Author Topic: K7000 Well Gardner-Vertical Fold over problem (Read 20250 times)

SEASHOREMBSC · « **on:** November 26, 2003, 02:32:15 am »

I have a k7000 that has a vertical foldover at the top. I have changed caps with cap kit. Anything else I can try?
Your help would be greatly appreciated.

jerryjanis · « **Reply #1 on:** November 26, 2003, 03:21:59 am »

I had vertical foldover at the bottom of my screen (WG25k7191) at certain resolutions. There is a pot labelled "50-60 Hz" in the back of the monitor. It's a very white pot that I needed to use a phillips head screwdriver to adjust. It fixed the curling problem.

I have several pictures of it on this page:

http://www.jstookey.com/arcade/WG_25k7191/

Hee hee, I just noticed what time you posted the message. Welcome to the message board. Servicing strange arcade questions 24-7!

menace · « **Reply #2 on:** November 26, 2003, 08:04:05 am »

Sorry to hi-jack but Jerry, what is that little board above your flyback? I have the exact same monitor but no little board there. Also, did you guys have the adjustment pots on a separate board with wires soldered to the main board? Mine was setup this way and I just thought it was someone's hack--could you take a picture of this board for me-especially one showing circuit paths--Thanks!

SEASHOREMBSC · « **Reply #3 on:** November 26, 2003, 08:35:44 am »

Quote from: SEASHOREMBSC on November 26, 2003, 02:32:15 am

I have a k7000 that has a vertical foldover at the top. I have changed caps with cap kit. Anything else I can try?
Your help would be greatly appreciated.

I have tried adjusting the little white flat pot and no luck.--Maybe it is bad also

jerryjanis · « **Reply #4 on:** November 26, 2003, 08:44:47 am »

Quote from: menace on November 26, 2003, 08:04:05 am

Sorry to hi-jack but Jerry, what is that little board above your flyback?

I don't know what a flyback is. Are you talking about the thing on the left? Big black box with 2 white knobs (screen and focus, I believe) topped with a metal casing? And on top of that metal casing is a little beige circuit board with blue things and some resistors and stuff. Is that what you're after?

Quote

Also, did you guys have the adjustment pots on a separate board with wires soldered to the main board? Mine was setup this way and I just thought it was someone's hack--could you take a picture of this board for me-especially one showing circuit paths--Thanks!

Yeah, I have the same thing - 6 pots on a little board on attached with maybe 2-3 feet of wire. It's really convenient.

You don't want pictures of the board with the 6 pots, do you?

menace · « **Reply #5 on:** November 26, 2003, 08:46:31 am »

If you want to make absolutely sure if its good or not--mark its current roation ( its current setting) with a black marker and then desolder it from the board and test it--it should read between 0 and 500 ohms. you might be able to test it on the board without removing but sometimes other components may mislead your readings.

Did you want a set of schematics for this?

SEASHOREMBSC · « **Reply #6 on:** November 26, 2003, 08:50:03 am »

I have a K7000 manual with schematics. Thanks

jerryjanis · « **Reply #7 on:** November 26, 2003, 09:01:28 am »

Quote from: SEASHOREMBSC on November 26, 2003, 08:35:44 am

I have tried adjusting the little white flat pot and no luck.--Maybe it is bad also

Oh, well. What do you have the monitor hooked up to, if you don't mind me asking?

Ken Layton · « **Reply #8 on:** November 26, 2003, 12:35:37 pm »

If a capkit has already been done and you still have vertical foldover problems then check the following parts:

VR9 the 50/60 hz trimpot may be open (it's 200 ohms)

Diode D25 may be open

Resistor R80 may be off value. It should be 5.6 ohms. If it's off value by even a couple of ohms then replace it.

jerryjanis · « **Reply #9 on:** November 26, 2003, 04:37:41 pm »

Here are a whole bunch of pictures of that weird circuit. Do you know what it is? It's not wired to anything, which seems strange to me (then again I don't know anything about monitors).

http://jstookey.com/arcade/WG_25k7191/monitor_circuit/

SEASHOREMBSC · « **Reply #10 on:** November 26, 2003, 10:49:29 pm »

Quote from: Ken Layton on November 26, 2003, 12:35:37 pm

If a capkit has already been done and you still have vertical foldover problems then check the following parts:

VR9 the 50/60 hz trimpot may be open (it's 200 ohms)

Diode D25 may be open

Resistor R80 may be off value. It should be 5.6 ohms. If it's off value by even a couple of ohms then replace it.

