JVC HR-S8000U Won't Rewind

[olePigeon]

Hello, I'm new to the forums.

I'm having issues with my JVC HR-S8000U. It won't reliably rewind. Usually it just attempts to rewind, then stops. Sometimes it'll rewind for a little bit, then stop. And on very rare occasions it'll rewind normally.

Play & Fast Forward work fine. Play used to not work reliably, but I loosened the tension belt a tiny bit, and now the Play seems to work fine.

Below is a video I made so you can see the issue. You can see I attempt to rewind several times, but it doesn't work. Fast Forward is fine. Play is fine. When I was attempting to troubleshoot it, I thought I had it reliably working by covering the Supply Sensor. But the next day when I went back to continue trouble shooting, even covering the Supply Sensor didn't help much.

I'm hoping someone else has run into this issue and might have some advice.

The chassis board that has the supply sensor is getting 12.5v (a little high, supposed to be 12v), but the Phototransistor is getting 5v on the dot like it should. I recapped the power supply because it had a bad cap. I also removed all the glue and adhesive pads from the various PCBs. The rewind issue has persisted.

https://youtu.be/KzowZIwONzU

Thanks for any help.

[Doug]

The end sensors need covered as it's exposed to light without the enclosure
There should be reel sensors under each reel.
Check the pulse on those.
Usually under the reels is a reflector with black stripes.sometimes
The black comes off or the reflector is dirty
If you clean just use water.
The optical sensor it uses may be weak also

[redk9258]

Is the mode switch clean?

[olePigeon]

Originally Posted by Doug

The end sensors need covered as it's exposed to light without the enclosure
There should be reel sensors under each reel.
Check the pulse on those.
Usually under the reels is a reflector with black stripes.sometimes
The black comes off or the reflector is dirty
If you clean just use water.
The optical sensor it uses may be weak also

Yeah, I had the end sensor covered. If it's not, the VCR will fast forward indefinitely looking for the beginning of the tape and won't let you change modes.

I remember the black stripes on my RCA. I don't recall seeing any when I removed the reels to oil the bearings. I'll take another look. Thank you.

Originally Posted by redk9258

Is the mode switch clean?

Oooh, I forgot about this. I read that it's a common point of failure for a lot of VCRs. That would make sense if it's all crusty and not engaging correctly. I hope it's not buried inside. The only way to get to the lower functions of this particular model is complete and utter disassembly.

[redk9258]

I'm not familiar with your model but it was built shortly after my HR-D470U. The mechanism looks similar but not exact. On my model the bottom panel comes off and if I remember correctly, you have to unsolder a couple of wires to gain access to the mode switch. I could be mixing this up with changing the mode belt too. LOL

[olePigeon]

Originally Posted by Doug

There should be reel sensors under each reel.
Check the pulse on those.
Usually under the reels is a reflector with black stripes.sometimes
The black comes off or the reflector is dirty

Looks like my reels have crenelations with an IR LED and photosensor on either side that reads the light as it passes.

Originally Posted by redk9258

I'm not familiar with your model but it was built shortly after my HR-D470U. The mechanism looks similar but not exact. On my model the bottom panel comes off and if I remember correctly, you have to unsolder a couple of wires to gain access to the mode switch. I could be mixing this up with changing the mode belt too. LOL

Mine is behind a plastic cage. Some of the stuff is accessible.

[olePigeon]

So, here's the back of the unit:

http://www.clickwidget.com/vcr/HRS8000U-back.jpg

And somewhere under here is the mode switch:

http://www.clickwidget.com/vcr/HRS80...haassembly.jpg

Even with the service manual, I couldn't figure out how to remove the mecha assembly. It doesn't tell you what screws to under, or in what order to disassemble things.

I removed all the screws and desoldered the board, but I couldn't figure out how to disengage it from whatever it was hung up on. I also have zero idea what the mode switch looks like.

Edit: Sorry, I can't get inline pictures to load.

[olePigeon]

It gets hung up here:

hangup2.jpg

[olePigeon]

Well, now I have to take it apart. The belt is slipping on the motor there in the lower right. I wonder if that was the reason all along.

[olePigeon]

Edit: Nevermind. Removing the mech assembly gets me nothing.

[redk9258]

The mode switch will look something like this..
https://kpcomponents.co/products/jvc...9444c846&_ss=r

I'm not saying that is the exact one for your model. Look at the SM for the part number. It may be called a slide switch.

[redk9258]

Be careful if you remove that bottom plate to change the belt. Things must be kept in time. There should be information in the service manual.

[olePigeon]

I've run into the problem that I can't get any further than I have. As mentioned above, it's stuck around something. I was able to determine it's stuck around a pin that connects to an arm. And that arm is either riveted to the mech chassis or screwed in inaccessibly from the opposite side. As far as I can tell, it would require that I completely disassemble the entire chassis just to get access to the section I need to replace the belt and gain clean the mode switch.

Unless someone else has worked on this model and can point out a different approach, I just don't see how it's even possible. I don't want to take it apart further than I have because I don't have a scope that would almost certainly be required to realign everything.

PIN.jpg

[olePigeon]

The service manual is not very detailed from a mechanical standpoint. It doesn't tell you in any great detail what to do. I assume from the order things are laid out, I disassemble the head assembly, followed by the Audio Control assembly (which is attached that arm that I can't remove.), followed by the tension band assembly, followed by the control arm assembly, followed finally by the control cam assembly. I guess? ¯\_(ツ)_/¯

And nowhere does it tell you what type of screws, in what order, or where they're even located.

If I owned a scope, the service manual would be invaluable as it shows all the waveforms for everything.

[olePigeon]

Originally Posted by redk9258

Be careful if you remove that bottom plate to change the belt. Things must be kept in time. There should be information in the service manual.

The service manual is not very detailed from a mechanical standpoint. It doesn't tell you in any great detail what to do. I assume from the order things are laid out, I disassemble the head assembly, followed by the Audio Control assembly (which is attached that arm that I can't remove.), followed by the tension band assembly, followed by the control arm assembly, followed finally by the control cam assembly. I guess? ¯\_(ツ)_/¯

And nowhere does it tell you what type of screws, in what order, or where they're even located.

If I owned a scope, the service manual would be invaluable as it shows all the waveforms for everything.