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Possible external physical causes of vertical collapse in an MS9-29S?


jaybeear

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Hi all,

 

What (if any) are the possible external physical causes for a vertical collapse on a Nanao MS9-29S? Could any of the connections to the chassis from the cab (power, degauss, v/h yoke, etc) cause this to happen? Or can this only be something amiss with the vertical IC that would always have happened?

 

For context I've performed a tosh tube swap today into my cab along with its originally paired MS9 chassis. They came together in a 'Sega cage' and were demonstrated working before purchase. A few months prior to the swap the chassis was sent off for a service to Jomac (being clear I'm not in any way suggesting it came back with issues!) so it should have been in tip-top condition, then was left alone mounted back in the cage with the tube. So today was the first time it was powered on by me since purchase once in the cab - got a few moments of fast rolling image that didn't vertically fill the screen then down into the bright horizontal line. Powering off, leaving it a minute and powering on to check led to just the bright line immediately and I think the protection circuit kicked in. Haven't powered it on since. I was extremely careful re-connecting everything as it was pre-swap (honest :) )

 

I actually have a second MS9 chassis handy that also had been off for a service, however I don't want the same thing to happen to it if there's something I'm either missing or just misunderstanding. Is there anything else I can safely test/adjust or should it be Jomac-bound again ASAP??

 

Much appreciated - I may one day get to play some games on this thing :rolleyes

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Obviously if the vertical winding of the yoke isn't connected you won't have any vertical deflection. Usually, but not always, if the yoke isn't connected you won't get EHT but that depends on the exact chassis.

 

I don't pretend to know this exact chassis but it's pretty obvious all connections need to be sound and in place BEFORE switch on or damage can be done to things like the vertical drive IC etc.

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I should maybe clarify it wasn't a yoke swap (nowhere near technical enough for that!), the whole intact tube with yoke was swapped out. Understood that if the yoke connectors were not seated right it could cause issues.

 

I snapped some pics of connectors prior to the first power-on just in case, will post them later on the off-chance something can be seen/corrected.

 

I do wonder if it's just bad luck and the vertical IC's time was just up.

 

 

Sent from my iPhone using Aussie Arcade

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Pics of vertical and horizontal yoke connectors that appear well-seated (plus the remote board connector in shot)

 

http://i.imgur.com/VSbwOGNh.jpg

 

http://i.imgur.com/PdmuWYSh.jpg

 

 

And just in case, this is the route the power takes to the monitor:-

 

1) AC 100v out of the Isolation transformer to two blue wires

http://i.imgur.com/ztjyd2sh.jpg

 

2) Blue wires spliced onto white and black wires. These two run right up to the connector on the chassis, along with two red and grey wires that are clipped and not connected to anything (the ends are visible in the pic)

http://i.imgur.com/nVZnHMih.jpg

 

3) Connector on the chassis - this is interesting, it's a 4-pin female connector that is physically compatible with the chassis' male 2 pins spacing and carrying AC over the two wires that match the pins. Of anything this seems a bit bodge-y but it gets power where it needs to go

http://i.imgur.com/KyeVInJh.jpg

 

 

I hope none of the above can cause a vertical collapse, because I've then got a chassis-killer cab that needs even more doing to it to be safe :( I don't want to risk my second MS9 chassis on it if it'll just cause the same issue, but then I also wouldn't like to send the current one off just to have it happen immediately when it returns - bit of a dilemma!

 

Thanks for reading and any advice is welcome.

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First thing I'd do is replace all the caps. They look like the originals and if that is the case, then they leak and go bad. It may not look like they have leaked but 10 to a brick chicken house they're bad.
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Not a single electro cap in that chassis is original , they have all been replaced with new original United Chemicon and Panasonic FR series caps hense why they look like the originals.

All the brown color caps are united chemicon same as they were built with , black and blue color caps are all panasonic which are even higher spec for known trouble area's.

There are a couple of nichicon caps used where values aren't available in the other 2 brands.

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Not a single electro cap in that chassis is original , they have all been replaced with new original United Chemicon and Panasonic FR series caps hense why they look like the originals.

All the brown color caps are united chemicon same as they were built with , black and blue color caps are all panasonic which are even higher spec for known trouble area's.

There are a couple of nichicon caps used where values aren't available in the other 2 brands.

 

I was sure to mention in the original post that it had already been away for a service, hence the question basically 'what am I doing wrong to it'!

 

To close this thread out the issue was my fault, but really unexpected - everything was hooked up correctly, however the JAMMA harness in the cab had an interesting 'feature' where on the wiring up to the chassis video connector there was a further physical connector. The JAMMA sync wire and the H-sync wire from the video connector both entered one side of this connector (so were spliced together), but if the connector was connected both these wires were output the other side to the V-sync video connector point.

 

So effectively with the connector closed, composite sync was going to the V-sync point on the chassis. With it open, composite sync goes to the H-sync.

 

Took a long time for me to suddenly realise what was up. Disconnected it, powered on... bingo. All that fuss over one apparently non-standard connector :blink:

 

Thanks all!

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