cadillacman
Well-known member
*info posted assuming you know how to solder, use a meter, and properly dischagre a monitor. Please get on youtube or a simular site and educate yourself before you attempt any monitor repair*
Hey guys... i figured id talk a little about some common issues ive come across with the wells gardner 13k, 19k,and 25k7000's.
*90% of this info doesn't apply to the new 7400,7500,u5000 series. Check this out for more info about those models:
http://forums.arcade-museum.com/showthread.php?t=193468
There are some common issues with these older wells gardner k7000 monitors and i figured i would take some time to discuss these issues. Im no "expert" but living around chicago i ran across these monitors alot. If you have a blog or other arcade site, feel free to repost this information.
SCREEN ISSUES???The first one is screen collapse or a lightning bolt effect if the monitor chassis is tapped on. There are varying degrees of this, but its something that usually changes with monitor run time.. There are a few larger resistors in the r98-r101 area. Do yourself a huge favor and unsolder and resolder those. A common issue is sometimes r101 traces will fry, or will tarnish black. You wont see this unless you UNSOLDER then inspect the trace pads.(its amazing how fried they get sometimes) Be sure to pull and ohm test r101 as sometimes it will actually change value due to running so hot. Sometimes you will get screen weirdness/jittering accompanied by a arcing sound. This is usually the flyback arcing out,the red anode lead arcing out, or a loose crt gorund wire.
There have been noted cases (but i have not verified) of C51 going bad causing screen size issues or in extreme cases screen collapse. C51 is a "dipped tantalum" electrolytic capacitor and it is NOT INCLUDED in any cap kit.
SOLDER::These monitors(like any other 30 year old piece of electronic equip.) also develop bad solder connections. It will look as if there is a circular crack or ring in the solder joint. This can vary from screaming obious to barely noticable. On the wells monitors, these tend be prevalant in the area of large resistors/components, yoke connector pins, power diodes, and ***the video input pins**** Cracked solder at the input pins can cause intermittent color loss or intermittent rolling issues/jumping..
FLYBACK ISSUES:These monitors have a high flyback failure rate. Theres 2 o.e. flybacks used on these monitors apparently. Both interchange, but i have seen a difference. The older monitors run a flyback with white adjustment knobs. This flyback sucks. The plastic casing will literally fall apart in your hand and they tend to crack alot. If you come across one, REPLACE IT NOW whether the monitor works or not! The other fly is all black. If you see a yellow goo bubbling out of the seams, its bad/going bad. Look it over very well. Find a crack? REPLACE IT! Replacing a cracked fly on a working monitor will save you alot of money in the long run. Black ones also crack but not as often. Some of the replacement flys have been failing too, make sure to double check if you have issues after a repair. Zenith made flybacks look nothing like these and are hard to find.
Note the yello goo coming out the seam.
Heres another blown fly, this one cooked in the center.
New and failed.
SHUTDOWN:Ok , heres our worst case senario. You have a monitor thats just dead. Heres some basics to start. CHECK POWER: do you have 120vac power at the power connector to the monitor? CHECK FUSES: is the fuse on the chassis blown? CHECK FUSE HOLDER:these will get weak and lose contact/tension, or the fingers will literally fall off.
VISUAL: check the chassis over well for cold cracked solder joints, check the flyback for cracks, check the chassis for cracked traces, check for bulged caps, etc.
This is also worth a read: http://www.therealbobroberts.net/dead.html
CHASSIS FUSE BLOWN??? Check the hot(horizontal output transistor) ohm in between the center and third pin... if you read anywhere near 0 ohms, its shorted.(pull; and retest to make sure) If the hot is shorted, theres a reason it failed... usually a flyback failure. In this case replace the flyback, hot,fuse, and VOLTAGE REGULATOR. WHen the hot fails, if usually takes out the voltage reg. Check saftey cap, c36, it will sometimes short out, especially if youve had a hot of flyback failure.. Ohm it out one meter lead at each end. Replace this cap if shorted. I have also heard about the large diodes shorting out, but ive never seen it personally*STILL WORTH YOUR TIME TO CHECK THESE* In rare cases, its also been documented that c38 will short. Keep in mind once you find the shorted part, you may have to go back and recheck everything else again.
