black there.
If the cathode was shorted or the output transistor shorted to ground the whole black would be "really" red :)
Thats only a wrong color adjustment to me, but my words doesn't make sense generally :D

grantspain

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Re: Wells-Gardner 19-K7901
« Reply #7 on: August 17, 2015, 05:04:41 pm »
remove the red drive transistor,that should prove if its a gun fault or not

some nasty convergence top right corner btw and i can't see much in the way of blue

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Re: Wells-Gardner 19-K7901
« Reply #8 on: August 17, 2015, 05:39:50 pm »
Take a look to the start flag on the ground: i can see a good black there.
If the cathode was shorted or the output transistor shorted to ground the whole black would be "really" red :)
Thats only a wrong color adjustment to me, but my words doesn't make sense generally :D

What you are perceiving is the effect of "simultaneous contrast". The red is clearly visible in the horizontal overscan area, that area would be black if what you are saying was true.
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baritonomarchetto

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Re: Wells-Gardner 19-K7901
« Reply #9 on: August 17, 2015, 06:00:50 pm »
Those raster lines are possibly due to a too high brightness: in that condition a non optimal red color level can make your black "reddish".
Anyway, i gave my two cents, let see what doatopgun say...

doatopgun

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Re: Wells-Gardner 19-K7901
« Reply #10 on: August 27, 2015, 11:16:23 pm »
There is no blue, and the only green I can get to show up when I wash out the screen with one of the green knobs.

The flyback was arcing, cap kit and flyback on ebay was 50+, and I didn't have good tools at that point so I just ordered one that had been rebuilt by someone else.  It came in and I realized it was the 8 pin version of the neck board and mine has a 10 pin version.  I'm thinking someone did a tube swap at some point?  I changed the neck board out with the 10 pin and it looked exactly the same without the arcing.  I did some adjustments and got it better, but the blue is not there.  Not sure about the green.

I ordered a new neck board, and I am going to try swapping out some parts from the 8 pin neck  board to the 10 pin.  I know I might be shunned by ordering stuff already fixed.  I've been a IT guy for 20 years, but I have never really delved into the circuit board side of things.  I'm getting good tools together and learning as I go.  I have a empty cabinet that will be from the ground up with a non working monitor so I want to learn the stuff.  I had to look up what a pot and transistor was tonight!  I need a circuit boards with multimeter guide for dummies!

grantspain

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Re: Wells-Gardner 19-K7901
« Reply #11 on: August 29, 2015, 05:16:28 am »
you can prove the crt guns by locating the colour cut off pots,even with no signal each should saturate the screen when adjusted with its particular colour
otherwise you can prove the guns by a momentary short of the gun pins of the crt socket to ground



you should check the wiring to the game board also and if necessary swap colour wires around to prove where the blue issue lies

doatopgun

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Re: Wells-Gardner 19-K7901
« Reply #12 on: August 31, 2015, 10:18:35 pm »
Swapped out the transitors and pots and still no blue.  Do color guns just go out?  Is their anything else i can check?  If not, anyone got a tube for sale?  :cry:

baritonomarchetto

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Re: Wells-Gardner 19-K7901
« Reply #13 on: September 01, 2015, 12:48:13 am »
A missing color is not a big issue 99% of the time, so it's not the case to give up: turn your monitor on without game (without video signal) and turn your screen pot up: what color is the raster?

doatopgun

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Re: Wells-Gardner 19-K7901
« Reply #14 on: September 02, 2015, 10:54:00 pm »
Got the new neck board and replaced it.  Still same issues.  I started to take the monitor out of the cabinet and took out the piece that holds the bezel, which has the speaker on it, and noticed a bright blue on the screen as the magnet passed by it.  Do you think a degausser could fix the problem?  Tried a electric drill, which didn't come close.

Without the game on it's red with horizontal lines.  I still can wash out the screen with red and green, but both blues do nothing.

I will take some pictures tomorrow.

baritonomarchetto

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Re: Wells-Gardner 19-K7901
« Reply #15 on: September 03, 2015, 12:49:20 am »
You probably have two issues. First, make me happy by running the monitor without game and try to fix the "red raster" issue by turning the red pot on the beckboard. If the pot has effect, you have no shorts, otherwise the cathode or output transistor is shorted.
Once the red is ok we can proceed with the missing blue issue.

With the magnet you have deflected the red or green beam and deflected the shadow mask so that the beam has hit some blue phosphor... not a useful test. You can damage the shadow mask, so dont do that.
« Last Edit: September 03, 2015, 12:53:33 am by baritonomarchetto »

doatopgun

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Re: Wells-Gardner 19-K7901
« Reply #16 on: September 03, 2015, 07:03:06 pm »
I took the game off and adjusted the red drive and cuttoff all the way up and this made the screen red.  Adjusting either the red cutoff or red drive down at this point would make the screen go back to blank.

I also took a picture of what I think is the raster lines?
« Last Edit: September 03, 2015, 11:01:31 pm by doatopgun »

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Re: Wells-Gardner 19-K7901
« Reply #17 on: September 04, 2015, 12:58:30 am »
Yes, those are raster lines.
Anyway, follow this checklist

-turn the "screen" potentiometer on the flyback down so that those raster LINES go away;
- calibrate your colors. There's a good tutorial from a klov user on youtube; this will eventually solve your red issue;
- run the monitor without video signal, rise the screen pot to have a white raster (the screen area) and take a look at the raster color. If it's white your blue is there;
-turn back your screen pot  down to remove raster LINES.

Follow this step by step or we will have no progress here...
« Last Edit: September 04, 2015, 01:20:07 am by baritonomarchetto »

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Re: Wells-Gardner 19-K7901
« Reply #18 on: September 04, 2015, 03:51:19 am »
its not clear from your info so i will ask,if you adjust the red cut off to minimum does the screen still remain a little red?

doatopgun

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Re: Wells-Gardner 19-K7901
« Reply #19 on: September 07, 2015, 11:07:07 pm »
I got that raster to show up by adjusting the main board, without touching the flyback pots.  I did adjust the flyback pots and was able to get rid of the red issue.  I tried to get the raster to show up as white but none of the neck board adjustments seem to affect the color.  The only thing that seem to affect the color of the raster is the adjustment to the flyback.  Turned up all the way, there was a purple.  I'm going to take pictures tomorrow. I know so little, it's hard for me to explain!