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Author Topic: G07 CB0 Monitor trouble (Problem Finally fixed.)  (Read 4183 times)

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eccs19

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G07 CB0 Monitor trouble (Problem Finally fixed.)
« on: November 12, 2005, 01:44:48 pm »
As you can see from the attached picture, my picture sags on the left side of the screen.  As suggested I installed a cap kit, but problem still exists.  I don't know if this is a hint of not, but if the picture rolls (from left to right) the left side of the picture rolls as well, so the sag follows the roll, it does not stay at the left side of the screen.  Any suggestions as to what I can try now?  Also is there any adjustment for brightness and contrast for this monitor, as the picture looks washed out, even after the cap kit.

Best Regards
« Last Edit: March 10, 2006, 08:09:53 am by eccs19 »
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Re: G07 CB0 Monitor trouble
« Reply #1 on: November 12, 2005, 06:50:54 pm »
I played with some of the pots, and manage to reduce the curling at the side, but not eliminate it.  I have also noticed that the left side of the picture has a slight pulse to it. I don't know if it's related to the same problem or not.  I'm not sure what else I can try adjusting without blowing any thing up.
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Ken Layton

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Re: G07 CB0 Monitor trouble
« Reply #2 on: November 12, 2005, 07:36:02 pm »
You have what's called "flagging" or "curling" which is caused by a weak sync circuit of this particular model of monitor. If you got the Zanen Electronics capkit for the G07, there would have been instructions for performing the optional (and highly suggested!) "sync upgrade" modification to eliminate this curl.

It can be reduced a little bit by adjusting the horizontal hold control (called H Freq on Electrohome) a teeny bit one way or the other.

There is no brightness or contrast control on this monitor. To set the brightness, you use the "screen" control next to the flyback. The top control is the focus, the bottom one is the screen. Turn the screen control counter-clockwise to darken the picture, clockwise to brighten it.

It is very common to need to readjust some controls on a monitor after doing a capkit.
« Last Edit: November 12, 2005, 07:40:56 pm by Ken Layton »

eccs19

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Re: G07 CB0 Monitor trouble
« Reply #3 on: November 12, 2005, 08:46:15 pm »
You have what's called "flagging" or "curling" which is caused by a weak sync circuit of this particular model of monitor. If you got the Zanen Electronics capkit for the G07, there would have been instructions for performing the optional (and highly suggested!) "sync upgrade" modification to eliminate this curl.

It can be reduced a little bit by adjusting the horizontal hold control (called H Freq on Electrohome) a teeny bit one way or the other.

There is no brightness or contrast control on this monitor. To set the brightness, you use the "screen" control next to the flyback. The top control is the focus, the bottom one is the screen. Turn the screen control counter-clockwise to darken the picture, clockwise to brighten it.

It is very common to need to readjust some controls on a monitor after doing a capkit.

I noticed information about this sync upgrade on Bob Roberts site, and was thinking that may be the problem.  I'm planning on converting to mame, and using a arcadeVGA card.  Do you think that I still need to worry about it with this card, or will the problem still exist?

Thanks Ken!
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Re: G07 CB0 Monitor trouble
« Reply #4 on: November 13, 2005, 12:00:22 am »
You can get away without the mod with a avga card by using seperate syncs.

http://www.ultimarc.com/vidamp.html


Has the mod to do to the video amp.

(This monitor REQUIRES the amp for a good pic)

Just cut one trace and wire up rgbghv and enjoy.


Later,
dabone

eccs19

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #5 on: November 13, 2005, 06:03:07 pm »
Well I ended up going to Radio Shack, and getting the CAP to do the sync upgrade.  After some adjustment, everything is ALMOST perfect. Nice clean  bright picture, but I'm still having the right side (bottom) of the monitor pulsing. It seems fine near the middle of the screen, but the further it gets to the top & bottom, the worse it gets. Any suggestions as to what I may need to change / adjust? I know there is one more adjustment that I have not touched, but it's not that easy to get to. I think it's the one for the B+ adjust. (I have no idea what B+ adjust is, so that was another reason not to touch it.

Any last suggestions?

Best Regards
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #6 on: November 13, 2005, 07:29:42 pm »
Don't touch the B+ adjustment.

The pulsing may be the degaussing circuit failing. Temporaily unplug the degaussing coil.

