Audio Technica AT-RMX64 Story…

[sarakisof]

I'm back. I finally found time to digitize some old Arabic obscure rare cassettes I always wanted to. Everything was running fine when suddenly after about 20 tapes the mechanism started chewing tapes (tape collected at the back of the pinch roller & stops).
First transport issues (when I got the mixer) had been sorted by replacing the old worn idler tire with a new chinese AliExpress one back then. Could maybe the issue be this again knowing their low quality?
Will replace with another one when go home later. But I don't think it's the culprit this time.

Meanwhile, @sweetbeats or anyone else, any thoughts on what I should look for in this particular deck when dealing with chewing tapes issue?

 

[sweetbeats]

Clarify what you mean by “back of the pinch roller”…is it bunching up on input side of the pinch roller, or the output? When this is happening are the tape reels turn at all, or only one or the other? Does your capstan shaft spin up?

 

[sarakisof]

Unfortunately during replacing the new idler tire I lost the tiny devilish e-clip washer. Will source an exact replacement one (I think it's M1.2) from a friend of mine as shipping from Ali will take 1.5 month. So as long as it's been installed I'll be back with results, describing better the whole case here.
If I remember correctly it's bunching on input side of the pinch roller though.

 

[sweetbeats]

Then the first thing I would do is check and see if the capstan shaft is spinning when a tape is inserted or when you press the tape sensor switch(s) in (to make the unit think a tape is inserted). The capstan shaft should be spinning at all times when a tape is inserted.

 

[sarakisof]

Yeap sure this is the first thing I checked, it spins fine. Starting to think it's that idler tire again. I have to wait since weekend for my friend to give me some e-clips. Or could maybe some cassettes be just bad / dry enough?
@sweetbeats do you think I should replace that only one tape mech's e-cap you were showing in your YT vid just for precaution purposes while waiting for the e-clip to arrive?

 

[sweetbeats]

The reel table drive mechanism with the idler roller tire shouldn’t cause the tape to bunch at the input of the captan shaft. In PLAY, with respect to the takeup side of the transport, the reel table drive mechanism only provides for takeup tension *after* the capstan shaft. If it wasn’t working right, the tape would bunch up between the capstan shaft and the takeup reel. The reel table don’t drive the tape in PLAY…the capstan shaft does all the driving. Did you install a new pinch roller? Check the pinch roller pressure? And you’re positive the capstan is spinning when in PLAY with a cassette loaded? The capstan might be spinning but it might be weak. Spin up the capstan without a cassette loaded. Pinch it with your thumb and finger. Is it easy or hard to get it to slow down?

On another note the idler tire you purchased…it’s specific to the AT-RMX64?

By “tape mech’s e-cap” are you talking about the electrolytic cap that’s on the capstan servo board? If so, it wouldn’t hurt to replace it I suppose.

 

[sarakisof]

Didn't install a pinch roller. It was like new.
Pinched capstan with thumb & finger. It's hard to slow it down (if at all), feels powerful.

I made a rec (normalized/boosted + 20dB louder, hope you can hear it) so you can hear to capstan motor's little noise. It's really hard to be audible but I don't know if that kind of noise (note that ~1900 Hz freq it produces & that "fade out / airplane landing" sound when I de-press the tape sensor switch) is normal.

Is it easy to oil capstan motor by not disassembling it? Could you show me with an arrow in your pic below the right point I should oil in? I've oiled capstan shafts the common way by just removing washer , pull off spindle by hand & put 1 drop of oil. Here I can see there's another bronze washer underneath that first black "washer area"..

EDIT: At the moment, with new idler tire installed (still wait for e-clip) & a NM condition cassette it works fine. Don't know how much it'll last though.