Thursday, October 31, 2019

Continuing diagnosis and repair of tape load on drive A of my Telex 8020 system

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VERIFYING VACUUM AT TAKE-UP REEL HUB I pulled the hose off the differential pressure switch for the take-up reel hub and held my finger ov...
Monday, October 28, 2019

Diagnosing failure in tape load operation in Telex 8020 drive cabinet A

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AUTOLOADING CARTRIDGE AND TAPE CARTRIDGE OPENER IBM introduced a feature on its tape drives, during the 360/370 era, where the operator on...

Start testing logic and power amplifiers in drive A

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INITIAL SHORT TEST I did a quick check of the power supply connectors to see if any of the loads are shorted, using the VOM to measure res...
Sunday, October 27, 2019

More work on the operator control panel of drive B

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REPLACING BROKEN DENSITY BUTTON I installed a mini pushbutton switch on stiff leads into the PCB, after removing the broken switch. Simple...

Starting testing of logic and amplifiers in drive B

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SCHEMATICS OUT OF SYNC WITH THIS DRIVE The book of schematics I own are a match for cabinet A, both the drive and the integrated control u...

Converting the Telex drives to different speeds

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DOWNGRADE MODELS AND PRICING STRATEGIES FOR MAINFRAME PERIPHERALS Mainframe makers had long pursued a strategy to build a peripheral devic...
Saturday, October 26, 2019

Start repair of operator control panel & finish repair of dump card from cabinet B of Telex 8020 tape system

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CONDITION OF CONTROL PANEL The panel has a number of wires dangling loose and I wasn't sure that everything was even still there. This...