Where to start: HV Shutdown, K7000

[nipsmg]

I just picked up a tekken 3 in a smashTV 25” cab that has a 25k7193 (K7000). On power up, the monitor powers up then shuts down almost immediately.

I’d love to repair this, and am willing to put in the work, but would love some ideas on what to start looking at.  I just RGB Modded a Trinitron I might be able to cram in this cab, but I’d love to get this monitor working.

[nipsmg]

Ok, so after some more research I came across this:



I will be starting here I guess.

[grantspain]

k7000 are pretty easy to repair, if you are not an experienced tech then i would suggest you get a cap kit, flyback, hot and hv safety cap and change the lot in one go- this will get 95% of all issues in one swoop

it might be just some caps and bad solder joints though and fuse holders have habit of corroding or breaking

[nipsmg]

I am not an experienced tech at all.. I’m going to do a capkit regardless, but am going to run down the flowchart to diagnose specifically.  I’m going to do the cap kit regardless, but am a little wary doing the Flyback given my soldering skills are less than ideal.

[nipsmg]

So I just picked up the following:

• Wells Gardner K7000 Series Cap Kit 105C Nichicon
• 2SD1398 (HOT)
• Mica Transparent Insulator MT-200 Package (5 Pieces)
• STR3123

I will be replacing those.  If a HAVE TO, I'll grab the flyback as well... but I'd rather not be soldering HV components if I can help it.

[behrmr]

So I just picked up the following:

• Wells Gardner K7000 Series Cap Kit 105C Nichicon
• 2SD1398 (HOT)
• Mica Transparent Insulator MT-200 Package (5 Pieces)
• STR3123

I will be replacing those.  If a HAVE TO, I'll grab the flyback as well... but I'd rather not be soldering HV components if I can help it.

Good luck.  K7000's are easy to repair but they have incredibly fragile traces and solder pads that have a tendency to burn up and lift when doing re-work.  So go easy and take your time.  Soldering HV components isn't any different or harder/easier than any of the other components so don't be afraid of that.  You may find once you get it working it will need a flyback as they are known for problems with focus and screen/brightness drift.

[nipsmg]

Yeah, I was watching some videos of K7000 repair and realizing I could probably have handled the flyback replacement.  Oh well, I've got the cap kit, the HOT, and the VR, so I'm hopeful those will fix it.

nteresting thing I didn't realize, I guess I need some thermal paste for the hot -- didn't realize the bracket it was attached to was a heatsink.

[nipsmg]

The Carnage..


Blown And bulging caps.. (anything special to clean up the gunk from that cap?

Can anyone tell me what the hell was gong on with the lifted resistor and the cap on the right of that image?

Also, something looks very bad here..  any feedback as to what this mess is and what to do about it?



And is this even a k7000? What does the HOT look so different than the replacement?

(See 2nd image above. Vs the 2SD1398 I bought)

[princess prin prin]

It's the Zenith version of the K7000 aka K7000A. It looks like something (soda?) was spilled on the chassis, in particular on the horizontal drive transformer which looks in really bad condition. You need to clean it all up.

[Zebidee]

Looks like a disintegrated IC near that big transistor on the heat sink in your last pic (is that the HOT?). Can't be good.

[nipsmg]

Ok, so that gunky mess was something spilled on the board and not cleaned up.  Was able to clean it out with some alcohol and cotton swabs.

I replaced the obviously bulging caps and the monitor came to life, however it was dim and out of focus.  The focus adjustment on the flyback helped a bit, but I couldn’t clean it up with the Contrast and black level adjustments or the screen adjustment on the flyback better than what you see below:



What it looks like:


What it should look like:


Ideas?  Neckboard pot adjustments?  Full Cap Kit?

[Zebidee]

You may-as-well test all the electrolytic caps, and replace as necessary, they may be failing without any obvious or visible signs.

Unfortunately, unless you have a good ESR meter you will need to remove the caps to test anyway, and not all multimeters have capacitance testing functions . Thus why people often "cap kit" monitors and just change them all in one go.

[nipsmg]

Yeah I am just going to replace all of them.  Screw it.

[nipsmg]

Doing a cap kit with a soldering iron and wick is kinda slow.  About 3/4 of the way through a recap after about 1.5 hours. (Getting much better and more confident as I go however.  Way faster to remove s bunch, place them, then solder them in instead of doing them one at a time. )

Should be done tomorrow.

