Emerging issue on Nanao 29" CRT.....oh and a couple of other monitor questions

[John_Smith]

I've had my ex-‘Sega Rally’ Nanao 29" Dual Res CRT for a good couple of years now and as much as it has a few years on it by this stage, its been fantastic overall, though over the last, say six months it’s started to display some disconcerting signs of the aging process. It has a couple of thin, slightly overly lit lines running vertically on the left hand side of the screen. I've attached an image of kinda what it looks like. I tried to capture it with a digital camera, but it didn't reproduce at all (who knows???). Baring in mind I simulated the effect in Photoshop and took it quite a bit over the top so ya'll could see what I am talking about.

It’s not that noticeable, but I'm sure its ever so gradually becoming more apparent over time. Any ideas?? I know that everyone with monitor issues seems to ask this, but could a cap kit fix this sort of thing?

Also, I’ve noticed that on power up the tube’s phosphors seem to glow a bit bright for say 5 minutes as it warms up before settling down to nice black blacks etc again, is this normal, or at least rectifiable??

I also have a question on a little Wells Gardner 20” I have too. I’ve mounted it on its side for vertical shooters and as you would expect, it required the once over with the Degaussing Coil to get rid of the discoloration symptomatic of the change in orientation. This is all well and good, but I’m finding that there is a certain amount of persistent discoloration and no matter how much manual degaussing I do, I can’t seem to get rid of all of it. Not a huge issue as it’s not particularly severe, just a bit annoying. Once again, any ideas????

Cheers in advance for any help with my precious CRT's!!

 

[ttooddddyy]

The problem you have is due to poor mobo to monitor common grounding. Run a heavy gauge wire from the chassis of the monitor to the ground pins on the jamma edge connect.

With the vertical crt purity issue, try placing the set horizontally again, degauss (let cool down for 30 mins) then rotate back to the vertical position before switching on, if that doesnt work try rotating 180 deg.

 

[John_Smith]

The problem you have is due to poor mobo to monitor common grounding. Run a heavy gauge wire from the chassis of the monitor to the ground pins on the jamma edge connect.

With the vertical crt purity issue, try placing the set horizontally again, degauss (let cool down for 30 mins) then rotate back to the vertical position before switching on, if that doesnt work try rotating 180 deg.

Hrmm okay, yeah I'll give that a shot! Thanks for the help on that man!

Cheers

 

[John_Smith]

The problem you have is due to poor mobo to monitor common grounding. Run a heavy gauge wire from the chassis of the monitor to the ground pins on the jamma edge connect.

With the vertical crt purity issue, try placing the set horizontally again, degauss (let cool down for 30 mins) then rotate back to the vertical position before switching on, if that doesnt work try rotating 180 deg.

Oh, and when you say chassis, do you mean the steel railing that supports everything or just a decent ground source on the Monitor's PCB?

 

[DaemoN]

the chassis is the monitor's "PCB".

Actually, following the naming properly, you have:

the tube (the actual display)

the monitor (aka chassis) -> the "PCB" your tube is plugged into.

 

[ttooddddyy]

Oh, and when you say chassis, do you mean the steel railing that supports everything or just a decent ground source on the Monitor's PCB?

Any decent ground source on the monitor is whats required.
In theory as close to the rgb to jamma output socket as possible.

 

[ttooddddyy]

How did you go John ?

 

[John_Smith]

How did you go John ?

Hey Toddy! Sorry for the delay, ya can't rush into these things ya know

I tried running a cable from a good ground source on the chassis to the ground pins on the JAMMA connector, but it made no difference. Come to think of it, I can see the faint lines even when I just have the CRT powered without a PCB connected. Any more suggestions?

Also, I asked previously about the CRT's phosphors glowing a bit on initial power up before dimming slowly over say 5 mins back to nice solid black as the monitor warms up, is this sort of thing something to worry about?

Heres a pretty technical query for ya, is it tricky to adjust the convergence on this type of monitor (Nanao 29" from '94/'95, typical of Sega Rally/Astro City cabinets)? I have a bit of colour separation mainly in the top left quarter of the screen. Not a big deal really, maybe I'm aiming for perfection on a CRT that has a few too many years under its belt to rise to the challenge.

Cheers mate!

 

[ttooddddyy]

Hey Toddy! Sorry for the delay, ya can't rush into these things ya know

I tried running a cable from a good ground source on the chassis to the ground pins on the JAMMA connector, but it made no difference. Come to think of it, I can see the faint lines even when I just have the CRT powered without a PCB connected. Any more suggestions?

It may be the video dc supply decoupling capacitor, maybe a capkit would help here.

Also, I asked previously about the CRT's phosphors glowing a bit on initial power up before dimming slowly over say 5 mins back to nice solid black as the monitor warms up, is this sort of thing something to worry about?

I wouldnt worry about it, sounds like the screen voltage is a little high, back it off slightly.

Heres a pretty technical query for ya, is it tricky to adjust the convergence on this type of monitor (Nanao 29" from '94/'95, typical of Sega Rally/Astro City cabinets)? I have a bit of colour separation mainly in the top left quarter of the screen. Not a big deal really, maybe I'm aiming for perfection on a CRT that has a few too many years under its belt to rise to the challenge.

With this sort of CRT static adjustment, if you are not experienced in this field, its probably better left alone, you are likely to end up with worse convergence errors than you started with if you start messing around, please trust me on this.