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-   -   JVC HR-S8000U Won't Rewind (http://www.videokarma.org/showthread.php?t=276909)

redk9258 10-07-2024 04:32 PM

NO do not remove the stuff from the top. Remove any plugs , wires etc. Remove the loading mechanism.. should be a couple of screws. Now you should see 3 or 4 screws holding the whole mechanism to the plastic frame. These should be pretty large screws. Now lift the whole mechanism out and flip it over carefully on a towel or something soft. Now you can get to the mode switch and mode belt.
The SM that I downloaded is missing parts of the exploded views. I'm guessing yours is the same.
Try this manual. I believe the mechanism is the same as yours....
https://freeservicemanuals.info/en/s...950E/HRD950EG/

redk9258 10-07-2024 07:57 PM

This video might be helpful to watch. Your mechanism is different but you can get the idea of how to remove the mechanism.
https://youtu.be/0bbJ-7tXMf8?si=ogz4QHSyXqxTSi_S

olePigeon 10-08-2024 10:29 AM

Quote:

Originally Posted by redk9258 (Post 3260340)
NO do not remove the stuff from the top. Remove any plugs , wires etc. Remove the loading mechanism.. should be a couple of screws. Now you should see 3 or 4 screws holding the whole mechanism to the plastic frame. These should be pretty large screws. Now lift the whole mechanism out and flip it over carefully on a towel or something soft. Now you can get to the mode switch and mode belt.
The SM that I downloaded is missing parts of the exploded views. I'm guessing yours is the same.
Try this manual. I believe the mechanism is the same as yours....
https://freeservicemanuals.info/en/s...950E/HRD950EG/

Yes, mine is missing the mechanism sheet. I could extract these pages and make a complete manual. It even has the cable I couldn't figure out how to disconnect, which was also covered by 12voltVid's video. Very helpful. I watched a lot of his videos before posting here trying to find an analogous VCR troubleshooting video that would help. I was tempted to send my VCR to him for repair, but the shipping would be cost prohibitive.

Unfortunately I still don't see how to access the mode switch without removing the entire mode assembly, which is interconnected with the A/C head assembly. That's what is stumping me. However, once I have the whole thing out, maybe it'll become more clear and easy. I'll also be able to take better pictures.

Thank you everyone for the help! It's been invaluable.

olePigeon 10-08-2024 10:43 AM

Well, here's a 12voltvids with a professional VCR with the same mechanism, with exactly the same issue I'm having. Even he thought it might have been the sensor at first, which was my initial conclusion. Such a weird issue.

https://www.youtube.com/watch?v=__PFQlKia68

Unfortunately it doesn't look like he did a Part 2. Or at least I can't find it.

redk9258 10-08-2024 03:41 PM

When you remove the mechanism, turn it over and you will have to remove a couple of items to access the mode switch. You may have to unsolder a PCB or remove the plate that holds the cam gear. I think it will be more apparent with the mechanism out. You will not need to mess with any heads or alignments. The gear timing is critical but should be obvious with it in front of you and the pictures from the SM.

olePigeon 10-14-2024 11:19 AM

1 Attachment(s)
OK, fully extracted. The mode switch (highlighted in purple) is beneath the motor & board highlighted in orange, which is interconnected with the mode switch motor assembly to the right.

As I suspected, this is looking like I'm going to have to completely disassemble it both for replacing the witch motor belt and cleaning the mode switch itself. This will, I would assume, require a full calibration, which I am completely unequipped to do. :worried:

Attachment 206903

redk9258 10-14-2024 03:30 PM

Pictures are not showing. You should not have to make any adjustments or calibrations.

redk9258 10-14-2024 03:41 PM

Here is a picture of the mechanism..
https://web.archive.org/web/20201126...com/mbk-42.htm

You do not have to disassemble anything needing re-calibration.
You may have to unsolder a couple of wires and maybe drop the capstan motor down to get clearance to get at the mode switch. It may be possible to get deoxit in the switch without disassembly. If you take the cam plate off - or whatever it's called, make sure you understand the timing marks. They are critical for reassembly. Also pay particular attention to where each screw comes from. They must go back in the same place!

redk9258 10-14-2024 03:48 PM

I just repaired another HR-D470U with a similar mechanism. Someone was in there before and it was making a horrible clicking sound and couldn't go through the different modes. One screw was in the wrong place causing the mechanism not to be able to cycle all the way through. I put it back the correct way, replaced an idler tire, 2 caps in the power supply and it works.

olePigeon 10-15-2024 10:07 AM

OK, then. I'll start dismantling it and taking lots of pictures along the way.

olePigeon 10-18-2024 10:46 AM

OK, it was easier than I thought. The main issue I had with extracting the boards was resolved by removing 3 screws to the big motor. It then lifts out and lets me unhook the mode assembly.

Unfortunately I don't know if my old problem was resolved because it now has a new problem: when I power it on, the mode control motor goes into reverse indefinitely until it hits the end of the gear track, then goes for a bit longer until the failsafe engages and the VCR powers itself off.

This did happen to me once before, but it was only because I had forgotten to plug back in the circuit board connected to the tape chassis. This time, however, it's doing it regardless.

I'm confident I have the V lined up on the mode switch, and I'm confident I have all the holes lined up for the gears on the mode assembly before attaching.

redk9258 10-18-2024 05:25 PM

Were you able to open the mode switch and clean it?
Is there a bad solder connection on one of those circuit boards?
Are all connectors plugged in correctly?
Mode belt not slipping?
It must not think it is home if it keeps running then times out.
Are you sure every timing mark is lined up?
With the power off, can you run it through a complete cycle manually? This takes a lot of turns. My model has a spot where you can use a screwdriver to do this even though it's not documented... there's a hole punched in the mechanism chassis for access.

redk9258 10-18-2024 05:27 PM

Where are you located?

redk9258 10-18-2024 05:39 PM

I watched the video from the first post again. When it's changing modes, I think I hear a little squeal. I'd check to see if that mode belt has enough traction to go through the cycles. You might get by cleaning it with acetone. Clean the pulleys grooves with alcohol.

olePigeon 10-19-2024 01:09 AM

I may or may not have soldered the mode motor in reverse. :stupid:

(OK, maybe I did.)

Phew. OK. After all of that, I'm back to where I started. It still won't rewind. :sigh:


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