Warpage Repair

 

 

One problem often plaguing old reel-to-reel magnetic tapes is tape warpage, which is one cause of tape dropout.  Tape dropout is observed as a periodic loss of signal, especially in the high frequency portion of the audio spectrum.  You can easily note if warpage is the source of the problem by observing the tape as it glides over the playback deck tape guides.  If the tape moves evenly over the guides, then the source of the dropout may be lost magnetic coating.  However, if the tape moves unevenly (wobbles) across the tape guides, the probable cause of the audio dropouts is tape warpage.  The reason for the dropout is that the magnetic tape surface does not maintain good physical contact across the playback head thereby lengthening the magnetic coupling pathway (and increasing the magnetic reluctance) of the system. There are two solutions for curing this problem at the transfer stage of your project.  If you have an old cheap tape recorder that used pressure pads, it will do a better job of transferring such a tape compared to a pro-machine which does not employ pressure pads.  But, if all you have is a professional / high-grade machine, you can create your own homegrown pressure pad for the transfer.  Follow these steps:

 

Remove the Tape Head Cover / Shield
Thread the tape through the tape path as you normally would do
Identify the play head (it will be the last head (right-most) in the tape pathway)
Obtain a small cotton ball and create a piece about inch square.
Cut a piece of Duct Tape to a dimension of about 2 x inches.
Affix the cotton ball to the center of a piece of duct tape
Wrap the tape with the cotton over the top of the head and down to the chassis of the machine, locating the cotton ball directly over the tape and the tape head. 
You may have to experiment a little to obtain the proper tension for a clean playback, but this will dramatically reduce the dropouts of your old tape.
Replace the Tape Head Cover / Shield to minimize hum pickup during the transfer.
You will have to remove the tape and cotton ball and repeat this process after each tape side that is transferred in this manner.