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  #1  
07-28-2012, 11:08 AM
Blackout Blackout is offline
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hi,

ahh, that ole chestnut. Yep. the dreaded jvc shutdown problem has inflicted my life.

The problem is that ive done many hours of searches and not found a single post where someone has fixed this problem. But it seems to affect many, many users.

my unit is a PAL JVC HR-S7600AM. One of the last good gold models with the TBC and NR etc.

VCR is in "off" mode...ie display shows four blue dashes " - - - -".

Hit power on button...VCR drops into "on" mode...display lights up...channel selection comes on...vcr stays on for approx 3 seconds...jumps back into "off" mode.

NOTE THAT THE UNIT NEVER SHOWS "AUTO". I REPEAT....THERE IS NOT "AUTO" ON THE SCREEN AT ANY TIME. The old "hold down power for 7 seconds on remote" trick does not make a difference.

alternatively...heres another scenario:

Hit on power button...unit drops into "on" mode...quickly insert VHS tape...tape drops in...you can hear head spins up, and tape is threaded ready to go. All good. Unit sits in "loaded" mode for 3 seconds...then unthreads tape, and jumps back to "off" mode..and you can hear the head spinning down to shutdown. AGAIN...IT DOES NOT DISPLAY AUTO. just does its thing and then shuts off.

so the tape is still in the VCR, but unloaded in "rest" position. I can then turn on the VCR again and quickly hit "eject" and out comes the tape just fine, then unit turns itself off again within a few seconds.

this is really frustrating. I just dont feel like its a power supply issue as it seems to perform all functions fine...for a few seconds. Doesnt seem to be a head problem as it spins up fine. Doesnt seem to be a jammed mechanism as it loads and threads and ejects tapes fine. what the hell?

it seems to me like its some kind of sensor malfunction. any help from someone who has actually had this problem and managed to fix it much appreciated.

Many thanks,
Blackout
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  #2  
07-28-2012, 12:25 PM
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i had that exact same problem with an HR-S9600U
most likely something on the mainboard - a bad cap or optical sensor
i never did get it fixed - i sold the unit for parts.
a new main PCB cost most than the unit was worth
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  #3  
07-28-2012, 01:52 PM
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There were several serious electrical storms in the area earlier this month, and lighting strikes caused issues on the local power grid, and it fried three UPS units here. When the UPS sacrificed itself, all items connected had power removed, and everything shut down. The JVC HR-S9800U in use here never would power up properly again, and is having this exact error.

Because this is an important unit, I will be getting it repaired in August. I'll reply to this post when I get this one repaired.

If you recall, all 1980P decks dropped like flies -- one by one, earlier this year -- and are still being repaired. I'll get at least one of them back in August. Hopefully two.

In the meantime, we're functioning entirely on backup decks (JVC SR-V10U units). And I'm not really thrilled. Those are good VCRs, but they have weaknesses not present in JVC 9600-9900 and AG-1980P units.

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  #4  
07-28-2012, 11:03 PM
Blackout Blackout is offline
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several posts have mentioned caps on the power supply. Im more likely to think it is an optical sensor problem like volks suggested. but if the problem happened straight after a power surge for you kp then maybe a revisit of the caps on the power supply might be the go.

ive got two of these HR-S7600AM units. so maybe i should start measuring voltages and comparing the two as the other unit is fine. its interesting that even though the model number is not as low as the 9000 series it seems to be one of the last made, with all the filters, NR, and TBC. maybe it is because its PAL or maybe they changed the model number for a few countries such as Australia. the AM models dont seem to be in other countries.

Anyways the second 7600AM is plugged into the same powerboard and does not exhibit this problem so i figured it was not a power surge problem or it would likely have affected both VCRs.

looking forward to your report kr...hopefully it will shine some light on this issue many thanks
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07-30-2012, 04:27 AM
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i really cracked with my patience tonite...and pulled open my 7600AM. i mean...completely open and upside down to get to the solder side of the motherboard. heres a few pics.

i had hoped to see some obvious dry solders in the power supply region but it doesnt look like it. no burns to the board or obvious popped caps either (when a cap goes it usually has a bump on the top metal outwards).

im going to re-touch solder some of the joints tonite, if that doesnt work after a full re-assemble then ill start on the power supply caps...replacing them one by one. my guess to start with is the big black cap....seems obvious. Big job to pull it all apart and then back together for one item at a time tho..it doesnt seem possible to run the VCR out of the case, too many other connections...


