Tape Speed; Routine Maintenance; Cleaning; Lubrication - Revox G36 Service Manual

Accurate and useful measurement of wow and flutter can only be made with an
appropriate instrument. The recorder is calibrated using the EMT Model 420.
Possible causes of flutter may well lie with the capstan, capstan motor. Wow can
usually be seen as associated with the pinch roller speed and in some cases a faulty
pinch roller may be the cause, and in others too much back tension or insufficient
pinch roller pressure. For all wow and flutter investigations the transport mechanism
must be completely clean.

2.1.7 Tape speed

Tape speeds can be checked by running a marked, measured length of tape through
the recorder. For a 100 sec. run 950cm would be required at 3 3/4 ips and 1905 cm at
7 1/2 ips. The difference in running time in seconds will be the speed variance as a
percentage. Some variance can be expected with temperature increase but this should
lie within the quoted tolerance. In very cold weather it may be noted that the recorder
runs accurately at 3 3/4 ips but slows down when switched to 7 1/2 ips. This is due to
drag from the cold grease in the capstan bearing, especially when new. After a short
time of operation at 3 3/4 the machine should be capable of running at 7 1/2 ips.
When detecting any deviations from the figures quoted, an accurate reading of the
mains frequency should be taken first before investigating pinch-roller pressure,
brakes etc. On a 50 cycle power line, a drop to 49.5 cycles will make the recorder run
slow by 1% and this should be borne in mind when checking equipment with a
specified accuracy of ± 0.3 percent.

2.2 Routine maintenance

2.2.1 Cleaning

From time to time the working parts of the recorder which come in contact with the
tape should be thoroughly cleaned. Cleaning of the head faces is particularly
important, especially in the case of four track heads where seemingly invisible
particles can often have an adverse effect on performance. On no account must any
deposits be scraped off with metallic tools. Loose tape dust, may be brushed off. For
cleaning of the heads and capstan shaft, use a cotton-swab soaked with methylated
spirits. (Avoid any solvents from coming into contact with the plastic parts of the
recorder).

2.2.2 Lubrication

The capstan motor, the capstan bearing and the wind motors are equipped with
bearings of sintered material. Each bearing has an adequate supply of lubricant which
should last for the life of the bearing. Should the replacement of a motor bearing
become necessary, return the unit to the nearest REVOX Repair Station. On wind
motors with ball bearings (Series I and II) it is advisable to replace the ball bearings