g07 questions, burned degauss PTC

vanillajackson

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Hi, I have a Ms. Pacman cocktail table that originally had a g07 chassis that was replaced with an aftermarket eygo chassis some time in the early 90s. Well, the eygo is dead, and I wanted to put a g07 back in so I bought an "as is untested" g07 chassis to try to refurb and put into the Ms. Pacman. The first thing I noticed was the posistor for the degaussing coil had been resoldered using a piece of wire because it had burned through the PCB.. So I desoldered the PTC and it rattles like crazy, my meter also jumps around a lot when trying to get a resistance reading on it so I'm thinking it's bad. I included a picture of where it burned through. I was wondering if anyone has a source for these?

Other than the PTC burning the PCB, the rest of the chassis looks decent besides being dusty as hell. Haven't found any broken solder joints, but I won't say there aren't any. I've replaced the flyback, and all the electrolytic caps with new except for the big c904 cap, and I was wondering what else should probably be replaced before I put it in the machine to test? The old flyback looked ok, no epoxy leaking that I could see but I found too many people who posted about blown flybacks after a cap kit, so I replaced it. I did test the HOT, but all I did was make sure it wasn't shorted to the chassis metal, F901 and F902 are good. I don't know if the x401 and x402 transistors are good, but they're not shorted. Also I did make sure that C302 was soldered in with the correct polarity. Oh, and I did have one resistor (R317) that was 4.7k ohms so I replaced it with a 390 ohm one and was wondering if there are any other problem resistors on the board?

The yoke wiring has the g07 connector back on it now so that won't be an issue. I still have to find an original video connector from the game, but other than that and the PTC I think I'm about ready to test. I've already discharged the tube and removed the eygo chassis.

Sorry if I'm asking too much, I appreciate any info I can get.
 

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i stock NTC but not the PTC but you should be able to find them at mouser. BTW: you can test it without that whole degaussing circuit connected. the fuses need to be tested out of circuit and i would test the HOT and VR out of circuit , and reflow solder on header pins and any other suspect areas and then power it up and see what you get.
 
Cool, thanks for the info. And thanks for the Flyback and capkit, I recently got them from your ebay store. I wish I would have known you were on the site, I should have looked around more before just buying stuff, lol. I pulled the regulators out and they test ok, the HOT measures .427 using the diode checker, so it seems to be good. Fuses also test good out of circuit.

I did find that some resistors near the metal heatsinks in the middle are slightly out of spec.. like R414 is supposed to be 3.3k ohms and my meter reads it as 2.7k, R415 is supposed to be 2.7k and the meter shows it to be 2.5k. Should I be worried about these being slightly lower than what the schematic shows? I did test them out of circuit too.
 
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if you have done the cap kit, flyback, tested the fuses out of circuit, tested the HOT and VR and reflowed solder on headers, etc and visibly checked everything than i think its time to give it a try and see what you get and what the B+ is at.

BTW: thanks for the support and we have way over 800 products on our website and cheaper than our ebay store since we don't have to pay ebay so make sure to buy at our website in the future.
 
I guess this post is really just a follow up. I finally got around to installing the chassis and testing it. The monitor turns on, and turning up the screen adjust shows horizontal white lines scrolling. The B+ is also low at 113v with the other end of the resistor showing 149v, not sure if that's too high, the B+ pot is maxed out, but seems to work as I can adjust it lower. Will test it out of circuit though.

I've been following the g07 flow chart and it seems to be hinting that I have two separate problems here. Possible regulator failure in the 900s section, and maybe a bad x303 and/or x304 transistors. Guess I'm gonna pull the chassis and start testing more parts, check closer for broken solder joints.

I'm gonna go ahead and replace the c309 cap while I'm in there as well. Discharging the tube is nerve racking for me, lol not lol, so I want to do as much as I can between tests. I'd also like to replace a bunch of those old resistors near the heatsink since they showed to be a little low, just for piece of mind. Unless the the values aren't low enough to worry about..?

Anyway thanks for the reply. Hopefully this thing is working soon.
 
Those resistors are probably fine.

Change x303 and

Use your meter and check for continuity in all directions from the flyback.

Have you changed r908 yet? That and r912 can give you b+ problems.

Also, anymore (since security0001 offers them), I always change the b+ pot as well.
 