[Zebidee]

I usually prefer a solder-sucker rather than wick, but people usually prefer one or the other.

[nipsmg]

So I finished the recap and powered it up, and all of the colors were present and perfect.. just a little too much bloom on the white text, so o went behind the cabinet and pushed some wires out of the way to get to the flyback..   and saw a flash.. monitor is dark.. fuse blow.  I think I shorted something.. . Going to replace the fuse and see if it comes back

[nipsmg]

Pulled out board:

Caps all look fine, nothing else looks blown up...

[nipsmg]

Fuse replacement worked.  Convergence is off.  Is this fixable via pots on neckboard, or is this a magnet adjustment?

[Zebidee]

Convergence looks good. You probably need to tweak screen voltage down a little bit on the flyback and adjust the focus (also on flyback usually). Then just normal brightness/contrast adjustments.

What caused the fuse to blow?

[grantspain]

contrast and cut offs are set wrong

[nipsmg]

So, that tube was shot.  All of the plastics were brittle, And broken, the tube was always blurry no mater what adjustments I made, and I could never get convergence right.

So I went with a tube swap. Found a Sharp 25in 25R-S100 locally (40 min drive) for $20. I opened it and found an RCA A63ahc26x tube in it.  Tube was a perfect drop-in replacement.

New tube with K7000 Chassis:


Had to cut the yoke connector down the middle
And plug in the left-half backwards (vertical wires)


I need to do some color adjustments (everything’s is a little too red/purpley), but I’m very happy with the replacement.

[Zebidee]

Grats, looks good.

The monitor looks a little precarious on top of that esky (icebox) 

[nipsmg]

Nah, that is the sturdiest surface in my garage probably, that thing is huge and stable.

I found a couple of guides for setting the color and white balance of a monitor.

https://forums.arcade-museum.com/archive/index.php/t-241815.html
https://wiki.arcadeotaku.com/w/Setup_Adjustments_For_CRT_Colour_Monitors

I'm pretty sure my issue right now is with the red cutoff.  I'll work on tweaking that tonight and I think I should be good to go.

[nipsmg]

Fixed the white-balance and the cutoffs.

Picture looks incredible now.

[Arroyo]

Tube swap eh?  Getting pretty deep into this nipsmg, I’m jealous.

[nipsmg]

Tube swap was stupid easy... way easier then recapping that chassis

[nipsmg]

On the plus side, the tv chassis is RGB moddabke, so I’m going to mod it as well as a backup.  If the k7000a ever dies, i’ll Have a backup chassis to drive it with.

[Arroyo]

Tube swap was stupid easy... way easier then recapping that chassis

Did you just look for any old 25” and cross your fingers, or is there a resource to check compatibility with the chassis?  I’ve been watching videos and know that you have to have the correct number of pins (i think it’s called that) on the yoke and the right resistance measurements, but I don’t know how you’d know that without taking the TV apart and measuring.......or is that how it’s done?

[Zebidee]

On the plus side, the tv chassis is RGB moddabke, so I’m going to mod it as well as a backup.  If the k7000a ever dies, i’ll Have a backup chassis to drive it with.

Vroooooom Vroooom, I always wanted an RGB moddabke, as well as a Harley and a Ducati.

Tube swap was stupid easy... way easier then recapping that chassis

Did you just look for any old 25” and cross your fingers, or is there a resource to check compatibility with the chassis?  I’ve been watching videos and know that you have to have the correct number of pins (i think it’s called that) on the yoke and the right resistance measurements, but I don’t know how you’d know that without taking the TV apart and measuring.......or is that how it’s done?

Check out this online resource, created by some KLOV members I think. Just input the tube number from back and it auto-fills the rest for you an shows "compatible" tubes (size, heater/G1 voltage, socket type) eg A51EAK01X:
http://tubular.atomized.org/

It does not show TV models, that would probably be asking too much

[nipsmg]

Yeah I used that resource a bit.

My tube isn’t even in that list.. only reference I could find to the tube number was someone over at John’s Aracde who happened upon it in a different model TV and used it for a K7000 swap.

Still tube swaps are pretty awesome.  All you really need is an old Tv and a chassis and a frame and you can construct a K7000 pretty easily.  You can piece that all together for under $200.

[Arroyo]

Thanks fellas.