One step back to begin with. Before I removed the tape transport I wanted to establish a starting point by taking an initial wow and flutter measurement. I decided to use WFGUI as has a good reputation and is, more importantly, free. It turned out to be a good choice as it downloaded to my 2015 HP Windows laptop without issue and latched on to my cheapo Behringer external sound card. I was expecting bad results as the wow was audible on long piano and guitar notes. There are a plethora of different W&F units. I’m told that Studer use the one that is called ‘peak’ or ‘quasi-peak’ here. So at the instant of the screengrab the reading was 0.57% and the worst seen in the preceding 10 seconds was 0.71%. Pretty bad, but TBH better than I had been expecting.
I decided to start by focusing my attention on the capstans and pinch rollers. I took a deep breath and with one finger carefully marking my place in the service manual, dismantled the capstan motors. I think it was at this point I finally realised what an extraordinary machine the A710 is. No belts! No brakes! Everything controlled by four motors getting instructions from sensors via a microprocessor. The capstan shafts were completely dry. I cleaned them, together with the shaft bearings and all the other bits and pieces. The sintered shaft bearings are an integral part of the housing, so I had to be satisfied with oiling them in situ, with Studer-specified PDP65 oil. A snip at an equivalent price of £1750/litre. Needless to say it was applied quite sparingly. Another couple of drops on the shafts and one on each of the thrust bearings, then I reassembled.
The service manual had sternly warned me to replace the clips and flywheels in exactly the same orientation to the shaft as they had been before for minimum W&F, so before dismantling I had marked them carefully. The shafts have slotted ends for the clips to slide over. It was only at this stage I realised the shafts would fit two ways, 180 degrees apart. And given there are two shafts, that’s four possible combinations - and I don’t know which one I had to begin with. I mentioned this to a friend with far superior repair abilities. “You say someone has obviously been inside this deck before?” he asked. Indeed, there are messages inside noting modifications that have been made to component values. “So how do you know he didn’t strip the capstans without noting the positions first?” I swallowed hard. Six possible positions for each flywheel. Thirty-six combinations. I decided to ignore this inconvenient possibility and forged ahead.
The pinch rollers were spongey-soft. I was also less than convinced that they were Studer-approved, given the plastic bearings. I ordered two new ones with sintered brass bearings from Germany and installed them with a drop of gold-dust oil.
Further #Studer A710 #cassettedeck refurbishment adventures. In this part, trying to improve the wow and flutter performance, I stripped and lubricated the capstans and changed the pinch rollers. Better explanations of what is going on can be found in the ALT texts for each photo.
