Intermittent Audio Playback Issues JVC GR-D250U but FireWire transfer fine

[ArcanaXIX]

I received a JVC GR-D250U MiniDV camcorder secondhand a couple years ago and ever since I have been playing with it. I've taken it on trips with my roommate to document our adventures, that kind of thing. Something about this old thing's whirring and the physicality of magnetic tapes appeals to me. Also, it was just going to be e-waste, and I feel like I'd rather have fun and make use of it than let it go to a landfill somewhere.

Anyway! Here's my dilemma. I like to host little "movie nights" where my roommate and I watch the horrible footage I took from our travels together. However.... for some reason, the audio playback is messed up on this thing. The tape is fine, the camcorder itself can read the audio for the purposes of FireWire transfer just fine, but it always has issues just playing back.

The audio just cuts in/out very frequently, just about every other second clips out into silence. I attached footage of an analog capture card capturing some random test footage to demonstrate the problem. I am not bothering to attach a FireWire transfer, just trust me when I say the audio is 100% uninterrupted over FireWire, so clearly the camcorder can read the audio for that. Both captures are of the same part of the same tape FROM THE SAME CAMCORDER.

So I can do FireWire transfers to my PC and all of the audio is transferred, no problem. The camcorder can record audio, and it can read it for the purposes of transferring/archiving. But it can't play it back LIVE without issue. The playback I can hear on the camcorder itself is choppy, and this also applies to its TRRS-to-RCA output that I hook up to my CRT TV for us to view (and to the capture card for the test footage supplied here).

So the problem is obviously the camcorder, since the tapes are fine - but for some reason it can read the audio to transfer over FireWire, but it has problems trying to play back the audio directly.

My questions are thus:

1. Is this possibly an alignment issue? I have heard that alignment issues can cause glitchy audio, but I wasn't sure that would be the case if the audio TRANSFERS fine over FireWire but only has issues in PLAYBACK.
2. If it IS an alignment issue, and I have recorded these tapes with the heads misaligned, do I risk anything if I fix the alignment and then revisit these tapes? As in, should I keep the camcorder as-is since it was in this state when it recorded the footage, and only try to fix it after I've finished transferring all of my existing tapes? Or is there no harm done in trying to fix the alignment now?

My first step would be to try to adjust the alignment, after watching this video: https://www.youtube.com/watch?v=lj6Wdl88a2k [the camcorder does have little holes to access with a flathead screwdriver to fix the alignment, so that should be easy enough.]

I just want to better understand what it might mean if I have recorded a bunch of tapes with misaligned heads before I do that. I don't want to make things any worse with the tapes I've already recorded.

The camcorder has other issues (which are visible even from this lazy capture of test footage) so even if this doesn't fix the audio I'm likely to try the alignment fix EVENTUALLY anyway. I just want to understand if it's likely to be the cause of my audio issue, or if that's something else entirely. I also want to gauge whether fixing it might make the existing tapes that were recorded with the camcorder in a faulty state play back any worse.

Any guidance is appreciated. Thanks!

[dellsam34]

If you don't have a problem transferring the footage to computer over firewire than don't worry about the playback to analog audio out. And no it is not an alignment problem if the camcorder is able to transfer the recordings to computer without audio problems, Unless I completely misunderstood your post.

[DB83]

Adding to the above.

It is not clear if the transfer over firewire simply solves the audio drop-outs or is of the same 'quality' as the analog transfer. And I state 'quality' since there is no discernable audio just a whole lot of noise.


Now some of that could be down to your TRRS-RCA cable. Was this supplied with the camcorder or acquired separately ? That 'noise' could well be interference from an incorrect connection from the camcorder since the plug might fit but is still not fit for purpose.

[DB83]

Oh. And that youtube video is 'dangerous'. One should practice what one preaches and actually demonstrate head alignment and not merely theorise.

And since your issue is not head alignment you should also not mess around with that since you could do more damage than it is worth.

[ArcanaXIX]

Thanks for the feedback. I had a hunch messing with the heads could be destructive so I'm glad I checked.

If you don't have a problem transferring the footage to computer over firewire than don't worry about the playback to analog audio out. And no it is not an alignment problem if the camcorder is able to transfer the recordings to computer without audio problems, Unless I completely misunderstood your post.

You didn't misunderstand at all, but I really do value the playback audio for the purposes of watching the footage back on my TV. I know that sounds silly but as you can see from the crappy sample this is not high quality footage so watching it together is almost more important than archiving it.

I suppose if fixing the playback audio is a nightmare I could burn DVDs from the transfers and we could watch those instead. Not ideal to have an extra step but not the end of the world if the playback issue is going to be a doozy.