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  #6  
07-30-2012, 04:47 AM
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Bad caps can also simply be out of value, or dried up. So searching for obvious visual damage isn't always a reliable method of locating bad caps.
You have to test them one by one with a meter.

Here's a good quick 1-minute video showing removal and testing of a capacitor:



... and that's all it takes. Obviously it takes a while when the board has lots of capacitors.

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  #7  
07-30-2012, 08:22 AM
Blackout Blackout is offline
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thanks admin. yeah i have a degree in Electronics. it was 10 years ago tho hehe and i dont use it much. except for days like this. nice vid!

update : no dry solders. and ive managed to get the unit operating completely apart out of the case. so its going to be a lot faster.

it seems most ppl just replace ALL the power supply caps and then it seems they get it working. But then no-one really knows which cap it was. There are so many ppl with this same identical problem, so in the interests of mankind im going to do it one cap at a time and keep testing. i have a feeling its the same cap thats failing for all of us. hopefully i can isolate the offender. it will save me time with my second 7600AM when it fails as well which im sure will be someday soon. ill report back in the next few days as i progress
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  #8  
07-30-2012, 02:48 PM
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It would potentially save me some time and money if you're able to figure this out....

... so post your successful results, hoping you get some.

I prefer to fix errors on my own, when possible. I'm brave enough to remove a 2-3 caps and replace them, but I'm not really that skilled on removing a whole board worth, one capacitor at a time. Not to mention I don't have meters, tools, etc. At some point, it is easier to pay somebody with both tools and skills. Plus my time is so limited.

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07-31-2012, 09:45 AM
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removed and tested every single cap down the right hand side of the whole motherboard. thats all the caps in the power supply and everything surrounding....and then some more. all ok.

its not a cap issue.

its some kind of solenoid thats jammed. its a mechanical problem.

when i turn on my good 7600AM with the front power button i hear a solenoid "whirr" for a second. that sound is what is missing from the bad 7600AM. something is jammed or one of the gears not reset properly.

more investigation....

Edit: ok i have figured it out! problem solved!!!!

there are small black gears that jamm below the heads. they adjust the head angle. look at the second pic i have posted, i am pointing at them with the tip of my screwdriver. all you need to do is turn on your VCR whilst giving these black gears a roll with your finger...and they will jump to life and reset. And your VCR will stay on@!!!!!

then its a matter of dropping some grease on the gears.

my unit is now up and running but i wander if it is just a jammed gear issue long-term or rather more serious in that the solenoid that runs the gears might be worn. time will tell over the upcoming days...but this is a great result !!!! please try this with your units


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  #10  
07-31-2012, 10:50 AM
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Our unit have these symptoms:
- Can power on without tape, powers off after 3 seconds.
- Can insert tape while powered down, unit powers on, accepts tape, powers off after 3 more seconds.
- Can press eject while powered down, unit powers on, tape ejects, powers off after 3 more seconds.

This is why I'm fairly certain it's not a mechanic error, but an illegal value somewhere, in something.

Did you look at any of the JVC service manuals attached to this site yet? This issue is in the 9600U manual, with a lit of solutions and troubleshooting ideas that are simply over my head. But you may stand a chance at understanding it.

I've seen similar behavior from consumer Sharp VHS VCRs and lower end 3000/4000 JVC S-VHS decks.

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  #11  
07-31-2012, 01:38 PM
NJRoadfan NJRoadfan is offline
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Quote:
Originally Posted by Blackout View Post
Edit: ok i have figured it out! problem solved!!!!

there are small black gears that jamm below the heads. they adjust the head angle. look at the second pic i have posted, i am pointing at them with the tip of my screwdriver. all you need to do is turn on your VCR whilst giving these black gears a roll with your finger...and they will jump to life and reset. And your VCR will stay on@!!!!!

then its a matter of dropping some grease on the gears.
Sounds like the Dynamic Drum system got gummed up (that is if the PAL 7600 has it like the NTSC one does). It wouldn't explain the problem with other JVC models with the same power down problem but don't have dynamic drum. Generally an immediate power down on a VCR means some sensor isn't responding to a self test.
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  #12  
07-31-2012, 05:53 PM
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Quote:
Originally Posted by kpmedia View Post
Our unit has these symptoms:
- Can power on without tape, powers off after 3 seconds.
- Can insert tape while powered down, unit powers on, accepts tape, powers off after 3 more seconds.
- Can press eject while powered down, unit powers on, tape ejects, powers off after 3 more seconds.