CHASSIS FUSE NOT BLOWN BUT STILL IN SHUTDOWN?This could be a blessing or a curse. If the fuse is good, this could be a simple fix. FIrst things first make sure you have power input. Visually check the shutdown pot to make sure its not broken. Visually check over solder connections. I have seen capacitors next to the shutdown pot get so dried out that the monitor shut down. Replacing just those caps fixed it, but i went ahead and recapped the monitor anyways. If you have a real grimy monitor chassis then mark the position of the shutdown pot knob. Move it back and fourth using pliers or a simular tool, then reset it to where you made your marks.. I have seen that pot be so dirty that it caused shutdown. Do you have screen "static"? do you have neck glow??? YES=you have some signs of life. Turn the screen control on the flyback just for gigs... sometimes you get lucky and somebody just turned down the screen knob at some point. NO= pull one leg of d10, does it power on now? YES= bad vreg or some other issue you need to chase down.**DO NOT leave d10 unhooked permanently!**
ALso check r103. if open, it wont powerup.
INTERMITTENT COLORS: :Sometimes you get lucky and its just a cold solder joint somewhere(usually around the video input pins or on the neckboard). However if your one of the unlucky folks to get a color that sticks on all the time or after warmup, then you may not be so lucky. Try swapping the drive transistor of the offending color to a color that works. Same for the pots. SAME? most likely you have a shorted gun in the tube. This can be diagnosed and sometimes repaired with a rejuvenator. Make buddies with a guy that has one heh...
I should also note that ive ran into uneven brightness issues. It looked like vertical jailbars but it was just like uneven contrast, worst on the left side for some reason. Replacing c56 or 57 fixed it, but i went ahead and did a full capkit anyways.
POTS POTS POTS For some reason, wells used these ceramic backed adjustment pots. They wear out easy, and crack VERY easily.
If you are having a issue with rolling, brightness, color, whatever, LOOK THE POTS OVER WELL. Ive missed a cracked pot a few times and wasted alot of time before i figured it out. If you have the wells monitor with remote board that has broken pots, you can get pots from bob roberts(www.therealbobroberts.net), or www.arcadepartsandrepair.com Or for just about the same price, you can get a brand new remote board assy from chad over at arcade cup (www.arcade-cup.com)
Left the crt-neckboard ground off??Well thats a bummer! Without ground itll try to arc and spark to ground anyway it can. I recently had one that i replaced the hot and vreg, got it to run finally however the pic was very skewed. It did not sync well and the pic was crooked and half off of the screen. I replaced ic2 (vert/horiz ic) per ken laytons suggestion and that cured my issue!
What size chassis do i have? This is open to debate. In my experience,19 inch chassis have been silkscreened with a "447 or 449" them. 25" chassis have been silkscreened with a "5xx" number. Some forum members have seen them either/or, which is odd. Between the # of the voltage regulator and the silkscreened number on the chassis, you can usually figure it out. (vreg ending with 123= 123v regultor, this is usually a 19" chassis. V-reg ending with 130= 130v regulator, this should be a 25" chassis.
Whats the difference between 8pin and 10 pin neckboards? It has nothing to do with tube size. Ive seen 13, 19, and 25 inch monitors with either/or. If you have a 10 pin tube and a 8 pin chassis, you can still use the chassis as long as it came form a monitor of the same size. Simply swap out neckboards and your good!
PARTS RESOURCES: www.therealbobroberts.net-- Sells arcade parts to the general public, good prices, and if you do repeat business with him and establish a friendship, he will usually cross ship our stuff! (currently on hiatus)
www.arcadecup.com chad over there in green bay, wi repairs monitor chassis' for those who cant fix them themselves. He has a decent turnaround time and fair prices. He also sells new and used monitor parts.
www.arcadepartsandrepair.com is a klov member, stands behind his products, and sells flybacks, cap kits, repair kits, pinball kits, etc.
www.mouser.com, www.digikey.com, www.bdent.com, www.future-electronics.com all sellers of replacement electronic components..
k7000 manual pdf here: http://arcarc.xmission.com/PDF_Monitors/Wells Gardner K7000 Manual.pdf
Hey guys... i figured id talk a little about some common issues ive come across with the wells gardner 13k, 19k,and 25k7000's.
