Thursday, August 3, 2017

Dive into the Telex tape drives to assess the restoration work ahead, plus prep for VCF-West exhibit


I put some time into the documentation and exploration of the two frames I have. There are a few challenges ahead. The main one is that the model 266 is a dual frame unit, A and B, with one tape transport in each frame. However, the vacuum and air pressure for both transports are mounted in frame B, as is the main input power connector, while the integrated control unit is in frame A.

What I received is frame A but no frame B. No place to connect the power cable nor any supply of vacuum or air pressure. The second frame I have is a model 6 drive that fell off a forklift and has quite a bit of damage. This unit has a transport and a set of vacuum/pressure pumps for itself. It is NOT, however the B frame that is part of the model 266.

Therefore I have bought the typical "Pile-o-parts" and not a unit that would ever have worked as it was sold to me. The damaged model 6 frame was obvious but the lack of the essential B frame for the purportedly working model 266 is a challenge.

I believe I can cannibalize the vacuum and air pressure unit from the damaged model 6 and use it to somehow complete the function of the 266 A frame. I can't, however, restore both to operation until I get additional vacuum and air pressure sources.

The tape transport uses a 3/4 HP motor to drive a vacuum pump operating at 30 inches of water and a pressure blower delivering at 50 inches of water. I don't know the flow rates, just the static pressure when these are operating in an idle drive. 

The frame of the damaged unit is severely bent and part of the supply reel holder is damaged but probably fixable. The cards and other components inside don't appear damaged. Certainly it serves as a source of spare parts for the A frame if I can get that working, but I had hoped to come out of this with two complete drives. Still, for $100 it is hard to complain too loudly. 

The input power cable is a large four pin connector for 3 phase 208/230V, although it has nowhere to attach inside the A frame. The good news I discovered is that nowhere inside the tape units is 3 phase required. The integrated control unit uses single phase, the transport in the A frame uses single phase and the transport in the missing B frame uses single phase. 

By attaching each of those three loads to a different pair of input phases, they save money on wire by dividing the load. However, I could easily wire all three loads across 220V single phase. The power for both A and B frames together and in operation is a bit below 3KVA or under 14A. Actual power used may be less depending on the power factor. 

The motors inside are all single phase, the vacuum and air pressure use a 3/4HP single phase AC motor. The capstan and both tape reels use a DC permanent magnet motor operating at 45V. Mainly this unit requires 5V, 15V, -15V, and 45V plus some AC to the blower/vacuum motor. 


We are exhibiting the Alto at VCF-West at Computer History Museum this weekend. We will set up on Friday evening and check everything out. I put some time into preparing my reverse wifi router, because the LCM built bridge for Alto networking requires a wired ethernet cable. We will pick off the wifi in the museum with my unit and deliver internet access through its attached ethernet cable.

Ken is preparing signage for our area while Marc is working on the final presentation material for our panel presentation and on-stage demo. Marc is going to display a sample logic board under plexiglas and I will bring a sacrificial disk cartridge for display purposes. We will meet tomorrow and wrap it all up prior to load in that evening.

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