Build Your Own Arcade Controls Forum

Main => Monitor/Video Forum => Topic started by: vizzinni on December 30, 2014, 01:40:25 pm

Title: [SOLVED] Black blob on WG 19K4914 arcade monitor
Post by: vizzinni on December 30, 2014, 01:40:25 pm

I just picked up a Mortal Kombat II cab from Craigslist, which turned out to be a conversion from a Gauntlet.  Got it cheap because it wouldn't power up, ended up swapping out the power supply which did the trick, although now there's a few issues like the black blob on the monitor, a WG 19K4914 manufactured in 1985.  Does this look like something a cap kit, or something else that's relatively easy, might fix?

Title: Re: Black blob on WG 19K4914 arcade monitor
Post by: lilshawn on January 06, 2015, 01:08:29 am

that looks an awful lot like something inside the tube is casting that shadow.

you didn't happen to transport the machine laying on it's back did you?

does this blob change shape at all with brightness contrast? does it wobble or stay still? if you bang the side of the machine does it move at all?

Title: Re: Black blob on WG 19K4914 arcade monitor
Post by: Ken Layton on January 07, 2015, 12:05:59 pm

Yes it could very well be a capkit is needed.

Title: Re: Black blob on WG 19K4914 arcade monitor
Post by: vizzinni on January 07, 2015, 12:50:18 pm

Quote from: lilshawn on January 06, 2015, 01:08:29 am

you didn't happen to transport the machine laying on it's back did you?

does this blob change shape at all with brightness contrast? does it wobble or stay still? if you bang the side of the machine does it move at all?

I transported the machine upright, but laid it on its side briefly when sliding it off the back of the truck.  The blob stays still.  I've taken the chassis out of the frame so I can't try the brightness adjustment or the "bang test."  I just got the cap kit from Bob Roberts in the mail this morning, so I'll be trying that next.

Title: Re: Black blob on WG 19K4914 arcade monitor
Post by: grantspain on January 07, 2015, 07:05:28 pm

looks like damage to the tube imo,it should just notice in daylight without the monitor powered
the shape is far too random to be chassis fault

Title: Re: [SOLVED] Black blob on WG 19K4914 arcade monitor
Post by: vizzinni on January 07, 2015, 08:25:43 pm

Thanks for the input guys...it turned out to be a bad cap.  I was looking through Randy Fromm's Big Blue Book and found a mention of a specific bad cap that could cause a "dark, irregular area," so I ordered the cap kit.  Fromm specified the C507 (47fu 160VDC) cap in the WG 4900 series, but I changed them all anyway, and the problem is solved. 

Title: Re: [SOLVED] Black blob on WG 19K4914 arcade monitor
Post by: grantspain on January 08, 2015, 03:31:17 am

well i am surprised by that,never seen anything like that in 30 years of working on monitors caused by a cap-unless it was a tear and the photo did not show well enough the actual issue

Title: Re: [SOLVED] Black blob on WG 19K4914 arcade monitor
Post by: lilshawn on January 08, 2015, 11:37:54 am

awesome it was something simple.

often things like this are the result of having a tub getting jarred with it's viewing face pointing up. (as it would if the machine was transported on it's back) this results in a piece of crud from inside the tube to get knocked off and down the back of the tube into the gun area. even a tiny piece of something can cause a shadow on the image, as the electron stream gets blocked by the debris.

 :cheers:

Title: Re: Black blob on WG 19K4914 arcade monitor
Post by: krick on January 19, 2015, 03:05:21 am

Quote from: vizzinni on January 07, 2015, 12:50:18 pm

I just got the cap kit from Bob Roberts in the mail this morning, so I'll be trying that next.

It's good to hear that Bob is still doing his thing.  I was concerned when there wasn't an update to this...
http://homearcade.org/BBBB/status.html (http://homearcade.org/BBBB/status.html)