*90% of this info doesn't apply to the new 7400,7500,u5000 series. Check this out for more info about those models:
http://forums.arcade-museum.com/showthread.php?t=193468
There are some common issues with these older wells gardner k7000 monitors and i figured i would take some time to discuss these issues. Im no "expert" but living around chicago i ran across these monitors alot. If you have a blog or other arcade site, feel free to repost this information.
SCREEN ISSUES???The first one is screen collapse or a lightning bolt effect if the monitor chassis is tapped on. There are varying degrees of this, but its something that usually changes with monitor run time.. There are a few larger resistors in the r98-r101 area. Do yourself a huge favor and unsolder and resolder those. A common issue is sometimes r101 traces will fry, or will tarnish black. You wont see this unless you UNSOLDER then inspect the trace pads.(its amazing how fried they get sometimes) Be sure to pull and ohm test r101 as sometimes it will actually change value due to running so hot. Sometimes you will get screen weirdness/jittering accompanied by a arcing sound. This is usually the flyback arcing out,the red anode lead arcing out, or a loose crt gorund wire.
There have been noted cases (but i have not verified) of C51 going bad causing screen size issues or in extreme cases screen collapse. C51 is a "dipped tantalum" electrolytic capacitor and it is NOT INCLUDED in any cap kit.
SOLDER::These monitors(like any other 30 year old piece of electronic equip.) also develop bad solder connections. It will look as if there is a circular crack or ring in the solder joint. This can vary from screaming obious to barely noticable. On the wells monitors, these tend be prevalant in the area of large resistors/components, yoke connector pins, power diodes, and ***the video input pins**** Cracked solder at the input pins can cause intermittent color loss or intermittent rolling issues/jumping..
FLYBACK ISSUES:These monitors have a high flyback failure rate. Theres 2 o.e. flybacks used on these monitors apparently. Both interchange, but i have seen a difference. The older monitors run a flyback with white adjustment knobs. This flyback sucks. The plastic casing will literally fall apart in your hand and they tend to crack alot. If you come across one, REPLACE IT NOW whether the monitor works or not! The other fly is all black. If you see a yellow goo bubbling out of the seams, its bad/going bad. Look it over very well. Find a crack? REPLACE IT! Replacing a cracked fly on a working monitor will save you alot of money in the long run. Black ones also crack but not as often. Some of the replacement flys have been failing too, make sure to double check if you have issues after a repair. Zenith made flybacks look nothing like these and are hard to find.
Note the yello goo coming out the seam.
Heres another blown fly, this one cooked in the center.
New and failed.
SHUTDOWN:Ok , heres our worst case senario. You have a monitor thats just dead. Heres some basics to start. CHECK POWER: do you have 120vac power at the power connector to the monitor? CHECK FUSES: is the fuse on the chassis blown? CHECK FUSE HOLDER:these will get weak and lose contact/tension, or the fingers will literally fall off.
VISUAL: check the chassis over well for cold cracked solder joints, check the flyback for cracks, check the chassis for cracked traces, check for bulged caps, etc.
This is also worth a read: http://www.therealbobroberts.net/dead.html
CHASSIS FUSE BLOWN??? Check the hot(horizontal output transistor) ohm in between the center and third pin... if you read anywhere near 0 ohms, its shorted.(pull; and retest to make sure) If the hot is shorted, theres a reason it failed... usually a flyback failure. In this case replace the flyback, hot,fuse, and VOLTAGE REGULATOR. WHen the hot fails, if usually takes out the voltage reg. Check saftey cap, c36, it will sometimes short out, especially if youve had a hot of flyback failure.. Ohm it out one meter lead at each end. Replace this cap if shorted. I have also heard about the large diodes shorting out, but ive never seen it personally*STILL WORTH YOUR TIME TO CHECK THESE* In rare cases, its also been documented that c38 will short. Keep in mind once you find the shorted part, you may have to go back and recheck everything else again.
