Servicing tape machines

 

It’s a little hard to generalise on what would be included in the service of a tape recorder as all have known issues over and above any specific faults which may have developed; given that we are rarely asked to just service a machine, it usually comes to us because it has stopped working or stopped working as it should.

 

However the following sumarises the key area:-

 

The first part of any service is making sure it’s safe and replacing parts that are known weak points, suppressors, capacitors are often best replaced even if they appear satisfactory, as failure can damage other parts of the machine.    

 

Getting the machines transport working correctly; basically getting it to run tape at the correct, speed, tension and handle the tape without damaging it, this will usually involve lots of cleaning, replacing belts, brake linings, control circuit components and general mechanical or electronic set up, depending on the design of the machine. Correct tape tension and smooth running are absolutely essential with any tape based recording device from cassette deck to studio mastering 2 track.

 

The audio circuits are tested for basic operation, very few machines work as they should without a few component changes, some, especially those that have not been used for years, require full scale component change. We have, on several occasions, had to change every capacitor, preset potentiometer, and semiconductor to bring a machine back to full operation, an expensive operation, but the only alternative would be breaking the machine for the few parts that did still work.

 

Set up and alignment can be very time consuming, and can often involve replacing further parts in the audio or transport circuits if it becomes evident that the machine will not perform as expected. This will only be evident once the tape heads, record and playback circuits are aligned and tested. Depending on the machine final test and set up involves setting the machine up for overall frequency response, for domestic machines a setup which works well with most tapes is appropriate, although it will generally be optimised for a high bias tape as this is likely to yield good results for 'new' recordings. For studio or high end audio then a machine would be optimised as required by the client for a specific tape brand/formulation, usually minimum distortion and flat response is the goal rather than pushing the bandwidth to extremes.