Fostex E-22

FALKEN

FALKEN

*************************
I am still having problems with this machine. The problem now is that when you RW, occasionally it goes SUPER slow....until you raise the right tension arm manually, then it picks up. I finally got my tentelometer....and an oscilloscope, and last night finished a full mechanical alignment. Brakes, Tension, Fast wind speed, everything in the manual. While the machine is running awesome now, it still occasionally has this problem. All I can think to do is to go back through all of the calibrations a 2nd time. I suspect it is something to do with the tension arm.... If anyone could help I would really appreciate it.
 
So the tensions are reading right?

What happens if you adjust tensions so the tension arm is in the proper position to drive a proper wind speed? Are the tensions off-spec then and by how much?

Are you certain the Tentelometer is properly calibrated? I learned some of the fineer points of this from Beck when I was having trouble with my 58 tensions.

Is there anything in the E-22 manual about checking the tesnion sensor voltage? On the Tascam decks there are test points to measure the voltage when the tension arm is unloaded and when it is loaded and there is a trimmer to adjust that window...

Just some ideas.
 
Yes the tensions are reading right. The tentelometer is brand new, and the folks at Tentel calibrated it based on a tape sample that I provided. (Quantegy 456, 1/2"). The FF and RW tension measurement is made with certain jumpers pulled so that the tape is not actually moving while the measurement is made. I am sure if I messed with the tension arm during this that the reading would change but that sort of defeats the point. I'm not sure about measuring the tension arm voltage. I might look for that. In the manual the calibration works like this. There is a hole in the chassis. there are 2 springs attached to the arm (big one and little one). The big one "takes over" when the arm passes over this hole. if it is not lined up, you unscrew some stuff and move it. when I looked at it it seemed fine. All I can think is to go through the entire calibration again just to be sure. Thanks for the ideas.
 
Tape is new. It seems to happen more on RTZ...as it approaches zero it crawls. I only finished calibrating it last night so I haven't used it much but I was able to get it to do it. Also, there is a calibration procedure where you hold down FF or RW, and it crawls, and then you make an adjustment while watching the oscilloscope... on RW the speed would vary but on FF it would stay the same...
 
At the risk of sounding stupid, is it supposed to slow as it approaches zero, so as not to overshoot too much? My 38 will slow down and then have to hunt a little bit to find zero, sometimes settling at 9999 or 0001 or so.
 
FALKEN said:
Tape is new. It seems to happen more on RTZ...as it approaches zero it crawls. I only finished calibrating it last night so I haven't used it much but I was able to get it to do it. Also, there is a calibration procedure where you hold down FF or RW, and it crawls, and then you make an adjustment while watching the oscilloscope... on RW the speed would vary but on FF it would stay the same...
Click to expand...

I had to adjust my MS-16 a few times to get the RTZ to work right. try adjusting again. I also noticed that RTZ will overshoot if the tape tensions are not set right. The difference in the reel torque is what makes the tape slow down and also determines tape tension. good luck. The braking action is produced by the reel motors and not the mechanical brakes. The mechanical brakes only job is to provide tape tension when the transport is stopped.
VP
 
I dont think I explained very good whats happening. on RTZ it will slow down around say :04, and then take 2 hours to get to :00, but it is moving. sometimes when you hit rewind, it will move that slow, until you lift the tension arm.
 
I have a tascam 32 so I know what you are talking about, how it overshoots and then finally reaches zero. The fostex's don't do that. what is happening is that when you hit rewind, it doesn't get enough "juice" to get the tape moving, until you lift the right tension arm, then it gets going and you can let go.

I am thinking it is either

-a mechanical adjustment of the tension arm springs (even though this is done via eyeball and eyeballing it it looks ok)
-tape tension (which all measures correct)
-count pulse duty (is as close to 50% as I can eyeball, tolerance is 45%-55% but on the scope I have no idea how one would even see that closely)
-fast wind speeds:

manual reads:

"Hold down the FF (RWD) button. Adjust R502 (REEL LOW) on the system control PCB so that wave length at test point 1 becomes 16, +0-1msec. "

OK the action when you hold down the FF or RWD button is identical to what is happening when you just try to rewind.

What I understand the manual to mean is that test point 1 should be 16 msec, or .16 seconds, so with my horizontal range switch set to .05 s/cm, the wavelength should measure 3.2 cm.

"Wind tape to the beginning and enter the FF mode. Adjust R503 (REEL HIGH) so that is is 0.78 ~ 0.82 msec."

I took this to mean .008 seconds, or with horizontal range switch set to .01 s/cm, .8 cm.

I made these adjustments to the best I could eyeball on the oscilloscope.

Does this look to be ballpark ?
 
Ok, from what I've read in the thread so far my intuition is this may be a logic control problem rather than mechanical per se, but that's just my gut and not my final answer.

I've got the manual for the E-2/E-22 so give me a couple days to go over some things. I may be asking you a few questions to narrow it down along the way. Hopefully we can get this up and running for ya.

~Tim
:)
 
You must log in or register to reply here.
Back
Top