Panasonic NV-HS930B audio dropouts?
 

Hi all,

I am just after some advice again if anyone has any thoughts.

Just received this player in my second attempt at a good VCR and I seem to have run into another problem. I seem to be getting very brief audio dropouts usually only a fraction of a second to a second long. This is when playing stereo sound (have not tried mono much yet) and seems to happen randomly. I have tried rewinding back to see if it repeats in the same place but it never does. It seems to be more prevalent on some videos than it does on others, ranging from every minute or two to only once or twice in an entire video, but this is only in limited testing so far. I have also tried the more problematic tapes on another (AIWA) player and there are no such issues.

I also have another video that plays fine in stereo on the Aiwa player, but will only play in mono on the Panasonic once I get past the first 10 minutes or so. Many videos tested so far however, seem to play fairly well with either limited or no noticeable audio dropouts. I should also mention that these are all retails videos, not recorded ones.

Is this all fairly normal in that some VCR’s will do better than others with certain tapes or do you think this is more of a fault/wear and tear or calibration issue?

The VCR itself seems to be in good shape. It is very clean inside and automatic head cleaner looks like it hasn’t seen an excessive amount of use, just a limited amount of dirt on the roller. I have however disabled it at the moment. I have also give the heads a clean with some rubbing alcohol and some paper with limited dirt coming off, which has made no noticeable difference.

I might as well mention that I have been having some (less frequent) patches of snow flash up on part or the entire screen during playback, which only last a fraction of a second. I don’t consider this particularly unusual for a VCR and always assumed it was dust as again it doesn’t usually happen again when rewound. Could it be dust causing the audio issue as well?

Anyway, that’s all it was. If anyone has any insight it would be appreciated.

Many thanks

PS: As a side note. Does anybody know where I might find a service manual for this player? I Couldn't seem to find one with a google search?

Audio dropouts? That's a new one for me. :hmm:

I'm sure it's possible, especially on a Panasonic (breaks too easily, more than JVC), but I've never come across this sort of audio error.

I can only guess the audio heads may be dirty or damaged?

Yes, dust is possible.

The tapes would be suspect, if not tried in another deck (with no dropouts).

Paging Dr. hodgey and Dr. dplomaki, VCR is sick, stat. :laugh:

Many thanks for the response, and also the many helpful comments you have made over the years, which have proved very useful :)

So, this is perhaps an unusual one then? So with the ruling out of the tapes being the definate issue (by playing on another deck) you would suspect either dust or damaged/worn heads? Any way to verify this?

Thanks

Anybody have any further thoughts on this?

I have since given the heads another more extensive clean with paper and rubbing alcohol, but no change....anything I can do to give a more extensive clean?

I don't really want to send this one back as it is otherwise seemingly working very well. But having the audio cutting out randomly isn't exactly ideal even if it is only very briefly.

I was reading in another thread about these players being prone to bad capacitors...could this possible be related?

Anyone know where I might get a replacement part to solve this issue? I'm in the UK by the way. Paid £115 for the player.

Many thanks

Yes. :2cents:

I don't know the specific model you have, so this is just speculation. The audio drop outs might be the result of the detected audio RF signal fed to the stereo audio demodulator dropping below the necessary level resulting in squelching. Since you report occasional weak signal (the noise) on the video as well as the audio issues, it might be that the problem is centered in the head amp board/section. Re-capping it might correct it by improving the gain. Another place to check is the HiFi audio demodulation section. Alternatively if you have a similar "parts" machine at hand you could try swap the head amp board as see if it makes a difference.

As short term a work around, since the drop outs appear at random, record the audio multiple times, open the recording in a audio work station such as Audition that supports multi-track, multi-session, and mix/switch between track recording as necessary to give you a good recording. (Or record the audio usign a different VCR and combine the good audio and video.

Many thanks for the reply and information.

Although I have a bit of experience with recapping (games consoles) I don't know if I have the time or inclination to get that invested in this, even though I would love to get it back in top shape. It might be different if I couldn't send it back or it was really cheap, but it just doesn't seem worth the effort/risk, especially as it could be down to any number of things.

I will have a think about it and I really appreciate the input from both of you, but I suspect I will end up returning it to the seller and trying a third time. I will surely find a good one eventually? :)

Thanks again

Hi again,

All change, I am keeping the player after all. The seller said he would not bother selling it again and offered it to me for £30. Knowing it was probably going to be a bad ending for this VCR I decided to keep it and see what I can do with it.

So with that in mind, you mentioned the "head amp board/section" am I right in assuming this is the board that sits on top of the main drum assembly? Also you mentioned the "HiFi audio demodulation section" where is this? Sorry, I am pretty new to much of the finer details of all of this.

Also, does anybody know where I might find the service manual for this model? This might be valuable guidance at this stage. I have had a search on Google and the only site I have found is charging for it and I am not sure I trust it. Anybody know where I can download it for free? Failing that, where can I buy it that is trustworthy?

