G08 driving me nuts!!!

FWIW, using a scope as an X/Y monitor is easy. So long as its a two channel and supports X/Y mode.

You will probably need to steer clear of the current crop of LCD scope though. They dont seem to reproduce the image correctly.

Like this. http://tinyurl.com/hgeqekg
 
Both X and Y are effected in that image. I really feel like its a board problem unless some how the clamp board is to blame.

You are swapping out the two boards that connect together via the ribbon cable, right? Is the ribbon cable known good?

Hmmm....

BTW, you have sound problems too. I'm sure you already knew that though.

Yes, it was those two boards I swapped out, plus I swapped the ribbon cable just to make sure that wasn't it.

Also, I did not know I had a sound issue. Missing sounds and speech? Distorted?

FWIW, using a scope as an X/Y monitor is easy. So long as its a two channel and supports X/Y mode.

You will probably need to steer clear of the current crop of LCD scope though. They dont seem to reproduce the image correctly.

Like this. http://tinyurl.com/hgeqekg

I will order one soon, building my test bench slowly, and thanks for heads up on making sure it's not an LCD.
 
Ok finally found some time, and made some good progress tonight. I got my spare G08 cleaned and put together, plugged it into the Star Trek, and boom, we got picture, very nice picture actually.

As most of us thought it was the board set, it turns out to be a monitor issue. Now knowing it's a monitor issue and not the boardset, the BIG question is WHAT is causing this weird image to appear on the current monitor???????

This boardset was just sent for repair not long ago, tested working on the repair end before being sent back. I plug it in and get this garbage on screen.

G08 experts?????

Pictures of boardset working on spare G08 monitor are below:

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I just thought of something. Could the two paddles that come from the fan need to be turned around? Right now the two wires going to each of them are parallel, but from what I remember, I think they were criss-crossed before I sent them out.

I should have taken pics of the chassis before hand and how they were plugged in originally.

Every picture I see online of G08's don't show the wires crossed, but from what I remember, mine were.

Would reversing the two paddles turning them 180 degrees cause any harm?
 
Ok, so I did take a few pics of the chassis before I sent it out for restore and repair. Anything look different the way they were hooked up as compared to now???

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the parts on the paddle boards should be facing the heatsink. Turning them around would probably be a bad thing, real bad thing. Plus they are keyed so I dont think you can without modifying the sockets.

So heres where things might suck. Since you've isolated the problem to the monitor and not the game board then you know for sure that you have a monitor problem. All of the parts to the right side from the middle of that board are simply pre drivers for the XY ouputs, they are probably good.

The one part thats handles the more complicated stuff, the IC on the board, might be bad. And guess what, thats a custom part thats nearly impossible to find.

So heres what comes next. TRIPLE CHECK the bad G08 chassis for solder bridges, cold solder and anything else that looks odd. If all of that checks out, swap those IC's.

On the bad board, do the teepee resistors get hot? They are supposed to BTW.

When you tested the game with the spare monitor did you use another clamp board? If yes, try that clamp board with the G08 thats acting crazy.
 
I just posted a bunch of photos and a parts list on my Dropbox here.

Hopefully something there will help.

Regarding gamefixer's comments, yeah, that IC600 is a bitch to replace. The odd rare times they've popped up for sale, they sell instantly and usually cost $50 each or more. They're unobtainium. Lots of unfortunate folks have decent GO8's sitting on the shelf due to this problem. The CRT's are the same as used in wg6100 so the GO8's are still valuable even when not working. The HV custom chip IC900 is almost as hard to source as IC600. Easily the scariest aspect of rebuilding the GO8-003 monitor is that you might totally rebuild everything and still wind up with a dud due to a bad IC.


Bill B.
 
I just posted a bunch of photos and a parts list on my Dropbox here.

Hopefully something there will help.

Regarding gamefixer's comments, yeah, that IC600 is a bitch to replace. The odd rare times they've popped up for sale, they sell instantly and usually cost $50 each or more. They're unobtainium. Lots of unfortunate folks have decent GO8's sitting on the shelf due to this problem. The CRT's are the same as used in wg6100 so the GO8's are still valuable even when not working. The HV custom chip IC900 is almost as hard to source as IC600. Easily the scariest aspect of rebuilding the GO8-003 monitor is that you might totally rebuild everything and still wind up with a dud due to a bad IC.


Bill B.

Bill's quite right about these chips. I picked up 4 of the IC600s NOS a couple of years back (had to do some serious internet searching to find 'em), but I know for a fact that the source no longer has any left now.

I have 2 working G08s that these are my backup/spares for so they quite precious and thus aren't for sale. And the other 2 went to other friend/collectors who also wanted them as backups for their respective Star Treks.

Having said that, I continue to hope that someone out there will eventually reverse-engineer these ICs and make available a replacement. I have heard that efforts have been made to do so, but nothing has yet come to full fruition.

Hopefully someday...

And hopefully your current problems with your G08 will turn out to not be due to the IC600.

Jon
 
Although I don't think your problem is due to the heat sink mounted transistors, I'd still think about replacing them...they sure do look a bit on the rusted side ;) .

