Disable 100Hz on CRT TV's

[andykara2003]

Hi - does anyone know if there are ways to electronically disable the 100Hz feature in 100Hz TV's? Not just using a VGA input but for 240p scart input.

I want to do this with a Loewe Calida, but I'm interested whether it is possible with CRT TV's in general.

Cheers.

[ikaruga007]

This pops up every once in a while but I haven't heard of anyone who's been able to do it.

[fagin]

You can sometimes do this kind of function within the Service Menu.

[andykara2003]

Nice one Fagin, that brings some hope! Do you or anyone know what makes of TV's allow this, and more specifically if the Loewes do?

[viletim]

Hi - does anyone know if there are ways to electronically disable the 100Hz feature in 100Hz TV's? Not just using a VGA input but for 240p scart input.

No, it's not possible. The horizontal and vertical deflection circuits are designed to run at a higher frequency.

You can sometimes do this kind of function within the Service Menu.

You cannot change hardware with a software setting. Perhaps the same software is used for multiple hardware configurations.

[andykara2003]

Thanks Viletim, I'm sure you're right. Funny thing is, I'm sure I've read somewhere else that this is selectable in the service menu for some models :/

[andykara2003]

I'm sure it must have been a misnomer. It's good to know I can put that one to rest.

Just out of interest, Viletim, I read that you did a DAC for the N64. Is the resulting picture a lot better than an RGB mod using the THS7314 amplifier?

[Ed Oscuro]

The better question to ask is this: Why put yourself through a bunch of unnecessary steps? Unless you specifically want the advantage of 100Hz models, avoid those models entirely. What is the benefit of 100Hz? There's no advantage for gaming. LCD and the few surviving plasma models are going to be better screens for television and video viewing anyway, so the rationale for 100Hz CRTs is essentially gone.

Checking online, there were still many reasonable Trinitron and other models being put out right up to the demise of CRTs in 2007-2008, without 50Hz modes. If you want a screen without the problems of flatscreen geometry, then you will likely be looking to models older than 100Hz anyway (like the AE-1 chassis).

[andykara2003]

There's an exact model of Loewe CRT that I'm looking for. I'm confident that I will eventually find a couple of 50Hz models in good condition but I was just pondering on the possibility of buying a much newer 100Hz one in the same range & disabling the 100Hz. They look exactly the same but are much more common and would almost certainly have less hours on it. Also, these TV's went over to 100Hz much earlier than the Sonys so the 50Hz models are now quite old. Since Viletim confirmed that's not possible, I'll happily wait for the right 50Hz models to come up.

[fagin]

Hi - does anyone know if there are ways to electronically disable the 100Hz feature in 100Hz TV's? Not just using a VGA input but for 240p scart input.

No, it's not possible. The horizontal and vertical deflection circuits are designed to run at a higher frequency.

You can sometimes do this kind of function within the Service Menu.

You cannot change hardware with a software setting. Perhaps the same software is used for multiple hardware configurations.

Obviously.... I'm referring to what you have alluded to - the ability to enable another hardware mode via a software option.

[andykara2003]

I really hope that this is a possibility - does anyone know of any 100Hz CRT sets from any manufacturer that has this function?

[matrigs]

I really hope that this is a possibility - does anyone know of any 100Hz CRT sets from any manufacturer that has this function?

I guess it's safe to say that no one ever tried to, as there is simply no point in doing so.

[andykara2003]

If you look a few posts back, I outlined a circumstance where it would be useful.

If you look a few more posts back, you will see that the question has come up a number of times.

[Ed Oscuro]

You cannot change hardware with a software setting. Perhaps the same software is used for multiple hardware configurations.

Obviously.... I'm referring to what you have alluded to - the ability to enable another hardware mode via a software option.

I think what viletim is referring to is the deflection type being set to only one configuration, that can't be changed. If there's no other "hardware mode" then it can't be software selected.

This suggests that 100Hz TVs have a "more rapid vertical flyback" and other improvements that prevent the set from using considerably more power than would be necessary on a 50Hz set. There's certainly some extra components here, but what I haven't found information on yet is whether the actual deflection magnets can be used for both 50 and 100Hz, but my intuition is that they can't due to optimizations to make the circuit run as efficiently as possible.

[fagin]

Ed,
I know what Viletim is referring to..... it's no different to what I'm referring to.

In retrospect I should have made a different statement, as I appear to be stating an absolute fact...... when I'm actually suggesting that from what I understand, you may be able to do this kind of thing via a Service Menu (I'm 99.9% sure I've read this for one set).

Apologies for the confusion.

[Ed Oscuro]

I think it would be an amazing feat to change the design of a flyback and the deflection magnets so that it could operate efficiently at both 50Hz and 100Hz...maybe disabling the digital memory (necessary for the second scan and other features like frame step and multiple channel view) wouldn't have been so difficult but I think the flyback and magnets had to be designed specifically for 100Hz.

Of course I would be very interested to see what we can dig up...I would like to know about this with more certainty, too.

[CMcK]

I've been looking for a way to disable the 100Hz features of my Loewe Aconda for ages. I have the full service menu for the chassis and I have tried switching various option bytes in the service menu but no joy.
I thought I may have cracked it with the option to disable 50Hz and 60Hz preprocessing but a quick go with a light gun game confirmed it hadn't really changed anything.
That option did appear to make the scanlines a little clearer though. The mask on the Loewe, which uses a Toshiba tube, doesn't seem to allow for heavy scanlines like my B&O MX6000. To be honest I'm not really bothered about that.
I had the Loewe professionally calibrated last year and the picture is fantastic for a consumer level CRT.

[andykara2003]

I've been looking for a way to disable the 100Hz features of my Loewe Aconda for ages. I have the full service menu for the chassis and I have tried switching various option bytes in the service menu but no joy.
I thought I may have cracked it with the option to disable 50Hz and 60Hz preprocessing but a quick go with a light gun game confirmed it hadn't really changed anything.
That option did appear to make the scanlines a little clearer though. The mask on the Loewe, which uses a Toshiba tube, doesn't seem to allow for heavy scanlines like my B&O MX6000. To be honest I'm not really bothered about that.
I had the Loewe professionally calibrated last year and the picture is fantastic for a consumer level CRT.

Cheers, it's good to hear that someone's tried, but shame it didn't work. Doesn't look too promising for the Loewes then