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02-19-2022, 09:46 AM
packsnap85 packsnap85 is offline
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I have a JVC HR-S5902U. I noticed excessive audio noise compared to other VCRs during playback. I cleaned the audio head and it didnít improve. I disconnected the audio head and I still hear the noise during playback. Cables are good because itís not an issue with other VCRs. Connectors in the back are good, because there is no noise until I press play. It seems to be coming from the video head, as I hear in the output if I tap the drum, hifi on or off. Is this a shielding/ground issue, and is there anything that can be done to improve this?
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  #2  
02-21-2022, 06:41 AM
timtape timtape is offline
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Quote:
Originally Posted by packsnap85 View Post
I have a JVC HR-S5902U. I noticed excessive audio noise compared to other VCRs during playback. I cleaned the audio head and it didn’t improve. I disconnected the audio head and I still hear the noise during playback. Cables are good because it’s not an issue with other VCRs. Connectors in the back are good, because there is no noise until I press play. It seems to be coming from the video head, as I hear in the output if I tap the drum, hifi on or off. Is this a shielding/ground issue, and is there anything that can be done to improve this?
Hi and welcome. Like seeing a picture, hearing the sound is much better than words... Any chance of uploading a sample of the problem audio?
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02-27-2022, 08:14 AM
packsnap85 packsnap85 is offline
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Audio clips and frequency plots attached.


Attached Images
File Type: jpg Baseline.jpg (102.3 KB, 9 downloads)
File Type: jpg 5902.jpg (99.9 KB, 8 downloads)
Attached Files
File Type: wav Baseline.wav (4.25 MB, 9 downloads)
File Type: wav 5902.wav (4.00 MB, 9 downloads)
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  #4  
02-27-2022, 03:21 PM
timtape timtape is offline
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Thanks for the two audio examples.

I cant be sure which noise concerns you most but I'm assuming it's the high frequency tones. The graph shows time on the horizontal axis, left to right. The horizontal lines represent the various tones, probably caused by the JVC on playback. Actually similar tones are on your baseline playback (which machine was used for that playback?) but they're not as strong, so darker in the graph. Some VCR's are more noisy in this respect than others.

To be thorough, the JVC audio head is probably somewhat more misaligned to the tape played ( a very common issue with consumer VCR's like VHS and Beta on linear audio playback). This muffles the wanted audio, making the high frequency interference even more noticeable by comparison. Unless you're tech-head enough to get into the VCR and tweak the head alignment to the tape played (most people arent), you'll have to live with it, on any playback deck.

Especially on the Baseline playback every 2- 3 seconds I hear a cyclic audio dropout. The top edge of the tape might be damaged.


Attached Images
File Type: jpg JVC 5902 monoed contrast up.jpg (75.3 KB, 9 downloads)
File Type: jpg Baseline monoed contrast up.jpg (78.1 KB, 8 downloads)

Last edited by timtape; 02-27-2022 at 04:06 PM.
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  #5  
02-27-2022, 09:13 PM
packsnap85 packsnap85 is offline
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Thanks for the reply. I tried to tweak the head alignment and that didnít seem to be the issue. The baseline was a JVC vp59u, which Iím pretty happy with (fed through a Panasonic ES10 for capture). I have just been trying to find an improved setup to get the best capture I can. The weird thing to me is that the noise still exists when the audio head ribbon is unplugged. On a different JVC VCR here, I did notice an improvement in audio noise by putting aluminum foil behind the video head ribbon and its connection. Are there any known issues with audio interference and JVC machines of that time period, or have the machines with issues just seen better days?
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  #6  
02-27-2022, 11:41 PM
timtape timtape is offline
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Quote:
Originally Posted by packsnap85 View Post
Thanks for the reply. I tried to tweak the head alignment and that didn’t seem to be the issue. The baseline was a JVC vp59u, which I’m pretty happy with (fed through a Panasonic ES10 for capture). I have just been trying to find an improved setup to get the best capture I can. The weird thing to me is that the noise still exists when the audio head ribbon is unplugged. On a different JVC VCR here, I did notice an improvement in audio noise by putting aluminum foil behind the video head ribbon and its connection. Are there any known issues with audio interference and JVC machines of that time period, or have the machines with issues just seen better days?
You're welcome.

Unplugging the audio head ribbon or cable often makes the noise worse although not from the head but interference within the VCR. It's not really a valid test though. Better to test with everything connected.

Yes sometimes extra shielding on the A/C head ribbon reduces interference as the ribbon is unshielded. Of course whatever extra shielding used needs to be grounded itself to the VCR metal chassis. But JVC is not the only VCR manufacturer which started to use unshielded ribbons from the A/C head. All of my later model VHS VCR's use the unshielded ribbon regardless of brand.

Later VCR's also changed to "Switchmode Power Supplies" which unless well shielded in a metal box themselves can radiate a lot of high frequency noise such as those horizontal lines displayed.

Hard to generalise but I get the impression the more pro rack mountable VCR's maintained quality engineering on linear audio into the later models even though they also carried HiFi stereo sound. Unfortunately being an S-VHS model is no guarantee the linear audio playback will be good quality.

Be careful adjusting the head azimuth. Only one of the usual three or sometimes four screws is the correct one! With a felt pen I write a mark or an arrow on the chassis indicating which is the azimuth screw. Adjusting a height/tilt screw accidentally can introduce new problems. It can be tricky to re establish the verticality of the head in the tape path.

Last edited by timtape; 02-28-2022 at 12:12 AM.
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