If pulsing still there then try unplugging the fluorescent light in the marquee. If still there then try moving the game cabinet away from any other games a few feet.

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #7 on: November 13, 2005, 07:34:12 pm »
Don't touch the B+ adjustment.

The pulsing may be the degaussing circuit failing. Temporaily unplug the degaussing coil.

If pulsing still there then try unplugging the fluorescent light in the marquee. If still there then try moving the game cabinet away from any other games a few feet.

Glad I didn't touch the B+.  Thanks!

Pulse is there without light on, and it's not near any other games.  Can you point me to the degaussing coil?  I will give that a try and report back.
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #8 on: November 13, 2005, 07:57:44 pm »
Degausser coil plugs into the main monitor board next to the large fuse. It can either be a single 2 pin gray connector that unplugs or it can be 2 seperate white single pin connectors to unplug. You would have had to unplug the degausser coil to get the chassis out in order to do the capkit.

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #9 on: November 13, 2005, 09:38:27 pm »
Degausser coil plugs into the main monitor board next to the large fuse. It can either be a single 2 pin gray connector that unplugs or it can be 2 seperate white single pin connectors to unplug. You would have had to unplug the degausser coil to get the chassis out in order to do the capkit.

Ken, as suggested, unplugged the degausser coil.  No change.  I don't know if this makes a difference, but I do get a small bit of static through the speaker. Could this be coming from the PSU? Do you have any other suggestions?  Unfortunatly I don't have any other machines to even test the monitor in to see if it monitor or something else.

Thanks again.
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #10 on: November 13, 2005, 09:54:23 pm »
One other note. I noticed the isolation transformer has a bit of a buzz to it.  I would think that if it was something like that causing the problem, then it would be the entire picture, not just part of it.  Food for thought anyways.

Thanks!
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #11 on: November 13, 2005, 10:39:30 pm »
I'm assuming that when the capkit was done that the silver metal shield cover over the integrated circuit was re-installed?

I'm also assuming that all monitor frame ground wiring was properly reconnected.

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #12 on: November 14, 2005, 08:23:34 am »
I'm assuming that when the capkit was done that the silver metal shield cover over the integrated circuit was re-installed?

I'm also assuming that all monitor frame ground wiring was properly reconnected.

Yes, and yes.  I will have a look and see if any other grounds are broken / disconnected.
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #13 on: November 14, 2005, 09:49:51 am »
Did you get your capkit from Zanen Electronics? If so then there would have been a resistor to change:R908.

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #14 on: November 14, 2005, 10:11:32 am »
Did you get your capkit from Zanen Electronics? If so then there would have been a resistor to change:R908.

There was no resistor with my kit.  Do you by chance know the value of it?  I can stop at Radio Shack on my way home and pick one up.

Thanks again Ken!
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #15 on: November 14, 2005, 11:08:56 am »
R908 is a 47 k, 1/2 watt (Radio Shaft # 271-1130).

If your kit did NOT come from Zanen then you also must replace capacitor C302 which is a 220 uf @ 16 volt (Radio Shaft # 272-956 or 272-1029 will work). Remember that C302's polarity markings (+ is marked incorrectly) on the foil side of the board is incorrect. The black dot on the top (parts) side of the board is correct (that's where the negative lead goes).

By the way, for those of you that have the Electrohome G07 service/parts manual, Resistor R908 has the wrong value listed in the parts list. It says 47 ohms in the parts list but that's wrong. It should say 47 k ohms. The value is marked correctly on the schematic though.

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #16 on: November 14, 2005, 11:15:26 am »
R908 is a 47 k, 1/2 watt (Radio Shaft # 271-1130).

If your kit did NOT come from Zanen then you also must replace capacitor C302 which is a 220 uf @ 16 volt (Radio Shaft # 272-956 or 272-1029 will work). Remember that C302's polarity markings (+ is marked incorrectly) on the foil side of the board is incorrect. The black dot on the top (parts) side of the board is correct (that's where the negative lead goes).

By the way, for those of you that have the Electrohome G07 service/parts manual, Resistor R908 has the wrong value listed in the parts list. It says 47 ohms in the parts list but that's wrong. It should say 47 k ohms. The value is marked correctly on the schematic though.