Many thanks again

This is VCR is new enough that it doesn't have a separate head amplifier PCB. Most of the video decoding (other than special stuff like SVHS and TBC/DNR which may be on a separate PCB), head amp and linear audio got combined together in one IC. There is probably be a separate IC for Hi-Fi audio though. The board on top of the drum assembly is the drum motor. I don't know if it's from the same generation, though the NV-HS870 service manual is the closest I can find. It does at least have the same mechanism.

I don't know about the audio part of things, but the video sometimes going to noise and back quickly is something I encountered on an older Panasonic NV-HS1000, where the issue was the head drum (it did also have some dodgy capacitors, but the drum turned out to be the main problem). I don't know if the actual heads were bad or if it was due to a bad solder joint which was an issue on the older panasonics. The NV-HS930 is a number of years newer though, so it's much less likely to have aging issues like caps going bad, but it is a possibility of course. It could also be something very simple like a dirty head amp ribbon cable or similar.

Hi,

Thanks for your reply, much appreciated :)

I don't know off hand which ribbon cable is for the head amp, so I will probably just take them all out one at a time and clean them all with some rubbing alcohol. I did already do that with the ribbon cable connecting the drum at the top, but not the bottom as that was difficult to access.

Failing this, it would seem that the drum might be a good place to start? As the problem is worse with some videos than others, my instinct tells me that it could well be head related? I have found a couple of people selling the whole drum on ebay so might be worth a go. Looking at the service manual you provided it looks like the drum is modular? Is this something that is relatively easy to swap out? I can see that I would need to get to the bottom of the motherboard to replace the entire drum, but perhaps not the top parts?

Thanks again

FWIW: https://www.user-manuals.com/advance...x=0&y=0&brand= appears to have it in PDF format for about $8 USD. I've obtained a couple manuals from them in the past and have been generally satisfied.

And for any manuals purchased, please post copies here. This information was never meant to be behind a paywall -- and those sites are not legal. Most are Russian (or similar). These are not their manuals to sell.

A lot of those are scraped. I've even seen where manuals were downloaded from this site, watermarked, then sold on theirs. We've had members kick themselves for giving money for the manual that were available as PDF on this site for free download. (The only requirement is to join as a member to download, which is free.)

Thanks for that. I will hold off for now, but if necessary it's good to know they are at least somewhat reliable...thanks for the recommendation :)

If I do end up buying it, then I will definitely post it here :)

Hi all,

I had a go at removing and cleaning all the ribbon cables last night, but unfortunately it made no difference.

So where to go from here? Try swapping out the main drum or something else?

Without a service manual and appropriate test equipment your options are limited.

You could do a close visual examination of the circuit boards for any evidence of bad components, especially capacitors. Look for evidence of bulging and/or leaking. Surface mounted capacitors were especially prone to early failures on some Panasonics. Also look for what might be cold solder joints. However, keep in mind that bad capacitors might not have any external indication of failure.

If you can find a "parts only" version of the VCR at a modest price you could try some parts swaps.

The service manual usually describes the "main drum" (cylinder) change process.

Thanks for the reply.

Yes, it is a little difficult, especially when I obviously have limited experience :(

I have had a look at the service manual for the NV-HS870, which was posted by hodgey, which does seem to be the same mechanism and have also had a look at this which is a service manual for the z-mechanism for this VCR if I am not mistaken?

The HS870 manual shows an exploded view, suggesting that the cylinder/drum is modular and could be replaced in parts from the top of the machine, although I am far from sure of this and could prove difficult for a novice.

The z-mechanism manual suggests you can remove the entire drum if you remove the entire mechanism? This looks like it might be reasonably straight forward as long as care is taken, but again I could be very wrong.

I have been looking at either just the drum (VEK9017) or a full spares machine or a similar parts player with the same mechanism.

As for the visual inspection. I have already done this on the areas I can see and everything looks in great shape as far as I can tell.

Hi all,

Just an update on this one. I purchased a cheaper (mechanically faulty) VCR that shares the same z mechanism and drum as the HS930. I took the whole mechanism out of the HS930 and dropped it into the cheaper player and the same audio dropouts were present, so the issue must be on the mechanism tray. I then decided to try swapping the drums around but now (as I somewhat expected) I have a B&W picture with some snow and slight squealing sound on playback. I tried going back to the original drum, but the same thing happens. I assume something is out of alignment? Any suggestions on what I can do to try to fix this?

If this isn't easily fixed I guess I will just get a cheaper fully working z mech player and swap the entire tray and then fingers crossed I might get a fully working player :)

I don't know if it would be helpful, but I was having some static/comet tails on my NV-FJ621 which is a hi-fi model from around the same time with the same mech. It seems it was caused by the screw (next to the loading motor) securing the shielding bit that sits behind the video head drum and around where the cable from it goes to the board being loose.