K7000 - C38 Width Capacitor Max Value

[dungeonmastr]

Alright, hopefully this is an easy one. I've not seen any consistent ceiling stated for it, but, is there a maximum capacitance value for the width cap at C38 on a K7000? I've never had to finagle with that cap quite so much as I'm having to now. The image on the monitor I'm working on looks great, it's just too dang wide and the width coil is, no surprise, stuck. I know they don't give you a ton of wiggle room, so I'm ignoring it.

Mine had a .33uF capacitor from the factory; I bumped it up to a .47uF with no real change. Then I added a .1uF in parallel and it got a little better. I swapped the .1 for a .22uF and, again, it got a little better than before, but was still too wide. In the end - now - I have two .47uF caps in parallel and the image fits perfectly. I'm a little concerned, though: is that too high a capacitance for that part of the circuit? It doesn't seem to be complaining at the moment, but I'd rather this chassis not spontaneously combust due to overcorrection of image width.

 

[behrmr]

Have you checked the B+ on your monitor? High B+ will make the image too large.

 

[security0001]

you definitely have something else wrong and i wouldn't go over about .56uf in that circuit which frankly there would be no reason to change the original .39uf if everything else is working fine.

check B+ as stated earlier

have you capped the chassis??

 

[dungeonmastr]

you definitely have something else wrong and i wouldn't go over about .56uf in that circuit which frankly there would be no reason to change the original .39uf if everything else is working fine.

check B+ as stated earlier

have you capped the chassis??

Capped and got a new flyback (both of which i just got in from you yesterday! ) Like I said, the image itself looks great now (it had some focus and color issues prior to rebuilding), but the dang thing is just waaay to wide. Prior to the cap kit, B+ measured 123v on the end of the ceramic resistor on the side of the chassis but, now that I think about it, I may have been measuring it incorrectly. I will test again tonight and report back. If it's out of whack, where should I start looking next?

 

[security0001]

Capped and got a new flyback (both of which i just got in from you yesterday! ) Like I said, the image itself looks great now (it had some focus and color issues prior to rebuilding), but the dang thing is just waaay to wide. Prior to the cap kit, B+ measured 123v on the end of the ceramic resistor on the side of the chassis but, now that I think about it, I may have been measuring it incorrectly. I will test again tonight and report back. If it's out of whack, where should I start looking next?

first thing i would guess if its off would be a bad VR.

 

[dungeonmastr]

Alrighty, just tested the B+ (red probe on the blue wire, black probe on chassis ground) and it sat right on 123.4 volts. I have to admit, I'm at a bit of a loss here if the regulator is on point. I've generally been able to fix whatever comes my way, but this is new to me.

For whatever it's worth, I reflowed darn near everything on the chassis and neck board, so I know I'm likely not dealing with anything cold-solder related.

 

[gutz]

I assume since your b+ is 123v, that you have a 19" chassis? The width coils on 25k7000 chassis don't change the width much. The width coil on 19k7000 can change the width considerably more. I would let the chassis warm up, power down, then see if you can wiggle back and forth to free up the width core.

 

[dungeonmastr]

Left the chassis running for a bit, but the core just wasn't budging. Thought "what the heck" and desoldered it, tossed it in the oven at 170 (as low as it would go) for ~10 minutes, pulled it out and, what do you know, it turned with no friction whatsoever. I think I may have let it either get too hot or stay heated too long (or both), because the threads in the well are a little... loose now. In any case, I swapped out the two .47uF width caps for one .47uF cap, put everything back together, and was able to dial it in perfectly!

Thank y'all for the advice and guidance - I'm a lot better off for it!

 

[behrmr]

Good work. You should put some anti-seize in there the keep it from sticking again. And make sure you never use a metal tool to adjust it. That causes the slug (your tool and your fingers) to heat up and the slug will melt itself back into the sleeve.

 

[dungeonmastr]

Good work. You should put some anti-seize in there the keep it from sticking again. And make sure you never use a metal tool to adjust it. That causes the slug (your tool and your fingers) to heat up and the slug will melt itself back into the sleeve.

Thanks! Will any non-conductive anti-seize compound work, or is there a product you've had good experience with that I should be on the look out for?

