[QuadList] was Saturday Quad Matinee feature..now magnetic scratches

[chill315 at aol.com]

I found the problem was more prevalent on the Ampex machines than the RCA machines.  We would demagnetize the decks at least 25 hours as part of our normal maintenance.

Chris Hill

On Nov 19, 2012, at 12:55 PM, Guy Spiller <quadruplex at verizon.net> wrote:

> 
> My experience was that the front side master erase head also contributed to this magnetic scratching problem.  It would develop little pits in which the magnetized tape particles would embed themselves with the same sad results.
> If I remember correctly, the service manual recommends cleaning those tiny holes out with a small wire from time to time.  Always seemed a little "iffy" to me to do, but I guess a thin soft copper wire wasn't going to scratch whatever hard metal that post was made out of.
> The elimination of the air guide post with a roller guide, a la Ampex,  and back-side master erase head on the 70C sure seems to help that issue...at least from what I've observed since having them.
> Guy
> 
> On 11/18/2012 12:33 PM, J. Mitch Hopper wrote:
>> 
>> That's exactly what they were!
>> Worked with TR60/61/70a,b - all had the same trouble!
>> I used a small vacuum cleaner with a small rubber snout to suck out the holes.  The only trouble was having a good master ruined to be the signal that it was time to get out the hoover! ha ha
>> 
>> 
>> J. Mitch Hopper
>> Custom Video Systems Co.
>> Rochester, IL
>> 217-498-8438
>> id at brainmist.com
>> 
>> It's been lovely but I have to scream now.
>> 
>> ----- Original Message ----- From: <bill.spencer at northstarstudios.tv>
>> To: <Steve.White at 800CallNow.com>; <quadlist at quadvideotapegroup.com>
>> Sent: Sunday, November 18, 2012 9:37 AM
>> Subject: Re: [QuadList] Saturday Quad Matinee feature--KCOP, 13,Los Angeles--1979 Rose Parade remote truck "Behind the Scenes" withDavid Crosthwait
>> 
>> 
>>> 
>>> Steve,
>>> 
>>> Those are 'magnetic' scratches.  They were more prevalent on RCA
>>> machines because of a guide that had little holes in it with air blowing
>>> through them to keep the tape from sticking.  Usually that guide got the
>>> holes filled with magnetized debris that shed from the tapes and it was
>>> enough concentrated magnetism to erase small portions of the record
>>> passing by.  They stay in the same place because a small line of
>>> magnetism gets segmented by the quad heads rotation and shows up as a
>>> pattern diagonally from top left to bottom right.  At least this is what
>>> someone told me about 50 years ago!
>>> 
>>> Bill Spencer
>>> RF Engineering Supervisor
>>> 
>>> 3201 Dickerson Pike
>>> Nashville, TN 37207
>>> Phone: 615-650-6000 x6610
>>> Cell: 615-445-5616
>>> Web Site: www.NorthStarStudios.TV
>>> 
> 
> 
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