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  #1  
04-22-2017, 11:26 PM
DrFinvard DrFinvard is offline
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Hello there gents. Recently I bought a Panasonic AG-1980 S-VHS with the following issue: when the player is turned on (and it's cold) the image looks very noisy, but when the player is warm the image is perfect. There are some screenshots taken while the unit was warming up, with a NTSC test pattern (The pics are listed in consecutive order). The first pic is when the unit is cold and the last pic is when the unit is warm.

I guess that the main culprit in my case are the capacitors.


Attached Images
File Type: jpg 1.jpg (129.4 KB, 34 downloads)
File Type: jpg 2.jpg (106.8 KB, 17 downloads)
File Type: jpg 3.jpg (79.2 KB, 15 downloads)
File Type: jpg 4.jpg (48.6 KB, 7 downloads)
File Type: jpg 5.jpg (47.3 KB, 8 downloads)
File Type: jpg 6.jpg (46.3 KB, 10 downloads)
File Type: jpg 7.jpg (40.2 KB, 7 downloads)
File Type: jpg 8.jpg (46.2 KB, 11 downloads)
File Type: jpg 9.jpg (38.0 KB, 11 downloads)
File Type: jpg 10.jpg (39.1 KB, 29 downloads)
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  #2  
04-23-2017, 03:37 AM
Quasipal Quasipal is offline
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Absolutely. And when you replace the capacitors you will get a brighter image than what you are getting now even when the unit has warmed up.

I have been going over all my machines and in many cases I am finding the early signs of failing capacitors even in units not known for this - rising measured value and ESR. At least we can easily get replacements.
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  #3  
04-23-2017, 05:56 AM
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lordsmurf lordsmurf is offline
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It's usually the opposite -- good image to start, degrades as the unit gets hot -- but it's caps.

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  #4  
04-23-2017, 05:35 PM
DrFinvard DrFinvard is offline
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Today I played a VHS tape with the TBC on to test the colors. The red color is bleeding in some parts and in one commercial the TBC darkens the image. The video is an old broadcast recorded in early 2000s with a low end mono VHS in spanish language. Keep in mind that the test was made when the AG-1980 was warm.

The video was captured using the following hardware, software and settings:

- VirtualDub (Uncompressed video @ 8-bit)
- Pinnacle 510-USB
- Adobe Premiere CC 2015 (To compress the video to a MP4 file, since the original is over 2 GB)

EDIT: The link to the video has been removed. Please wait until I upload the video to Dropbox.

Last edited by DrFinvard; 04-23-2017 at 05:49 PM.
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04-23-2017, 05:43 PM
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lordsmurf lordsmurf is offline
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If you want Site Staff to look at your video clip, then it needs to be attached (therefore under 100mb). Or use Dropbox. Most other site members are the same. Mega is one of those obnoxious sites that insists on injecting itself into your browser, countdown clocks, etc.

It sounds like bad caps.

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  #6  
04-23-2017, 06:12 PM
DrFinvard DrFinvard is offline
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Quote:
Originally Posted by lordsmurf View Post
If you want Site Staff to look at your video clip, then it needs to be attached (therefore under 100mb). Or use Dropbox. Most other site members are the same. Mega is one of those obnoxious sites that insists on injecting itself into your browser, countdown clocks, etc.

It sounds like bad caps.
Thanks for your feedback. I uploaded the video again but in Dropbox.

Here's the link: https://www.dropbox.com/s/5v48pbdcmr67mv5/Test.mp4?dl=0

EDIT: I added a somewhat small file to the forum if the dropbox link doesn't work. It has a small bitrate but the file quality is the same as the Dropbox file


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File Type: mp4 Test2.mp4 (89.22 MB, 19 downloads)

Last edited by DrFinvard; 04-23-2017 at 06:48 PM. Reason: To add the video file in the post.
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  #7  
04-23-2017, 07:15 PM
sanlyn sanlyn is offline
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Quote:
Originally Posted by DrFinvard View Post
Today I played a VHS tape with the TBC on to test the colors. The red color is bleeding in some parts and in one commercial the TBC darkens the image. The video is an old broadcast recorded in early 2000s with a low end mono VHS in spanish language. Keep in mind that the test was made when the AG-1980 was warm.

The video was captured using the following hardware, software and settings:

- VirtualDub (Uncompressed video @ 8-bit)
- Pinnacle 510-USB
- Adobe Premiere CC 2015 (To compress the video to a MP4 file, since the original is over 2 GB)
We all hope that what you describe is not the way you normally capture VHS. Capturing uncompressed is a waste of space and likely is captured as RGB, which is also not a good idea. Most would capture to YUY2 losslessly compressed with huiffyuv or Lagarith.

You can't really go by level and color balance changes that occur in commercials during TV broadcast. Ad color and levels can be all over the ball field. I doubt you can blame blame a TBC for it. I see see three commercials in your sample. What leads you to believe that your TBC affected one commercial but not the other two.

The tape is in horrible condition, the repair and restoration work made more difficult by poor luma level control during capture and crushed darks (which is a little odd because the black levels are so high and are clipped at about y=40). I don't enmvy anyone who'd have to improve thesse captures, I've been through a few bad tapes myself. It looks as if TBC and DNR are both turned off.

Quote:
Originally Posted by DrFinvard View Post
EDIT: I added a somewhat small file to the forum if the dropbox link doesn't work. It has a small bitrate but the file quality is the same as the Dropbox file
I have to disagree. The quality of the smaller re-encode is far worse than the lager sample.

Last edited by sanlyn; 04-23-2017 at 08:02 PM.
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  #8  
04-23-2017, 07:37 PM
msgohan msgohan is offline
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The levels in the commercials are really messed up and do appear to be capacitor-induced.
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  #9  
04-23-2017, 07:43 PM
sanlyn sanlyn is offline
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It's possible, but levels are a mess in every segment of both samples. I don't think the dnr is working, either. The player clearly needs some caps work and has alignment problems that seem to be giving the tbc board a very difficult time.


Anyone notice that the samples are telecined/interlaced video encoded as progressive? Pretty much ruins the samples with blended fields and bad chroma ghosting.

Last edited by sanlyn; 04-23-2017 at 08:34 PM.
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  #10  
04-30-2017, 01:36 PM
DrFinvard DrFinvard is offline
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Since I don't live in USA, I'm gonna put this VCR on the backburner for a while until I get the necessary $$$ and parts to rebuild my VCR to factory specs

@sanlyn: Are you saying that my VCR has electric, electronic or mechanical adjustment issues?. Because the unit is practically flawless in regards to the mechanism. My AG-1980 has the best tracking among my other VHS VCRs (I have other Panasonic, Sony and JVC mono and Hi-Fi VCRs who track my tapes with varying degrees).

I'm quite grateful with your help, guys. I have some Betamax and VHS service manuals to share in appreciation for your help, but unfortunately I don't have a scanner to digitize my service manuals.
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  #11  
04-30-2017, 04:14 PM
sanlyn sanlyn is offline
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I agree with othjers who've looked at the samples. Capacitor and other small electronic component maintenance would be the main issue.
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