WG K7000 series (now Wei-Ya 826HR) - replaced width adjustment cap, issues...

[Numbski]

Okay, so I've been tweaking the width adjustment cap, trying to get the picture just right.  I'm noticing an odd side-effect, rather two:

1.  The tube now makes a "sizzling" noise.  I kind of presumed it was moisture that had gotten into the tube being burned off, but it's still unsettling. :\

2.  The picture is wider in the middle, and gets squished off to the sides.  I'm not sure exactly how else to describe it.  It's like the image in the middle is getting stretched wider than normal, and the picture at the sides is squished smaller than normal.

Any ideas?

[Numbski]

The sizzling/popping is getting really disconcerting.  I just noticed with the lights off that the picture is flicking pretty good too. :\

[gokun]

is there any kind of ozone/electrical smell accompanying the noise?
also, can you provide some pics of the picture distortion?
baring in mind I don't know NEARLY what the regs here do, have you checked your tube to see if there are any cracks/breaks in it? or can you see any sparks/electrical 'spiders' etc back there?
could maybe be the flyback going out also...see any cracks in the flyback perhaps?
but again, I am no expert, so hopefully the regs will chime in with some better info for ya in the near future, but in the meantime you have a couple things to check
[EDIT]
This probably goes without saying, but just in case...do NOT touch the thick red wire going to the tube while you're back there...or really anything else for that matter unless you're familiar with electronics. Sorry if you already know that, but better safe than sorry...

[Ken Layton]

With the room lights out (at night) take the back door of the game off and power up the machine. Do you see any arcing anywhere?

Could be the flyback arcing due to cracks in it's case.

Is the high voltage wire (red wire with the suction cup on the end) securely fastened in the anode hole in the picture tube? The clips in the suction cup should snap firmly into the hole in the tube.

Are you using the correct style of capacitor (and voltage rating) for the width capacitor? The wrong style or the wrong value will break down and arc in minutes after installing it.

And last but not least, the yoke might be going bad.

[moose]

I noticed a lot of static crackling on my wg k7000 series monitor after doing a width cap replacement, too. I'm assuming for the time being that it's something along the lines of warming up the tube or something like that.
The picture is fine on mine though, and there are no real concerns other than the little crackles, and the crackles seemed to decrease in frequency (though not stop) after a few minutes of on-time.
I replaced my width cap with a larger capacitance and higher voltage cap, non-polarized.

[Numbski]

is there any kind of ozone/electrical smell accompanying the noise?

Now that you mention it, yes.

also, can you provide some pics of the picture distortion?

I can try.  It'll be tonight though.

baring in mind I don't know NEARLY what the regs here do, have you checked your tube to see if there are any cracks/breaks in it? or can you see any sparks/electrical 'spiders' etc back there?

could maybe be the flyback going out also...see any cracks in the flyback perhaps?

I hadn't noticed any, but I'll try more closely inspecting it.

This probably goes without saying, but just in case...do NOT touch the thick red wire going to the tube while you're back there...or really anything else for that matter unless you're familiar with electronics. Sorry if you already know that, but better safe than sorry...

Yeah well - the thing fooled me last night.  This is the first time I've truly had to discharge the tube.  Last time it had been shut off for months - apparently long enough for the charge to dissipate.  It's a trial and error thing getting the width right, and I'd though I'd probably discharged by touching the clip.  NOPE.  Went to put it back on and the thing bit me.  Not as bad as I'd thought, but my thumb was swollen up pretty good for most of hte evening.

[Numbski]

With the room lights out (at night) take the back door of the game off and power up the machine. Do you see any arcing anywhere?

When the picture flickers, it appears to arc a little inside the tube at the very back.  I feel like I'm confused about what the flyback is now.  I thought it was the very back part of the tube.  It isn't the white plastic box on the neckboard, is it?  There's a little bit of exposed wire on the outside of that (oops! that was a mistake from when I couldn't figure out how to get the neckboard off - I do-soldered that wire, and re-did it.  Apparenlty it wasn't a perfect job).

Could be the flyback arcing due to cracks in it's case.

Yeah....see above.

