common k7000 issues - common repairs

cadillacman

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*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..
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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.
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Note the yello goo coming out the seam.
Heres another blown fly, this one cooked in the center.
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New and failed.
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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
 
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7/2013: A LIMITED AMOUNT OF ZENITH K7000A FLYBACKS HAVE BECOME AVAILABLE!:
http://www.ebay.com/itm/95-4149-Fly...h=item1c330ece13&ssPageName=RSS:B:SHOP:US:101

Path of r101 traces. You can see in this pic the traces have already been "repaired" but personally i'd reinforce and resolder all solder joints in this area togther if you have one thats pretty fried.
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courtesy of modessit. It shows commmon areas to check for bad solder joints on these chassis.
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Cant adjust your width enough? Make sure your width coil isnt broken, and make sure your b+ is in the correct range( this varies depending on model/regulator). If your width still just doesnt quite adjust correctly, then follow mods advise: "C38 is the width cap on the K7000. Larger value means smaller picture. Lesser value means larger picture... " Bob roberts can supply you with "width adjustment assortment" of capacitors to try.

Vertical collapse issues If you have a shrunken picture vertically(collapsing), especially if you have had a failed ic2 or ic3, then check r80. It should be a 3.1 ohm resistor. If it has opened up electrically, you will see a screen with an image in the center 3-6". You can fine tune the screen size by changing this resistance if needed. Less resistance= taller picture. Higher resistance= shorter picture.
Also per r3ll1k: "It's a lot easier to test R91 to see if it's open rather than checking for +24DC at pin 6 of IC3. C50, IC3 and R91 are on the flowchart but I have found that a bad D13 will cause vertical collapse as well" Dont forget to check d13 and r98 If you had a flyback failure

Convergence issues? Besides the basics(misajusted purity rings, yoke not centered, needing degaussed, user NATE1981s had an odd one.
"Smearing/retrace lines/colors not balanced. Installed cap kit. Monitor 100% fixed--for a few days. Most of the problems started coming back. Saw light flashes at startup. Odd, Convergence was off by 1/4 inch or more both red and blue and focus was very poor. Replaced Flyback and all problems and convergence error went away."

WHy does my k7000 chassis look odd and use a odd looking flyback? If you are for sure its a k7000 chassis, it is likely a zenith made k7000a. Back in the heyday wells gardner was so backlogged they contracted enith to build monitors to meet the demand. THe k7000 capkit should be the same or close, but that zenith fly is UNAVAILABLE. If you have a dead enith chassis, just swap in a wells gardner built chassis.

Another klov guy kept blowing h.o.t.s. He found D18 cooked itself out of the circuit (diode is fine, pads are shot), which killed another HOT. It also made a lot of funny snap-crackle-pop noises (almost sounded like arcing).
LINKS FROM OTHER USERS

Shuts down if monitor tapped on http://forums.arcade-museum.com/showthread.php?t=306914

New flyback blew/defective batch http://forums.arcade-museum.com/showthread.php?p=2723029#post2723029

Wont focus, even after flyback replacement, tube is ok.

Vertical collapse as chassis warms up http://forums.arcade-museum.com/showthread.php?p=2023909#post2023909

Do i have a med res k7000? http://forums.arcade-museum.com/showthread.php?t=213897

Video input pinout: http://forums.arcade-museum.com/showthread.php?t=139218

Makes raster lines, but no picture: http://forums.arcade-museum.com/showthread.php?t=154153

Vertical collapse: http://forums.arcade-museum.com/showthread.php?p=1888986#post1888986

Before and after capkit still has very dim picture: http://forums.arcade-museum.com/showthread.php?p=1652643#post1652643

Why does my k7000 have odd lines through the picture only at the top 2-3" ? 50/60 pot http://forums.arcade-museum.com/showthread.php?t=175666

Vertical collapse even after replacing ic2 and ic3: http://forums.arcade-museum.com/showthread.php?t=177166

Repaired chassis has b+ but seems to have no high voltage: http://forums.arcade-museum.com/showthread.php?p=1565702#post1565702

Dead after capkit, not blowing fuses: http://forums.arcade-museum.com/showthread.php?t=137847&page=2&highlight=k7000

Has 160v b+, no hv. Failed t2, see post 106 in this very sticky: http://forums.arcade-museum.com/showthread.php?t=134818&page=3

