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Main => Monitor/Video Forum => Topic started by: morksouth on July 29, 2009, 02:22:32 am

Title: HELP: horizontal distortion at top of picture issue
Post by: morksouth on July 29, 2009, 02:22:32 am

Hey guys,

I'm getting some horizontal distortion at the very top of the picture on my monitor. 

My cabinet and monitor are only about 3mths old (a 4P 1069-in-1 Arcade Mania cabinet from Pinnacle Wholesalers in Melbourne). 

The distortion only started happening about 2wks ago, and seems to always distort in the exact same pattern.  See pics below:

(http://img200.imageshack.us/img200/4013/img0745iab.jpg)

(http://img33.imageshack.us/img33/2197/img0747r.jpg)

(http://img200.imageshack.us/img200/9256/img0748r.jpg)

It's very annoying in games that display important information across the top of the screen like high scores. eg:

(http://img233.imageshack.us/img233/156/img0750q.jpg)

Any ideas what is causing the problem, or what I can do to fix it?  I have tried degaussing with my wand, and also fiddling with the display knobs inside the cabinet, but no luck as yet.

Thanks.

Title: Re: HELP: horizontal distortion at top of picture issue
Post by: qrz on July 29, 2009, 12:58:49 pm

if it had more age to it , i'd think  bad cap(s) in the Hosc circuit and/or pwr sup ....

per description, it may still be under warranty - check with the dealer - ASAP !

Title: Re: HELP: horizontal distortion at top of picture issue
Post by: Hamselv on July 29, 2009, 05:08:15 pm

Qrz,

I am about to change caps on my TV chassis and I experience pretty much the same distortion as the OP here. I posted a pic in this thread: http://forum.arcadecontrols.com/index.php?topic=94697.msg996446#msg996446 (http://forum.arcadecontrols.com/index.php?topic=94697.msg996446#msg996446)


Could you explain what you mean by the "Hosc circuit" and if possible, how to locate it on a chassis? By power supply, do you mean caps in the general vicinity of the power supply?


Thanks :)

Title: Re: HELP: horizontal distortion at top of picture issue
Post by: qrz on July 29, 2009, 10:12:38 pm

Hamselv - actually , i DID see ur post . didn't find a schematic and then forgot about it . sorry !
Hosc is an abbreviation for the Horizontal oscillator. which, based upon ur pics, is not the problem.

have a look at the vert output ic , pump up ( retrace) cap/diode , and the small value caps in the Vosc/output stage.
the ic's VCC supply could have a leaky diode/filter cap as well  ;)

betting the ic will need to be replaced . but check  the other stuff 1st...

Title: Re: HELP: horizontal distortion at top of picture issue
Post by: Kevin Mullins on July 30, 2009, 02:09:04 pm

What happens if you shrink the Horizontal width a bit ?