1 set, 4 pieces TRIACS 

For the tape transport drive printed circuit boards 

1.177.317 and 1.177.315

For all Studer Revox PR99 (MKI to MKIII) 

and all B77 (MKI and MKII)

Whenever the motors cause problems, 

the motors hum loudly, forward, play or reverse not work, 

it is often one or more of the 4 Triacs that switch the AC voltage of the 

motors are faulty.