Sony BVM-A20F1M scratch repair

[PeterWar]

I'm sad to report that I accidentaly got a scratch on my precious Sony BVM-A20F1M (don't know how this happened), I've cleaned it the best that I could but I'm pretty sure it's a scratch, albeit varely visible playing it still bothers me, is there any way to repair/repolish it?

Thanks in advance for your thoughts

[fernan1234]

Can you feel any depth or indentation when you run your finger on it? If so then yeah it's a scratch, but if it's bumpy then maybe it really is some kind of hard stain. What have you tried for cleaning it?

There are success stories of polishing scratches off glass tubes, but there's always a risk of it ending up even more noticeable.

[Josh128]

Scratches in glass are quite easy to buff and polish out with a $20 Wal-mart high speed rotary tool. All you need is the little 1" round sanding disc kits that include the mounting wheel/pad and discs that can be gotten from Ebay or Amazon for cheap. Try to get one that has 1000 grit, 3000 grit, and 5000-7000 grit discs. Then you need a small amount of cerium oxide polishing powder.

You simply start with 1000 grit, which will take material off to level the scratched area. You will see the glass dust flying off the scratch edges as you lightly hit the glass. When you cant see or feel the scratch you will be left with a permanent smudge/blurry spot. Go over that spot with 3000, then 5000-7000, it will become less smudgy. Finally, some cerium oxide water slurry with a low speed drill or a damp rag using circular motions (this works just as well). The scratch will be gone and the glass will be just as glossy and shiny as it was new. Its very satifsying, actually.

Now-- just make sure there is no film or anti-glare coating (its usuallys a blueish color) on the screen before you begin the process. If there is, you would need to remove it first. It it just appears as clear glass, you should be good to go!

**Edit-- this actually looks extremely light. I would first hit it with 7000 grit to see if it simply disappears. If not, try 3000 or possibly 2500 if that doesnt work. If it disappears but leaves a "greasy" look, work your way back up with 3000, then 7,000, then cerium oxide slurry with a damp rag. It sounds like a lot, but its really, very, very easy. Hit back if you need more help.

[PeterWar]

Can you feel any depth or indentation when you run your finger on it? If so then yeah it's a scratch, but if it's bumpy then maybe it really is some kind of hard stain. What have you tried for cleaning it?

There are success stories of polishing scratches off glass tubes, but there's always a risk of it ending up even more noticeable.

I can't feel any indentation, it's actualy bumpy, I've tried glasses cleaning fluid as and water, perhaps I should try with something more aggresive? is it ok to use isopropil alcohol?

[LDigital]

If you haven’t already done so you have the option of removing the anti reflective film. I’m pretty sure it would have one. You probably haven’t touched the glass

[fernan1234]

is it ok to use isopropil alcohol?

Yes, it'll probably be your best chance. These tubes are completely uncoated, so there is no risk in using something like this.

[PeterWar]

Great news! I got it off! fernan, LDigital, Josh thank you very much for your prompt amicable feedback. I was really scared this monitor would have permanent damage as it's really a low hours tube and the screen was always in mint condition, I am much relieved now.

Isopropil alcohol did the trick. My best hypotesis to explain this was that I was using a glue stick some hours ago and got some glue in my hands, I might have used to clean my hands by mistake the same cotton cloth I use to clean the screen, silly me!. Latter, when I gave the screen a routine clean I noticed the "scratch", it was probably some residue that melted with the alcohol.

Josh, I have another BVM-A20F1M , that one has a scratch and I might use your polishing suggestions to try to eliminate it.

We've at the very least validated that Isopropil alcohol does not harm the BVM-A20F1M screen in any way. I'm unsure if my monitor has antiglare or not though.

[maxtherabbit]

Scratches in glass are quite easy to buff and polish out with a $20 Wal-mart high speed rotary tool. All you need is the little 1" round sanding disc kits that include the mounting wheel/pad and discs that can be gotten from Ebay or Amazon for cheap. Try to get one that has 1000 grit, 3000 grit, and 5000-7000 grit discs. Then you need a small amount of cerium oxide polishing powder.

You simply start with 1000 grit, which will take material off to level the scratched area. You will see the glass dust flying off the scratch edges as you lightly hit the glass. When you cant see or feel the scratch you will be left with a permanent smudge/blurry spot. Go over that spot with 3000, then 5000-7000, it will become less smudgy. Finally, some cerium oxide water slurry with a low speed drill or a damp rag using circular motions (this works just as well). The scratch will be gone and the glass will be just as glossy and shiny as it was new. Its very satifsying, actually.

Now-- just make sure there is no film or anti-glare coating (its usuallys a blueish color) on the screen before you begin the process. If there is, you would need to remove it first. It it just appears as clear glass, you should be good to go!

