K7000 chasis failure

seamaster32

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Hey all... Im both new to this forum and a newby to arcade game ownership! I recently acquired an original Marvel vs. Street Fighter in great shape (as a bonus, there was large envelope in the bottom of the cabinet with all the original paperwork and manuals too). I purchased knowing the monitor was not working but the game function itself was working fine. Upon reading literally hours of forum traffic and researching what I had, and potentially needed to do, I started to get somewhat of an education. In some cases just translating the vernacular (...check the output of your B+ as an example) proved time consuming for sure.

Here is what I have and what I know (or don't know probably)

K7000 (non zenith) 25", no tube glow, no anode discharge (typical copper wire wrapped screwdriver grounded to chassis), however upon removing and re-seating the neck board (sorry... not sure what the true name of it is) I heard the typical static sound from the tube once I plugged it in but still no neck glow.

The caps (per the note on the side of the chassis) were replaced in 2014 (I could only visually inspect as I do not have a meter that can check capacitance...none leaking, none bloated all flat topped with no visual irregularity) along with an inscription "HV re solder" (maybe one or more of the 6 flyback pins?)

Only other thing I noticed was the chassis ground (green/yellow stripe) from the main power supply plug was not connected.

I purchased this for a family Christmas present and would love to have this working by then. I have no problem re-soldering as necessary but from what I have read... even **if** the problem is the flyback, it is highly likely that it could have been caused by a different component failure or could cause additional component failures.

Can you guys make some recommendations for both what to do next and what meter I could use to test the caps? I am not a EE and do not have any training on board repair, but am pretty capable and a quick study.

Until I can properly troubleshoot this, I would like to purchase (ASAP) a refurbished chassis that has been reflowed, new flyback and caps and burned in.

Thanks in advance!
 
Thx Security0001...regarding your inventory, do you sell the entire refurb'ed chassis? I will reinstall chassis tonight and power up and check and post results
 
to your point about reconnecting the neckboard and "typical static sound", the neckboard doesn't produce the static. :)

it's actually an interesting technology. the flyback anode shoots protons into the tube, while the neckboard is what drives the levels of the output of the electron guns in the neck of the tube. the combination of those is what generates the picture on the screen.

at security's urging, you will only know what's going on if you test the B+. if the B+ is hitting 170V for instance, you have a failure in the horizontal deflection circuit. or perhaps a bad voltage regulator, which is a common failure. if you lose the voltage regulator, it won't be able to maintain the B+ at normal operation -- it will thus go too high and trigger the high voltage shutdown. this is to prevent the monitor from damaging itself.

there's also a fuse in the upper left corner of the chassis; I've made some real bonehead mistakes in the past neglecting to check that first before I test a monitor. then when it inevitably shows dead I get this mad rush of ideas and then only find out after the fuse is either missing or blown. missing, you have a 50/50 chance of it working again -- you put a new one in and it works or it blows.

if you're blowing fuses there's a number of reasons why that happens. that's a bad HOT Q11, bad flyback (give it a visual inspection first; is it cracked at all?), or the rectifier diodes are blown. the diodes only really get blown if you plug the monitor into a non-isolated power source. if your cabinet is magically missing an isolation transformer, well...

but about testing B+. the metal heatsink/frame of the chassis is your ground. it should have some wires interconnected: one comes off the ground strap of the tube itself and runs to the ground on the bottom of the neckboard; this is CRT ground. there should be an additional wire that routes from the neckboard back to the heatsink/frame. your test points for B+ are the large ceramic resistor on the upper left corner of the frame -- there are blue and pink wires here. I honestly can't remember which is which, but using your meter set to 200V DC range against the frame for ground and either of the tabs on that resistor will show you a regulated voltage (you're expecting 130V on a 25" monitor) and an unregulated voltage on the other (roughly 160V I think). as noted before, if it's hitting 170V, you will be in high voltage shutdown, and you will have parts to test or replace.

if for whatever reason the B+ is 0 however, you may be in luck, because there's an array of resistors that carry power, and the solder joints typically break down or the solder pads break off from the traces due to their heat output. most people make the mistake of replacing caps and not redoing the solder on these points and that's how you wind up with a dead chassis.

hope this is a start in the right direction.
 
Thx Security0001...regarding your inventory, do you sell the entire refurb'ed chassis? I will reinstall chassis tonight and power up and check and post results

i don't sell the whole chassis generally but if your looking at replacing the whole chassis i would check with Paul400, Buffett, or Chris25810 on here and one of them will for sure have a rebuilt one available.

yeah let us know the results of your power up.
 
Additional info after reading the replies...

Isolation transformer is in place, checked for visible cracks on the flyback, (not leaking either), fuse is intact and not blown, (but I did not think to check continuity though)

mecha.. thanks so much for the details on how to check the B+ and the location. I had an inclination that the ceramic resistor on the top left of the heatsink frame was it, but quite honestly I was never able to confirm to thanks!

Regarding the anode shooting the electrons into the tube, this would intimate that the anode IS powered and getting voltage from the flyback right? Why would I hear that, but not get a discharge from it?

The weird thing about this whole thing is that the guy I bought it from showed me a picture of it working right before he transported it to his warehouse.
 
I emailed buffett and pm'ed about a chassis but have not heard back from him yet
 
Additional info after reading the replies...

Isolation transformer is in place, checked for visible cracks on the flyback, (not leaking either), fuse is intact and not blown, (but I did not think to check continuity though)

mecha.. thanks so much for the details on how to check the B+ and the location. I had an inclination that the ceramic resistor on the top left of the heatsink frame was it, but quite honestly I was never able to confirm to thanks!

Regarding the anode shooting the electrons into the tube, this would intimate that the anode IS powered and getting voltage from the flyback right? Why would I hear that, but not get a discharge from it?

The weird thing about this whole thing is that the guy I bought it from showed me a picture of it working right before he transported it to his warehouse.

with no high voltage, it simply doesn't work. and it's protons. not like that really matters.

I laid out everything you need to do. you can fix it or not fix it.
 
I tested both the HOT and the VR. The HOT was within range however post 3-4 showed a dead short in the VR. So obviously I need to replace the VR right? Are there any other likely components that would need to be replaced due to the faulty VR or could the VR have caused another component failure?
 
I tested both the HOT and the VR. The HOT was within range however post 3-4 showed a dead short in the VR. So obviously I need to replace the VR right? Are there any other likely components that would need to be replaced due to the faulty VR or could the VR have caused another component failure?

what was your B+ reading??
 
Buffy's like Allstate with this stuff. you're in good hands. ;)

do report what the B+ is. if the VR is bad then it's probably sky high.
 
.. and it's protons. not like that really matters.

I love you and the information you have provided the internet, but stop with the proton statement.

Electrons are the only thing moving around in electronic circuits.

Positive charge carriers are lattice sites void of electrons ('holes'). In theory, it is helpful to think of them as in motion also, but electrons are the only things zipping around.
 
Buffett TOTALLY hooked me up. Luckily I am only about an hour and a half from his shop so the drive was really worth it (although rush hour traffic took me almost 3! (still totally worth it) I got to hang out and help with a D&D dungeon build out then off to the workshop. Buffett went through the entire chassis and fixed some cold solder joints, complete cap and flyback replacement and reflowed the main and neck board. Then he rejuv'ed my tube and put all three guns in the green.

Could not be happier. Thanks again Buffet!

"peace"

James
 
it was awesome having you by the shop.

i had a good time shooting the breeze.

glad your monitor is looking fantastic.

come on by anytime.

Peace
Buffett
 
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