 

[behrmr]

Thanks! Will any non-conductive anti-seize compound work, or is there a product you've had good experience with that I should be on the look out for?

I would think so. I usually give a little squirt of deoxit.

 

[dungeonmastr]

I would think so. I usually give a little squirt of deoxit.

Been meaning to pick some deoxit up for cleaning up some stuff, so that'll work great - thanks again!

 

[arcadeaction]

good thread and freeing up width coils, there is always good stuff to learn here, glad it all worked out

 

[dungeonmastr]

good thread and freeing up width coils, there is always good stuff to learn here, glad it all worked out

I plan on trying this out with some fubar'd coils I have lying around to see how reproducible (and safe) this process is. If it works, and someone around here has a lead on where to acquire replacement ferrite cores, maybe some folks can resurrect their broken K7000 width coils.

I'm actually kind of curious, though: why hasn't anyone reproduced those things? There are replacements for other Wells & Gardner monitors (and even the G07), but not the K7000. Is there something weird about them that makes them difficult to reproduce?

Edit: I should say that, by K7000, I mean the 19K7000. Apparently there are replacements for the 25K7000 width coil available!

 

[security0001]

I plan on trying this out with some fubar'd coils I have lying around to see how reproducible (and safe) this process is. If it works, and someone around here has a lead on where to acquire replacement ferrite cores, maybe some folks can resurrect their broken K7000 width coils.

I'm actually kind of curious, though: why hasn't anyone reproduced those things? There are replacements for other Wells & Gardner monitors (and even the G07), but not the K7000. Is there something weird about them that makes them difficult to reproduce?

Edit: I should say that, by K7000, I mean the 19K7000. Apparently there are replacements for the 25K7000 width coil available!

because the 25inch are still available and the 19inch will work fine with the 25inch coil.

Plus the boobins and ferrite slugs would have to be made and the last die i had made for a boobin cost me $7000.00 and there was a MOQ of 20K pcs so that would make the price crazy high. i do make some coils sine i have a CNC winding machine but boobins and slugs are super tough to come by. NOW multiply those costs by every model people want and you could burn up 100K dollars super quick on only a few models and at the end of the day there is virtually no demand.

 

[dungeonmastr]

because the 25inch are still available and the 19inch will work fine with the 25inch coil.

Plus the boobins and ferrite slugs would have to be made and the last die i had made for a boobin cost me $7000.00 and there was a MOQ of 20K pcs so that would make the price crazy high. i do make some coils sine i have a CNC winding machine but boobins and slugs are super tough to come by. NOW multiply those costs by every model people want and you could burn up 100K dollars super quick on only a few models and at the end of the day there is virtually no demand.

Yowch! That's a heck of a price tag (and a good dissuasion from making them, lol). And thanks for the insight! I had no idea the scale at which you would be required to operate to crank something like that out - there's no way demand would ever make up for something like that.

Also, what's a boobin? Not gonna lie, google wasn't exactly helpful at defining that.

Edit: Also,

because the 25inch are still available and the 19inch will work fine with the 25inch coil.

This is news to me! I'll definitely be looking for some of those in the near future.

 

[security0001]

Yowch! That's a heck of a price tag (and a good dissuasion from making them, lol). And thanks for the insight! I had no idea the scale at which you would be required to operate to crank something like that out - there's no way demand would ever make up for something like that.

Also, what's a boobin? Not gonna lie, google wasn't exactly helpful at defining that.

Edit: Also, This is news to me! I'll definitely be looking for some of those in the near future.

boobin is the plastic housing that the magnet wire is wrapped around including the terminals for mounting and hooking up. if i could get the boobins with terminals i could probably wind any width coil with my cnc machine.

here are the 25inch
https://www.arcadepartsandrepair.co...parts/wells-gardner-009a2838-001a-width-coil/


here are all the ones we stock currently.
https://www.arcadepartsandrepair.com/product-category/monitors/monitor-width-coils/

 

[LyonsArcade]

I think it's spelled Bobbin which is why google fu wasn't working. I am not a spelling nazi and it pisses me off when people do it, but I figured I'd mention it since somebody was trying to research it.