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The mechanism for detecting autoreverse needs attention.
Usually there's a tension spindle that detects if the tape has ended, becauaw the pulling lug pulls and theres no more tape to feed.
Maybe the spring lost tension?
You need more info, probably an expert, but you can retension it by removing it and twisting it while heating in a fire (doesn't work great but might be enough).
I bet this is it
I'll check that out. The unit is in very good condition otherwise and I have the service manual. I probably will have to attempt to locate an expert. I've taken it apart since I got home and couldn't identify the problem.
Sorry, also one of the capstans or rollers could be sticking, increasing the resistance which also signals that the tape has reached its end.
Interesting way to confirm: Does it autoreverse both ways equally? If so it is more likely to be the spring, if not then one of the capstans or rollers or the reversed lug is sticky.
You know what? Before I turned off autoreverse it was reversing at random and it would do so for a good couple of seconds before righting itself. Everything sounded fine, no assymetric speeds or anything. Maybe I should turn it back on and see what it does. Its set to no autoreverse right now. But I dont have the dongle so switching modes can be a guessing game. The WM-EX631 seems to have one capstan so its entirely possible the seller gave it to me and I wore it out already by being excited. At least, the service manual only points to the one. The pinch rollers are clear and clean too.
If the speeds are right, that's almost a smoking gun for a weak autoreverse spring.
You might be able to jury-rig it temporarily, I don't know this unit's design, but either remove the spring and replace it with string or wire so the autoreverse sensor can't trigger, or fix the spring itself.
Pull it and see what kind of tension it has.
Heat treating is the proper method to fix it, here's the directions from chatgpt, it's not wrong, usually I've just seen it kept relaxed and heated with a lighter for 10 seconds, then left to cool.
Heat the spring to ~400–600°F (204–316°C) depending on material (e.g., music wire, stainless).
Hold for 30 minutes.
Let it cool slowly in air.
Thank you, I'll attempt this the next chance I get. Hopefully I can source a new spring from fixyouraudio or something but in the meantime I'll employ your method. I really appreciate the advice and just talking about Walkmans. When I get to it I'll be sure to post an update here.
Np, good luck.
I miss my old Walkman from when I was young (actually think the one I used most was a Toshiba). Favorite was a Panasonic fm radio though, still love that thing, might have it in storage actually.
They were awesome for the time, best of luck with yours, ask if you have other questions!
Little update, the seller is just sending me a new unit. I will still attempt the heat treating though. The unit I currently have is really cool and it would be a shame to leave it in this state.
So I remembered how the autoreverse worked on my toshiba, there was a roller on a rocker arm with a spring, when that roller displaced from tension the rocket arm triggered the action.
I'm pretty much positive it's the spring, but you might be able to test this by finding the rocker arm and adding tension with a paper clip to see if the problem stops.
Thank you for all of your advice. The mechanism seems to be more or less the same with this unit. When I get home tonight I'll take a look at the springs on the rollers. The design of this unit means I gotta take it completely apart to get to them but it will be worth it.
Oh, the sensor itself could be glitching, but I kind of doubt that, the springs almost always go first.
It sounds like It may be a chewed up tape. Is this happening with every tape or just one?
Unfortunately its all of them. I can get it to fast forward and rewind. It just won't play, and if its in autoreverse mode it constantly switches sides.
That's mad weird.... Beyond me there bud I'm sorry.
I appreciate it regardless. Thank you.
Try a different tape. Maybe your tape is getting stuck.
Its all of them :\ even my test ones.
Ok one of the capstans is likely to be on a pivot, to detect tape tension for auto reverse. See if it is sticky etc. Try web search for this problem?
I did, even found a video of a teardown and asked questions. No responses. I have a service manual that I'm going through. I just thought I'd ask Lemmy, too. I'll check the capstan when I'm off work and can take it apart. Thank you.
https://duckduckgo.com/?q=cassette+autoreverse+in+middle+of+tape
Gets some results
Thank you, most of these links are purple for me but I'll keep looking.
I don’t know your specific machine and haven’t used cassettes for years, but from experience back in the day the first thing that occurs to me is uneven tension - what happens if you manually fast forward the tape to the end then rewind it? Does retensioning the tape help at all?
That was the first thing I did :\ unfortunately it does this to all tapes I put in it. I opened a fresh cassette I just got yesterday to test it and the issue persists. As a slight update, I contacted the seller. I feel bad as they are sending me a new unit. I do not think this was their fault in any way. But I appreciate it nonetheless. Another user suggested heat treating the springs, that will be my next go-to. Thank you for your help though, I really do appreciate it.