My kit didn't come from Zanen, but I did replace a cap that had the polarity marked incorrectly. (as noted in the instructions)  Can't remember for sure if it was C302, but the number does sound familiar. (Will check when I get home)

Thanks for the info on the resistor.  Will pick one up on the way home.
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #17 on: November 14, 2005, 07:09:34 pm »
R908 is a 47 k, 1/2 watt (Radio Shaft # 271-1130).


Darn. Radio Crap didn't have any 1/2 in stock. Only 1/4.
« Last Edit: November 14, 2005, 07:26:44 pm by eccs19 »
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #18 on: November 15, 2005, 07:09:49 am »
Ken, as stupid as this may sound, if I can only 1/4 watt resistors, can I run 2 of them in parallel, and will it work OK, or is this a really bad idea?
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #19 on: November 15, 2005, 10:25:54 am »
In this particular application I would advise against paralleling 1/4 watt resistors. Get the single 1/2 watt I mentioned.

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #20 on: November 23, 2005, 11:41:33 am »
In this particular application I would advise against paralleling 1/4 watt resistors. Get the single 1/2 watt I mentioned.

Ken, I've got a local supplier sending me a resistor (free of charge, sending as a sample), but I notice that it's a 1.0 Watt.  I know using a 1/4 watt is low, but do you see any trouble going to high on this application?

Thanks once again.
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #21 on: November 23, 2005, 11:46:19 am »
No problems using that. A 1 watt gives better heat dissipation. It will be physically a little bit bigger so mounting will be a consideration.

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #22 on: November 23, 2005, 12:26:18 pm »
No problems using that. A 1 watt gives better heat dissipation. It will be physically a little bit bigger so mounting will be a consideration.

I don't expect I should have any trouble with the mounting. (I hope)  Considering it's free, I couldn't argue no matter how I looked at it.

Thanks again!
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #23 on: November 25, 2005, 06:11:18 am »
In this particular application I would advise against paralleling 1/4 watt resistors. Get the single 1/2 watt I mentioned.

I'm hoping to get that resistor installed this weekend. One other thing that I have found now that I have the machine together and running, is that I can adjust the curl and totally eliminate is (Sync kit installed), but once the monitor warms up, it starts to curl down.  I again adjust it, and all is good.  If I shut it down, and go to use it the next day (or a few hours later), it's curled up quite a bit.  Again adjusting fixes it, but it keeps returning.  I've taken contact cleaner to the pot, but that made no difference.  Do you think I have a bad pot, something else gone, or will this resistor I'm replacing also fix this problem?

Best Regards
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #24 on: November 25, 2005, 10:13:27 am »
As to the curl, flip the chassis over to see if there are 3 diodes installed on the foil side of the board connected to the red-green-blue signal input connector. They are covered with clear or frosted heat shrink tubing for insulation. If your chassis has these diodes (they are only present on very late production run) then that capacitor sync upgrade is not needed. The factory installed the diodes.

On many G07 chassis, the factory had mistakenly installed the wrong value resistors in the sync circuit. Double check yours to be sure that these resistors are the correct value:

R314, R317 (the ones most often incorrect)

R303, R306 (sometimes I found these were also wrong)

All of the above resistors are supposed to be 390 ohms, 1/4 watt. The factory had mistakenly used 4.7 k which of course is way off from what's supposed to be there. With these incorrect resistors in there, the sync circuit is too weak causing drift and or curl.

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #25 on: November 25, 2005, 11:03:15 am »
As to the curl, flip the chassis over to see if there are 3 diodes installed on the foil side of the board connected to the red-green-blue signal input connector. They are covered with clear or frosted heat shrink tubing for insulation. If your chassis has these diodes (they are only present on very late production run) then that capacitor sync upgrade is not needed. The factory installed the diodes.

On many G07 chassis, the factory had mistakenly installed the wrong value resistors in the sync circuit. Double check yours to be sure that these resistors are the correct value:

R314, R317 (the ones most often incorrect)

R303, R306 (sometimes I found these were also wrong)

All of the above resistors are supposed to be 390 ohms, 1/4 watt. The factory had mistakenly used 4.7 k which of course is way off from what's supposed to be there. With these incorrect resistors in there, the sync circuit is too weak causing drift and or curl.

Boy, after reading all these things about this monitor, they sure don't seem to be very well built / engineered.

From the number of times I've had that sucker apart, I don't remember seeing anything soldered on the back side, so I expect that I do have the older one.  I couldn't fix the curl at all with out doing the sync upgrade.