Is the high voltage wire (red wire with the suction cup on the end) securely fastened in the anode hole in the picture tube? The clips in the suction cup should snap firmly into the hole in the tube.

So far as I can tell, yes.  Granted, the thing DID bite me pretty good that last time  I guess it's possible that it's not on as tightly as it should be.  I kinda wanted to get my courage back up before futzing with it again.

Are you using the correct style of capacitor (and voltage rating) for the width capacitor? The wrong style or the wrong value will break down and arc in minutes after installing it.

Well, I got the kit from Bob Roberts:

http://arcadecontrols.com/BBBB/width.html

What I found was that a .1uf cap was way too wide, but a .22uf was too narrow (although I think I was failing to give the ferrite adjustment slug enough credit), so I chained a .22uf and .33uf in series, thinking that would give me .11uf-ish.  I'm tempted to go back to the .22uf and try to be a bit more aggressive with the ferrite slug, but the page says not to.

I'm wondering why you couldn't just use one of these instead:

http://www.oselectronics.com/ose_p96.htm

Put it in and adjust accordingly...I'm guessing there's a reason why you don't do that, but I don't know what it is.

And last but not least, the yoke might be going bad.

I don't suppose there's any way to test for that?

[Numbski]

Well crap.  I was reading, and apparently the "correct" value for this is a .39uf.  Meh...

[gokun]

As I understand it, the flyback is that black plastic thingy with the screen and focus knobs on it that the red anode wire connects to on the chassis board...
but if the arc is coming from the back of the tube area I would think the flyback isn't the issue...again, the regs know more than me and can give you a firmer answer on that one...
the arcing thing worries me somewhat though....can you closely examine the area where you saw it, while the monitor is off, for cracks or breaks?
And yeah, I would definately replace that cap with the correct one...
as for the yoke, I do not know how to test them but I believe the yoke is the area around the back of the tube where you saw the arcing, so that might not be good...
anyhoo, the regs will be able to give you better info when they come back around...just trying to help out a little in the meantime.

[grantspain]

did you mess with one of the high voltage polypropylene caps??
if so what was the original value(i.e 473j 1500v) and what value did you put in?

[Numbski]

I only replaced what was in the Bob Roberts Cap Kit, and those were 1:1 values.  C38 is the only one I took liberties with.

Also, the two things seem to be related.  The sizzling, popping and cracking have ceased after I went back to the .39uf cap, and all distortion is gone, but now the picture is far too narrow.  I put in a .22uf cap, and here's what the picture looks like.  Sorry about the quality, it's off of my camera phone:



Pay special attention to the letter in Blanka's name.  The one at the far right on player 1 vs the one on the far right of player 2.  That doesn't happen with the .39uf cap. :\

[grantspain]

pull up a grid pattern in test and look at the geometry

[Numbski]

Give me a sec.  I was testing to make sure I wasn't going insane and put a .1uf in at C38:



So I'm right, I need something greater than .1uf, but less than .22uf.  Fun.

[grantspain]

whats the exact chassis here,it looks like a 19" but is it a 7200 or 7000

[Numbski]

Here you go!

[Numbski]

whats the exact chassis here,it looks like a 19" but is it a 7200 or 7000

I never did find out.  It's definitely an older revision - it doesn't have the external pot board for adjusting height, brightness, contrast, etc - that's still on the main board.  Also, this isn't a 19".  It's a 25" (diagonal). 

[grantspain]

yes it the old 7000 chassis,this cap you changed a c38-what is actually written on it,it should say 394j 200v
also important to note that cap is right in line with the horizontal linearity coil

[Numbski]

"Linearity Coil".  You mean the ferrite slug I keep adjusting?

Anyhoo - any cluse as to why this is happening?  394J means what exactly?  I know 39, 4 zeroes - so 390000, and Mr. Roberts says to move the decimal point 6 places to give us uf, so .39uf.  Originally, before I did the normal cap kit, the picture was too wide at .39uf.  Now after the cap kit, it's too narrow at .39uf, and putting a smaller value  at C38 does make the picture wider, but it also distorts the image.

What does the J, or K, or JK on some of these caps mean?

