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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 14th Jan 2018, 9:27 pm   #1
Ted Kendall
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Default Teac X1000R logic fault

I've had one of these in for repair - reminds me of exactly why I prefer Revoxes, but still...

After the usual stuff with stripping the mechanics to sort out the glue/grease issue, testing revealed a novel fault in the tape transport. It goes like this :

Fast forward is OK - responds to controls as expected. Slightly slower acceleration than rewind, but OK.

Rewind - responds to controls until full speed is reached, but then reacts to any control by accelerating further and ignoring any input except pressing the rewind control again, when wind returns to normal speed. When the tape runs off the end and the autostop engages, all is reset.

The various speed and tension adjustments are all within reasonable limits, so for the moment I'm baffled. Anybody seen this before?
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Old 14th Jan 2018, 11:38 pm   #2
jamesperrett
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Default Re: Teac X1000R logic fault

Do you know Sam Palermo? He regularly posts on some of the other reel to reel forums and seems pretty knowledgeable on Teac stuff.

https://www.linkedin.com/in/sam-palermo-51312616/
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Old 9th Feb 2018, 12:24 am   #3
Ted Kendall
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Default Re: Teac X1000R logic fault

Well, this one was a barrel of laughs

The locking-out of controls is a known fault caused by excess fast-wind speed, which flips the logic into an illegal state. The fast-wind speed is explicitly set by a preset on this design. Suspicion then fell on the tension adjustments. There are four of these - forward and reverse play tension and fast wind and rewind stall tension. Out with the Tentelometer and tweak. Three out of the four pulled in OK, but reverse play was incredibly touchy and wouldn't stay set.

Dodgy preset, thinks I, and put in a new Bourns. No change. Dug a bit deeper and found no output on the tension arm sensor on the left hand side. Opto-interrupter duff. Not only duff but now made of purest unobtanium. Close equivalent found in RS catalogue and fitted. Wild oscillations of tension in reverse play. The cause of this was the very narrow aperture on the replacement interrupter. Hacking the plastic out allowed the thing to work as intended.

Tension adjustment in reverse play still touchy. Brute force and ignorance prevailed and I fitted a multi-turn pot. At last everything could be adjusted and the thing now works well.

What a performance!
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Old 9th Feb 2018, 9:48 pm   #4
TIMTAPE
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Default Re: Teac X1000R logic fault

Thanks for the report and well done. For future reference will keep in mind the possibility of an opto interrupter fail and fitting a multiturn trimpot.

From memory the X1000R is the only Teac model in that line with the reel servo tension feature. With that electronic tension control sophistication some sort of tacho circuit to limit reel motor absolute speed might have been a good design addition.
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Old 9th Feb 2018, 11:02 pm   #5
Ted Kendall
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Default Re: Teac X1000R logic fault

The 2000 series has a similar set-up. Whether the other 1000 series decks do I don't know. The fast wind speed is set by adjusting a pot for a given period of square wave at a test point. If the illegal state is entered, boy does it go!

Other superficially similar Teac decks are far simpler - the swing arms on the X series are little more than decoration...
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