CHASSIS FUSE NOT BLOWN BUT STILL IN SHUTDOWN?This could be a blessing or a curse. If the fuse is good, this could be a simple fix. FIrst things first make sure you have power input. Visually check the shutdown pot to make sure its not broken. Visually check over solder connections. I have seen capacitors next to the shutdown pot get so dried out that the monitor shut down. Replacing just those caps fixed it, but i went ahead and recapped the monitor anyways. If you have a real grimy monitor chassis then mark the position of the shutdown pot knob. Move it back and fourth using pliers or a simular tool, then reset it to where you made your marks.. I have seen that pot be so dirty that it caused shutdown. Do you have screen "static"? do you have neck glow??? YES=you have some signs of life. Turn the screen control on the flyback just for gigs... sometimes you get lucky and somebody just turned down the screen knob at some point. NO= pull one leg of d10, does it power on now? YES= bad vreg or some other issue you need to chase down.**DO NOT leave d10 unhooked permanently!**
ALso check r103. if open, it wont powerup.
INTERMITTENT COLORS: :Sometimes you get lucky and its just a cold solder joint somewhere(usually around the video input pins or on the neckboard). However if your one of the unlucky folks to get a color that sticks on all the time or after warmup, then you may not be so lucky. Try swapping the drive transistor of the offending color to a color that works. Same for the pots. SAME? most likely you have a shorted gun in the tube. This can be diagnosed and sometimes repaired with a rejuvenator. Make buddies with a guy that has one heh...
I should also note that ive ran into uneven brightness issues. It looked like vertical jailbars but it was just like uneven contrast, worst on the left side for some reason. Replacing c56 or 57 fixed it, but i went ahead and did a full capkit anyways.
POTS POTS POTS For some reason, wells used these ceramic backed adjustment pots. They wear out easy, and crack VERY easily.
If you are having a issue with rolling, brightness, color, whatever, LOOK THE POTS OVER WELL. Ive missed a cracked pot a few times and wasted alot of time before i figured it out. If you have the wells monitor with remote board that has broken pots, you can get pots from bob roberts(www.therealbobroberts.net), or www.arcadepartsandrepair.com Or for just about the same price, you can get a brand new remote board assy from chad over at arcade cup (www.arcade-cup.com)
Left the crt-neckboard ground off??Well thats a bummer! Without ground itll try to arc and spark to ground anyway it can. I recently had one that i replaced the hot and vreg, got it to run finally however the pic was very skewed. It did not sync well and the pic was crooked and half off of the screen. I replaced ic2 (vert/horiz ic) per ken laytons suggestion and that cured my issue!
What size chassis do i have? This is open to debate. In my experience,19 inch chassis have been silkscreened with a "447 or 449" them. 25" chassis have been silkscreened with a "5xx" number. Some forum members have seen them either/or, which is odd. Between the # of the voltage regulator and the silkscreened number on the chassis, you can usually figure it out. (vreg ending with 123= 123v regultor, this is usually a 19" chassis. V-reg ending with 130= 130v regulator, this should be a 25" chassis.
Whats the difference between 8pin and 10 pin neckboards? It has nothing to do with tube size. Ive seen 13, 19, and 25 inch monitors with either/or. If you have a 10 pin tube and a 8 pin chassis, you can still use the chassis as long as it came form a monitor of the same size. Simply swap out neckboards and your good!
PARTS RESOURCES: www.therealbobroberts.net-- Sells arcade parts to the general public, good prices, and if you do repeat business with him and establish a friendship, he will usually cross ship our stuff! (currently on hiatus)
www.arcadecup.com chad over there in green bay, wi repairs monitor chassis' for those who cant fix them themselves. He has a decent turnaround time and fair prices. He also sells new and used monitor parts.
www.arcadepartsandrepair.com is a klov member, stands behind his products, and sells flybacks, cap kits, repair kits, pinball kits, etc.
www.mouser.com, www.digikey.com, www.bdent.com, www.future-electronics.com all sellers of replacement electronic components..
k7000 manual pdf here: http://arcarc.xmission.com/PDF_Monitors/Wells Gardner K7000 Manual.pdf
Last edited by a moderator:

