Intermittent static, white streaks during VHS playback? (JVC)

dinoman64 · #1 05-01-2022, 02:08 AM

Hi, a little backstory, I have been working on and off for a few months trying to perfect my VHS capture setup for archiving my old home movies which are all on vhs-c tapes.

My current setup is a JVC HR-SC1000U>DMR-ES10>Panasonic WJ-AVE5(digital frame sync)>BM Intensity pro

I think I've gotten the capture chain looking pretty solid, its good enough for my needs, very stable video so far.

The issue I'm having is that the JVC VCR used to play tapes perfectly, but all of a sudden it has horrible static and white streaks on the video (dropouts?). I noticed it come and go before, but last time it wasn't nearly this bad. The tracking was all off and it had some vertical jitter as well. I have cleaned the heads with some printer paper, done an alignment of the rollers and audio head, no improvement other than better tracking. The same tapes play fine on another cheap vcr combo unit that has its own unrelated issues. The JVC a rare machine, pretty old, but built very well and takes VHS-C tapes without the need of an adapter. It was great until it started doing this.

My main concern now is that the heads are damaged, I inspected them as close as I could, and they appear clean and undamaged. The other thing that makes me suspicious is the sound the head makes when playing tapes, you can almost hear it spinning against the tape (think card in bicycle spokes but very quiet and much faster) not sure if that's normal but it sounded the same back when it played well. I'm hoping it could be a bad capacitor in the circuit that deals with the heads or something. I've heard of slightly newer JVC units having a white streak problem related to grounding of the head drum, maybe that's related. I plan on getting a service manual and going through everything. It's just strange how it started doing this all of a sudden, after sitting for a month. The only thing that changed was running the signal through the dmr-es10, and after removing it, the problem persists.

Please let me know what you guys think of this. What does it look like to you? Any ideas on fixing it?

Have a look at the attached screenshots of the same tape, same machine, taken 1 month apart. (please ignore the interlacing artifacts lol)

latreche34 · #2 05-01-2022, 02:31 AM

I see a problem before and after, Possible tape recorded on a miss aligned camcorder, but now the VCR is confirmed out of adjustment, What could have been a simple fix turn into a big job now. never mess with tape path alignment unless you have the skills, the tools and a good reason for re-aligning it. VCR's don't go suddenly out of adjustment on their own, it takes a brutal event for that to happen. Always check other causes for miss tracking first such as bad tape/cassette, bad pinch roller, not fully seated cassette basket ...etc.

dinoman64 · #3 05-01-2022, 04:29 PM

The screenshots where both taken prior to any adjustments of the tape path, and yes that particular tape was recorded badly as you can see from the fuzziness at the bottom. The adjustments I made improved the reliability of the automatic tracking, although I performed them without a scope, I plan on re-adjusting when I eventually find a oscilloscope for a good price. After I started this thread last night I stumbled upon this thread: http://www.digitalfaq.com/forum/vcr-...ag-1980-a.html

I think this may be the answer to my problem. I had already replaced the caps in the power supply because of a fishy smell coming from the VCR, the smell went away immediately after, but within the past week it has come back slightly, I think that's a pretty good sign that it is probably just some more bad caps.

Thanks for taking the time to reply.

latreche34 · #4 05-01-2022, 09:15 PM

No, that's a different problem, your VCR does not show comets, just white dots from RF noise due to miss tracking.

dinoman64 · #5 05-01-2022, 10:00 PM

Please take a look at another sample, although there is no audio in the clip, the hifi audio was playing fine through my monitors, and tracking was consistent and smooth throughout the tape from what I can tell. I did notice that when the tracking is purposely set out of wack or when automatic tracking starts searching at the beginning of a tape that the comets do appear more severe. Maybe it is a tracking issue, it wouldn't make much sense to me that the problem appeared before I even touched the tape path adjustments. Could bad capacitors maybe mess up the control track signal and throw the tracking out of wack?

latreche34 · #6 05-01-2022, 10:19 PM

I told you your VCR is miss aligned you will need to re-aligned using a calibration tape or a well know pre-recorded tape.

hodgey · #7 05-02-2022, 03:22 AM

IMO it looks like there is something else than tracking/alignment here. Also if tracking/alignment is off it should be noticeable on hi-fi audio too. Something is causing interference on the signal, could bad caps or grounding, hard to say. It looks like it's something occurring before the video is demodulated and noise reduction so if it's not in the power supply, maybe head amplifier or video board.

latreche34 · #8 05-02-2022, 09:15 AM

Look at the noise bar at the bottom, that's P guides miss alignment.

hodgey · #9 05-02-2022, 09:21 AM

There is a bit of that too, mainly on the first pictures (which may be tape or vcr), but I don't think that's what's causing all the noise elsewhere, and it's on both "before" and "after" pictures. If it is you should be able to make part of the image clean like in the "before.jpg" one if the tracking is at the right spot.

latreche34 · #10 05-02-2022, 03:14 PM

When the tracks are not aligned with the heads, RF signal weakens and you get that noise, this is pretty common. He made a mistake by messing with the guides, It was just the tape but now both.

lordsmurf · #11 05-02-2022, 08:57 PM

I agree with hodgey.

Head damage is possible. Had it just been the tracking noise, then just being misaligned was likely. But timing errors, and odd noise? Eek. Again, head damage possible, even likely.

FYI, this is why eBay decks are mostly crap. Most tend to be heavily abused now, damaged, out of spec.