I will have a look at those resistors, and probably pick up a pack of those 390 ohm ones from Radio Crap on the weekend.

Thanks once again Ken!
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #26 on: November 25, 2005, 11:54:39 am »
Radio Shaft doesn't have the 390 ohm resistors in 1/4 watt rating but they do have it in 1/2 watt (# 271-1114) which will be fine for you.

Actually the G07 is a decent monitor that's cheap & easy to fix-- it's just that the sync/curl problems weren't discovered by the factory until the game manufacturers started using negative sync. Up until that time, games like Defender, etc. used positive sync. These resistors are in the negative sync part of the circuit. Now you can see why so many got out of the factory with the wrong resistors. The factory pattern generators they used when initially setting convergence, size, width, etc only used positive sync so they wouldn't have known about the negative sync problem until some techs started calling the factory and telling them what they had found with negative sync problems.

I sure hope that the factory had fired the dufus that stuffed the wrong value resistors into the board---must have been color blind or something.

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #27 on: November 25, 2005, 12:41:16 pm »
Radio Shaft doesn't have the 390 ohm resistors in 1/4 watt rating but they do have it in 1/2 watt (# 271-1114) which will be fine for you.

Actually the G07 is a decent monitor that's cheap & easy to fix-- it's just that the sync/curl problems weren't discovered by the factory until the game manufacturers started using negative sync. Up until that time, games like Defender, etc. used positive sync. These resistors are in the negative sync part of the circuit. Now you can see why so many got out of the factory with the wrong resistors. The factory pattern generators they used when initially setting convergence, size, width, etc only used positive sync so they wouldn't have known about the negative sync problem until some techs started calling the factory and telling them what they had found with negative sync problems.

I sure hope that the factory had fired the dufus that stuffed the wrong value resistors into the board---must have been color blind or something.

Actually those Radio Crap part numbers you typically give me are no good.  Technically Radio Crap doesn't even exist anymore in Canada.  The are now all called "The Source by Curcit City".  They don't sell individual resistors, you have to buy a mixed pack and figure out the color coding yourself. (I hope I can remember from school, if not, that's what the internet is for <g>)
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #28 on: November 25, 2005, 01:47:49 pm »
I know you're in Alliston, but if you ever get into the GTA, there are a bunch of electronic supply stores...you can order from them too...Active electronics is a good one, A1 electronics isn't bad (they're across the street from Starburst)...
I've used these guys a few times...they have good prices on super bright LEDs...

http://www.e-sonic.com

I've been to the shop...you go in, find what you want in a catalog, and then go to the counter and order...after a little bit someone brings it out...the best thing to do is find the parts on line, order over the phone, and pick up at the end of the day...

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #29 on: November 25, 2005, 02:48:36 pm »
I know you're in Alliston, but if you ever get into the GTA, there are a bunch of electronic supply stores...you can order from them too...Active electronics is a good one, A1 electronics isn't bad (they're across the street from Starburst)...
I've used these guys a few times...they have good prices on super bright LEDs...

http://www.e-sonic.com

I've been to the shop...you go in, find what you want in a catalog, and then go to the counter and order...after a little bit someone brings it out...the best thing to do is find the parts on line, order over the phone, and pick up at the end of the day...

I actually found a place in Barrie that seems to have parts as well.  They are not that cheap, but in a pinch they will work. 

I did talk to a guy at e-sonic, and that's where I'm getting my free resistor from.  He said they don't normally do that, but for the 1 single little resistor that I needed (I think he said it's was about $0.02, and $10 flat fee for shipping), he would just send it in the mail as a "Sample".  Gotta love free stuff!!!
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #30 on: November 25, 2005, 03:16:15 pm »
Glad to hear stuff like that...I like going to places where they are friendly, and will help you out if they can...
I may have a cap kit to do...have you checked to see if they have any kits there?? 

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #31 on: November 25, 2005, 03:55:39 pm »
Glad to hear stuff like that...I like going to places where they are friendly, and will help you out if they can...
I may have a cap kit to do...have you checked to see if they have any kits there??
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #32 on: November 25, 2005, 04:01:18 pm »
Glad to hear stuff like that...I like going to places where they are friendly, and will help you out if they can...
I may have a cap kit to do...have you checked to see if they have any kits there??

