What's new
By:
Filters

Blast city nanao pincushion issue

S

saucydaddy

Student
Joined
Aug 18, 2021
Messages
51
Reaction score
16
Location
Illinois
Hey guys wondering what to do here. I sent in a monitor chassis to be repaired because of the squished image on the right side. A pincushion issue, here are some before pictures
1000002559.jpg
1000002558.jpg


They said they could fix the pincushion issue but when I got it back it didn't look much better and they said they also changed the flyback and all the caps. Here are some after repair photos
1000002519.jpg

1000002514.jpg


They said I could send it back to recheck it but wondering if I'm being too picky about this? I know these monitors are old as hell and won't be perfect but it kinda looks the same to me. I've tried adjusting the spc15 values but it doesn't do much. This is a blast city stock nanao ms29 monitor.

Just looking for some advice on what to do since I'm not really familiar with monitors, is it possible to have this fixed or kinda stuck with this?
 
It looks like the flyback screen pot is set too high and the rgb probably needs adjustments too. Was there something wrong with the flyback that they needed to change it? Hopefully they did not put a Chinese flyback in there, because they’re not very good compared to the original.

I’ve never got a perfect pincushion with any of my blast cities. I get them as good as I can and kind of just accept it for what it is.

Looking at your pics, it looks pretty good imo.
 
Sharp Image repair did it, they said they sourced the flybacks from Spain I believe. They said it was making a really loud noise or something, a little upset that they changed it without confirming with me but I'm a bit new to this and I've heard great things from them so took their word for it.

After looking at it for a while though, noticed that the left side of the image is a bit bigger and the right is squished so don't think it's really a pincushion issue since they said on their tubes it was great. I'm beginning to think it's maybe something with the yoke. Potentially shifted or something, maybe those induction strips. I've never done anything like that but guess it doesn't hurt to learn, don't think there's anyone in the midwest that does this kinda stuff. Appreciate the link @frsj8112

If anyone knows anyone around the midwest that does it, that would be cool if not I may dig in one night and try not to die playing with it.
 
What you're looking for is Horizontal Linearity. It's not something you can adjust via a pot or OSD to my knowledge.

I've had two of these 2931's with the same sort of poor horizontal linearity. I thought it was my yoke so I did a yoke swap as I was originally running one for a Toshiba trisync (whatever came with a Windy 2), then re-did that. I tried another tube and the result was the same. To absolutely rule out that I'm not doing anything wrong (you never know lol), I hooked up 2 different Nanao 2934's which exhibited perfect geometry.

As for how to fix this horizontal linearity I'm terribly sorry I don't know. But I've been following along in the hopes something comes up. Best of luck mate.
 
Hmm if it's the linearity problem someone mentioned you could adjust the H Drive to see if it helps. Wondering if slight adjustment there would help since the problem isn't really that bad but then again this pot is sealed to prevent adjustments and don't want to blow up my chassis/tube.
https://forums.arcade-museum.com/threads/nanao-ms-2931-how-to-adjust-horizontal-linearity.464853/

@phokkun are you saying you put in a new complete monitor the nanao 2934 or the chassis from that? Wondering if replacing this chassis with a different one potentially fix the problem? Or if it's possible to swap chassis with other models?

@BlinG when you said "flyback screen pot" are you referring to the focus pot on the flyback or I think the other one is brightness right.
 
There’re also a number of other adjustments I recall in a couple of extended OSDs. I think it’s in the manual as to which buttons you press together to enter the menu.

Edit… @SuperPang on AO wrote - Figured it out, you hold "-" for 3s to get the extended menu, "+" for 3s for the factory menu.

Arcade Otaku states:

How to Use the OSD​

To bring up the normal menu, press mode. This gives you adjustments for H POS, H SIZE, V POS, V SIZE, CONTRAST, BRIGHTNESS, DEGAUSS, and RESET. A Degauss can be performed every 250 seconds. To use the reset function to restore factory settings, go to reset and hold down or up for a few seconds. To cycle through all of the options, use the mode button. To go back up to a previous option, hit mode and down at the same time. To bring up the extended menu, hold down for five seconds. This gives additional adjustments such as TRAP, PARA, HLIN, VLIN, SPC, CORNER, and more. You can also access all of the normal menu's adjustments within the extended menu. Resetting the extended menu works the same way as resetting the normal one.
 
The service manual is easily accessible https://wiki.arcadeotaku.com/images/3/34/MS-2931_Service-manual_full.pdf

Refer to page 46 for adjustments : there is not a HLIN adjustment. It is not something you would typically find in most sets.

Page 38 mentions this.

1709165084394.png


Page 59 in the troubleshooting section manual does have something as well.

1709165171297.png


RY refers to Relay. Seeing as your chassis has been serviced, we can probably rule out any electrolytic capacitors.

The last 2 pages of the service manual linked above show a schematic, I couldn't immediately locate the section with the relays in question but I did notice this lol.

1709165961983.png


Good luck mate.
 
Thanks and appreciate all the help guys Going to wait until I have another cab before I start changing/adjusting components on the chassis. Also gonna reach out to some people in the area and see if I can test with their chassis to see if that fixes the problem.

I'll try to remember to update here if I find a fix for this
 
You must log in or register to reply here.
Back
Top