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-   -   Elite BVP-4 BVP4+ proc amp [REPAIR GUIDE] (http://www.digitalfaq.com/forum/vcr-repair/2035-elite-bvp-bvp4.html)

admin 02-19-2010 10:19 AM

Elite BVP-4 BVP4+ proc amp [REPAIR GUIDE]
 
7 Attachment(s)
What's a BVP-4 ?

The Elite BVP-4 and BVP-4 Plus (BVP4, BVP4+) proc amps --- video processing amplifiers --- are very powerful devices used to adjust the color and luminance of video.

The adjustments are often described as brightness, saturation, luma gain, contrast, IRE, black level, white level, tint, flesh tone, coring, depth, warming, cooling, chroma gain, chrominance, and other related terms.

And while it works very well at this -- being a truly broadcast-grade device -- the unit is not completely without its nuisances.


Why Does it Need Servicing ?

For example, when the video overscan is visible (computer monitors, for example), vertical lines can be seen on screen -- the result of a bad mask location. The mask location can be adjusted in the unit, by taking it apart, and tweaking the control with fine eyeglass-sized screwdrivers.

Example:
Attachment 683

Notice how the left mask is mostly black, very straight and narrow. This one is fine, not very noticeable, and often not very adjustable. In the sample image shown, most of that black line is actually broadcast overscan. Most TV shows aired in 4:3 have black lines on one or both sides, especially on re-runs. A TV broadcast image is usually not edge-to-edge, except on "fullscreen" 4:3 versions created from widescreen 16:9 originals.

But the right mask is pretty awful! It's not straight, it moves and wiggles a bit, and it has this awful flashing rainbow effect along the visible interior edge. This is fully adjustable, by tweaking the main flathead screw in the BVP4+


How Do I Fix This ?

Open up your proc amp. It only has four screws, two on each side.

Notice the four "user serviceable" parts in the BVP4:
  • power fuse
  • flathead overscan adjustment screw
  • pair of phillips-head adjustment screws
Attachment 684

On the front board attached to the dials, on the left side, look for the small blue, gray or black box, with a metal flathead screw.

Attachment 685

DO NOT TRY TO USE A LARGE SCREWDRIVER! If you try to push a screwdriver head that's too big into the slot, you may damage the entire board. This is a delicate board, use the fine eyeglass screwdrivers. Home, auto and even most computer screwdriver sets are all going to be too large. You have been warned! The pressure needed to jam a big screwdriver into the flat head slot will also damage the small box.

Attachment 691

You'll also need to pull out a decent VHS tape -- one that tracks properly and has a good signal -- and use it for monitoring your changes. No, you cannot use the "blue screen" or some other type of menu or test pattern. It needs to be an actual live video, and VHS is the best one to tune from.

Yes, this means you'll be adjusting it while plugged in, turned on, and connected to your video gear. You cannot adjust this powered off and unplugged -- it doesn't work that way. Unless you're a cyborg or robot AND you're touching the metal doo-dads on the power board, you're in no danger of being electrocuted or "shocked" or anything along those lines.

Beyond that, it has to be done with a computer capture card on any computer -- or on a broadcast monitor (fancy expensive TV set). Because a standard television set hides the overscan area, you can't use it to view adjustments being made in it.


How Much Do I Turn the Adjustment Screws ?

Turn the flathead screw (clockwise, usually) until you see the overscan just disappear off the edge of the screen.

See video in next post: http://www.digitalfaq.com/forum/show...48&postcount=2
Note: It should open in a new tab or new window. It may ask you to reload/refresh the page once, before you're able to watch it!

If you turn it too far, your video image will flicker!

http://www.digitalfaq.com/forum/imag...4flicker-1.gif Attachment 688

Notice the dark/light flickering at the top of the screen. It's very similar to Macrovision or other copyguard/anti-copy protection. A video error is being created in the signal, which interferes with the luma values.

