About 75 ohm terminators on a BVM

[wgs]

Hi, this is my first post here.
I recently bought my first BVM, a BVM-2010P which I'm realy happy with as it outputs an amazing picture. Almost perfect geometry and absolutely perfect convergence. It leaves nothing to be desired for me.

Only question I have is: are 75 ohm BNC terminators absolutely necessary, do I actually risk breaking anything by not using them? I tried to look it up for hours but never found any definitive answer.
The Manual says to use them when not daisychaining the signal to another monitor. Previous owner told me he never used any.

Point is I've tested the monitor with and without terminators and with them on the picture is just too dim and I have to crank contrast and brightness almost all the way up for decent results.
Without them and the contrast just turned a little bit down it looks much, much better to me. Bright but not too bright and colorful, not oversaturated, not overblown.

I hope someone can help.

[KPackratt2k]

Going by your experiences mentioned in this thread, I would say you don't need the 75 ohm terminators for your BVM.

I've never actually heard of anyone damaging their displays by not using the terminators, so you should be okay without them. The only time you would need to use the terminators is if your image is too bright without them.

[NewSchoolBoxer]

Generally you want to not run high contrast to keep the tube life to a maximum. Having to crank the brightness and contrast up, I interpret as a sign the tube is aged. Not near death but not going to last another 10k hours? Maybe someone can expand upon that better than I can.

Here's the thing. When you don't have 75 ohm termination, the video signal reflects back and causes interference. Newer BVMs are self-terminating, meaning the 75 ohm connector is working when the output is not being used. Every professional monitor in existence uses or tells you to use 75 ohm terminators. It's to avoid this reflection that degrades the quality of your video signal. You only need 1 terminator in the chain, meaning if you go TV -> TV -> TV daisy chain, only the last TV needs the terminator. You'd need 4x for RGBS.

I would question you saying the video looks better with them off unless they're damaged or something. I don't believe you're going to destroy or damage the television in any way without using them since we're talking interference from a 1 volt or less, low current signal.

I bought expensive Amphenol RF brand terminators but that's just me.

[Gara]

Weird that it's looking so much better without terminators. Assuming it was calibrated with them off, I would think it would still look a bit iffy. Are you sure you're not blowing out all your details at your desired brightness? A properly calibrated monitor is nowhere near as bright as a modern screen and you usually have to be in a low light environment to enjoy them. If I saw this behavior in person I'd probably assume the tube had an awful lot of use already.

I'd re-calibrate the set with terminators and just accept the monitor needs the settings near maxed out to compensate for its age. No reason to accept any extra risk. It's a hard call on if I'd accept the lower brightness and contrast or just say screw it and drive the monitor hard.

[wgs]

Thanks for the answers. Good point mentioning that it was likely calibrated with them off, haven't thought of this. As for the age of the tube, it's hard to say how worn out it is.
Without terminators the image can get bright if I turn it just a bit beyond halfway up, and I mean BRIGHT. Of course I'm not running the tube like that all the time to ensure slow degradation.
Also this old monitor doesn't have an OSD menu, so no operation hours counter. No way to know how much it has been used.

Or maybe it's just that my eyes just need to adjust to the dimmer image idk. Also the terminators I have are just some cheap china products, but I can't imagine getting the resistance right is that hard.

[maxtherabbit]

Have you measured the Chinese terminators to make sure they are actually 75 ohm and not 50 or something else?

[fernan1234]

You can easily tell if your monitor needs termination if there is a little squiggly symbol next to the output that indicates it self-terminates. The manual should also mention it.

With a monitor that self-terminates you'll also see no difference when placing and removing terminators on the output connectors, so obviously yours does need terminators. Really avoid using it without them. Just keep them on and re-calibrate brightness and contrast as needed if it had been set up for use without them.

[wgs]

Have you measured the Chinese terminators to make sure they are actually 75 ohm and not 50 or something else?

Yup. 75 ohm. Checks out.

You can easily tell if your monitor needs termination if there is a little squiggly symbol next to the output that indicates it self-terminates. The manual should also mention it.

With a monitor that self-terminates you'll also see no difference when placing and removing terminators on the output connectors, so obviously yours does need terminators. Really avoid using it without them. Just keep them on and re-calibrate brightness and contrast as needed if it had been set up for use without them.

Ok, maybe thats for the best. Will do when I get the chance.

[NewSchoolBoxer]

Weird that it's looking so much better without terminators. Assuming it was calibrated with them off, I would think it would still look a bit iffy. Are you sure you're not blowing out all your details at your desired brightness? A properly calibrated monitor is nowhere near as bright as a modern screen and you usually have to be in a low light environment to enjoy them. If I saw this behavior in person I'd probably assume the tube had an awful lot of use already.

I'd re-calibrate the set with terminators and just accept the monitor needs the settings near maxed out to compensate for its age. No reason to accept any extra risk. It's a hard call on if I'd accept the lower brightness and contrast or just say screw it and drive the monitor hard.

Are you a genius or did I lose my common sense after I graduated high school, or both? Calibrated with terminators off is the one explanation that makes sense to me.

Doesn't apply in OP's case but here is grainy pic of the lightning bolt / squiggly symbols that mean the video outs are self-terminating. Audio not self-terminating but such low frequency it doesn't matter.

Spoiler

What I think is kind of cool is the era of professional video monitors that have on/off switches for the terminators. Turn off if you connect the video out to something. Engineers not smart enough to make auto-switches until the 90's I guess. Would be nice to re-invent for the BKM-129X and BKM-68X clone cards.

[Gara]

Are you a genius or did I lose my common sense after I graduated high school, or both? Calibrated with terminators off is the one explanation that makes sense to me.

Doesn't apply in OP's case but here is grainy pic of the lightning bolt / squiggly symbols that mean the video outs are self-terminating. Audio not self-terminating but such low frequency it doesn't matter.

Spoiler

What I think is kind of cool is the era of professional video monitors that have on/off switches for the terminators. Turn off if you connect the video out to something. Engineers not smart enough to make auto-switches until the 90's I guess. Would be nice to re-invent for the BKM-129X and BKM-68X clone cards.

I must be a genius! After I read "Previous owner told me he never used any." I figured there was a decent chance that person calibrated it without any terminators. Hopefully OP can get the desired look with a re-calibration. Playing with all the advanced settings is half the fun of owning a professional monitor.

I went out of my ways to outfit my monitors with Canare terminators after getting a good deal on a box of them. Wonderful build quality compared to the various cheap ones on Amazon and such.
https://imgur.com/fpwnHuA