I never wholesale change a ton of stuff when working on a board. it makes it easier to find the problem when I make a mistake, it limits my field of focus to a fewer amount of things instead of trying to figure out if it was multiple things that went wrong.
 
I never wholesale change a ton of stuff when working on a board. it makes it easier to find the problem when I make a mistake, it limits my field of focus to a fewer amount of things instead of trying to figure out if it was multiple things that went wrong.

Yes if you are working on a board and you are trying to keep a log of what does what, etc. I could see that.

The original poster already said it's nerve racking for him to discharge the monitor. We've only suggested a couple of things that directly affect the B+ , and the bright lines which are his current problems.

He should pull X303 and test it, change the B+ pot , and check R908 and R912 and fire it up again. My guess is the B+ will be adjustable, and if he still has the white lines (after changing X303), it's likely cracks around the flyback.

I realize there are different approaches. I'm not saying yours is wrong.
 
I promise to post back as I make progress on this, I hate dead end threads.. I've just been slow getting back on this, but for the past few days I've been messing with this chassis and not making any progress really.

I replaced x303 even though the old one tested good, still have a scrolling picture with lines. I also replaced the B+ pot since the old one seemed to max out at 1.7k instead of 2k, but the new one does too so Idk. I don't think my meter is off since it reads other resistors and components correctly. I haven't tried to adjust the other pots on the board yet, I guess I should try to adjust those before troubleshooting different parts?

B+ is actually a little bit lower with the new pot, maxing out at 112v. I can still lower the voltage, but that don't do me no good. R908 and r912 are good, I've gone over the 900s section a couple of times testing parts, and checking traces. I do have continuity on all the traces coming from the flyback.

Couple things I didn't think to mention before.. This chassis has had caps replaced in the past, the cap at c511 was a 10uf 250v instead of 47uf. And the positive leg snapped off from corrosion when removing it. I put the right cap in when installing the cap kit, but could this have damaged other parts? And also the F901 fuse has been replaced with a BUSSMAN 1.5A 250v fuse instead of the 1.25A, didn't know if that matters or not.

I got a video this time of what the screen is doing, the screen is dim but I assume it's because of the low b+

https://www.youtube.com/watch?v=lDD9-3moK8s
 
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Finally got a picture. And it was all over my video connector. I had to make a connector and I just followed the schematic and saw the H and V sync on pin 5 and 6 of the big connector and wired the sync from the game into the 6 pin connector. I didn't even pay attention to the negative sync connector. After making another connector and switching pins around I now have a good picture, although a bit squished on the sides, but I still need to make some adjustments..

Also I can now adjust the b+ to 120v, but the pot is maxed out, and another thing I'm kind of worried about is there seems to be a slight staticy tick sound coming from the flyback, gets faster as it warms up. Should I be worried about this? I've only let this game run for about 20 mins total because the ticking kind of freaks me out, lol.

Thanks to Liteyear98, who helped me out through pm, and asked me how my video wiring was connected. Yep, that was it, haha.
 
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fire up the monitor in the dark and see if you see a discharge spark for your staticky tick. I have had a soldered lead go through a board too deep and it discharged to the metal case the board was mounted on.
 
Van

I have had 2 G07's I have rebuilt tick at me - The FB is arcing to the frame from the ferrite coil (Right Rear)

Resolution
I dont remember what I did with #1 (I think it is on a shelf)

On #2 I replaced the new (Ticking) FB with the next new FB in line and it fixed my issue. I dont know if it was my soldering or the FB was bad and I am not saying that you have a bad flyback, just what happened to me.

Do you have the old FB?
Maybe someone that knows more then me will come along and walk you on to target with what else might cause the ticking, but I would consider a new FB (Thats just me)

Note: Not sure how you are working on this, but I have learned to ALWAYS put the screws back into the frame to hold the chassis in place.

Finally got a picture. And it was all over my video connector. I had to make a connector and I just followed the schematic and saw the H and V sync on pin 5 and 6 of the big connector and wired the sync from the game into the 6 pin connector. I didn't even pay attention to the negative sync connector. After making another connector and switching pins around I now have a good picture, although a bit squished on the sides, but I still need to make some adjustments..

Also I can now adjust the b+ to 120v, but the pot is maxed out, and another thing I'm kind of worried about is there seems to be a slight staticy tick sound coming from the flyback, gets faster as it warms up. Should I be worried about this? I've only let this game run for about 20 mins total because the ticking kind of freaks me out, lol.

