Customer had this R2R in storage for over 15 years, came out to use and found that the capstan was not moving, but the reels would spin, asked me to take a look.
Confirmed the symptoms, no capstan movement (and no motor whirr when tension arm lifted). Could see belt was non-existent but should have at least had drive. Confirmed power at servo board, so removed motor from chassis to test, was working again, so perhaps was just a bit of ‘stiction’ or at a point where the brushes had tarnished and wasn’t making good contact with the commutator.
After preliminary cleaning of motor pulley (large pulley on this 15IPS machine!):
More bits of belt:
At this point had to order replacement belt, which turned out to be a minefield as plenty of suppliers saying same as X3 belt which is a completely different pulley. In the end had to source directly from overseas (121mm dia 10mm flat 0.7mm) as no-one locally had any stock.
Asked the customer if they just wanted the belts swapping or a full service/alignment performing. Opted for the latter (may as well since got the covers off!)
Whilst waiting for belts, gave it a good clean inside and out and performed what mechanical adjustments were necessary according to the service manual (yay! a service manual, remember those?!), so clean/demag heads, adjust capstan thrust clearance, adjust brakes, tension arms, take-up/brake/back-tension torques (all out quite a bit), pinch roller pressure, reel table heights, lubrication, tape path alignment.
After receiving the belt, the other mechanical and electronic adjustments were performed, speed was off quite a bit but brought back in line:
All 8 channel level pots (4 playback, 4 record) were very scratchy so treated with Deoxit F5 before anything further done.
This particular deck has 3 heads and 4 tracks so at least 4 times the number of adjustments of a typical stereo 2 head machine as the record head can also be used to play back channels (simul-sync – to record at the same time as playback for multi-stage recording/overdubbing):
Here we have to adjust (for each channel) – output amplifier gain, vu meters, levels, playback head azimuth (both low/high speed), playback levels and frequency response, SNR, recording performance, bias trap, record head azimuth, record bias, record level and record frequency response, SNR, erase efficiency, channel separation.
And then repeat for ‘simul-sync’ operation (playback from record head).
All in all, an excellent condition unit ready to give its owner many more years of quality service! Everyone happy 🙂