What's new

snakeGrave

Enthusiast
Joined
Apr 13, 2016
Messages
201
Reaction score
169
Location
Delaware
Hi all I've had this ms2931 inside of a Blast City for a few years and maybe a year back it began exhibiting some strange behavior.

The screen would randomly expand almost like I would hit the demag button on it. I am pretty sure it is not the case as it occurs even with the degaussing coil is unplugged from the chassis.

I've recapped the chassis as well as the psu and the behavior persists. Has anyone experienced this before?
I managed to catch the screen bugging out on video, it happens when the continue count down reaches '7'. I'd say 99% of the time the monitor acts as it should.

EDIT: oops forgot the video
https://streamable.com/no7px1
 
Might be a good idea to replace any transistors you can find on the chassis, looks like an over voltage issue maybe?

Could also be worthwhile checking the pots on the remote board.
 
I just poked my head inside the cab real quick to take a look and also checked out the schematic I have. There doesn't seem to be much on the remote board aside from some tact switches that lead into a micro controller on the chassis. Maybe that's starting to goof up.

Pulling and testing the turn on voltage of each transistor sounds like a plan for now
 
the b+ needs to be monitored, if stable then likely a sign of flyback starting to fail- the kortek 2914 does exactly the same as this when the flyback start to fail
 
b+ was pretty stable, varied by less than a volt while playing through ddp

even when the screen bugged out I couldn't see a noticeable change

any word on those reproduction flybacks @gunblade ?
 
I think that the flybacks may be available again through TB focus https://item.taobao.com/item.htm?id=594979186324&ft=t&toSite=main

Was hesitant to post about this before because it took awhile for them to respond but they just sent me some pictures of my order so I'm pretty sure they are real :P
https://imgur.com/WiLQ91m

I know some users say that the picture size isn't quite right but I figure I'll give these a shot when they show up and report back
 
Mine does this too. Keep me posted on what you find.
 
I put one of these in my ms2931 tonight and I had a similar experience to the post made by xga that is linked to below
Nanao MS-2931

Overall it seems to be a lower quality part, there are no screw posts like there are on the original part, and the anode is more like a paper clip than a barb.

Same as xga my picture size was larger with the new flyback. It has not stuttered/expanded at all yet. I ran it for maybe an hour so far. One thing that did vary between myself and xga is that I adjusted the h-drive (I think that is the name of the pot) just a little bit and was able to get my picture to a size that I was happy with.

https://i.imgur.com/hcMZ3VZ.jpg
 
That looks promising! Did you check the B+ so see if it's in the normal range?
 
Nah but I'll hopefully find time to crack open the cabinet and measure tonight.
 
Sweet! I really hope a good replacement comes around for for this fly back. These monitors are too nice to not keep running.
 
B+ steady at 180volts with no adjustment after fly back replacement
 
I wonder if this is a newer batch that are working better. Regardless, very cool that it’s working for you!
 
Back
Top