CurtPalme.com Home Theater Forum

[mp20748]

[cmjohnson]

Just curious. Of course I understand that the caps have a limited lifespan and need to be changed before the power supply starts misbehaving or fails.

Has recapping this supply resulted in any visible picture quality improvements?

Or, more to the point, would there be any apparent decrease in projector performance as a result of aged power supplies that will need recapping soon?

I would imagine that there is some difference but I'm asking the expert (you) for your professional and experienced opinion.

[mp20748]

That is a brand new power supply that had bad caps in it. Scope sweeping the rails lead me to pull this new power supply out and find one cap bulging on the top. Looking at the caps they were using, they are not good quality at all, nor should they be used in a high frequency switching power supply as such.

So all caps with the exception of the Nichicons (3) and a few others.

The next time someone comes by I'll do a demo comparison to show what the difference is

[tschaeikaei]

Did you change resistors, too?
There is a brown one in the lower right, that seems to be a carbon resistor.
The others seem to be metal film.
What amount of ripple do you call normal and what is too much on those LVPS rails?
What revision is this model? Thanks for sharing,
Regards Julian

[mp20748]

Give me Until later today on this. Right now I'm on my cell.

[mp20748]

I'll get back to you Julian later to answer your questions. But have since made a few more changes to the LVPS.

Have not touched any setups on my Marquee, it still has the same focus, convergence, etc for more than two months.

[tschaeikaei]

I always see quiet a bit of unsharpness in your screenshots.
I think it is the camera, but it would be better if you took photos with a higher resolution, maybe in manual mode.
They do not look that great to me as they are intended to look (and the setup does most likely to a live viewer).
But to me, movie pictures always are kind of not too meaningful. I can judge much better if seeing a shot of
e.g. a Windows desktop, text is always a good indicator for sharpness, tight convergence and so on.
In movies, there are always unsharp parts (where the camera isn't focussed to the according distance,
motion blur, artistic stuff like Gaussian blur and so on).
I never have any benefit of seeing pics in the screenshot thread so i started ignoring it.
Could be that there are people who can see something in those shots, but i don't.

So if it's all about colors: I'd propose this: go to some wallpaper- site on the net, choose any wallpaper you like
and display it with the projector. Avoid scaling.
Post a photo of that wallpaper on your screen and a link to the file on the same post.
That should have more expressiveness than pics out of a movie i (and others) don't know.
That's how i would do it (if i did not keep destroying my HDM and therefore being stuck at the setup).

So please don't think i doubt your setup and mods are great, this is just no way for me to see it myself.

Here is a shot i took with my phone camera, it is not that great and i did not intend to use it as a reference.
But compare it to your shots, please.

Regards, Julian

[mp20748]

[tschaeikaei]

Yes, i know that this thread is not about sharpness.
What i meant is the expressiveness of movie- screenshots in general.
Sharpness is the thing most discussed overall at the forums and it is something rather good to judge if seeing a screenshot, so i took this as an example.
Colors are in my opinion not ratable at all, because everyone uses a different monitor, cameras add their own imperfections and so on.
The reason i tell this to you, Mike is because you post many many movie- screenshots.
And as it is for me quiet hard to read anything in these pictures, i proposed to take pics of images (wallpapers+ desktop symbols and text)
which you can easily compare 1:1. Screenshot taken with a camera and the same thing as screenshot via the "print"- botton on your keyboard and
saving it via paint or something similar. This will surely only work with a HTPC as projector source. Otherwise you still could use a BR disk on the projector
and play the disk again in your PC and take a "print-button-screenshot" after the photo.

To stay in the topic of this thread: Could you take before-after-shots?
I mean you take a photo off your harddrive that was shot previous to the mod and post it.
Play the same movie again on the projector, use the same camera with the same settings with the same scene and post that picture.
That way it would be possible to compare both and see the effect the mod makes.
Regardless of this, the camera will always add noise that can only be minimized, not be avoided completely.
In other words, the camera always makes the picture worse that it is in real life.
For a viewer who never was at your home and saw the projector in action, it is hard to only predict how it would look.
This is the problems i always had with mods: Everyone uses different screenshots, different settings, different camera.
How on earth could you be able to compare the different results, different people have?

I saw the same effect you describe on my projector, looking directly into the tubes. A layer of noise over the picture itself, filling the whole raster area.
But i didn't see it on my screen. And after changing resistors in the HVPS, this has even become less.
I followed Nashous instructions in his "Marquee modifications and enhancement"- thread. I know he partially took ideas from you and other people.
So that question for me at the end is:
My LVPS are both fully working and i didn't see any reason to change caps there, so far.
If you could point out, maybe supported by numbers from your measurements (noise voltage level), telling which of the supply rails do affect the overall picture quality and so on,
this could really help me. I am not a fan of simply changing all caps (mine have worked since 2001) if only one or two caps are worth to be upgraded.
You said this yourself ( "this is a new LVPS that failed" ) and i assume you would not have opened it if it did not fail.
If i found a cap fail in my LVPS and most other caps were the same manufacturer and type, i would surely have done the same you did.
I know i express myself kind of laborious, but i hope you get what i want.

Regards, Julian

[mp20748]

Actually, what doing here would be more relevant to sets that has my mods in them. So maybe I should be posting this in a forum that deals more with that.

Also, I'm not into doing before/afters, nor posting scoped readings. I don't really have the time to go through this and don't think it would accomplish anything, other than holding myself hostage to proven I've actually made changes.




The LVPS for the most part, does not need the caps replaced. It really depend on what you're doing with the projector. If running stock video chain and no real image upgrades, there should be no need to change the caps. Things could be different depending on the level of performance improvements wanted.

[tschaeikaei]

Are you feeling offended by anything i wrote and why?
I did not intend to do that.

[mp20748]

[tschaeikaei]

Mike, you get me wrong.
I proposed to take before-after pics not to prove anything but to allow people (including me) to see what difference the mod makes.
If i only see an after-pic, i cannot tell anything about the mod. Why do you think i want you to prove anything?
What i want is to decide for myself if it is worth my effort to do the same with my own projector.
I did not use the word prove and i knew from the beginning what the thread is about.
The example with sharpness is an example, nothing else.
If you don't have the time to do something i asked, no problem.
The pic i posted was about sharpness.
Because i think your pics are quiet a bit unsharp, that makes the effect of your mod even harder to see for me.
That may be partially because of unsharpness caused by the camera, partially because of the motion blur in the paused movie frame.
Let me even say that there is always noise in a movie.
All these are gone if you take photos of a wallpaper or something similar.
Again; i know the mod isn't about sharpness, but unsharp pictures generally make it difficult to interpret.
I don't tell you to do anything, please do as you like.
I just think it would be nice if you could do what i said. Because it would help me.
We are not talking about the mod at all here, everything is about pictures.
So maybe let's go back to the mod itself if you like.
Regards, Julian

[mp20748]

[mp20748]

Still lowering noise

[El Duderino]

[mp20748]

[MeV]

[mp20748]

[MeV]