The MJ21196s are what I have in the relatively recently serviced/rebuilt G08 that's in my ST upright, and they work great. Game has been to a couple of CA Extreme shows with no problems (knock on wood!).
 
I just posted a bunch of photos and a parts list on my Dropbox here.

Hopefully something there will help.

Regarding gamefixer's comments, yeah, that IC600 is a bitch to replace. The odd rare times they've popped up for sale, they sell instantly and usually cost $50 each or more. They're unobtainium. Lots of unfortunate folks have decent GO8's sitting on the shelf due to this problem. The CRT's are the same as used in wg6100 so the GO8's are still valuable even when not working. The HV custom chip IC900 is almost as hard to source as IC600. Easily the scariest aspect of rebuilding the GO8-003 monitor is that you might totally rebuild everything and still wind up with a dud due to a bad IC.


Bill B.

Thanks for that Bill. You are wealth of resources and information, and genius in this hobby. Thankfully I found out it was not a custom chip at all.

Although I don't think your problem is due to the heat sink mounted transistors, I'd still think about replacing them...they sure do look a bit on the rusted side ;) .

The MJ21196s are what I have in the relatively recently serviced/rebuilt G08 that's in my ST upright, and they work great. Game has been to a couple of CA Extreme shows with no problems (knock on wood!).

Those are the before pics you are referring to. Go to the beginning of the thread, and you will see those were replaced along with a whole slew of parts. Plus everything was cleaned. Mikerk, a member here did the full restoration, and a fantastic job.



We narrowed the problem down to the small circuit board on the metal rail the video cable connects to. I unplugged that little board, and connected the video cable directly to the chassis. Boom! We had picture, wider, bigger, but the picture was clear.

Who the heck would have thought it was the small video board??????

Now to narrow down what on the little board is the issue. mikerk thinks it might be a grounding issue somewhere on the cable, connector, or the pcb.
 
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That's awesome that it's the clamp board. That board is not complicated so it won't be hard to fix. Even if you end up shotgunning the board that's still better then that ic being bad.

Glad to hear it!!!!
 
I'd do the obvious first, those 4 10mf caps should get replaced. If they have been replaced make sure they are in right.
 
I'd just repopulate the entire input protection board, header and all. The parts needed are listed in the parts list in the dropbox folder here. There is also an edited photo showing the placement of the 2N3904 and 2N3906 transistors. I've never seen a Sega placement drawing for that PCB so the photo should be helpful. The diodes are simple 1N914 or 1N4148. You can recognize all the resistor values by the color bands in the photo.

Oh and (obviously) make sure the PCB is mounted on the nylon spaces so it doesn't short on the bar.

Bill B.
 

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We narrowed the problem down to the small circuit board on the metal rail the video cable connects to. I unplugged that little board, and connected the video cable directly to the chassis. Boom! We had picture, wider, bigger, but the picture was clear.

Who the heck would have thought it was the small video board??????

For anyone who wasn't paying attention... gamefixer called it twice, on Nov 11, 2016 and earlier today Jan. 4, 2017.

I think it's excellent news that the problem was just that simple little board. What a huge relief eh?

Bill B.
 
So CW, did you ever receive your VL MG/MS kit? If yes, are you going to install it and the BXXYR kit (from me) soon? How exciting will that be eh?

Bill B.
 
I'd do the obvious first, those 4 10mf caps should get replaced. If they have been replaced make sure they are in right.

Those were replaced along with everything else on the small board.

I'd just repopulate the entire input protection board, header and all. The parts needed are listed in the parts list in the dropbox folder here. There is also an edited photo showing the placement of the 2N3904 and 2N3906 transistors. I've never seen a Sega placement drawing for that PCB so the photo should be helpful. The diodes are simple 1N914 or 1N4148. You can recognize all the resistor values by the color bands in the photo.

Oh and (obviously) make sure the PCB is mounted on the nylon spaces so it doesn't short on the bar.

Bill B.

As stated above thankfully everything was already pretty much replaced on the small board. I used the original nylon spacers. They worked well.

For anyone who wasn't paying attention... gamefixer called it twice, on Nov 11, 2016 and earlier today Jan. 4, 2017.

I think it's excellent news that the problem was just that simple little board. What a huge relief eh?

Bill B.

You guys rock, I think the toughest thing was finding the time to get to diagnosing it. It was a weird one because it had just come back from getting a complete overhaul.

So CW, did you ever receive your VL MG/MS kit? If yes, are you going to install it and the BXXYR kit (from me) soon? How exciting will that be eh?

Bill B.

Bill, I finally did get everything from VL about two months ago. Now that I got all the monitor issues squared away, I am crazy excited to install your BXXYR kit and the VL kit. It will take this game to a whole other level of awesomeness.

I fixed the problem tonight with the small board. After doing some continuity tests, I found a broken trace for the ground....added a small jumper, and it works like a charm.

On a side note, my spinner is tight, what you guys suggest to do and use to get it spinning fast and smooth?
 
so all this time is was a broken ground on the clamp board? Good thing your logic board didnt decide to puke out bad vectors. Open grounds and bad signals from the logic boards is why G08's fry. Thats awesome that it was that easy though.

I use a light oil on the bearings on that spinner. Tri-Flow as a matter of fact.
 
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