Focus Module to increase sharpness on Sony BVM ?

[Virtual_Tintin]

Hey group

I have some questions about the Focus Module on Sony BVM (see picture), the one which is on the top right side of the monitor, when you see the BVM from the front.

First question : is it safe to turn it ? Indeed, I see it’s sealed by glue in factory, so I wonder if there is any risk to damage the monitor turning the knobs ?

Second question : I want to slightly turn them to increase the focus of my picture, so am I in the right place for that ? Indeed, one of my BVM have a slightly less sharp picture than others, especially in the extreme top, while my others BVM have perfect focus, even in extreme edges of the screen. So, could that be related with this focus module, or rather with a recap ? Indeed, the BVM in question has been recapped on its Analog and Deflection Boards five years ago, while my other BVM have been recapped one year ago. Besides, DF settings in OSD Maintenance Menu don’t change anything on the screen, like if they were inactive (could it have other settings for Focus in OSD Menu ?).

Third question : does the sharpness could be related with the hours on the tube, or by the Series ? Indeed, the BVM I talk about is a 20F1, so a F-Series, with ~10.000h on the tube, while my other BVM are D-Series, so more recent, with ~6.000h on their tubes, so less hours.

https://imgur.com/gallery/HF2dhuC

Thanks for the answers you could bring to me.

[Anonygoose]

Yes, no problem. You can twist them to adjust focus. The settings in the maintenance menu do not seem to change much. You'll have to look very close to see any changes. The focus pots should be enough in most cases.

[Virtual_Tintin]

Yes, no problem. You can twist them to adjust focus. The settings in the maintenance menu do not seem to change much. You'll have to look very close to see any changes. The focus pots should be enough in most cases.

Thank you for your reply, I’ll try to turn those knobs to increase sharpness !

Any thoughts about an eventual sharpness’ difference between BVM from different Series ? I know F and E Series have "Evergreen" chassis (if I’m not mistaken), and D Series not, so perhaps that makes any difference ?

[Anonygoose]

I've never seen a D20 in person but have seen F and E. The F and E can be calibrated to near perfection as they have much more dynamic convergence controls.

I'm not sure what the difference between the F and E is, aside from the 1000 line tube in the E. They seem identical in everything else. I wouldn't be surprised if they had the same tube.

The F has the same tube found in the D, A, G, L5, L4 and M4. Sony claimed the difference is in the grading only, the 900 line ones had 'higher' graded tubes than the 800. You can find that grading mark on the tube's sticker. It will mention the grading such as MZ1 or FT3 for example above the tubes serial number.

If you do have an E series, please share a picture of the serial number on the actual tube.