Panasonic upper drum. Excessive wear? - UK Vintage Radio Repair and Restoration Discussion Forum

dj_fivos_sak · 3rd May 2022, 4:05 am

Hello. This is a picture of the upper drum of my NV-7500 top loader. It uses a VEH0121 upper drum like all the NV-7000 series models and the SV-P100 PCM recorder. The drum was shiny last year, then I had a look recently only to find that there's surface wear where the grooves for creating the air gap are. Could this be an aftermarket drum or did original Panasonic drums wear that quickly? I don't know the history of the machine and I don't have a video head tester to check the head chips themselves.

Fivos

Welsh Anorak · 3rd May 2022, 8:43 am

That doesn't look too good. It's possible they've used poor tapes, but on nearly all older Panasonics the back tension was set too high resulting in premature head wear. Should be around 20-25 g/cm, but most we replaced heads on had it around 50 to off the scale.

greg_simons · 3rd May 2022, 11:39 am

Back tension without doubt, also check the tape collection, see if there's any duffers in there, that sort of thing used to be common through over use of the head cleaner, or held on pause for long periods....
Greg.

Heatercathodeshort · 3rd May 2022, 12:36 pm

Yes! back tension! [Best Panasonic deck was the NV370, in fact the whole machine.]
I had many later Panasonic models with back tension off the scale resulting in ruined heads. John.

Norman Raeburn · 3rd May 2022, 3:53 pm

Yes, backtension. We replaced MANY Panasonic heads under warranty. The back tension was adjusted after head replacement. Norman

its ur aerial · 3rd May 2022, 6:22 pm

As other members have stated, excessive back tension on Nat Pan VCR`s was
pretty much de rigueur, resulting in premature upper Drum wear.
Back in the day, fitting pattern replacements was usually a nice little earner

Ken, G6HZG.

dj_fivos_sak · 3rd May 2022, 7:02 pm

Thanks for your answers. I am fully aware of the excessive back-tension setting on Panasonic machines of this era and I did suspect the back-tension but I already reduced it when I got this machine 4 years ago. Perphaps the excessive use of the search (cue/review) function is a factor for this issue? I am asking this because I use cue and review on this machine very frequently and for long periods of time before returning back into play mode, for quickly scanning through the material when I preview old tapes.

Fivos

Maarten · 7th May 2022, 10:55 am

Regulation of backtension may be less accurate when using cue and review? I don't think the adjustable tension band is used when doing this.

Nickthedentist · 7th May 2022, 11:20 am

The chap who installed our first video (VT-11E) told us never to use cue or review or pause. We didn’t, and the heads outlasted the machine when was in use until digital switch off.

HamishBoxer · 7th May 2022, 12:06 pm

Worse thing to destroy heads, were Cleaning Tapes!

its ur aerial · 7th May 2022, 8:40 pm

A good and valid point.

3rd May 2022, 4:05 am	#1
dj_fivos_sak Heptode Join Date: Mar 2015 Location: Lefkada, Greece Posts: 969	Panasonic upper drum. Excessive wear? Hello. This is a picture of the upper drum of my NV-7500 top loader. It uses a VEH0121 upper drum like all the NV-7000 series models and the SV-P100 PCM recorder. The drum was shiny last year, then I had a look recently only to find that there's surface wear where the grooves for creating the air gap are. Could this be an aftermarket drum or did original Panasonic drums wear that quickly? I don't know the history of the machine and I don't have a video head tester to check the head chips themselves. Fivos Attached Thumbnails

3rd May 2022, 8:43 am	#2
Welsh Anorak Dekatron Join Date: Apr 2005 Location: North Wales, UK. Posts: 6,927	Re: Panasonic upper drum. Excessive wear? That doesn't look too good. It's possible they've used poor tapes, but on nearly all older Panasonics the back tension was set too high resulting in premature head wear. Should be around 20-25 g/cm, but most we replaced heads on had it around 50 to off the scale. __________________ Glyn www.gdelectronics.wales

3rd May 2022, 11:39 am	#3
greg_simons Octode Join Date: Jul 2004 Location: Evesham, Worcestershire, UK. Posts: 1,423	Re: Panasonic upper drum. Excessive wear? Back tension without doubt, also check the tape collection, see if there's any duffers in there, that sort of thing used to be common through over use of the head cleaner, or held on pause for long periods.... Greg. __________________ Picture, sound?, DOOR.

3rd May 2022, 12:36 pm	#4
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Panasonic upper drum. Excessive wear? Yes! back tension! [Best Panasonic deck was the NV370, in fact the whole machine.] I had many later Panasonic models with back tension off the scale resulting in ruined heads. John.

3rd May 2022, 3:53 pm	#5
Norman Raeburn Heptode Join Date: Feb 2008 Location: Leven, Fife, Scotland Posts: 823	Re: Panasonic upper drum. Excessive wear? Yes, backtension. We replaced MANY Panasonic heads under warranty. The back tension was adjusted after head replacement. Norman

3rd May 2022, 6:22 pm	#6
its ur aerial Hexode Join Date: May 2009 Location: Ryde, Isle of Wight, UK. Posts: 419	Re: Panasonic upper drum. Excessive wear? As other members have stated, excessive back tension on Nat Pan VCR`s was pretty much de rigueur, resulting in premature upper Drum wear. Back in the day, fitting pattern replacements was usually a nice little earner Ken, G6HZG. __________________ Life is not Hollywood, life is Cricklewood.

3rd May 2022, 7:02 pm	#7
dj_fivos_sak Heptode Join Date: Mar 2015 Location: Lefkada, Greece Posts: 969	Re: Panasonic upper drum. Excessive wear? Thanks for your answers. I am fully aware of the excessive back-tension setting on Panasonic machines of this era and I did suspect the back-tension but I already reduced it when I got this machine 4 years ago. Perphaps the excessive use of the search (cue/review) function is a factor for this issue? I am asking this because I use cue and review on this machine very frequently and for long periods of time before returning back into play mode, for quickly scanning through the material when I preview old tapes. Fivos

7th May 2022, 10:55 am	#8
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,203	Re: Panasonic upper drum. Excessive wear? Regulation of backtension may be less accurate when using cue and review? I don't think the adjustable tension band is used when doing this.

7th May 2022, 11:20 am	#9
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,864	Re: Panasonic upper drum. Excessive wear? The chap who installed our first video (VT-11E) told us never to use cue or review or pause. We didn’t, and the heads outlasted the machine when was in use until digital switch off.

7th May 2022, 12:06 pm	#10
HamishBoxer Dekatron Join Date: Aug 2007 Location: W.Butterwick, near Doncaster UK. Posts: 8,935	Re: Panasonic upper drum. Excessive wear? Worse thing to destroy heads, were Cleaning Tapes! __________________ G8JET BVWS Archivist and Member V.M.A.R.S

7th May 2022, 8:40 pm	#11
its ur aerial Hexode Join Date: May 2009 Location: Ryde, Isle of Wight, UK. Posts: 419	Re: Panasonic upper drum. Excessive wear? A good and valid point. __________________ Life is not Hollywood, life is Cricklewood.