[Numbski]

yes it the old 7000 chassis,this cap you changed a c38-what is actually written on it,it should say 394j 200v
also important to note that cap is right in line with the horizontal linearity coil

Somehow I missed that this was a question, not a statement.

394J
200  t

I currently have a .22uf in it, but I still have the .39uf.

F224K @
630MPP1

[grantspain]

i would put the original value caps back in and then look at the grid pattern,if you then have too much width but correct geometry perhaps you are looking at a different problem

[Numbski]

The issue was actually not enough width, but correct geometry. (After I got the board repaired, that is - prior to the cap kit, it was too wide, but correct geometry at that value)

I'm suddenly glad I outboarded C38 to perfboard.  It's saved me a TON of time doing these tests.  Bob Roberts seems to always have great suggestions.

[Numbski]

Well, crap.  The geometric distortion is identical to the image above, only on a smaller scale, so it was less noticeable.  That grid makes it much more obvious.

CRAP.  Now what???

Oh, in researching this, I've learned a few things.  A couple of good resource pages:

http://www.repairfaq.org/sam/flytest.htm
http://www.overclockers.com.au/wiki/TV_/_Monitor_/_Fault_Diagnosis

And since the Bob Roberts page now makes sense in retrospect, the way to calculate the capacitance of two caps in series (end to end daisy-chained) is this:

(cap 1) x (cap 2) / (cap 1) + (cap 2)

Literally the product of the two divided by the sum.  Makes sense when you're in a mathematical state of mind, but for some reason I kept reading it as the sum divided by the quantity, or:

(cap 1) + (cap 2) / 2

Don't make that mistake.

[grantspain]

if your width is now functioning then i would look to the linearity coil,maybe its broken-some lin coils had an ferrite core that could be adjusted

[Numbski]

Nope, width is even LESS functional now.  I need to tweak the value of C38 to get the width right (unless there's another way to do it?) as right now the picture only takes up 2/3 of the tube.

Yeah, the ferrite slug next to it is what I was trying to adjust.  You mean that coil around it would cause the geometry distortion I'm seeing if it's busted?  I don't mind ordering a new one (and in fact Bob Roberts has a kit with that, the Flyback, and a couple of other parts I might as well get while I'm at it just to be sure.

I'm just wanting to understand what might be causing it before I throw more parts at it.  If the concensus is that the proper value cap should not be drawing a picture that small, then I can get these other parts and clean things up.  I can also continue tinkering with the width using C38 - but if I'm wasting my time there, I'll quit.  I think I'd like to order a new .39uf cap though - the original is looking pretty crusty, and the kit I got from Bob Roberts did not include one.

[grantspain]

wierd,i think you could have a broken width pot and a problem with the lin coil
no one has changed the flyback on this have they?

some of those caps are important to be their original value unless you want to be sterilised

[Numbski]

Just so we're on the same page here (literally):

http://arcadecontrols.com/BBBB/width.html

Again, all caps were replaced with the same value, except C38 - per that page.  I've put the original cap back in.  Original symptoms were picture too wide, colors bleeding a bit.  I figured I'd do a full cap kit, and adjust the width.  After the cap kit, the tube wouldn't fire up.  Finally took it in for repair and was told that "a transistor was shorted", brought it home, fires up just fine, but now it's far too narrow.  That leaves me to adjust C38, and in the process of doing so I noticed that it wasn't "just fine", but the geometry is what you see above.

If the coil can/does cause this sort of thing, no problem - I'll order a new coil.  I'm just hesitant to throw parts at a problem if that part isn't known to cause this sort of issue.

[Numbski]

.149uf seems to be about right on the width, but the picture on the right side rolls over onto itself. :\

That, and of course the omnipresent geometry problem remains.

[Numbski]

Looks like this same issue came up for the user "dabone".

http://forum.arcadecontrols.com/index.php?topic=18527.0

Apparently C37 impacts this too - and the guy that fixed my chasis could very well have changed it - it certainly looks new.  The manual says C37 should be ".15".  Am I safe to presume that's .15uf, 200V?  If so, where can I get one?  There's not one of that value in my cap kit. :\

[gokun]

I get most of my caps from either http://www.digikey.com/ or http://www.jameco.com/
You could see if either of them has it(got all the caps for my wg from digikey last time).

