Our native mobile app has a new name: Fora Communities. Learn more.

Skyworth: Oscilloscope tests.

993 Views 11 Replies 6 Participants Last post by Bosef, Oct 23, 2001

Bosef

Discussion Starter · Oct 16, 2001

Here i'm trying to translate a message wrote by the guy who sold me my crt. I gave him my Skyworth (August's batch) and he made tests to it.

ECP 4000 perfectly converged and tuned, screen with 1,2 gain, 2M base (6'6") RGBHV out.

Movie: Mission impossible 2

"I noticed veary soon that the flesh tones were a bit strange, going to green, and the whole background too. Pretty strange but understandable.

I took my oscilloscope, opened the case and mesured the three RGB components with black signals.

Blue and Red were perfect but green gave a tension level wich was six times stronger than B and R... the Green bias was too high (this is probably the reason why the movie was a bit green).

I tried to mesure the same stuff but with a 100% white signal.

The oscilloscope told me that the peak level whas 20% lower than the standard level. So, when you use it with a Projector this kind of output, the results you get is like if you have a lower light output with the contrast at the same level.

Conclusion.

This player may be working well, if you use it with a CRT, where you can set both the bias and the gain of the tubes, but when you use it with a DLP or a LCD where this controls are generally missing, the results could be a troble.

If i compare this player to other progressive players or line doublers, the deinterlace process is really good.

The problem with the rgb can be fixed.

How?

With the construction of a dedicated video buffer. this will output a perfect and standard RGB signal. It could also be integrated inside the player".

Did anyone noticed the same things?

What do you think about it?

Anyone did tests with an oscilloscope?

Sorry for the bad translation but it wasn't easy... and i've never studied English ;p

See less See more

Save

Status: Not open for further replies.

1 - 12 of 12 Posts

Frode

· #2 · Oct 16, 2001

Does your Skyworth have the fixed capacitor? If not that may account for the lower light output.

Save

cvye

· #3 · Oct 16, 2001

The picture produced by my Skyworth 1050P on my Panasonic DT-M3050W broadcast monitor had a very green cast to it. I was able to fix it (by eye) by resetting the gain and (especially) the bias controls on the monitor.

What is bias, anyway?

Save

Bosef

Discussion Starter · #4 · Oct 16, 2001

Quote:

Originally posted by Frode
Does your Skyworth have the fixed capacitor? If not that may account for the lower light output.

No, i didn't change the cap. I've never had any problem and the karaoke board and the blue lights are switched off.

I don't think it has something to do with the bad cap anyway.

Skyworth said they've fixed the problem and in facts i've never heard about such problem in the later batchs.

I think it's is a problem of the output board.

Save

Brian Dickie

· #5 · Oct 16, 2001

Bosef,

Your translation is fine.

I seem to be having similar problems via the rgb/ sync input on my ECP 4501. However, it doesn't seem to be a problem on my Sony 1031 via it's scart input.

At the moment, I'm still trying to set up my ecp but I'm having problems with an extron rgb 105 interface which doesn't seem to want to output anything to the projector. However, if feed my Skyworth directly into the projector the picture is much darker than the vga output from a pc or mac. I'm hoping that when I get the ecp properly set up, I'll be able to boost the vga output from the Skyworth with the extron unit.

I have done the cap mod but I still have my blue lights (which i like) and karaoke board connected.

I'd agree that it's probably an issue with the vga output.

On my Sony 1031 the Skyworth looks fine. I use a vga to scart connector which simply combines the h and v sync cables onto the composite video pin on the scart.

I'll keep you posted although it might take a week or so.

Brian.

See less See more

Save

jcmccorm

· #6 · Oct 16, 2001

I don't have the datasheet for that DAC (7123 I think) with me but I believe that if you have the DAC set up for sync-on-green, the level of green rides a little higher that red and blue so that it has room to dip down when sync comes along. Maybe they have sync-on-green turned on??

Hopefully Mark Fontana will read this and have some insight (he's been digging deep into these Skyworths)

Cary

Save

Bosef

Discussion Starter · #7 · Oct 18, 2001

Thank you for answering.

I'm not worried about the -20% in the RGB max output because it's really easy to avoid the problem, just turnin' up the contrast's control.

The real issue it's about the green.

The offset level ( The tension's level when the player put out a completely black signal) is 60 mV for R and B but it's 600mV for G!!!

I wonder why my friend was the first one to notice that.

Maybe it is just a problem of my player, but it doesn't seem to be this way.

I really hope that Mark could take a look at this.

See less See more

Save

Bosef

Discussion Starter · #8 · Oct 18, 2001

Quote:

Originally posted by jcmccorm
Maybe they have sync-on-green turned on??

Cary

I don't know, but my Projector could use RGB with sync on green.

If i use R G B without the cable for the Composite Sync i can't get any image on the screen and the Pj produces the same noise he does when he can't sync with the feeded signal... so i don't think it has Sync on green and it is really another problem

Save

Geordie

· #9 · Oct 22, 2001

I started another thread about the Skyworth RGB output not being as bright with my projector as the output of my VCR is. It died without any result.

My Skyworth does not have a problem with green but I think it is down on brightness slightly. I cannot simply fix it with the contrats control on the CRT projector.

Any way of raising the RGB output level or whatever to get a brighter image would be great!

Save

Bosef

Discussion Starter · #10 · Oct 22, 2001

Quote:

Originally posted by Geordie
Any way of raising the RGB output level or whatever to get a brighter image would be great!

The only way to avoid this problem, if you can't just adjust this with the contrasts control, would be that Video buffer my friend talked me about... but it would cost nearly 90$.

We'll try to solve the problem, re-setting the colors with a colorimeter with the signal coming from the Skyworth, this should work anyway.

Save

Brian Dickie

· #11 · Oct 22, 2001

Hi everyone,

I've just been setting up my ecp 4501 over the weekend (using a extron rgb generator) and I've now got a much better greyscale than I had previously.

I've had the Skyworth directly connected to the projector and it would appear that I need to raise the contrast and brightness levels a bit. However, these adjustments seem to be fine and I'm not running the projector into blooming.

This is all done with the h and v sync output cables combined together with a bnc t-connector at the 'combined' input on the projector.

Brian.

See less See more

Save

Bosef

Discussion Starter · #12 · Oct 23, 2001

Quote:

Originally posted by Brian Dickie
I've had the Skyworth directly connected to the projector and it would appear that I need to raise the contrast and brightness levels a bit. However, these adjustments seem to be fine and I'm not running the projector into blooming.

Ok Brian, so, it seems that the low rgb peak signal is a common problem. Now i'm asking if the *greenish* black is also a common problem... i couldn't see that before, because i've recently changed my lenses with a set of HD-6C ML color corrected, so i had my colorimetry a bit out (the blue tube and the gren too, are less filtered and i had much blue/green on the picture). I realised by myself that the picture with low light seemed to be a bit greener than what it should be,but i didn't know what was the reason. Anyway ,in few days i'll get the set properly calibrated.

Thank you.

Save

1 - 12 of 12 Posts

Status: Not open for further replies.

Top Contributors this Month