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #33 on: November 25, 2005, 07:51:23 pm »
By the way, for those of you that have the Electrohome G07 service/parts manual, Resistor R908 has the wrong value listed in the parts list. It says 47 ohms in the parts list but that's wrong. It should say 47 k ohms. The value is marked correctly on the schematic though.

Ken. Guess what I found?  I was looking at the board, and the resistor that is in the R908 is only a 47 ohm, not a 47k.  With this being wrong, is there a chance anything else could be damaged?  Would they have mixed this one up at the factory as well, or would you figure someone changed it in the past and put in the wrong value? (You mentioned that it is listed wrong in the manual)  If it was the wrong value, do you think this could be what's giving me all this greef?

Best Regards
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eccs19

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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #34 on: November 26, 2005, 09:56:10 am »
As to the curl, flip the chassis over to see if there are 3 diodes installed on the foil side of the board connected to the red-green-blue signal input connector. They are covered with clear or frosted heat shrink tubing for insulation. If your chassis has these diodes (they are only present on very late production run) then that capacitor sync upgrade is not needed. The factory installed the diodes.

On many G07 chassis, the factory had mistakenly installed the wrong value resistors in the sync circuit. Double check yours to be sure that these resistors are the correct value:

R314, R317 (the ones most often incorrect)

R303, R306 (sometimes I found these were also wrong)

All of the above resistors are supposed to be 390 ohms, 1/4 watt. The factory had mistakenly used 4.7 k which of course is way off from what's supposed to be there. With these incorrect resistors in there, the sync circuit is too weak causing drift and or curl.

Ken, I got the board out, and those 4 resistors are correct.  All 4 of them are 390 ohms.  As per my previous post, could that other resistor being wrong, be causing the curling to be moving around?  If not, do you have any other things I should check while I got this thing apart?

Thanks!
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Re: G07 CB0 Monitor trouble (UPDATE) 1 last issue
« Reply #35 on: November 26, 2005, 10:51:34 am »
OK I admit it. I'm getting more confused.   ???

I had a look at the back of the board as suggested by Ken, and there are 3 diodes attached near the RGB hookup.  You mentioned this was a factory fix for the curl, but I was not able to get rid of the curl till I did the cap swap you suggested.  Now I can get rid of it, but it keeps returning. (see previous posts) Plus I still have my other mysterious issue with the one resistor not being even close.  I have not yet changed it, but I am hoping to later today.  Just not sure what else I should look at before I put everything back together.

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dabone

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Re: G07 CB0 Monitor trouble (getting more confused by the minute<g>)
« Reply #36 on: November 26, 2005, 03:37:55 pm »
I've got a g07 that curls a little bit no matter what I do. (It's in a Karate Champ at the moment)

Those monitors seem to take seperate syncs much better than composite sync.

Are you using this with a pc or a real arcade board?


Later,
dabone

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Re: G07 CB0 Monitor trouble (getting more confused by the minute<g>)
« Reply #37 on: November 26, 2005, 03:49:54 pm »
I've got a g07 that curls a little bit no matter what I do. (It's in a Karate Champ at the moment)

Those monitors seem to take seperate syncs much better than composite sync.

Are you using this with a pc or a real arcade board?


Later,
dabone


It is currently a real arcade board, but I will be converting after Christmas.  I can get rid of the curl, it's just that once it warms up, it curls. I adjust it, and it's fine till it's shutdown for a bit, then I have to go through the whole process again.  If it was just a little, I wouldn't mind so much, but after cooling down, and turning back on, the curl makes it unplayable.  Needless to say I have not put the back on the cabinet.   :(
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Re: G07 CB0 Monitor trouble (Well that didn't work either)
« Reply #38 on: November 26, 2005, 08:22:09 pm »
OK this is getting to be a little crazy now.  I replaced the 47 ohm with the proper 47K, and turned it on, and there was no curl. I thought I was home free, but alas, it return and had to manually adjust it again to get rid of it.  It also have the shake / waviness on the right side of the screen.  How I'm at a loss as to what to try next.
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Ken Layton

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Re: G07 CB0 Monitor trouble (Well that didn't work either)
« Reply #39 on: November 27, 2005, 01:54:34 am »
I can't think of anything else you can do aside from using seperate syncs instead of composite.

I don't think you have a bad pot, but maybe the integrated circuit might be drifting internally as it heats up?

  
 

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