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Vintage Television and Video Vintage television and video equipment, programmes, VCRs etc.

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Old 4th Feb 2018, 9:56 pm   #1
dj_fivos_sak
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Default Panasonic VCRs and brake bands...

Hi guys. I recently acquired a National NV-390 VCR which internally seems to be exactly the same as the NV-333 but it's front loading and multi system (You guessed it, it's one of those bizzare-looking, Middle East market models with NTSC 4.43). The problem is, as all of these old Panasonics, the back-tension pad came off the band. I tried to glue it using super glue and it seemed to work (As in the picture). But now, it seems there's excessive tension and the tape barely moves and the playback speed is extremely slow especially when the tape is past the middle of it. Would a worn pinch roller cause tape slippage? The capstan belt is definitely not the problem as I checked that. I appreciate any help.

Fivos
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Old 4th Feb 2018, 10:18 pm   #2
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Default Re: Panasonic VCRs and brake bands...

I very much doubt a p/roller would cause your problem.Check the idler tyre and not excess back tension.I was not to lucky gluing those bands.
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Old 4th Feb 2018, 10:26 pm   #3
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Default Re: Panasonic VCRs and brake bands...

I doubt it's the idler. FF and REW works pretty good and the tape doesn't go slack in play mode. As you can see, it has a separate idler for FF/REW and play. I probably need this:
http://www.donberg.ie/catalogue/vide...s/23103-g.html
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Old 4th Feb 2018, 10:41 pm   #4
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Default Re: Panasonic VCRs and brake bands...

Superglue is not very good for sticking the backtension band back on with, it tends to soak into the felt going hard and very rough causing excessive backtension, a better glue is something thicker and more flexible like a contact adhesive (Evostik impact in the UK).

This ^^^ adhesive worked ok on the earlier type bands that were copper coloured metal but could not be used on the later clear plastic type (they melt with that type of glue).

Back in the day we only glued them back on if we did not have the required band in stock, and even then it was only to check out the rest of the machine for any further problems before quoting the final repair bill, the band was ultimately replaced for new in any event should the estimate be accepted.

We often required the full maintenance kit for the (Panasonic) Machine in question to be fitted anyway for a reliable paid for guaranteed repair.

The above still stands though RE: type of glue used even if the repair is for yourself.
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Old 4th Feb 2018, 10:59 pm   #5
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Default Re: Panasonic VCRs and brake bands...

Check the condition of the pinch roller. Take it out of the machine to get a good look.
There is a thread here from a couple of years ago where I revived an ancient panny front loader. The pinch roller on it was pitted and shiny, causing bad wow and slurring, and replacing it was the cure.
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Old 4th Feb 2018, 11:34 pm   #6
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Default Re: Panasonic VCRs and brake bands...

Well, that pinch roller looks like it's shot. What do you think?
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Old 5th Feb 2018, 12:47 am   #7
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Default Re: Panasonic VCRs and brake bands...

That's even worse than the one I mentioned before. It's definitely past it!
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Old 5th Feb 2018, 1:00 am   #8
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Default Re: Panasonic VCRs and brake bands...

Yeah. I'm amazed it didn't ruin my tapes. Surprizingly, the belts on the bottom look OK. Btw, is that called the "A" mechanism/chassis? It looks very similar to my NV-7500 but that one has a direct drive capstan motor whereas the NV-333/390 is belt-driven. This particular 390 is dated December 1982.
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Old 5th Feb 2018, 11:11 am   #9
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Default Re: Panasonic VCRs and brake bands...

I'd echo R2B's comments. Evo-Stik or Bostik's contact adhesive is the one to use - sparingly. Superglue tends to make the band harden. We used to replace the bands with the newer type along with all the other items in the excellent Panasonic maintenance kit, but sometimes had to use glue, especially when money was a problem for the customer.
Replace that horrible roller, then concentrate on getting the tension to around 25g-cm. If you don't have a gauge, slacken the band off until it's free, then gradually increase the tension till picture search is just acceptable. After all, you don't want to put too much strain on the heads. The drum may also need a polish by now.
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Old 5th Feb 2018, 11:13 am   #10
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Default Re: Panasonic VCRs and brake bands...

P/roller is certainly lined up for tape damage,fit the repair kit they are excellent.
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Old 5th Feb 2018, 12:52 pm   #11
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Default Re: Panasonic VCRs and brake bands...

We used to glue the pads back all the time without any problems.

But we used a contact adhesive to do it.

Sounds like you will need to replace the brake band and readjust the tension.
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Old 5th Feb 2018, 1:46 pm   #12
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Default Re: Panasonic VCRs and brake bands...

Thank you all! Yeah, I think the super glue I used has harden the band. The pinch roller has definitely seen better days. Is there any way to make the band soft again?
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Old 5th Feb 2018, 1:53 pm   #13
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Default Re: Panasonic VCRs and brake bands...

Quote:
Originally Posted by Terry_VK5TM View Post
We used to glue the pads back all the time without any problems.

But we used a contact adhesive to do it.

Sounds like you will need to replace the brake band and readjust the tension.
How is back tension adjusted? I only ever found a three position slot for the spring, but all gave too high tension. The screw in the tension band holder is for adjusting the tape tension guide pole position and did not seemingly change the actual tension.
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Old 5th Feb 2018, 2:50 pm   #14
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Default Re: Panasonic VCRs and brake bands...

This could be the Lower Head Drum that needs polishing,that will certainly upset things.
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Old 5th Feb 2018, 3:22 pm   #15
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Default Re: Panasonic VCRs and brake bands...

Quote:
Originally Posted by IanNVJ35 View Post
How is back tension adjusted? I only ever found a three position slot for the spring, but all gave too high tension. The screw in the tension band holder is for adjusting the tape tension guide pole position and did not seemingly change the actual tension.
That's how it's done according to my manual.
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Old 5th Feb 2018, 3:54 pm   #16
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Default Re: Panasonic VCRs and brake bands...

Like others have said i would suspect the lower drum, i never found polishing worked very well but perhaps i was doing it wrong ( Duraglit)

when playing feel the tape tension either side of the drum with a finger if much slacker at the supply side then it's probably the drum
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Old 5th Feb 2018, 4:03 pm   #17
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Default Re: Panasonic VCRs and brake bands...

I've experienced drum friction problems with old Sanyo Betamax machines but not with any VHS. The reason is because Beta leaves the tape threaded during FF/REW modes and that causes the drum to wear faster. What do you use to polish the drum?

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Old 5th Mar 2018, 10:46 pm   #18
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Default Re: Panasonic VCRs and brake bands...

Hey guys. Just a quick update. I took some parts out of a fubar NV-G10, including the back-tension band. I had to take apart the actual band from the plastic holders because the D chassis of the NV-G10 is different from the one of the NV-390 (I think it's the A chassis). Then I installed the new band in and now it's playing fine. So I would say this was successful. I will buy the service kit though because I also need a new pinch roller and the one the G10 uses doesn't fit. As "Red to black" said, the newer style is made of a clear plastic band rather than copper as it was on the older style.

Fivos
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