[Numbski]

I'm starting to wonder about the HOT (horizontal output transistor):

http://www.neo-geo.com/forums/showpost.php?s=d6db37d151cffece854bbf007ab5795b&p=2580690&postcount=8

The narrowness problem fits, but I can't tell from the picture - he has a later revision K7000 series, so the board looks nothing like mine.  I don't know where I would find the HOT on my board.  Since the guy that did the repair clearly stated that "a transistor was shorted", it makes me wonder....

Anyone know where it should be on my board?

[Numbski]

After going through many images, I'm about 99% certain that this is a Well Gardner 25k7191, FWIW.  At very least the board layout is nearly identical.

http://forum.arcadecontrols.com/index.php?topic=30237.msg255973#msg255973

[grantspain]

I'm starting to wonder about the HOT (horizontal output transistor):

http://www.neo-geo.com/forums/showpost.php?s=d6db37d151cffece854bbf007ab5795b&p=2580690&postcount=8

The narrowness problem fits, but I can't tell from the picture - he has a later revision K7000 series, so the board looks nothing like mine.  I don't know where I would find the HOT on my board.  Since the guy that did the repair clearly stated that "a transistor was shorted", it makes me wonder....

Anyone know where it should be on my board?

thats not a HOT,its the width transistor-i am not sure how your chassis does the width,normally these are direct to the bridge coil in the circuit

[Numbski]

Horizontal Output Transistor (ie width) is not the same as the width transistor?  What's the difference?    

[grantspain]

http://www.repairfaq.org/sam/reppic/horiz-tv.pdf

explained better than i ever could

[Numbski]

Okay - well, I located C37, removed it - and it's the .15uf variety alright - but I found something soldering across it in parallel on the solder side:



It's labelled:

IN4936
GI 823

Best I can tell, it's a capacitor too.  I didn't put it there though.  Problem is, I tried running without it, and something arced on the neckboard between the 4-pin molex and the connection to the tube.     I immediately shut it down after that.  I can't tell the value of that cap, and I tried outboarding C37 too, since it's too much of a pain to keep putting back in there, but yikes...

EDIT:

CRAP!  That was D15!  Someone removed it and then soldered it back onto the solder side of the board!!!   Ick.

[grantspain]

no thats a diode mate,you will end up killing yourself the way things are going-probably there to prevent reverse current

[Numbski]

So I noticed, although I tried putting it back and the neckboard arced in teh same spot again.

Okay, I think I've lost my nerve for one night.  I'm going to sit tight until someone can give me a hint on how to proceed without winding up dead.


EDIT:
So I lied - I got the diode back in.  It would figure that on a 50/50 shot, I'd put the diode back in backwards.  Ugh...I still don't know what to do about the picture other than start buying a bunch of parts for the width circuit and hope that I find the bad one.

[Numbski]

I'm about ready to give up and pitch this thing.  Makes me mad - this was working fine before the cap kit, it was just too wide.  Now it's like everything has gone nuts.

 

I'm literally out of ideas.  I hate the idea of just randomly buying a bunch of parts and replacing them all - I tend to like to know what causes a symptom, and fix JUST THAT.  Doesn't make sense to throw parts at something and not know why you're doing it.  Right now I've had the following named off:

Flyback
Yoke
HOT
Width Pot
Width Coil

So....I guess I could buy all of those things and pray, but is there one that's more likely the culprit than another?  Is there *any* way to logically test through this to narrow it down?

[Ken Layton]

Parts you see soldered on the foil side of the board were put there on purpose by Wells-Gardner as part of their undocumented production improvements. Never remove them!

You say it was fine before you started working on it so it's obviously something you did and you're making things worse.

Perhaps you should cut your losses and just buy this brand new replacement chassis:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150294277959&refid=store

It has a jumper to select the width range (narrower or wider) plus the most commonly need adjustment controls on a remote board.

[Numbski]

I'm certainly not opposed to it.  Just confused as all get out. :\  Cap kit, now this.  Feh.