JVC HR-S9800 VCR audio playback problem

[n6nfg]

Those of you with a JVC HR-S9800 (or even a 9600) I have a question for you on audio playback. I recently aquired a 9800 used and found that it has its audo playback level to "hot". The front panel level meter on playback frequently goes to its highest (in the "orange") setting, and the corresponding audio is distored (clipped). This happens on commercial tapes, or home recorded tapes. Using the "normal" audio output, it is not quite as bad as the "HIFI" setting, but they both are too high on peaks.

Is there an internal level adjust for this? I noticed a record level control in the menus, but nothing about playback.

Anyone with a service manual care to comment please??

[lordsmurf]

Wiring sounds bad

[Bob W]

Just a guess but it sounds like the AGC circuit in the player is defective.

[n6nfg]

lordsmurf writes:
Wiring sounds bad

Since this is reflected on the front panel level controls during playback, I am guessing you are refering to internal VCR wiring? Otherwise the external connections have nothing to do with playback.... Let me reiterate, this is a playback problem, not a recording issue, and the same tapes that result in distortion on this JVC play fine on other VCR's in the same environment using the same external cables and audio amplifier.

Bob W:
Just a guess but it sounds like the AGC circuit in the player is defective.

I might believe this, but the "normal" audio tracks (the linear ones on the outside edges of the tape) have the same problem as the "hifi" audio tracks (the helical ones embedded in the video, and the linear tracks probably aren't sent through the same AGC circuit as the video (spiral). Also, since the video is good, I would hesitate to point the finger at AGC just yet.

I really could use a peak at the service manual, may have to cough up a few more bucks for the manual, or send it in to a service center

[lordsmurf]

If I can find my manual, I'll look.

[n6nfg]

lordsmurf writes:
Posted: Mar 22, 2004 02:53

If I can find my manual, I'll look.

Do you ever sleep ?? Must be middle of the night your time!

Hey, if you can take a look I would really appreciate it. I can get a service manual PDF off of EBAY if necessary, and I know my way around a schematic.

[wulf109]

On my 9500 just press the menu button,the hi-fi level control is separately listed item in the first menu. It has a default sttting and an adjustable range control. If setting the range lower doesn't work you've got a defective used VCR.

[n6nfg]

wulf109 wrote:
On my 9500 just press the menu button,the hi-fi level control is separately listed item in the first menu. It has a default sttting and an adjustable range control. If setting the range lower doesn't work you've got a defective used VCR.

I checked this setting, and varying the level adjustment does cause the level meters to go up/down and the audio from the VCR to go up/down, BUT this only applies to live audio (from the built-in tuner or from the external inputs. On tape playback audio, this adjustment has no effect (and this makes sense to me as this is a "record" level, not a "playback" level).

So good try, but I don't think this is the answer

[wulf109]

The meters control the record input level only. If you record a movie the input level can be adjusted to fall within a normal range and can be preset to a normal level for recording.
The level controls do not effect playback. If you record something with a normal range does it playback in that same normal range?
It isn't a "nice try" it simply the way the VCR works.

[n6nfg]

wulf109 wrote:
The level controls do not effect playback.

Precisely, and this is why I can't use this feature to fix the problem I an experiencing. If I record something, the played back audio does indeed vary when the record level is adjusted. The problem is I have previously recorded tapes from other VCR's that this JVC plays back with the audio too high. I am convinced there is an internal problem with the VCR audio playback circuit.

If you record something with a normal range does it playback in that same normal range?

Good idea, I'll try this when I get home to establish a base line for stuff recorded by THIS VCR. Maybe the results will narrow down the problem area.

Can you (anyone with a 95/96/9800 model) try something for me? If I set the recording level to the mid range, and listen to the audio from the TV tuner, while the VCR is stopped. everything sounds good, and the level meters indicate a single "orange" peak once in a while. If I then increase the record level so that the "orange" range is consistently reached, the monitored audio immediately begins to clip (distort). I get noticeable clipping as soon as the second orange line is reached on both left or right channels. It would appear that my unit has very little head room for the audio being overdriven. Is this what the rest of you experience when setting the level a little bit "too high"?

[n6nfg]

Update from last night:

I verified that whatever level I use to record at is reflected in the playback level. Recording at "normal" level results in playback at "normal" level. Recording at "high" level" results in playback at "high" level, so everything seems to work OK in this regard.

Tapes recorded at a slightly high level (peaks well into the orange) play back well on other VCR's, but playback distorted on this JVC. I conclude from this that the record capabilites seem to be fine.

If the record level is slightly high (peaks into the orange) and you just monitor the audio in real time from the output jacks, the audio is distorted. Note that the VCR transport is not engaged at this point (no record/plaback is being performed. The source of audio for this test is the built-in TV tuner.

Tapes that have been recorded with high audio (from either this VCR or any other VCR) play back distorted on this VCR, and fine on other VCR's.

From the above two experiments, I conclude that the problem must be in the output audio driver feeding the rear panel jacks, and does NOT involve the transport and its electrionics. This limits quite a bit where I need to start looking for trouble if true.

[lordsmurf]

On my JVC 9800, adjusting the REC LEVEL will change the audio system-wide, whether played, recorded, or just plain pass-through.

It's actually the cheap-shot method I'm using now, passing coax feed to JVC, RCA output to DVD recorder, with REC LEVEL set higher to overpower the hiss on the coax. Works okay. Better than raw coax to recorder.

[n6nfg]

LordSmurf:

Are you saying you can play a tape, and adjust the audio output of the audio leaving the rear panel RCA jacks by using the record level controls? Mine doesn't work like this!

If it did, I wouldn't have such a problem, I could just turn the level down on tapes that were too "high", and keep the level out of the orange zone.

[lordsmurf]

Yes. Maybe your REC LEVEL isn't working.

[n6nfg]

Ahh, very interesting. This is all starting to make sense now if true. It would appear that the record level menu adjustment has NO EFFECT on the output leaving the rear panel jacks when playing a tape. Under all other conditions, this level adjust works fine. It would appear that it is set to its "maximum" setting on tape playback. I put a scope on the audio out from the rear RCA jacks, and confirmed that the audio is clean (not clipped), but it is definately above the "normal" line levels you would expect on rca audio jacks. This higher level is overdriving the sound card on my PC (SB live 5.1) causing the clipping to occur inside the PC.

Lordsmurf, not that I don't believe you, but can you (or anyone else with a JVC 9xxx series) confirm again that the "record level" menu adjustment various the audio out from the rear panel during tape playback, as well as audio passthrough and recording. Any other menu controls that might cause mine not to vary the playback volume?

Thanks,