388 won't stay playing.

  • Thread starter Thread starter Actualchambers
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Actualchambers

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Hello all. I've been lurking trying to learn as much as I could about the 388 and haven't seen anyone ask about this, so here goes. I have a 388 that will start playing, or start FF or RW, and then stops right away. I rewound the tape by hand (spinning the reels on the machine, oof) but it doesn't seem to make a difference. I have ordered a new capstan belt but I can't see how that could make a difference.

Video to make sense of all this:

 
It looks rather like the deck has detected a fault and shut down. First, is the capstan turning? If not, that could mean a belt problem, but it could also be a problem with the sensor on the right-hand tension arm. If it thinks the tape has become despooled it will stop. You might try manually pushing up the tension arm and holding it there when putting the machine into play/fast forward and see if that makes a difference. It is possible that it's a tape tension issue, e.g. the initial movement is enough to start it, but afterwards the tension drops enough for the tension arm to hit the 'off' position and stop the deck.

The other thing that springs to mind is the tach roller. Some decks will stop or otherwise behave abnormally if they don't get feedback from the tach roller. Not sure if the 388 is one of those or whether it just uses it for the tape counter. The tach system might be photosensor-based, in which case it might be as simple as a buildup of dust on the sensor.
 
jpmorris said:
It looks rather like the deck has detected a fault and shut down. First, is the capstan turning? If not, that could mean a belt problem, but it could also be a problem with the sensor on the right-hand tension arm. If it thinks the tape has become despooled it will stop. You might try manually pushing up the tension arm and holding it there when putting the machine into play/fast forward and see if that makes a difference. It is possible that it's a tape tension issue, e.g. the initial movement is enough to start it, but afterwards the tension drops enough for the tension arm to hit the 'off' position and stop the deck.
Click to expand...

The capstan is turning. I actually did try all sorts of things with positioning of the tension arm, and nothing helped. Left alone, the arm stays more or less centered on it's path of travel and doesn't come close to being loose. I do wonder if my tape is too sticky, but I don't have any more so I can't test it.

The other thing that springs to mind is the tach roller. Some decks will stop or otherwise behave abnormally if they don't get feedback from the tach roller. Not sure if the 388 is one of those or whether it just uses it for the tape counter. The tach system might be photosensor-based, in which case it might be as simple as a buildup of dust on the sensor.
Click to expand...

I'm going to clean the tach sensor and report back. Here's an interesting thing: if I don't have any tape loaded, it works just fine. So I think there's a few options:

1) Maybe the tach roller is being screwy.

2) My tape is sticky.

3) The transport motors are worn out.

4) Something else I haven't thought of yet.


Thanks for your help, I'll let you know what I find.
 
sweetbeats said:
What tape are you using?
Click to expand...

It's some tape that was already loaded on the machine when I found it in the back of the warehouse. I came across some 456 still in the package and sealed up, but if I can't get any action on this I may open it up.
 
Old 456, even if sealed, can be sticky as well.
Can't automatically trust it. If made after 1994 and from Alabama, its usually good.
Check the sticky tape 'stickie' on this forum for more info and how to check tape date codes.
I've found that anything made in the Redwood City plant is the bad stuff. It will tell you manufacturing location on the back of the box.
 
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Duh... yes. What you're describing sounds a lot like a sticky-shed problem, now that I think about it. Try getting some RMGI LPR35 and see if the problem persists.
 
Sticky tape will slow and stop a tape transport quicker than flies will be attracted to sh#t!
Check your heads and guides fir the telltale brown gunk.
 
Looking at the video though it doesn't look like it's a sticky shed thing...it stops instantly rather than getting mired and quitting.
 
sweetbeats said:
Looking at the video though it doesn't look like it's a sticky shed thing...it stops instantly rather than getting mired and quitting.
Click to expand...

Here's a video of it playing without tape. If the variable in this case is tape, and it's probably not sticky tape, then what could it be? Also, I cleaned the tach sensor and it didn't change anything.
 
Actualchambers said:
Here's a video of it playing without tape. If the variable in this case is tape, and it's probably not sticky tape, then what could it be? Also, I cleaned the tach sensor and it didn't change anything.
Click to expand...

Hmm. I'm not seeing a link to the video. Is it operating more correctly without the tape on? If so that at least rules out the control logic, which is a good thing because it seems to have an EPROM and the machine is at least twice as old as the EPROM's life expectancy.
 
jpmorris said:
Hmm. I'm not seeing a link to the video. Is it operating more correctly without the tape on? If so that at least rules out the control logic, which is a good thing because it seems to have an EPROM and the machine is at least twice as old as the EPROM's life expectancy.
Click to expand...

Yeah, when I say "Here's a video," what I mean is "I will forget to hit paste and then remember several hours later." Let me rectify that:

 
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Actualchambers said:
Yeah, when I say "Here's a video," what I mean is "I will forget to hit paste and then remember several hours later." Let me rectify that:
Click to expand...

That's still a little unusual - most decks will spin both reels in opposite directions to provide back-tension. Anyone know if the 388 does something else or is this possibly related to the problem?
I'm not sure I like how the pinch roller instantly releases in Play, either.
 
The 388, without tape loaded, the reels should spin in opposite directions.

Does FFWD or REW work with tape loaded?
 
sweetbeats said:
The 388, without tape loaded, the reels should spin in opposite directions.

Does FFWD or REW work with tape loaded?
Click to expand...

No, FFWD, REW, and play all do the same thing, where it runs for just a sec and then stops. When it pulls on the tape it doesn't pull the tensioning arm all the way up, so I don't feel like it's over-tensioning... It just seems to give up. I'm really scratching my head.
 
When any deck does that I have to suspect the diode to the Hold voltage of the solenoid. Decks typically get two voltages when operated. First there is a flash voltage and in about 1 second the flash goes away and the remaining hold voltage is there to keep the solenoid plunger seated. What happens at times is the flash works but the hold voltage through a diode is missing due to the open diode. Look at the schematic and see where the hold voltage diode is at and then check it.
The reel rotation can not be a sign of what is happening when the tension arms are in unknown positions. Those deck with tension arms and opto sensors can have anything from fast moving motors to a complete lack of voltage to them depending on the tension arm position and how they were adjusted.
 
Yeah wow what he said. All good points. D408 on the Control PCB is the one to check. You can also check to see if the pinch roller solenoid is getting the power...it should be +24V DC at the solenoid when you hit PLAY...but that shouldn't effect things in FFWD or REW. Hmmmm....
 
Do you know if a reel motor was ever replaced or worked on?

And is this a new problem? In other words since you've owned this 388 did it used to act normal and then for no reason, with no cause or event, it just started misbehaving?
 
Been a while since I used R2R, but the drive bands on the take-up reel always seemed to get loose with age. Would that mess up the sensors?
 
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