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Old 6th Oct 2016, 6:04 pm   #1
Vauxfan2k
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Default Panasonic NV-L25

Working on this machine at the moment which is my first and possibly last Panasonic machine depending on how this goes.

The machine plays fine but when trying to rewind/fast forward, the clutch (I assume this is what it is) at the base of the capstan motor which drives the only belt (toothed with adjustable tensioner) slips and the tape winds really slowly.

Playback is ok, but at first the machine was sluggish to take in all the tape upon pressing eject. This has since sorted itself with a biit of exercise. The tape would get snagged round the guide pins.

Another unusual but possibly normal trait for this machine is that it keeps the tape in contact with the sound head at all times, which I thought would cause drag when rew/ff the tape?

It disengages when the tape ejects.

It's meant to be a "super 4 head" machine as per front screen. But I count only 2 heads!!

Did Panasonic think we were stupid?

Any thoughts?
Thanks

Steve
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Old 6th Oct 2016, 6:25 pm   #2
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Default Re: Panasonic NV-L25

Hi Steve,

Tape kept against the audio head all the time is for the index search function, which will stop the machine at the beginning of each new recording when in either rewind or fast forward. Very handy.

Look very closely at the head tips, you may find that there are actually two right next to each other, in the same "hole" as at were.

Mark.
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Old 6th Oct 2016, 6:28 pm   #3
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Default Re: Panasonic NV-L25

here is some of the spec
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Old 6th Oct 2016, 8:41 pm   #4
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Default Re: Panasonic NV-L25

I have tensioned the belt with the adjuster (handy it has one)

Everything except fast forward works as it should. It will fast forward a tape about 2/3rds then the clutch will start slipping.

Is this part replaceable? Or part of the capstan motor itself.

Thanks
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Old 6th Oct 2016, 8:56 pm   #5
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Default Re: Panasonic NV-L25

Clutch slippage could be mechanical in nature (surfaces dirty or gone shiny) or it could be a sign that the transistor driving the clutch has gone low-gain. If the latter is the case, it will be getting warm.
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Old 6th Oct 2016, 11:44 pm   #6
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Default Re: Panasonic NV-L25

Just a few comments. If the belt is slipping the tensioner needs to be replaced - the centre spindle wears and so the belt becomes loose. Check for side to side play with the belt off the pulley. I don't think there is a clutch at the bottom of the capstan - just looks like it. Sluggish tape retraction is caused by gummy lube on the half load arm - it needs removing, the old grease cleaning and new grease fitting. If you flick it with your finger it should snap back - if slow then the grease has gone hard. It is a four head machine - look at the top of the head and you will see four sets of contacts to the rotary transformer. Second set of heads for LP and clean pause.
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Old 6th Oct 2016, 11:58 pm   #7
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Default Re: Panasonic NV-L25

Hey,

The tensioner is tight now with room to tighten further, I treated the belt with rubber renue to prolong it. The slippage is definitely coming from the black spindle in the middle of the motor/gear though.

I will try and get a video of it happening tomorrow.

The tape is retracting fine now, wouldn't say the picture quality is anything to write home about, and the pause has noise bars across the screen even when the frame is advanced.

Cheers
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Old 7th Oct 2016, 9:18 am   #8
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Default Re: Panasonic NV-L25

If you can share a photo of what is slipping I may even have one spare to send you FOC.

As far as I know it is a toothed belt so should not slip by design - unless someone has replaced it with plain rubber. I have never seen a toothed belt slip - usually they outlast the machine!

If the picture is not that great, it may just be the tape. On some pre-recorded tapes you can never get a perfect pause, however by advancing frame by frame (may have a 'slow' button on the remote) you can use the tracking to get the best image. These decks should have 'good to very good' image quality, but tired capacitors in the PSU can cause excess blue shimmering noise in the picture. Also if the heads are worn the picture will be a bit softer.

Its worth fixing I think, if you can be bothered.
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Old 7th Oct 2016, 9:44 am   #9
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Default Re: Panasonic NV-L25

"Pause" normally works best on 4 head machines
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Old 7th Oct 2016, 11:02 am   #10
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Default Re: Panasonic NV-L25

Hi,

The belt isn't slipping and it's still the original toothed belt. The capstan motor turns fairly quickly with the black clutch turning at the same speed, however the pulley that the belt wraps round turns slowly. This only happens 2/3rds of the way into a tape (any tape)

The pre recorded tape in using is very good, the older machines like the 3v30 and the fisher machines have almost DVD quality picture and pause with it.

I tried a new unused pre recorded tape on this Panasonic and it was the same, it's almost as if the sharpness is turned all the way down and there is a lack of vibrancy in the colours compared to the other machines.

Will get a pic of the clutch tonight when I get home.

Cheers
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Old 7th Oct 2016, 10:51 pm   #11
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Default Re: Panasonic NV-L25

On 3- and 4-head machines, you count the heads by the connections or by the screws with which they are mounted on the drum, since they are grouped together.
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Old 9th Oct 2016, 4:01 pm   #12
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Default Re: Panasonic NV-L25

Managed to get a vid done of what's happening, although I had to move the motor manually as it was spinning too quick for the camera to pick up.

The slip as you can see is what's causing the sluggish rew/ff.

It's pretty easy to turn the motor while holding the belt still, should have thought there should be more resistance than this?

https://youtu.be/Mh5blI5PozQ
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Old 9th Oct 2016, 11:28 pm   #13
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Default Re: Panasonic NV-L25

That is not supposed to do that so that collar is slipping -It's not a clutch.
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Old 10th Oct 2016, 12:16 am   #14
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Default Re: Panasonic NV-L25

Check the two felt brakes around the reels. If they wear down sufficiently they can end up becoming stuck and permanently engaged to the supply/ take-up reels. You can often save them by gluing new bits of felt over the old.

If you wish to observe/ cycle through the mechanism by hand, you can do so by flicking the little solenoid switch and then turning the plastic flywheel (see pic). When it pings back up, press it again to go on to the next mode.

Just make sure you have a tape inserted/ dummy load beforehand, or know how to defeat the tape carriage switches. The tape carriage will not lower, otherwise. Also be careful not to exert too much force. Gently does it!
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Old 10th Oct 2016, 9:13 am   #15
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Default Re: Panasonic NV-L25

The machine is working fine apart from the collar slipping, I'm guessing il need to undo the clip and take it off the motor to see what's going on. The felt pads are fine.

Cheers
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Old 16th Oct 2016, 8:15 pm   #16
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Default Re: Panasonic NV-L25

Managed to get this machine to behave itself now.

I think lack of use for a few years had caused the grease to harden up making the mechanism sticky.

The picture has improved altho this video is of a recording not a pre recorded tape.

Not sure if this machine is ntsc compatible but it will play at normal speed but the picture is black and white. Sound is fine.

https://youtu.be/7yk18dceUNY
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