JVC SR-VS30U SP/EP mode switch rubbing sound?

[aramkolt]

Video attached with sound of a HR-VS30U that is making heavy rubbing noise at a certain point during mode switching. I am just going back and forth between regular rewind and fast forward. It is a strong rubbing sound that happens in both directions whenever the large horizontal bar plastic bar that you can see sticking out of the far left side of the mechanism as it goes past a certain point in the cycle. I’ve probably worked on 15 of these mechanisms and have never heard this. Seems too aggressive-sounding to be just lack of lubrication to me.

The actual VCR itself works fine, but that rubbing probably isn't good for longevity.

I’ll probably have to pull the deck again and try to narrow down further, just wondering if anyone else has heard this heavy rubbing sound in a JVC mechanism and if so, what it turned out to be? The mechanism is basically the same for all TBC containing JVCs other than the SR-MV series which are completely different.

JVC Heavy Rubbing Sound.MOV

[themaster1]

what about back tension ? do you manually turn the other reel ? The vcr will not like it otherwise

[NJRoadfan]

My SR-VD400US makes the same noises. Never really knew why. Doesn't seem to effect operation.

[aramkolt]

Not sure how back tension would play into the noise specifically, For the video, there's a dummy tape shell in it and the reels aren't connected (as there is no tape or even hubs on them), so there's really no tension at all. I'm alternating back and forth on rewind/ff so that the VCR doesn't have time to realize that the spools aren't connected. If I just leave it on play, ff, or rewind with the dummy tape, it'll eject on its own.

I suppose it could be a normal variant, just seems odd since every other VS30U and JVC of the same design I've worked on has not made this noise. Really seems like something very grippy (like rubber) is dragging across a smooth metal surface and making that rubbing sound. I have verified that the capstan isn't actually turning when the noise is made and that the loading motor belt is not slipping to cause that noise either.

[timtape]

Are the noises related to the absence of the hubs? Are the noises still there when the machine is fully assembled?

[aramkolt]

Yep, still there when a regular tape is there. Since it's only during mode switching, It really only does it when you switch from going from a forward direction to a reverse direction and once when it is first loaded right at the end of the loading cycle.

Still kind of debating whether it's worth pulling the mechanism out again to mess with since it functions fine and there's always a bit of risk of damaging the ribbon cable coming off the video head each time that's disconnected. I did already pull the mechanism once to clean the mode switch.

[aramkolt]

Pulled the mechanism and figured it out! The rubbing that occurs is between the grey plastic insert and the white gear shown in the picture here. The only purpose of this mechanism is to lift the front tape door, but it does still move when the door isn't moving because it is directly driven from the main cam gear. I added some lubricant between the grey and white part of the gear from the underside (circled) and it is now dead silent. This does explain why it doesn't affect operation, but it was pretty annoying to me to have to hear that whenever switching from a forward to reverse direction during playback and questioning if there was a problem with the mechanism.

Rubbing Plastic Surfaces.jpg