G07 horizontal hold won't lock in

80scoinops

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Recapped monitor, reflowed cold solder joints, pic looks good but horizontal hold won't lock in. Tried the 3 sync wire positions. Tried cleaning the pot with no luck. Nudging the pot but not turning it will change direction of rolling screen. Is the pot bad, or is something else the culprit? Thanks in advance!
 
Yeah, everything went back together properly. It definitely sounds like a sync issue which is what's so confusing. I wasn't sure if a bad pot could cause that or if it's obviously not the pot based on the way it's behaving. The monitor was DOA when I got it but the recap and fuse / flyback replacement fired it right up.
 
Well, I've had a bad HH pot on G07's before keep it from locking. But a quick pic of the connector would be nice. As well as some info as to what game it is hooked up to...
 
It's a Crystal Castles, sync connector looks like this one from Bob's site:

sync5.jpg


I'm a little confused on the jumper issue. Thanks again guys.
 
According to the Crystal Castles wiring diagram, it doesn't use composite sync, so you don't need to jumper it.

Sounds like you should try replacing the horizontal freq pot.

but first, is your B+ measuring 120vdc? If it's off by enough, it'll mess up the hold...
 
B+ is 117-123 vdc depending on where I adjust the pot. No change in HH. If I nudge the H Freq pot but don't spin it, the picture will roll in a different direction, depending on where it's nudged. Sounding more like a bad pot is to blame? Something else?
 
If flexing the pot makes it change the screen, then yes, replace the pot. Might not fix it, but at least you'll know that's not the problem...
 
There are two resistors in the Horizontal hold circuit that were commonly the wrong value from the factory. About 1 in 3 G07's I have come across have the wrong value in there. I think the number is R317 but I am not certain as I do not have a chassis in front of me. I cannot tell you why they worked correctly for so many years then get the "rolls" after a repair or cap kit but simply swapping in the correct resistor will solve the problem... if your chassis has this problem...
 
Ken Layton's post on the subject from 2004:

On some G07's the factory has mistakenly inserted the wrong value resistors at locations R314 and R317. They both are supposed to be 390 ohms, but the factory stuffed in 4.7 k resistors instead. Both these resistors are in the sync circuit. Check for this factory error first before you change any transistors.

Most G07's also need to have the negative vert sync and neg horiz sync jumpered together for proper operation.
 
Finally replaced all the pots... no change. Still won't lock in. R317 abd 314 are correct.

Before drop kicking the G07 from hell into the nearest dumpster, anyone have suggestions on where to look next for the possible culprit?
 
I've been seeing this pop up on the board a lot lately. It's usually one of a few different things:

1) bad cap.

b) bad pot

iii) bad IC501

four) broken solder joints.

Or a combo of more than one. Start digging, and let us know what you come up with.
 
I'm having the exact same problem, but with a Spy Hunter using negative sync.

http://forums.arcade-museum.com/showthread.php?t=138850

The vid harness I was working with was ratty to begin with, so I am in the process of rebuilding it. I will keep up with this thread to see where it goes. I am having the same response from my horiz freq pot - If I 'nudged' it, I would get subtle changes in the rolling. Turning the pot gave me very large coarse changes in the rolling.
 
I have a local buddy that fought this problem for the past few days, and had asked me to bring him over an IC501 so he could try swapping it out, but then called to tell me never mind because he'd fixed it. Turned out to be a broken trace...
 
I have a local buddy that fought this problem for the past few days, and had asked me to bring him over an IC501 so he could try swapping it out, but then called to tell me never mind because he'd fixed it. Turned out to be a broken trace...
Was working on this one again today looking for bad traces and found that R514 had a previous repair attempt by former owner:

- pads are pulled up
- they had the wrong resistor was in there, legs are way too heavy to fit the holes on the board
- resistor was on the solder side, not the parts side

What resistor should be in there / what's the best source? Bob?
What's the best way to connect a new one now that the pads are pulled up? Scrape away the foil and solder to the trace?
 
Anyone know what resistor should be at R514? I have the PDF of the schematics, but can't find it. I'm probably staring right at it and can't figure out the page breaks.
 
Anyone know what resistor should be at R514? I have the PDF of the schematics, but can't find it. I'm probably staring right at it and can't figure out the page breaks.

The schematic I have has it at 820 Ohm 2 Watt. Kind of a weird value. The CAO is listed as 470 Ohm 2 Watt.
 
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