This is also ancient non-suggested model of JVC.

dinoman64 · #12 05-03-2022, 02:06 AM

Thanks for the replies, in regard to the screenshots I first posted, the noise at the bottom was definitely from a tape that was recorded with improper alignment. The bar at the bottom (seen in the video I posted) that kind of streaks the last couple lines has been there since I got the machine, no amount of messing with the guides has gotten rid of it. I'm going to replace all the caps I can as a starting point, I have a gut feeling the return of the fishy smell is related to the noise problem. If you watch some videos on alignment from 12voltvids on YT, alignment without a scope is perfectly acceptable, as long as you are competent and careful. I have meticulously inspected every inch of tape that runs through the machine to make sure it is not being curled or rippled when playing after making any adjustments, I look at the reflection on the tape, and you can't even tell its moving its that stable.

Again thanks for all the input, I'll post an update after I replace some caps. Wish me luck!

latreche34 · #13 05-03-2022, 04:20 AM

Why you keep insisting on playing back the same faulty tape? Why don't you use a good pre-recorded tape and try re-aligning the P guides, it may save you an unnecessary recap job.

RobustReviews · #14 05-03-2022, 06:35 AM

Quote:

Originally Posted by dinoman64

I think this may be the answer to my problem. I had already replaced the caps in the power supply because of a fishy smell coming from the VCR, the smell went away immediately after, but within the past week it has come back slightly, I think that's a pretty good sign that it is probably just some more bad caps.

Thanks for taking the time to reply.

If the smell is particularly strong or offensive this points squarely toward breakdown of the X/Y capacitors across the primary of the power supply.

This is a potential fire hazard, or at best they'll explode and leave a big mess to clear up (RIFA) as well as a repair. Usually this happens at power-on with inrush current as the capacitor charges and.... BOOM! You'll know when it has happened as your room will full with acrid smoke and your power will probably disconnect.

The others aren't such a concern, but the capacitors across the primary must be in good order as if they fail short you'll be relying on your Automatic Disconnection of Supply being in good working order. I think failure of these components is sometimes what is attributed to transient over-voltage as they do age and fail in all cases given enough time and can cause damage to some styles of power-supply.

If you have changed those ones, then keep digging, but if you haven't they're the ones that must be replaced if they are at all suspect as it is a safety concern, if nothing else when they let go you'll smell it!

As these capacitors straddle Live/Line/Hot/Phase (pick your local terminology) and Neutral/Cold they absolutely must without any doubt be of the correct type, not just random ones with matching numbers out of your box of odds and ends. They must meet 'Class X' as they are designed basically to 'pop' in the event of failure rather than standard capacitors which have an indeterminate failure state. Something bridging L & N as a low impedance connection is of tremendous concern.

Not aimed at the OP at all, but I've seen too many 'forum experts' moan about smelly machines without grasping the safety implication or replacing XY caps' with normal general use parts.

If in doubt, cut 'em out is one strategy, I have done this in a pinch - I do not recommend this unless you know precisely what you're doing.

hodgey · #15 05-03-2022, 09:05 AM

I know the next gen of JVC SVHS decks like the S5800, and S6800 have electrolytic capacitors elsewhere that go bad (mainly power supply filtering and SMD electrolytics on video and audio modules and on the mech - this has a different mech so it probably doesn't have that one). So, wouldn't surprise me if that is the case with this one too.

dinoman64 · #16 05-27-2022, 10:57 PM

Update: Replaced capacitors in the power regulator board, and the video head amplifier board. No difference. Bought a blank cassette to record on in an attempt to "demagnetize" the heads, no change after recording for about 15 min. The main video board has over 100 capacitors on it, and so far I haven't found any out of spec with my ESR meter. Next step: replace the upper head drum assembly. I'm not really an expert on capacitors but I'm not sure that ESR can really tell you enough about the condition of a cap, so I don't doubt there are still some bad ones, there's just too many to replace all at once.

latreche34 · #17 05-28-2022, 01:02 AM

As I explained above, capacitors don't make the tape transport go out of alignment, There is a general rule about miss aligned VCR's, they play their own recordings perfectly, not always true but for the most part this is a good test to find out about the condition of the tape transport, So feed a clean signal and record it, play it back and let us know.

Also before going out and replacing more parts blindly, read post #13 if you haven't done so.

dinoman64 · #18 05-28-2022, 02:51 AM

As I have explained before tracking is no longer an issue, I recorded a tape and played it back on the same machine, and it is still very grainy and has white streaks. Tomorrow I will try the recorded tape in another machine to see how it looks. Also I did not blindly replace parts, all the capacitors replaced where ones that tested bad on the esr meter plus a few extra in areas like the power supply as a preventative measure. Thanks for your input though.

dinoman64 · #19 05-28-2022, 08:43 PM

So I tried the tape I recorded in another machine, and to my surprise the video quality is flawless for the SP recording. EP has some noise and tracking problems. The audio doesn't sound good though, on the original machine it sounds fine but the newer VCR has some static and dropouts, unfortunately I can't tell if the newer machine is using HIFI or standard audio.

So this is where I think the problem is revealing it's self, could the heads be bad even if they record fine? or is it another issue down the signal chain within the VCR? I already ordered a new head drum so I'm hoping that wasn't a waste of money.

This is a SVHS machine with 5 heads, I'm assuming that means 2 video, 2 audio, and 1 flying erase head. They appear to be dual azimuth from the large gap seen in 2 of the heads. That's as much as I know. Any advice is much appreciated.

themaster1 · #20 05-29-2022, 02:30 AM

P-guides and perhaps the AC (audio control) head may need adjustment i'd say. 1 step at a time though. The rule if you do that without scope is to start with the worst signal and work your way up, so EP>SP>SP HIFI>S-VHS Hi-Fi. That's how i do. You also have to disable auto-tracking. Use preferably good retail tapes, ideally (expensive) calibration tape (one for SP one for EP or LP whatever)