I made a thread regarding this in the tape forum a while back, but didn't really have the time to troubleshoot it. I do have the time now. Story goes, I got the 9191 off of craigslist. Seller said it worked flawlessly. Stupidly, I simply bought it and took it home instead of having it tested at his place first. Brought it home, and here are the issues...

1) Auto-stop incessantly engages at seemingly random times. Maybe a third of the time I can get it to play for a minute or two before it engages, the other times it will only play for two, three seconds tops.

2) FF/RW work, but they seem a tad sluggish after a few seconds, and eventually they appear to slow enough that the auto-stop engages. Pressing FF/RW again and it will rewind or fast forward for a bit more, slow, and stop.

3) Meters are flaky. Sometimes they both work perfectly (when I can get it to play). Other times one channel's meter (and actual output) is much less than the others.

I deoxited the FF, RW, Stop, Play, and Record switches on the front panel, as well as the two long switches document in this thread (http://www.audiokarma.org/forums/showthread.php?p=359621&highlight=honking#post359621). I'm going to investigate the FF/RW issue following this thread (http://www.audiokarma.org/forums/showthread.php?t=163690&highlight=CT-F9191) starting tomorrow. My main (and most irritating) concern is issue #1 above.

Got some ideas?

If you have sufficient takeup torque, I would suspect the sensor switch that opens and closes as the TU reel turns to send a switched pulse to the auto-stop circuit. Or maybe the two belts that go to it. When I used to work on 9191s, I routinely replaced those switches (not the belts necessarily) for shutdown problems. The bearings in the sensor switch would get ovaled out because the belts from the counter and to the takeup reel put a twist on the axle shaft going through it and the bearings would wear and cause it to seize and shut sown intermittently like you describe. That was when they were just a few years old! You've Deoxit'ed the switches so not sure about the rest.

http://www.audiokarma.org/forums/attachment.php?attachmentid=155704&stc=1&d=1245558214

I made a thread regarding this in the tape forum a while back, but didn't really have the time to troubleshoot it. I do have the time now. Story goes, I got the 9191 off of craigslist. Seller said it worked flawlessly. Stupidly, I simply bought it and took it home instead of having it tested at his place first. Brought it home, and here are the issues...

1) Auto-stop incessantly engages at seemingly random times. Maybe a third of the time I can get it to play for a minute or two before it engages, the other times it will only play for two, three seconds tops.

2) FF/RW work, but they seem a tad sluggish after a few seconds, and eventually they appear to slow enough that the auto-stop engages. Pressing FF/RW again and it will rewind or fast forward for a bit more, slow, and stop.

3) Meters are flaky. Sometimes they both work perfectly (when I can get it to play). Other times one channel's meter (and actual output) is much less than the others.

I deoxited the FF, RW, Stop, Play, and Record switches on the front panel, as well as the two long switches document in this thread (http://www.audiokarma.org/forums/showthread.php?p=359621&highlight=honking#post359621). I'm going to investigate the FF/RW issue following this thread (http://www.audiokarma.org/forums/showthread.php?t=163690&highlight=CT-F9191) starting tomorrow. My main (and most irritating) concern is issue #1 above.

Got some ideas?

Mate, I'm only a newb, but heres my 2 cents worth. As for 1) and 3), there are others here that may help, but as for 2), it could be as simple as the old lube has gone stiff and may not be letting the idler assy move properly. This may also not be helping point 1)...

I reemplaced the tires that moves the numbers
and now is perfect !!!

The counter seems to be working fine. How would I know if the sensing switch is bad? Not sure where to find a replacement for it except a donor unit.

The counter seems to be working fine. How would I know if the sensing switch is bad? Not sure where to find a replacement for it except a donor unit. Did you download the service manual? On page 14 it goes into a good description how the sensor switch and circuit works. I would take my O'scope ( you do have an oscilloscope, right?) and look at the switched voltage on the terminals of the switch as the reel rotates for nice clean high-low switching, and go from there. Or could be some old dried out electrolytic capacitor in that circuit, like C810. So it could be several things causing the problem.

This is assuming that the belts driving the sensor are in good shape.

Put a voltmeter across c807(22uf), R902 (12k) tries to charge C807 to the positive supply voltage (+12v or so), while the rotation of the sensor shorts across the cap to ground - discharging it. R909 (4.7k) is across the cap making the charged voltage about 8 volts. This sends a series of spikes through C803 (33uf) triggering Q807 to discharge the steadily charging C810.