Smoking yoke: http://forums.arcade-museum.com/showthread.php?p=1201208#post1201208

Will a zenith k7000a tube and yoke work with a wells chassis? http://forums.arcade-museum.com/showthread.php?t=133984&highlight=k7000

Video is jumping intermittently: http://forums.arcade-museum.com/showthread.php?t=132811&highlight=k7000

Chassis identification mysteries: http://forums.arcade-museum.com/showthread.php?t=127390&highlight=k7000

Doing caps- which way does c20 go in? http://forums.arcade-museum.com/showthread.php?t=124583&highlight=k7000

Blows fuses from hell: http://forums.arcade-museum.com/showthread.php?t=120496&page=6&highlight=k7000

Another failed fix with a fuse popping k7000: http://forums.arcade-museum.com/showthread.php?p=1366401#post1366401

25" K7000 BLOWING FUSES: http://forums.arcade-museum.com/showthread.php?t=134618
K7000 blows fuse..NOT THE COMMON FAILURES.... repaired!!
https://forums.arcade-museum.com/showthread.php?t=414771
Keeps blowing r103 WITH FIX http://forums.arcade-museum.com/showthread.php?t=213631

Missing blue?: http://forums.arcade-museum.com/showthread.php?t=137296&highlight=k7000

Uneven brightness(vertically not horizontally): http://forums.arcade-museum.com/showthread.php?p=1248149#post1248149

Hot lighting up/arcing near mounting screw after replacement: http://forums.arcade-museum.com/showthread.php?t=165298

Where do the remote board wires go if some have been disconnected?( soldered on style not plugin style) http://forums.arcade-museum.com/showthread.php?p=1550841#post1550841

My new and old flys do not look identical. WHats that thing on the focus wire? http://forums.arcade-museum.com/showthread.php?p=1697924#post1697924

Nintendo k7000 versus standard k7000 http://forums.arcade-museum.com/showthread.php?t=149066

Odd vertical pattern, removed the undocumented vertical adjustment board http://forums.arcade-museum.com/showthread.php?p=2010649#post2010649

Post cap kit image is stull curled at the top http://forums.arcade-museum.com/showthread.php?p=2013150#post2013150

OOPS I WASHED THE AQUADAG OFF MY TUBE, NOW WHAT? http://forums.arcade-museum.com/showthread.php?t=273536

Picture washed out after capkit: http://forums.arcade-museum.com/showthread.php?p=2613851#post2613851

Was ran without neckboard ground: http://forums.arcade-museum.com/showthread.php?p=2664485#post2664485

Vertical collapse: http://forums.arcade-museum.com/showthread.php?p=3029602#post3029602
 
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Requested that this be made a sticky.

Also reserving spot for any helpful info I might come across. :D
 
Cad - did you ever fix that 25" you were having problems with?

And how did this get stickied when so many other worthy threads haven't...
 
Good info, the pictures of various failures helps.
 
WHO SHOULD I SEND MY CHASSIS TO IF I AM NOT UP TO FIXING IT?

Lucky for you, there are several members here that fix k7000s. Buffett, modessitt, dokert, arcadecrt all fix monitors.

Ok. Going to post the article originally from the late(sniff) gameroom magazine, with kevin steeles permission. It is just a general article on recapping a k7000, but i feel this is worth posting. IF YOU ARE WAITING FOR A PDF EMAIL BEAR WITH ME. THE COMPUTER I HAVE THE PDF ON IS DEAD AT THIS POINT IN TIME

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(whoever allowed me to post 5 pics THANK YOU)

NEW 5/1/13: BUFFETT k7000 vids!!




 
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And how did this get stickied when so many other worthy threads haven't...
You have to request the sticky. I pm'd ChannelManiac with the url of the thread and asked that he sticky it. Do you think there should be subforums for the different manufacturers? If you know of any other threads that are sticky worthy then you might want to shoot ChannelManiac a PM.
 
I think there are quite a few topics that should be stickied:

1) How to ID a monitor before asking questions about it.

2) Basic monitor terminology and troubleshooting techniques, including how to use a meter to do so.

3) How to do a tube swap, including info on figuring out what tubes will work.

Just to name a few...
 
BTW - I also don't like seeing a bunch of stickies that I have to scroll down to read posts (check out BYOAC's monitor section for an example). I'd rather see a sticky subforum entitled "READ THIS FIRST BEFORE POSTING IN THIS SECTION". It would be helpful in other repair categories, too...
 