Thanks- I will check these and hopefully one of these will solve problem.

menace · « **Reply #11 on:** March 27, 2004, 08:04:22 am »

My 25" K7193 project board (I say project cause thats all its been

) now works (bad flyback so I replaced it) but now I have a pronounced foldover. I checked VR9 (500ohms--check) diode 25--check, R80 (3.1ohms) check--everything reads as the scematic says it should--anyone have any other ideas as to what could be causing it?

jerryjanis · « **Reply #12 on:** March 27, 2004, 10:47:35 am »

Where is the foldover?

menace · « **Reply #13 on:** March 27, 2004, 11:41:10 am »

Top--it almost like if I had a few more degrees of adjustment in the VR9 that it would go, but sadly i don't

Ken Layton · « **Reply #14 on:** March 27, 2004, 12:25:44 pm »

Hey menace:

Replace the little tantalum electrolytic capacitor C51 (0.68 mfd @ 35 volts). It's located right directly behind the 50/60 hz pot. I just recently had several of these fail suddenly (either by going open circuit or changing value way off). If you can't find this cap locally, then you can use a regular 1 mfd @ 50 volt electrolytic but you won't quite have enough vertical height (maybe about 1" shy top and bottom). Remember tantalum caps are polarized and their markings are often hard to read without a magnifying glass. Capacitor C51 is typically NOT included in the usual capkits, but it is failing too often now and I think capkit providers should now start including this cap in the kits.

I'm assuming you already installed a capkit.

menace · « **Reply #15 on:** March 28, 2004, 08:02:18 am »

Thanks Ken--I'll try that--yes a new cap kit was installed as well as a new flyback IC4, IC3, R101... The problem with this thing is that I find myself saying--well its just one more part--all too often

but i refuse to let it win

menace · « **Reply #16 on:** March 29, 2004, 06:29:47 pm »

Dropped in a new C51--no change--this is the best I could get it--here's a pic--what you can't tell is that the picture is centered on the screen with 3" on the top and bottom with 1-2" on each side. I even dropped in a 2K pot for the VR9 and this will take care of the top rollover but then the bottom gets squished right up? Any other ideas? what is controlling my vertical size--it seems like it may be dead or something

Ken Layton · « **Reply #17 on:** March 30, 2004, 12:47:35 am »

Double check that new C51 to be sure it's on value. I had a bad one right out of the package from my local supplier. I took my cap meter with me when I went back back and found that my supplier had 50% of them were bad (been on the shelf too long).

Try replacing the vertical size trimpot also since it's in series with the 50/60 hz pot. You might also try changing the value of R80. On the 7193 model it's 3.1 ohms (1 watt). On the 7191 model it's 3.9 ohms (1 watt). On the usual k7000 series it's 5.6 ohms (1 watt).

Make sure the vertical position pot is good.

JasonF · « **Reply #18 on:** March 30, 2004, 08:16:54 am »

The pots on the K7000's are very easy to break, so when examining them, make sure that you gently try to rock them side-to-side. A good pot won't move, but one with a broken leg will quickly expose the flaw.

Also, it's possible that a previous owner broke a pot off and replaced it with the wrong value, so double check against the manual/schematic.

menace · « **Reply #19 on:** March 30, 2004, 10:47:12 am »

My k7000 has the up front board setup--so i took the board off my working machine and plugged it into the non-working--all the pots on the board work as they should. I was reading randy fromm's which chip is which article so I swapped IC3 and IC2 out (IC3 was an unknown) and am going to check the rest of the vertical deflection circuit at some point.

JoeB · « **Reply #20 on:** March 30, 2004, 10:50:38 am »

Wow.. so many people with the same monitor..

Jerry, thanks for all those great pictures. You have a REALLY good digi cam there.. Can't believe how close you can take the pics of those caps with the writing on it. What is it?

As far as that special circuit board on top of the flyback.. I too do not have it.

As far as the fold over, the only time I had it was when I ran vertical games and wierd resolution games (like all the midway games). The fold would occur on the bottom. I now play all these games with H/W stretching, and they seem fine.

I also recommend that you use only smoothmame (or now, NO MAME). Since it looks the refresh rate at 60hz, and that's what this monitor really likes.

The only problem I do have, and would love to see what the rest of you can say about it, is the actual colors.

Some games have build in color bars. I'll try to take a snap of them, as well as run a few tools. I'd be interested in seeing the results. Also, I started noticing that if I pump up the brightness, the blue starts bleeding. Menace, you got anyone in Toronto that can rejouv a CRT? I also have a 29" Toshiba TV that needs to be "zapped" back to new condition.

jerryjanis · « **Reply #21 on:** March 30, 2004, 11:02:58 am »

Quote from: JoeB on March 30, 2004, 10:50:38 am

Jerry, thanks for all those great pictures. You have a REALLY good digi cam there.. Can't believe how close you can take the pics of those caps with the writing on it. What is it?