Adding to the above.

It is not clear if the transfer over firewire simply solves the audio drop-outs or is of the same 'quality' as the analog transfer. And I state 'quality' since there is no discernable audio just a whole lot of noise.


Now some of that could be down to your TRRS-RCA cable. Was this supplied with the camcorder or acquired separately ? That 'noise' could well be interference from an incorrect connection from the camcorder since the plug might fit but is still not fit for purpose.

The noise is my roommate running the kitchen sink in the background and is how the audio is meant to sound. I used a clip without speech to respect their privacy but I see how that was probably confusing..

It's not the cable because this (sound cutting in and out) is also how the audio sounds on the camcorder itself when playing back for a FireWire transfer. No RCA out at all there. But miraculously the FW transfer is perfect. So it's the camcorder but somewhere that makes audio playback messed up but transfer fine. Does that make sense?

Edit: since it's not the alignment my guess is a real fix will probably require surgery. I have opened up and resoldered stuff before but nothing as delicate as a camcorder, so I'm only willing to do it if anyone can point me to good documentation or resources on doing so as asafely as possible. Open to additional thoughts..

[DB83]

Sorry. But you confuse the issue even more since you originally stated that transfer over firewire was 'perfect'.

There is, in my humble opinion, noise that can not be explained as you have attempted. Maybe you should post another sample where the tap is not running and more than that send both the firewire AND RCA versions of the same sequence.

[ArcanaXIX]

Sure, happy to do that later, but you can trust me when I say FW captures the audio without interruption and cam playback + RCA out both cut out intermittently. "Perfect" meant uninterrupted, the quality itself is bad because the source footage is crappy test footage.

I'll post requested samples when I have more time later today.

[dellsam34]

I would assume the issue is somewhere in the audio DAC board where the data is extracted from tape and converted back to analog audio, Most likely surface mounted capacitors, The troubleshooting and repair are beyond an average person, It would involve heating up and freezing individual components on the PCB and see which one improves or worsen the problem, Once the component is identified a replacement will follow, Replacing SMD components is not fun, I would just call this a right off and buy another camcorder that works, Usually miniDV camcorders are not that expensive unless you want to get into the HDV territory even then some do go very cheap online.

[ArcanaXIX]

That makes sense. Hmm.... I think I'm going to do the following.

1. Finish transferring all tapes as is (almost done)
2. Go ahead and risk surgery
3. If I break it.... roommate and I can just watch the captures digitally while I order a new cam lololol

I've done capacitor and other part replacements on circuit boards before, but this would probably be the trickiest I've attempted. If I break the device (worst case scenario) and have to buy a different one at least I'm not much worse off. The hardest part is going to be identifying the exact cause of the issue on the board, as you've said... but if I can spot the speakers and where their signal is coming from on the board maybe I can figure it out. I could try just replacing all the capacitors on the audio signal path and see if it fixes anything.

I will post here if I do attempt surgery later and whether or not I break it in the attempt (as a cautionary tale, haha). I'll post the samples when I transfer the remaining tapes to demonstrate, but I think dellsam is right on the money with where the issue lies.

[DB83]

Well rather you than me in this situ

If you have not outsourced the Service Manual(s) they are available here:


https://elektrotanya.com/jvc_gr_d250.rar/download.html#dl

[ArcanaXIX]

So I have a very belated update to this. I have still not solved the problem, but I've made a lot more progress, and since the purpose of a forum is to document and archive knowledge for reference, I wanted to provide what I have learned.

TL;DR - Jumping a blown fuse fixed an unrelated battery/power issue, audio issue still persists, more diagnosis work needed to figure that out.

First: a little transparency on all of the camcorder's symptoms. The audio issue is not the only issue with this camcorder. It was the first issue to appear, but after that it started having another issue where it constantly throws a "unit in safeguard mode/remove and reattach battery" error - and on top of that, even when plugged directly into an outlet, it sometimes can't seem to muster the power to rewind a tape. It was turning into glorified e-waste.

It occurred to me that there's a possibility that these issues are related - if it's having power issues, maybe that's interfering with its ability to play back audio somehow. Can't rule it out. So now that I have a multimeter, first thing I did was verify the A/C adapter is actually outputting the voltage it's supposed to. It is, so can't blame that.

At this point I had to start taking it apart. @DB83 thank you for linking the service manual, this thing was an actual nightmare to disassemble even WITH instructions. It has a thousand screws, all different lengths so you have to keep track, and even once you take the screws out it feels like it will snap if you don't pull the pieces apart JUST the right way, genuinely seems like it was built to be put together and never opened again. Since it's from 2004 and they tried to make it such a small form factor it is all extremely tightly puzzle-pieced together and impossible to pull back apart. But enough complaining - I did in fact manage to take it apart.

