G07 SYNC MOD

[FrizzleFried]

So...is the G07 SYNC MOD even worth the effort?   I have a little bit of a curl at the top inch or so of my image at certain resolutions,  and from what I have read,  this mod MAY rectify the curl?   

I recently did a cap kit,  and i'm not all that keen on taking the chassis out again being that I managed to take it out once without killing myself and/or it...

[FrizzleFried]

Welp...I answered my own question.   I got bored with TV (as I oftentimes do) so I decided "what the hell" and pulled the chassis.  I have to say that discharging the monitor for the 2nd time is MUCH MUCH less scary than the first time.   That said,  my heart still picked up the pace a bit as I discharged with a similar >tink< that I experienced last time.

The mod was just about as simple as they come...even for someone with my marginal soldering experience (busting a cap kit on this chassis was the first time I had ever soldered at a component level...before that soldering wire for a car stereo system was about all the soldering experience I had). 

It was with trepidation that I turned on the cabinet...half expecting the unwelcome stench of burning electrical components...but no...the cabinet fired up as usual...and with some minor adjustments of the H frequency I was able to COMPLETELY ELIMINATE both the curl at the top of the monitor AND the annoying wave that the top portion of the monitor exhibited at certain resolutions.

Mortal Kombat used to have a pretty severe wave at the top inch or so...it's GONE.  Donkey Kong and similar vertical resolutions experienced a pretty annoying curl at the top inch or so of the monitor...GONE!   Every single resolution that had issue before no longer has issues now.   I even got a "wave" of sorts through the whole monitor from top to bottom at one vertical resolution...GONE.   I would say I am 90% satisfied so far.  With the help of a friend,  some fine tuning should get me damn near 100%.   Unfortunately this monitor will never be 100%.   It has some MINOR Centepede burn-in.

For ANYONE with an Electrohome G07 arcade monitor who is experiencing even the slightest curl at the top of their monitor...(side if running vertical i'd imagine?)...I HIGHLY recommend the G07 Sync mod.

[Ken Layton]

The sync mod is only needed if using negative sync.

Remember also to look at the schematic and double check the values of some of the resistors in the sync circuit against what's on your particular main board. The factory goofed on quite alot of G07's and they had installed the wrong value of resistors. The values in the schematic are correct.

[FrizzleFried]

Ken,


I am a NEWB.  Can you please explain the difference between positive and negitive sync,  how each is obtained,  and what the benefits/issues each may cause?

I am using a JPAC to hook my PC up to the cabinet.   Do I have an option to hook it up with negitive sync or positive sync?

Pardon my newbness,  but at least I am VERY interested in learning.

[Ken Layton]

In the early days of coin-op video games, manufacturers used "positive" sync. All the early classic Williams games like Defender used positive sync signals. Then the manufacturers all wised up when they found that positive sync didn't have the latitude for a good solid & stable sync signal. Then suddenly everyone switched overnight to negative sync. Everything was more stable and the sync locked right on target with just about any old signal.

[FrizzleFried]

Ken,

BTW:  My monitor was manufactured in January 1980.   The picture is now pretty damn nifty (though it it IS slightly off center to the right in some resolutions and I HAVE changed the jumper from the middle to the right...

Any chances the possible issues with the CAPS being wrong might attribute to this slight problem?  If I am not all that bothered by it would you recommend I still re-remove the chassis and poke around?