Head relapping
Why relap?
Almost all magnetic heads are designed around specification stressed by the original equipment manufacturer (OEM). Because of the intricate role magnetic heads play in the overall operation and quality of a tape recorder, optimum performance must be achieved in manufacture and maintained in the field. The very nature of the tape transporting process involves wear in one form or another. During this process, an abrasive, flexible material (magnetic tape) is pulled across a relatively soft or an extremely hard and brittle non-moving material (magnetic head) with sufficient wrap and tension to insure intimate continuous contact. The inevitable result is...wear!

As a magnetic head wears in normal operation, certain conditions and minor problems develop which indicate a gradual deterioration in performance. These indications include:

  • Slight loss of high frequency response
  • Signal amplitude instability
  • Overall loss of level
  • Unstable tracking and tape path
  • Distorted signal
  • Excessive oxide build-up

Generally these symptoms can be attributed to an uneven change in contour due to wear, or in the case of ferrite, gap deterioration caused by material erosion. The change in performance is usually very slight; it can be normally compensated for by adjusting record or playback equalization and mechanical head alignment. As the wearing continues, however, a point is reached in which the acceptable performance can not be achieved by compensation or adjustment. Our studies show that in most cases, less that 50% of the depth of the gap has worn at this stage. As a result, proper relapping will restore an unserviceable magnetic head to its original performance specifications.

Proper relapping procedure insuring optimum performance

If you'd like to learn more about heads and head wear, we suggest that you read the illustrated articles "Taking a Head Trip" and "Tape Heads: An Introduction", each of which will open in a new window when you click on these hyperlinks.

JRF is proud to offer a completely equipped and staffed relapping facility including a laboratory dedicated to providing fast, complete and professional servicing of most audio magnetic heads used by:

  • Recording Studios
  • Tape Duplicating Systems
  • Mastering Laboratories
  • Commercial Broadcasters
  • Equipment Manufacturers
  • Servicing Organizations
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JRF's relapping program
Every magnetic head receives a complete optical and electrical inspection prior to relapping. This includes:
  • Gap Condition (Optical Comparitor-50x/or Microscope up to 1000x)
  • Depth of Wear (Optical Comparitor)
  • Inductance (Digital Bridge/All tracks)
  • D.C. Resistance/All Tracks
Microscope Guy
Upon successful completion of laboratory inspection, all heads receive our precision relapping and polishing process. Ferrite heads are ultra high polished by utilizing the latest in diamond compounds and vapor spraying technology.

The JRF relapping procedure is designed to insure the absolute maximum life from a recontoured magnetic head. This is made possible by removing only the material at the gap to the point of its deepest wear or erosion.

Relapping a head
After relapping, all heads undergo a final inspection consisting of:
  • Complete Optical Inspection (up to 1000x)
  • Inductance (all tracks)
  • Mounting, Wiring and Optical Alignment (optional)

A JRF Lab Report is now completed documenting optical, electrical, and final inspection procedures. A copy of this report is enclosed with the completed order.

Note: Any magnetic head failing any portion of our program (including final inspection after relapping) will be documented in the lab report. It will be returned to the customer at no charge.

John at comparator
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