I tested all of the pins and connectors on the ribbon cable connecting the rear module, since that's where the power comes from and where the battery is mounted, but everything came back normal and as expected.

I was a bit stuck because the circuit board is way more complex than any others I've looked at so far (all my previous repairs have been pretty simple stuff) and I had a really difficult time figuring out how to read the schematics sheet. I tried to look up some camcorder repair videos, just to get a feel for what good basic troubleshooting steps are. I found this one, and even though it's a totally different kind of camcorder, decided to watch: https://www.youtube.com/watch?v=C5DNd54ksgE

In his case, a blown fuse was the culprit. Well, I didn't have any other leads, so I poked around in the open camcorder and immediately located a fuse on the main circuit board (F6001), and after testing it, found that it was indeed blown! No continuity on the circuit across it.

I also tested the 2 fuses on the other board just out of curiosity but they were fine.

After looking at the schematics again, it looks like this fuse comes right off of the main power and is like point 1 of failure on the whole machine's power system, so it would be a high priority to fix.

If I were doing this repair for professional standards, first of all I am NOT qualified for that, but I would want to replace the fuse with another fuse. However, at this point I just want the dumb thing to work, so I decided - as with the person in the video - to just try to jumper across it.

Approximately 3 of the most frustrating hours of my life later, I somehow managed to do it. I melted the plastic of one of the adjacent ribbon cable clips in doing so and also melted some solder on adjacent components, because this thing is FREAKING TINY. But I did it. I was testing continuity between one of the pins on the ribbon cable connecting to the rear module and a capacitor on the backside, because those were the 2 first points I found that connected to the two ends of the fuse respectively. So I was able to be certain I'd jumped over the fuse by testing those points.

I am not above posting my horrendous solder job as a visual aid:


[Attachment 83123 - Click to enlarge]

[Marker is not mine, it looked like that when I opened it.]

But I can say that this seems to have fixed most of the power issues.

Fixed symptoms (jumping fuse F6001):

• Not having enough power to rewind tapes even when plugged directly into outlet
• Battery seems to charge more and hold a charge better
• "Unit in Safeguard Mode - Remove and Reattach Battery" message MUCH less frequent (but has still appeared)

Now, I suspect the battery itself may have gotten screwed up by whatever was wrong with it before, so I might try to get a new one eventually and test. Or maybe it just needs a few cycles of fully draining the battery and recharging to fix itself. But from the limited testing I've done so far it definitely is a much happier camcorder. If it's plugged directly into an outlet it works perfectly and if it's on battery it's much more reliable than it was before. So that's all great.

HOWEVER.... this has in no way improved the audio issue. Playing back a tape the audio on the speakers audibly chops in and out in discrete intervals just like before (and just like it did over A/V).

Now, one thing that surprised me looking at the schematics is that the audio output for the inner speakers, and the audio output for the A/V out, are COMPLETELY DIFFERENT PINS on the audio chip. I had assumed it was the same output signal which is why I got the same issue on both, but it's 2 different outputs on the same chip. So whatever is causing the issue is happening "before" the audio chip, in some way.

[For reference: the audio chip is labled IC2201 on the schematics sheet, and the actual chip is an AKM AK4660VQ.]

The data transfers fine over FireWire, so the audio chip itself is probably fine because it's able to record audio.

Anyway, after the nightmare solder job I just had I am not about to dive back into this immediately, and I'm glad to have fixed an unrelated issue. But for the audio issue, I think I will have to look at the schematics again and try to figure out what other parts of the circuit board(s) might be the problem. I do think i can "hear" something PHYSICAL/MECHANICAL in the camcorder itself kind of "jumping" or "clicking" when the audio cuts in and out. But I need to learn a bit more about the components interfacing between what reads from the tape and the audio chip to figure out where to start zooming in on my troubleshooting.

There is more research to be done, but I've at least fixed a battery issue, and made a little more progress on narrowing down where the audio issue might be lying. Apologies for the bump given I didn't actually fix the issue, but I did fix a different issue on the same camcorder and confirm that fix did not have anything to do with this symptom, so it still feels like progress on the same subject.

[dellsam34]

Some TV's back in the day did have iLink input to watch the footage directly on TV from a camcorder like yours, Check to see if you can hunt one down in your area, Although it is a lot easier to get another miniDV camcorder. Good luck on your repair adventure.