View Single Post
Old 23rd May 2020, 4:25 am   #4
ricard
Octode
 
ricard's Avatar
 
Join Date: Mar 2006
Location: Lund, Sweden
Posts: 1,631
Default Re: Repairing tape counters

I have (or had, not sure if I sold it or not) a Tandberg whose counter reset failed because some of the thin blades that press on the cams had cracked and fallen off (I think because the heat generated by the pilot lamp illuminating the counter had caused the plasticizer in the plastic to evaporate, leaving the material brittle).

I fixed this by drilling small holes in the bar which the blades emanate from and supergluing piano wire into the holes. This fixed the problem, but I'm not sure how long it will last, because the bar surely has suffered the same drying-out fate as the blades, and is now subjected to fairly large point forces where the piano wire enters the bar.

As can be seen in the picture, getting the holes in the right position was tricky and I didn't completely succeed, but on the whole the operation was a success.

(In the pictures, the first one shows the reset mechanism at rest, the second one shows it in operation, pressing against the cams.)

BTW, it has always struck me as interesting that the 'push-to-zero' mechanism didn't appear until the mid 1960s or so, before then, the counter reset mechanism on many machines at least used a thumbwheel mechanism which pulls all the digit wheels around until they reach 000 or 0000. I suppose everyone thought that was good enough until someone came around and invented the pushbutton reset. The thumbwheel reset seems more robust; I can't think of a single machine I've had where it's failed, whereas sticking pushbutton reset mechanisms are common.
Attached Thumbnails
Click image for larger version

Name:	TB-counterfix.jpg
Views:	102
Size:	78.6 KB
ID:	206497   Click image for larger version

Name:	TB-counterfix-reset.jpg
Views:	101
Size:	72.9 KB
ID:	206498  
ricard is online now