I think there are quite a few topics that should be stickied:

1) How to ID a monitor before asking questions about it.

2) Basic monitor terminology and troubleshooting techniques, including how to use a meter to do so.

3) How to do a tube swap, including info on figuring out what tubes will work.

Just to name a few...
Sounds like you're putting one together already. Thanks Mod, all of us monitor noobs appreciate it! :)
 
Thanks for this. Really helpful. I still need to do a cap kit on my K7000.

Though, my adjustment pots have been replaced with a remote board. Should that be something added to this list? I feel like the remote board covers more than one adjustment per pot and is extremely sensitive. I don't know if this is normal or if I have a remote board that's wired incorrectly and/or dying on me.
 
NTE Cross References for K7000 Voltage Regulators:

19"
STR3123 - NTE 1741
STR30123 - NTE 1776

25"
STR3130 - NTE 1742
STR30130 = NTE 1777
 
Bob Roberts says there is no replacement flyback for that model, what do you guys do in that case?

What model? K7000 flybacks are available. Bob has them listed on his site for $19....

Oops, you said Zenith. That's a K7000A. If you need one, find a parts board for now...
 
What model? K7000 flybacks are available. Bob has them listed on his site for $19....

Oops, you said Zenith. That's a K7000A. If you need one, find a parts board for now...

Thanks! The board works, I think you saw the issues it was having in another post, mainly there is was looks like a faint waterfall on the left 1/3 of the screen, and color bleeding. The tube may be bad but I was able to a much brighter picture after discovering so dope had messed with the RGB drive pot and RGB cutoff pots on the neckboard. I figured I would start with a capkit, check for bad solders, and converge the guns and see how it looks.
 
a standard wells k7000 chassis should swap right in. Iirc, zenith used that weired flyback, well, so that they could use thier own parts.(suprise suprise)

EDIT 6/2013: It appears as if some nos flybacks have become available. Stay tuned.
 
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Ran into this again today, and although I mentioned it somewhere here, I'm too busy to go find it now.

Chassis Model - K7000

Symptom - Dead. No neck glow or HV. In HV shutdown.

Troubleshooting - New cap kit and flyback had been installed. No bad parts or cold solder joints or broken traces found. On a previous repair with a similar issue, I had found a reference online as to C36 (the critical safety cap) being out of value, causing the chassis to be in HV shutdown. The proper value is supposed to be 6100 picofarads, which is usually indicated on the cap by .0061 or 612. Checking C36 on this chassis showed the number to be 432 - or 4300 picofarads (same as with the previous repair). This was a factory installed part (and the chassis powered up with the old flyback), so this was not a user-install error.

Solution - Replaced C36 with the proper 6100pF cap, and the monitor now works.


I'm not sure why the 4300pF cap works with the old flyback, but not with the new flyback. Perhaps the new reproductions have a slighlty different tolerance window that requires a much more specific value on C36 than the original flybacks used. But this is worth checking if you have done everything else and still have a dead chassis....
 
huh.. thanks for posting that mod, i sure hope this sticky will help alot of folks out with these frickin monitors. I still havent dug back into my perosnal fuse popping 25er lol
 
Here's another one. Had a K7000 today that didn't have enough vertical deflection, because I swapped in the tube out of a television set, lol.

Anyways, after searching, I found that Randy Fromm mentioned adding resistors to R80, changing the value will change the size of the deflection. I shorted the resistor and found that it makes the screen HUGE. So upon looking around some more, I noticed that R80 was a 10ohm resistor. The higher the value of this resistor, the less deflection you have vertically... so I swapped in the correct 3.1ohm that it's supposed to have, and had a pretty good looking picture, even though it was a television set tube/yoke. So if you have vertical size problems, mess with the value of R80!

ALSO, R83 which is right next to it? It changes the position of the vertical center (which is then adustable by the vertical position pot). The higher the value of the resistor, the farther up the tube the image goes. If you cut the damn resistor out, it still works and is now as high up as it'll go since the resistor now has infinite resistance (it's disconnected!). This is usefull if you can't get the image centered.. if you make the resistor a dead short, it makes it the farthest down the tube possible. After you do any of this, you can still tweak it with the vertical position pot.
 
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it's been many years since intro to electronics...

by "shorting" do you mean you like jumper the two legs of the resistor together? or do you have to hook it to a ground?
 
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