Sanwa 29E31s Tube with MS9 Chassis

[Zeroh]

Hello,
I need a tube to test an MS9 Chassis, the only tube I have is the one from a Sanwa 29E31S/Shangai Novel (Model 73SX...) combo.
Specs seem to match, and I'm not really concerned about geometry, basically I only need to make sure that the Nanao chassis is working (turns on/displays something).

So, I searched most of the posts and found this post from AO which seems to confirm it's doable, however I also read this post from @Hatsune Mike:

As such it's basically the same as MS9-29 but the use of pin 4 on the neck means you cannot just swap that chassis in without consequences

From this thread.

And this post from @nem :

There's also a gnarly video in that thread where you can see what happens when you connect one of these tubes to a chassis that doesn't have pin 4 connected.

Taken from here.

Linked video is not available, what are the consequences?

 

[trashedcabs]

https://www.neo-arcadia.com/forum/viewtopic.php?t=80997

Pin 4 in the Novel tube is an HV feedback pin. It will arc to the neighboring pin if you don't give it a path. You can put a 10Mohm 1W resistor from pin 4 to ground and it should work. I did this on a PFX and it worked fine.

 

[Zeroh]

Ok, that info was also on the AO thread that nem linked, but I wanted to know what were those "consequences".
I.e. does the tube crack, does the chassis blow, maybe the whole setup goes up in flames...

Anyway I went ahead and tried:
Put an MS9 chassis on a Shangai Novel tube and I had a picture! However there was a frightening squeal/whine coming from the neck .
I did put the resistor and I also tried a direct GND connection to pin 4, however I hadn't noticed that the yoke connector on the MS9 is missing the
metal stud on pin 4.
So, I dismantled the yoke connector, removed the metal contact from pin 12 (unused), populated pin 4, re-soldered the connector and added the 10M Resistor between pin 4 and GND.
The result is that the monitor is perfectly working and quiet as a mouse!

So I can confirm that with a simple mod:

The Nanao MS9 chassis is a match to the Shanghai Novel tube.
There is no need to adjust the vertical limit trimmer: The picture fills the whole screen vertically and horizontally.
The image is square and stable: No wobbly sides. I only adjusted the spc trimmer.
Image looks good!

Please be advised that I only tried 15Khz mode and just one Jamma pcb.