Tascam 688 problem diagnosis(PLZ HELP)

Powchang

New member
Hey guys! so I'm new to this forum and this is my first ever post!

So I recently bought a Tascam 688 Midistudio from an ebay seller for a steal of a price! I knew there would be some problems with it because it was being sold as is, but I felt comfortable buying the unit and trying to fix it. Usually, with the old Tascams the problems can be quelled with a new motor and/or capstan belt. So I figured this would be a relatively easy job.

I started out by testing the unit. The FF and RR(sometimes the rewind only works for a couple seconds) buttons worked well enough, but I could not get the tape to play(using the play button), the heads would engage the cassette, but then would fall back down after a second or two. I thought this was odd since FF and RR were working. So I opened the unit up and got it to play with no tape in it by holding these two small black arms that are usually pushed up when a tape is in the unit. When I did this, I noticed that whenever I pressed the play button, it would run flawlessly and not stop randomly. But only one motor would be moving. So I figured the motor that wasn't moving was broken. I replaced it and tried testing it again, it still didn't move and all the issues I described persisted. However when I was inside the unit I did notice that the motor I replaced would whir like it was idling when it touched the metal surface of the unit. So I don't think the replacement motor was a dud, but I still have no idea what the problem could be, any help would be appreciated!
 
I'd suspect the capstan system, if FF and RW are working correctly but play isn't. That might be a pinch roller problem, a belt problem or a capstan motor problem. I'm not terribly with it on cassette decks, so I'm not sure what to suggest specifically. However, if it's a belt drive, the capstan belt is probably the first thing to check.
 
Also- Make sure you're using only Type 2 Chrome Cassettes in it... If you try a normal bias cassette- it's not going to work.
 
It may be the pinch roller...I already replaced the capstan motor so thats probably not it. And yes, I am using high bias type 2 tape.
 
Greetings, I have the EXACT same problem with my 688. Did you resolve the issue and if so can you tell me what the fix is please.
 
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