[GreenKeys] Model 33 Auto Paper Tape Reader Intermittent Start

[Robert Jarratt]

I have made some great progress with my auto tape reader on my Model 33. It
needed a replacement contact block as the original one was broken. When I
replaced it I cleaned every single contact and checked continuity of all
wires and contacts with my multimeter. Once I put it back together it
worked, reading the tape and printing the characters.

 

However, I am still getting a problem where it won't always start when I
push the control lever to the start position. The problem is intermittent,
although right now it is not starting at all.

 

As far as I can tell, the problem is not related to the contact wires
controlled by the control lever. When I push it to the start position the
contact wire creates the necessary short, and the other control wires create
the expected open or closed circuits. When the problem happens, and I have
not switched on the machine for a while, I can hear a faint click in the
reader's power supply when I operate the control lever for the first time.
If I operate it again shortly after, there is no faint click.

 

I have checked that power is reaching the contacts, it appears to be about
24VAC as measured with my multimeter, with one probe on the machine chassis
and the other on the contact. I find the TeleType wiring diagrams hard to
follow, but I *think* it might need to be 48VAC.

 

Any suggestions what I might look at?

 

Thanks

 

Rob

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