Watch the full flickering video at: http://www.digitalfaq.com/forum/show...49&postcount=3
Note: It should open in a new tab or new window. It may ask you to reload/refresh the page once, before you're able to watch it!

Therefore, ONLY adjust the overscan off the edge. The more you turn it, the more it will damage the signal. On some BVP4+ units, it may not be possible to fully remove the overscan without causing flicker. Your goal is to hide as much as the mask as you can WITHOUT harming your video.


What About the Other Screws?

To be honest, I forget what those are for. I adjusted them real quick when making the above sample videos/images, but did not notice any visual changes. The markings read "PIHER SPAIN" etched in the black plastic around the screw.

Attachment 684

Attachment 686

Attachment 687

I believe the left screw is for tweaks to the chroma gain.
And then the right screw is for either luma, resolution or the black enhancer.

Post here if you figure it out. Or if your memory is better than mine.


How Important Is This?

Again, to be completely honest, it's really not that important. A good modern HDTV television set will crop your image properly -- you won't see this on screen. (An exception would be if your proc amp is very out-of-spec, with the mask border reaching into the visible image area.)

Most owners of this device will be using it in a restoration workflow, with video captured to a lossless or uncompressed AVI file. This "error" can be masked with a black matte during the editing, restoration or encoding stages of a project. When it gets masked depends on the software -- for example: VirtualDub, Adobe Premiere, Sony Vegas Video, and TMPGEnc Plus MPEG Encoder can each mask.

The only time this "overscan noise" will matter is when video is being converted or recorded directly to MPEG (DVD-Video), with no further restoration or editing --- AND --- being viewed on a full-view display device (no overscan), be it a computer monitor, laptop or low-grade HDTV set that is not properly made.

Read more about cropping or masking the edges of noisy video.

admin 02-19-2010 10:24 AM

1 Attachment(s)
Watch or download the BVP4+ edge fix video:

"Reload page to view video."

admin 02-19-2010 10:31 AM

1 Attachment(s)
Watch or download the full BVP4+ flickering video: http://www.digitalfaq.com/forum/show...49&postcount=3

"Reload page to view video."

dyfan 02-19-2010 03:59 PM

please inspect?
 
2 Attachment(s)
I went clockwise (several turns!!!) until the image started to "glow", then counter-clockwise a little until the image was natural again...
Except for the laughable (by your standards, anyway!) way I had to cobble equipment together to see a "live" image, this was even easier than setting the idle mixture screws on a Holley 750 double pumper I used to have!
If that's all Elite Video needed to tell me to do, to turn an adjustment screw clockwise +/-720 degrees with a jeweler's flatblade...well, shame on them. And my hat's off to you for creating a guide that a youth could understand!
Really, thanks! NOW I can get to work fixin' up 'junk' for folks-

before
Attachment 694

after
Attachment 695

admin 02-19-2010 05:00 PM

Moved your post from the other BVP4 thread to this one, since it's about the service/repair topic. Also moved your sample images in-line.

WHOA! That was majorly off. I mean SERIOUSLY off base. I can understand now why somebody saw it visibly on screen. That was definitely bleeding out of the safe zone into the visual area of the image.

And you know you have to share the story about the cobble job. ;)
I've shared many of mine here, and I'll be sharing quite a few more in the coming months. Had to take photos they're so good.

NJRoadfan 06-19-2011 08:30 PM

Does anyone know the specs for the original fuse that came in the BVP4+? I have a unit here with a blown fuse. It came with a 5x20mm glass fuse (GMA type) rated at 1amp. I just want to confirm this is the rated amperage fuse the unit originally came with.

admin 06-19-2011 08:47 PM

Confirmed: 1 amp, GMA type, 5x20mm, 250 volt
And I matched the original fuse 1:1 with a package from Radio Shack a few years ago.
So easy to get proper replacements.

NJRoadfan 06-20-2011 06:47 PM

The fuse was the issue with mine. Now that I have an AC Adapter, I tested it tonight and it works great.


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