This is why I'm fairly certain it's not a mechanic error, but an illegal value somewhere, in something.

Did you look at any of the JVC service manuals attached to this site yet? This issue is in the 9600U manual, with a lit of solutions and troubleshooting ideas that are simply over my head. But you may stand a chance at understanding it.

I've seen similar behavior from consumer Sharp VHS VCRs and lower end 3000/4000 JVC S-VHS decks.
man this is my exact symptoms also. and i fixed it as above. the gears siezing up send a error to the processor which says "whoah theres a problem" and it shuts the unit down. open the lid and turn it on and off. you should hear a short "whirr" as the black gears adjust. they do this for every power on. if you dont hear it and just hear a quiet" tick" or nothing at all then your unit shuts back down, head straight for these black gears and turn the unit on whilst rolling them at the same time with your finger. you only get a 3 second window to get them moving again....
.
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  #13  
07-31-2012, 07:06 PM
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There are days where I wonder if creating a forum was a good idea, because of all the time and expenses involved. It's not just all the time needed to answer questions of members -- the bulk of the time, no doubt -- but the amount of time spent on fighting spam, monitoring exploits, and thread/member moderation.

... and then there are days like today, when I know it's a good idea.

You just fixed my VCR.

I don't think I can even begin to explain how much I was not wanting to drag it cross-country, pay $100 to get it analyzed (possibly repaired), and drag it back again. Not to mention time spent (beyond what's already been spent) not having a VCR for projects.

Thank you.

I think it's a power-down problem. If the unit is not properly powered down, the gear must stay locked in some sort of position, and then possibly get stuck. There's a few more decks here with similar problems -- both S-VHS and VHS, none of which have a dynamic drum -- and I may start to fiddle with gears, as well as look for hidden ones. I'd never even noticed these small black gears before.

You assessment of the noise was spot on.

It would near-silently "tick" once when the gears were jammed. When unjammed, it makes a double buzzy "whir-whir" sound, and then locks into position. On proper power down, it may do so again, depending on the most recent activity (and whether or not a tape is still inserted).

I had my face down real close into the unit, near a window for extra light, and was trying to be gentle. I'm glad nobody was around. I probably jumped back a foot when it sprang back to life and started to make noise. So for anybody else that tries this -- be prepared.

I'll spent the rest of the night re-racking the primary now. Bye-bye SR-V10U. Back to the closet you go.

I've seen this topic on quite a few forums, newsgroups and Q&A types sites for years now. This is the first time I've seen anybody come up with an actual fix. I wonder how many "broken" JVC VCRs have been put onto eBay (or worse -- the dumpster!!) through the years? And all it took to fix was a gentle push on a semi-hidden tiny gear). Who'd a' thunk it?

I also don't remember this one being listed in the service manual.

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  #14  
07-31-2012, 08:31 PM
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If it was indeed the dynamic drum control, it might be one reason why JVC phased that feature out in later models.

Regarding service, it seems you can get these decks to spit out error codes if you have a service "jig" remote controller. Looking at the list in the manual, it likely generated an E08 or E09 error. The AG-1980 might be a pain to service, but at least anyone can get it to spit out error codes!
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08-01-2012, 06:49 AM
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Kpmedia....man...how awsome so glad i could help! a great story! i was so excited when i found the problem! amazing eh!

NJ youre probably right...it was just one more thing to go wrong inside for JVC. Maybe it was too expensive to make also thats why JVC phased it out. but it does make for nice and clean fast forward pictures

i also have seen this problem on so many forums and not a single real fix. This forum is gonna get some hits now with this fix posted just watch! It did make sense at the time for it to be a cap problem, it also felt like a cap was charging up, then dropping its charge within 3 seconds and then voltage was dipping below a threshhold and the cpu was shutting it down. that is why i spent so much time going through every cap, desoldering, testing and re-inserting. but i had to go through that process to know that it had to be something else.

