Some thoughts on my first 82104A repair

[flimshaw]

Hello there! First time posting, just in the hopes this is helpful for someone.

I recently successfully repaired a very gummed up card reader I bought to save programs from my 41CV using the excellent documentation on the museum and also over here.

I had to do it a few times, after trying my luck with the smallest o-ring I could find at my local US hardware store. Things seemed to run smoothly, and I was able to read some cards that had come with the reader and had old programs on them, but writing new cards would consistently fail at the end. I took a guess that the ring was a bit too big, and thus was running too fast and cutting off the final part of new programs, but was perhaps slow enough that older programs could (generally) be successfully read.

To confirm that data was being written and check for differences with older cards, I used this magnetic viewer and it was actually super helpful. There was a bit of difference on the tail end of newer cards, but information was indeed being clearly written. Here's a photo, very handy (and fun) for diagnosing magnetic data storage.

   

In the end, I ordered some proper 005 size o-rings, but also in my impatience disassembled the card reader once more, and tried to sand down the o-ring I had just a bit. After reassembly, it is now working pretty well! I probably will go in one last time and put a proper o-ring on, and attempt to actually get the spring clips in place (gave up on this until I knew I wasn't going to have to take it apart a final time).

Anyhow that's all, hope it is helpful or interesting for someone! One thing I've noticed too is that the battery on my calculator seems to run very low if I leave the card reader plugged in, even if the calculator is off. Is that the expected behavior or is there something amiss that I should look into? Also, not the best picture, but to my eye the head here looks awfully worn down, though I've mostly worked with cassette tape machines. Is it difficult to source new ones that are a match, or is this a fairly generic stereo tape head?

   

Thanks all,
-Charlie