A bad switch would not discharge c807, leaving the 8v across it stable as the sensor rotates, thus a scope isn't needed.

You could also disconnect a wire at the switch, connect an ohmmeter across it and rotate the switch manually to check it's condition.

C807 - C810 could have dried out enough to affect things, replacing them may be a good first step before messing with the irreplaceable sensor switch. Ed's pointing out C810 as a culprit is spot on, loosing value would charge faster making the stop very picky .....

I don't have any probes at the moment, but will pick them up from my other residence later this week. As such, I'm currently relying on my multimeter.

Across C807, with the tape running, I measure values from 0V to 1V DC, continually changing and reading many intermediate values. Without the tape running I measure 0V across it, as both leads are 13.33V with respect to ground. As such, I believe the switch is not bad.

I'll order appropriate replacement capacitors today. Thanks so much for the help.

Caps have arrived. Will install tomorrow and update. Also ordered a new belt kit...just in case...can't hurt. Stay tuned.

Got the new caps (807 through 810) installed today. Seems to have fixed the auto-stop problem where it constantly engages. Yay! Thank you Mark and Ed and everyone else. Hopefully this isn't only an intermittent moment of success. Will update if things turn sour.

Now I have to make my way through the second thread I linked to in the original post.

Quick question: When FF/RWing, should the auto-stop engage once it reaches the end of the tape?


EDIT:

Ugh. I spoke too soon. It just auto-stopped twice on me in the middle of playing. I can confidently say it's not stopping as nearly as much as before, however. I'm crossing my fingers the new belts that are in the mail will fix things once and for all.

Let the caps "settle in" for a while before any next steps. It's called forming. the insulating oxide film on the aluminum foil is being generated. Should be done before we get them, but they still may be creeping up in value.

Caps have arrived. Will install tomorrow and update. Also ordered a new belt kit...just in case...can't hurt. Stay tuned.Hopefully you bought your belt kit from wjoe? He also now sells the motor pully kit which wouldn't hurt to replace while you have it all apart. http://www.wjoe.com/vintageandantiques.htm#CTF%20series
Also check your tape alignment. When it stops during functioning, look for a tape loop, tape sag on the take-up side. If it is, it could be a problem with the Reel-Base torque. Page 29 of the SM. It also points to dirty or worn idler tires, etc.
Quick question: When FF/RWing, should the auto-stop engage once it reaches the end of the tape?
Yes.

Got the new belts in a few days ago. Having quite the time trying to install them, however. Looks like all the important screws that need to be removed have some sort of green goo stuck to them, causing my to strip one or two. Looks like something the factory would put on to hold them in place. Tips on their removal or others regarding belt replacement?

The screws are very tightly torqued in, and you must be careful not to hurt the screw sockets, a sharp screwdriver blade of the exact correct size pressed in HARD is what's needed to get them loose. The green glue is a lock to prevent vibration from loosening them, but it is not the source of your difficulties.

It's the motor mount plate for the capstan belt, right?

You'll have to cut slots (dremel tool) to fit a flat screwdriver blade. You could also try driving the screws IN a bit with a punch to loosen any possible "cold weld" between the threads that has developed over the tears or jar the torque lock loose.

If the offending screws have their heads exposed, you could try filling 2 flats on each side of the head with a needle file, watch out for where the filings go, then work loose with a good set of the largest pliers you can fit in the space.

If they are countersunk or recessed, get a screwdriver that fits as good as can be got in a stripped head, prefferably with a steel shank/handle. Put it in the screw head and give it a shrp blow with a metal "hammer" (plier jaws work well). Make sure you have something solid behind the area of the screw. This will re-form the driving socket of the screw. If done well, you can reuse the screw when assembling.

All the best.

In my case (FT-8282) the auto stop issues were belt related since the sensor is belt drive and in turn drives the counter. With new belts from wjoe it doesn't have auto stop problems anymore.

My FF/REW with the new tires, and subsequent to adjusting tape speed, is now much more sluggish than before so curious to see what yours does after the belt/tire swap.

The odd meter behavior, for me, was greatly reduced after I sprayed deoxit on all the pushbutton switches (play, record, particularly) as well as the output level pot. It was doing this on both channels constantly. Now it is intermittent on one channel despite at least a dozen deoxit sprays.

To get to the output pot, I had to do some disassembly to get to an opening on the pot's case so I could squirt deoxit into both halves. Even after this it is still not perfect and will occasionally have the left channel level go way low.

I gave up on the darn thing for now :) Not sure this was much help... :o

Michael