Gee, thanks! It's a FujiFilm FinePix A101. The secret is that there's a little switch. I can switch between a "flower" and a "mountain". When I switch to "flower", I can take pictures very close-up.

menace · « **Reply #22 on:** March 30, 2004, 12:50:40 pm »

Sorry JoeB no idea who would do that around here--best guess would be to call starburst and see who they get to service machines--you might just try a regular tv place as I'm sure they would have the equipment to do it--prolly not cheap though $:-\$

menace · « **Reply #23 on:** March 30, 2004, 04:22:49 pm »

EUREKA!! at last this monitor works again! IC2 was bad. switched it, adjusted it and it looks great. Thanks to all those who helped me out--especially ken L for suggesting parts I never would have thought of before.

jerryjanis · « **Reply #24 on:** March 30, 2004, 06:31:47 pm »

Congratulations, that's great!

Ken Layton · « **Reply #25 on:** March 30, 2004, 06:37:42 pm »

Let's see a picture of how it looks now, please.

sslakkerr · « **Reply #26 on:** November 20, 2014, 11:08:59 pm »

I know, wtf am I doing replying to this thread 10 yrs later??!! Well the recommendations here helped, so I thought it was useful to have this here for future peeps searching this issue.

I have a 25" k7000; P538 chassis
I had a very similar issue with top foldover. my 50/60 was turned at full counter-clockwise and I had top foldover. The vert position was also maxed (full clockwise) just to get the picture raised up to center it. I first replace IC2, but that did not change things. Then I replaced C51 and I saw that the foldover reduced. After I adjust the pots for 50/60 and vert pos it's looking good. I still have vert pos. maxed out to raise the image, but the fold is gone so fk it, I'm happy. So in a nutshell, I replaced C51 to fix my top foldover problem. Thanks Master Ken.

Expressline99 · « **Reply #27 on:** December 27, 2014, 09:51:52 pm »

I have the same top fold over issue going on with my k7193. I'll need to get a picture of before and after the c51 change. However, with mine when I go completely counter clock wise on the 50k-60k pot the fold over gets worse. About a 1/16th backed off is the least amount of fold over currently. However, it really expands when playing some games... to the point I can't read "top score" where it is above the actual score.

I don't look forward to pulling that monitor out again though. I've already capped it prior to this...however like Ken Layton said it's not usually included in the cap kits.

Expressline99 · « **Reply #28 on:** December 31, 2014, 08:49:13 pm »

awww the c51 change didn't fix it

Ken do you fix these if I get to bummed out to do it myself?

Expressline99 · « **Reply #29 on:** January 10, 2015, 11:45:26 pm »

Well changed out the 50/60hz pot and still no luck. My R80 is reading a around 3.7 ohms... would that do it? (k7193) Should be 3.1?
Ordering IC2 next

oh well talk to myself on this one.

grantspain · « **Reply #30 on:** January 11, 2015, 02:19:59 pm »

ic2 and ic3 both could give the issue you are seeing

Expressline99 · « **Reply #31 on:** January 11, 2015, 04:38:28 pm »

On IC 3 it says it is a UPC1378 will a UPC1378H work for this? It is all I can find to purchase.

grantspain · « **Reply #32 on:** January 12, 2015, 01:45:56 am »

Quote from: Expressline99 on January 11, 2015, 04:38:28 pm

On IC 3 it says it is a UPC1378 will a UPC1378H work for this? It is all I can find to purchase.

yes should be fine

Expressline99 · « **Reply #33 on:** January 12, 2015, 07:05:31 pm »

While I wait for my repair parts... pictures of my issue. (before of course)

grantspain · « **Reply #34 on:** January 13, 2015, 12:33:24 pm »

looks more cut off than a foldover?

Expressline99 · « **Reply #35 on:** January 13, 2015, 07:22:56 pm »

Uh oh. Does cut off cause that blue on the line on the first picture? (I hope I'm not just dumb.)

grantspain · « **Reply #36 on:** January 14, 2015, 01:23:14 am »

Quote from: Expressline99 on January 13, 2015, 07:22:56 pm

Uh oh. Does cut off cause that blue on the line on the first picture? (I hope I'm not just dumb.)

vertical issue can manifest themselves in many different ways so you can rule out a fault in the vertical circuit,what would be intesting though is if you had a jamma board to connect-that fault could be to do with the resolution setting of the pc you are using

Expressline99 · « **Reply #37 on:** January 15, 2015, 07:23:00 pm »

vertical issue can manifest themselves in many different ways so you can rule out a fault in the vertical circuit,what would be intesting though is if you had a jamma board to connect-that fault could be to do with the resolution setting of the pc you are using
[/quote]

Ok what should I do next and should we move this to a new thread?

Expressline99 · « **Reply #38 on:** January 17, 2015, 05:14:02 pm »

I'm using an arcadevga board so the resolution should be ok... I've gone through all the trouble shooting for that board and nothing in there relates to the blue line/cut off or fold over that I seem to be getting. I'm at a loss.

grantspain · « **Reply #39 on:** January 18, 2015, 04:54:24 am »

did you replace both the ic?


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