Panasonic NV-HS850 tape not loading?
 

I’m having some pretty strange issues with a Panasonic NV-HS850 VCR.

First of all, I found a small broken piece of a gear inside the unit — just a tiny corner, but clearly from a plastic gear. The person I got it from told me that there’s a damaged gear somewhere on the left side of the cassette loading area, and that it “needs a bit of adjustment,” although I don’t remember exactly what he meant.

Now, the behavior is very weird:

When I insert a tape, the machine pulls it in normally and starts loading it. It actually brings the tape all the way down into the mechanism, but almost immediately after that, it ejects it again.

At the same time, the front display goes crazy — it keeps rapidly switching between states as if there is a cassette inserted and then not inserted, over and over again, like flickering constantly.

So basically:
• Tape is accepted and partially loaded
• Then immediately ejected
• Display keeps flickering between “cassette in” and “no cassette”

Given the broken gear piece I found, I assume this is a mechanical timing or loading issue, possibly a damaged mode gear.

Has anyone seen this behavior before on this model or similar Panasonic decks?

We have seen not only this :) But it is impossible to tell by distance what is your case and what gear you are talking about. Common issue is hardened grease on pinch roller shaft. Remove pinch roller assembly in accordance with SM, clean shaft (that stud assembly moves up and down) and add a few drops of sewing machine or turbine oil (not grease) on shaft. But if someone tried to "repair" it before, probably something is broken. I have seen few K mechanisms in overall mint condition but with fu*ked pinch roller mechanism, including broken gear and other plastic parts.

Welcome. :)

Photos, even videos, are generally needed to troubleshoot Panasonic decks. They're beasts.

And as per @radiokom, yes, be very wary of somebody else's botched DIY repair work. Even bad professional work (like one of my prior TGrant AG-1980s). I've seen too many ruined VCRs in the past 5 years. The pandemic gave a lot of people Dunning-Kruger, and those people have totally screwed up so many decks.

Well after some time of troubleshooting, the problem is that the vcr take in the tape and load it but the right reel didn’t move forward to move the tape. So almost in a sec unload the tape and eject the tape (no jam, nothing else bad). So in the middle I found a set of three gears that goes to the left easily when the tape loads and move the left reel but I thing that these are the same that have to change position and move the right reel also. So I guess this is the problem am I right? And if so how can I make it work? I try gently move the three gears set into the right reel and moves the reel manual but when I insert the tape the instantly the three gears set goes back to the left reel and does the same loop load tape - unload tape - eject.

Carefully inspect the clutch and the gears for cracked parts, this is common issue

Here’s a video that may help:
And also a picture of a broken piece of (gear?) or something that I find when I first open the unit.

https://youtube.com/shorts/YSxpBi5mv...iMVuFO74KSmzdZ

Plus one more video in action, any idea would be helpful am already 10 hours in a raw here :)

https://youtu.be/72AWaz05Cv8?is=BXzEiQukM4Ew7W65

I am confused. I believed NV-HS850 has K mechanism but this is Z.

Perhaps your part is from broken take-up loading gear.
Look at attached SM.

After more troubleshooting, I think I’ve finally narrowed down the issue. I found a part called the conversion lever A (the black part). When I manually push it slightly, the idler gear assembly (the three-gear set) can move much more freely toward the right reel. When I do that and push the gear assembly to the right reel, it clicks into place and the right reel starts rotating normally in both directions.But after some stress the lever or (?a locking mechanism?) unlock and pops the three gear set. Even sometimes only lock one gear from the three, and wants even some push to lock again the three gears set again.Without touching the conversion lever, the gear assembly seems to hit or interfere with the main lever when trying to move toward the right side, so it never fully engages the take-up reel. What is supposed to actuate the conversion lever A in normal operation? At the end of the video I also show a broken part, that I find inside the vcr but after a lot of research from sm it didn’t match to any gear, or something else. Maybe is the lock part that is missing? Every idea would me helpful, thanks :)

https://youtu.be/vR5vDTAabwA?is=O0TvrMBvRHNtUaYR

The first you should find from where that part is. I am not deeply familiar with Z mechanism. K is last good Panasonic mechanism. Z is crappy, Capstan motor assembly is crap (shaft simply pushed in plastic bush) and so on. Anyway you need a parts deck. I would not advise to waste time and mess with that 850 but get good Panasonic with G or K mechanism with line TBC (or JVC). Model depends on where you are. But if you still want to repair that I can look in boxes, I remember I have Z mechanisms somewhere so if you are in Europe I can find one and send you for free, only actual shipping cost. So PM if interested.