Thanks to Liteyear98, who helped me out through pm, and asked me how my video wiring was connected. Yep, that was it, haha.
 
Are you sure it's the FB ticking? I had a G07 snapping at me and couldn't figure it out. Turned out it was inside the neck socket. The copper on the leads of the spark gap were corroded and was causing arcing. I replaced the socket and it was fixed.
 
Are you sure it's the FB ticking? I had a G07 snapping at me and couldn't figure it out. Turned out it was inside the neck socket. The copper on the leads of the spark gap were corroded and was causing arcing. I replaced the socket and it was fixed.

I have heard neck socket ticking as well - it is much fainter (I have hearing loss lol) than the FB ticking (Almost like a Tick, Tick, Tick Pause, Tick, Tick, Tick, Pause).

I assumed it was water left over from cleaning them (Yes, I let them dry thoroughly)

Now I want to go back and investigate that chassis!

Van - let us know what you find out
 
Hey, thanks again for the replies. I let it run last night in the dark for about 10 mins straight trying to see if I saw anything arcing, but nothing that I could see. Had to pull the only working bulb in the cab cause that thing is actually pretty bright on its own, lol. I did get the image straigtened up, and it looks almost perfect other than the tube needing to be degaussed.

The ticking continues, no component legs sticking too far down I don't think. The tick also comes from neckboard area, seems to come from both places, with the flyback area being the louder tick. I do have the old flyback, and I assume it is good, as all the other critical parts are. But I never tested it before capping it and replacing the flyback. I just new it was old and I wanted to start with new parts.

And I'm also getting that same Tick Pause, Tick sound, it is also very faint, and if it didn't get faster the longer it ran, I'd assume it was normal operation, which I guess it still could be just the boards warming up in that area and adjusting to the heat, but I'm not sure.. I have video of it when I first noticed it, but the quality after uploading is poor, so you can really only hear the tick from the flyback area. It's very quiet so it's kind of hard to hear.. It's also very dark, but I'll post it anyway.

https://www.youtube.com/watch?v=d3Dt11tovho



Also I tried mouser and a couple of other places trying to find that PTC thermistor, can't find one anywhere, was tempted to buy a parts chassis to rob parts off of. A google search doesn't bring up much. I have an old sony trinitron chassis that has a similar looking thermistor but I can't find any info on it either, lol.

Anyway, I really appreciate the help guys. I'm really excited to even see anything on the screen. I've had the game for 3 years, and finally decided to tackle the monitor again. Lol.
 
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Use a card board tube from a paper towel to hone in on the tic
A light tic sounds like the neckboard like mentioned earlier - it seems like you can open those up and look inside if I remember correctly
 
I've seen a tick happen with a nib bad flyback. (more than once)

I'd put another known working flyback back in and see what happens.
 
Hi, sorry for the late reply. I haven't had much time to play with it. No progress on the tick, but I've opened it back up again and I let it run for about 30 mins. The picture shows fine, and never distorts or twitches or anything, except for when the AC comes on, lol. It looks almost perfect other than the side of the screen being a little purple.

Still can't really pinpoint where the sound is exactly, but definitely gets louder over the flyback. It seems to tick every half second from the neckboard, and the flyback ticks about every couple of seconds, kind of randomly really. The sound from the neckboard is a lot more quiet. I tested for continuity from the crt socket pins to the pcb and they seem good, but I haven't done anything else.

I do have the original flyback. But I'm still a little nervous to use it, plus I kind of messed up the pins desoldering it, I could make it work but... I'd rather just get another one. I only have one other friend with a few arcade games but none of his monitors are a G07, plus he doesn't do his own repairs so he'd probably be like HELL NO you can't have my flyback. lol.

I dropped my soldering station on its face a few months ago and I guess I messed up the socket for the iron and it causes it to be intermittent sometimes. So it just wasn't melting the solder very good so I just assumed it was maxed out, and the traces were just absorbing all the heat. So I sucked off what solder I could and topped a few pins trying to wiggle them free, so they're shorter now. Then I found out my soldering iron problem and sucked the rest of the solder out. Pulled right out then...

Sounds horrible I know, lol. The pads to the flyback are still solid though, even after all that wiggling.
 
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