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Main => Monitor/Video Forum => Topic started by: Witchboard on March 08, 2005, 11:29:53 am

Title: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Witchboard on March 08, 2005, 11:29:53 am

Still working on that G07 CAO board.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Ken Layton on March 08, 2005, 11:40:22 pm

I believe the CAO accepts positive sync signals only.

As to no hor/vert deflection, you may have lost power to the integrated circuit or a coupling or filter cap was in backwards. Always remember that sometimes a brand new capacitor could be bad right out of the package.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Witchboard on March 09, 2005, 08:39:52 pm

Positive sync only eh?  I didn't know there was a difference.  So, I'll need to find a game that outputs positive sync to get the monitor working.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: dabone on March 09, 2005, 09:36:13 pm

7404 Ic Sync inverter.




pin 1 on the 7404 - sync FROM game
pin 2 on the 7404 - sync TO the monitor
pin 7 on the 7404 - Ground
pin 14 on the 7404 - +5


Boom, negative sync input.

Later,
dabone

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Witchboard on March 10, 2005, 09:13:41 am

Quote from: dabone on March 09, 2005, 09:36:13 pm

Boom, negative sync input.

Do you mean, "BOOM, positive sync input?"  I'll google the 7404 IC.  Thanks for the heads up.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Ken Layton on March 10, 2005, 10:26:37 am

That 7404 sync inverter trick is an old Star Tech Journal article and it's often reprinted in the Romstar conversion kit manuals like Black Tiger and Sky Shark.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: dabone on March 10, 2005, 04:09:24 pm

It inverts the sync you give it, so negative sync from the game/jpac/avga/whatever becomes positive sync for your monitor.




Later,
dabone

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Witchboard on March 10, 2005, 10:05:59 pm

Thanks guys.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Ken Layton on March 11, 2005, 12:18:11 am

Yup, a 7404 or 74LS04 is a hex inverter chip. Very common part.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Witchboard on March 11, 2005, 12:42:25 am

Yeah, cheap too. ^_^  Thanks again guys.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Witchboard on March 19, 2005, 10:50:30 pm

Hmmm.. that's not good.  I setup the chip on the monitor the way I read the description and flipped on the game.  Looked the same to me, so I turned the horizontal hold one way, then back thinking maybe I just needed to tweak something.  Then, the screen went dark... and didn't come back on.  I could hear the high pitch of the monitor, but it looked like the heaters went out.  This chassis is a nightmare.  :-\  Next time I see a CAO chassis, I'm leaving it where it lay.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Ken Layton on March 20, 2005, 12:44:45 am

Hmmm....maybe at this point you should just order that Wei-ya replacement chassis for Electrohomes from Alva Amusements.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Witchboard on March 20, 2005, 02:24:04 am

I'm not one to give up.  I just need a break from that particular chassis.  I did check out Alva, but couldn't figure out which chassis I would need for replacement.  I'm presuming the 820H or 814S.  I'll keep them in mind, but it just kills me for this thing to get the best of me.  ;D

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Ken Layton on March 20, 2005, 02:47:14 am

The 820H is the one to order for your monitor.

Title: Re: What would cause both Horizontal and Vertical Deflection to Stop Working?
Post by: Witchboard on March 20, 2005, 09:53:30 pm

Thanks Ken.  I'll look at that as a last resort.  I feel the more I work at this the more I learn.  First thing I'll do is maybe take the chip back out and see if the picture comes back.  Maybe I burnt up the chip?  Who knows.  Maybe the thing just finally died.  The tube isn't the best and I'm not sure if I want to drop $$ on a new replacement chassis for it.  I have more time than money at the moment.  ;D  Thanks again for all the help.  If I get the thing figured out I'll post up the results.