**Edit-- this actually looks extremely light. I would first hit it with 7000 grit to see if it simply disappears. If not, try 3000 or possibly 2500 if that doesnt work. If it disappears but leaves a "greasy" look, work your way back up with 3000, then 7,000, then cerium oxide slurry with a damp rag. It sounds like a lot, but its really, very, very easy. Hit back if you need more help.

thanks for the writeup - which rotary tool are you talking about? a dremel or something larger like a die grinder?

also for removing a electroplated anti-glare coating do you think just using the cerium oxide and a polishing pad alone would be sufficient?

[Josh128]

$20 rotary tool (or a more expensive Dremel, if you must) from Walmart is what I use. 1 inch hook and loop sanding discs that come with high speed rotary tool attachment as seen below. You only need a very small amount of cerium oxide, just a steady supply of water in a spray bottle to keep it wet when you are doing final polishing. Final polishing done with felt tip on low speed tool, such as electric drill, or a rag by hand (this does actually work, lol).

As far as removing the anti-glare coating, I really cant speak to that, as all the sets I have done were the Hitachi 27MM20/30B 27" dual scans, which dont have any coating. I tend to think that it would take it off though, because it takes off enough to make a greasy/blurry spot left by a 3000 - 7000 grit disc perfectly glossy. Although to do an area that large I'd try a 2" to 3" pad. Still have to use a low speed tool, because it slings very easily.

https://www.ebay.com/itm/274121314285?h ... R5qj5Y6MYw

https://www.walmart.com/ip/Hyper-Tough- ... hbdg=L1103

https://www.ebay.com/itm/224588403937?h ... R9qzpo-MYw

[maxtherabbit]

$20 rotary tool (or a more expensive Dremel, if you must) from Walmart is what I use. 1 inch hook and loop sanding discs that come with high speed rotary tool attachment as seen below. You only need a very small amount of cerium oxide, just a steady supply of water in a spray bottle to keep it wet when you are doing final polishing. Final polishing done with felt tip on low speed tool, such as electric drill, or a rag by hand (this does actually work, lol).

As far as removing the anti-glare coating, I really cant speak to that, as all the sets I have done were the Hitachi 27MM20/30B 27" dual scans, which dont have any coating. I tend to think that it would take it off though, because it takes off enough to make a greasy/blurry spot left by a 3000 - 7000 grit disc perfectly glossy. Although to do an area that large I'd try a 2" to 3" pad. Still have to use a low speed tool, because it slings very easily.

https://www.ebay.com/itm/274121314285?h ... R5qj5Y6MYw

https://www.walmart.com/ip/Hyper-Tough- ... hbdg=L1103

https://www.ebay.com/itm/224588403937?h ... R9qzpo-MYw

I already own a dremel, so using that would be cheaper than buying anything from walmart

It can be dialed down to a pretty low speed

[mrsmiley381]

I might be trying this out on a scratched Commodore 1702 unless someone recommends against this method on that monitor. No rush on that advice, either. I am way too busy these days.

[Josh128]

$20 rotary tool (or a more expensive Dremel, if you must) from Walmart is what I use. 1 inch hook and loop sanding discs that come with high speed rotary tool attachment as seen below. You only need a very small amount of cerium oxide, just a steady supply of water in a spray bottle to keep it wet when you are doing final polishing. Final polishing done with felt tip on low speed tool, such as electric drill, or a rag by hand (this does actually work, lol).

As far as removing the anti-glare coating, I really cant speak to that, as all the sets I have done were the Hitachi 27MM20/30B 27" dual scans, which dont have any coating. I tend to think that it would take it off though, because it takes off enough to make a greasy/blurry spot left by a 3000 - 7000 grit disc perfectly glossy. Although to do an area that large I'd try a 2" to 3" pad. Still have to use a low speed tool, because it slings very easily.

https://www.ebay.com/itm/274121314285?h ... R5qj5Y6MYw

https://www.walmart.com/ip/Hyper-Tough- ... hbdg=L1103

https://www.ebay.com/itm/224588403937?h ... R9qzpo-MYw

I already own a dremel, so using that would be cheaper than buying anything from walmart

It can be dialed down to a pretty low speed

As far as the sanding with the Dremel goes, ~4K-5K RPM is probably around ideal speed for the process. My cheap rotary tool has an dial from 1 - 10, and use around a 3 or 4 to do it. I have really no idea what RPM that actually is, but my best guess is ~4K-5K.

As for the cerium oxide slurry, the Dremel is an absolute no-go, even at the lowest speed. You need maybe 250-450 RPM max, any more and it will start to sling uncontrollably. A power drill at ~1/4 speed or less is about right. As I said earlier, even vigorous circular motions by hand with a cotton rag will make it happen. The cerium slurry is absolutely just for the finish step, the final mirror-polish. If you can feel anything with your fingernail at all, it must be tackled by the sanding discs.