For VCRs that do not have dynamic drum, the cap issue could still very much be the problem.

But i will bet for 90% of the JVC SVHS ones that the jammed black gears is the issue. And you may be right it could be a case of power loss at just the wrong time that causes it to get confused. Either way it does not hurt to grease the gears up to be sure.

i had the extra comfort of having a second identical working machine sitting next to it that i could compare against, screw for screw, gear for gear, cap for cap. so i guess it made me more confident to get my hands dirty.

Keep up the good work with the forum KP.

All the best,
Blackout
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  #16  
08-08-2012, 07:26 AM
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Johan Li Johan Li is offline
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Thank you Blackout!

My JVC HR - S9500 had the same symptom some weeks ago. I started dismantling it, but saw nothing obv. wrong.
I had searched the Internet for advice earlier but found nothing helpful, just comments from others with similar problems.
Then I found your solution.

I followed your advice and it is back in order ! Thank you ! I would not have found this one myself.

/Johan Lindeberg
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08-09-2012, 04:24 PM
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I had this exact same problem on my HR-S9500 for about 2 years. Mine initially went wrong the day after a power outage. I was in the middle of fast reverse searching when the tape froze and it powered down. Twice I managed to "fix" it by lifting the back of the unit about 2inch and dropping it.

I have trawled the net and found other similar but not identical problems but no solution. I had all but given up when I did a google search today and found this thread which describes it so well. Mine would always power up and would always correctly load a tape but would only last either 3s or 6s with the tape load. It would even eject properly.

I was eager to get home from work and hope to fix my unit. I was too eager and forgot to join the form and look at the photos so I wasted an half an hour pulling the entire board out of the case only to discover that you can't see the bottom of the heads for underneath. Doh, I should have remembered that.

When I put it back together and plugged it in there was a whir-whir and it stayed powered up !!! Success but I wish I knew what I had done.

I have now found the thin black gear just poking out from underneath the bottom of the drum so if it happens again I hope I can fix it. I will apply a little grease to be on the safe side.

Now I can go back to copying my old VHS stuff to DVD.

Many, many thanks to Blackout.
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  #18  
08-13-2012, 06:48 AM
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thanks to all for the kind words

my machine is still working. although today i was playing a tape and i put it into fast-forward shuttle for the first time since the fix, and i heard the little black gears burst into action and then some fairly serious gear-slipping crunching. So the black gears obviously tilt the head so that a FF or FR SHUTTLE picture looks stable...which is why JVC dynamic head VCRs dont have lines across the screen when you FF normally. But i think mine may be slipping, or missing some teeth, which may be why my machine went into shutdown mode last time. my machine is still ok (not shutting down) but it didnt really sound comforting.

so i think once a machine exhibits this problem you might want to relegate it to your SVHS transfer machine that only uses play and stop and normal FF or Rev. and use a cheap machine for shuttle duties (really if you want to save your heads you should be doing this anyways). I use a mono VCR i found on a nature strip! to shuttle thru old video tapes to see whats on them, and then put them into the JVC SVHS for transfer duties.

if you have hit shuttle FF since this fix and heard crunching gear problems pls post...

Cheers,
Blackout
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  #19  
08-13-2012, 10:38 AM
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The JVC went into shutdown mode a few times over the weekend, it seems to happen if I leave it in pause for more than 10-15s. I was able to fix it with a wiggle of the gears in the power-up time window so at least I can confirm that the fix also works on the HR-S9500.

It doesn't make any horrible gear noises although the machine does sound a bit clunkier than I remember. It doesn't sound like the heads just the tape handling mechanism.

I added a tiny amount of contact cleaner/lubricant to the 2 black gears twice and since the second lube it hasn't failed but I am avoiding using pause.

These tapes haven't been played in 10-15 years and occasionally it made me jump when it shutdown due to odd tape tension. It started up without any prodding.
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  #20  
08-13-2012, 10:44 AM
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i would agree not to use these good VCRs for mundane tasks - save them for capture.
i have cheaper JVC VCRs i use to see what is on tapes and rewinding etc.
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