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-   -   Panasonic K-Mech: FF/REW scratch, then error F03? (http://www.digitalfaq.com/forum/vcr-repair/10936-panasonic-mech-ff.html)

promoter_2000 08-28-2020 06:52 AM

Panasonic K-Mech: FF/REW scratch, then error F03?
 
Hello.
I have a strange problem with the K mechanics of my Panasonic NV HS950. The vtr works perfectly in everything, except in FF / REW. When I send the tape in fast rewind / rewind (not in cue) the tape initially run slowly(as it should) but when the pinch roller detaches from the capstan, to increase the speed, the mechanics begin to scratch and immediately afterwards the appliance goes into protection F03. To get out of this block, I have to turn off the device (go to stand by), turn it back on (the mechanism starts scratching again) and immediately afterwards press the "eject" button: at this point the mechanism stops scratching and ejects the cassette correctly, the display returns to normal and if I reinsert the tape it plays regularly. Basically the vtr works in everything, except for the fast winding / rewinding (except the first seconds, at reduced speed, with the pinch roller still in contact with the capstan). I have already cleaned the mode switch (including the external contacts) and changed the whorm gear under the loading motor (I put a new one even if the old one was perfectly intact) but it didn't help. I have also replaced the center clutch and the link belt but without success. I checked all the teeth on the wheels, under the supply and take up plates and the idler, but they are all intact. The brakes and the felt band are also intact. I do not know what to do. Where could the problem be and how could I go about solving it (apart from rewind / rewind tapes with a second VCR)? Thank you all.

dpalomaki 08-28-2020 09:30 AM

FWIW: The followingn are for the F03 indication from the AG-1980P (K-Mechanism)service
manual.

Cause: Mechanism locks during more transition, except Eject mode.

Remedy/checks:
1. Check the loading motor drive circuit
2. Check the mechanism phase alignment
3. Check the mode switch.

Perhaps a gear has slipped a cog to put the phase off slightly?

promoter_2000 08-28-2020 10:29 AM

I honestly don't know what to think ... I cleaned and re-lubricated the mode switch just this morning ... I checked the loading motor and the internal pin is intact (the loading and unloading of the tape is smooth). Do the fast foreward / rewind functions also depend on the loading motor?

dpalomaki 08-28-2020 07:52 PM

A failure in the loading motor system would probably cause a malfunction in the loading and unloading of a tape. It wouldn't load to play or might not eject.

Have you verified the phase adjustments ads described in the K mechanism Service Manual?
Did you check to make sure all contacts in the switch are good and making contact at each position?

promoter_2000 08-28-2020 11:29 PM

I tried to change the switch mode to another one, removed from a working machine, and the problem remains. Until now I haven't checked the phase because I thought that if all the other functions were running smoothly the damage was from elsewhere. But now, I too believe there is a corrupt alignment.

dpalomaki 08-29-2020 09:32 AM

Also check the circuits/wires that connect the position switch to IC6001, and the signals in/out of IC6003.

Does Cue/Review playback work?

Quasipal 08-29-2020 06:25 PM

Sounds like the clutch is slipping. It's held together with the same plastic that the infamous coupling gear is made from. A common symptom is loops of tape when you go into visual rewind while playing.

Bogilein 08-29-2020 06:45 PM

I think this part is broken:

https://www.cdlens.com/?item=20407

promoter_2000 08-30-2020 04:53 AM

Quote:

Originally Posted by dpalomaki (Post 71072)
Also check the circuits/wires that connect the position switch to IC6001, and the signals in/out of IC6003.

Does Cue/Review playback work?

Yes, work without problems.

promoter_2000 08-30-2020 04:56 AM

Quote:

Originally Posted by Bogilein (Post 71087)
I think this part is broken:

https://www.cdlens.com/?item=20407

No (unfortunately): I have already checked the loading motor and that piece is intact (in fact the tape loads and unloads regularly).

promoter_2000 08-30-2020 05:01 AM

Quote:

Originally Posted by Quasipal (Post 71086)
Sounds like the clutch is slipping. It's held together with the same plastic that the infamous coupling gear is made from. A common symptom is loops of tape when you go into visual rewind while playing.

I also thought about the center clutch (VXP1409) and I also changed it with another one but ... the problem has not been solved.

Quasipal 08-30-2020 08:53 AM

Quote:

Originally Posted by promoter_2000 (Post 71102)
I also thought about the center clutch (VXP1409) and I also changed it with another one but ... the problem has not been solved.

Was it a known good one? Just I am seeing multiple failure of this item.

Few other things...

Check capstan is free to move. They can seize up for some reason.
Make sure slider under the mech is undamaged and the grease not gone gluey.
Make sure roller is free on the shaft it slides up. They can stick.

promoter_2000 09-22-2020 07:30 AM

Problem solved! For the sake of consideration, I changed the VDP1434 pawl on the loading motor shaft and everything started working again.

Strange because the pawl I removed seems perfectly intact.

Having completely recovered the mechanics, however, I found another problem (I hope the last one): playing the tape you can hear the stereo sound perfectly but only white sleet appears in the video; even when recording a new tape, sleet appears (but if I use another vcr I see the recording). I have already tried to change the RF amplifier, power supply and head drum (all of which are definitely working because they were removed from other working machines) and the problem persists. Since in the passband (connecting a camcorder to the AV3 front input) both video and audio pass regularly, I am led to believe that the defect is on the YC PACK card (the one planted on the main board through 3 comb connectors and equipped with a metal shield) located on the rear of the chassis, just next to the power outlet. Do you think I'm wrong?


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