Roland RE-120 space echo fluttering

[Mars Amp Repair]

Hello folks,
I searched a bit for any info on the board for this issue & it looks like this one is new.

The space echo has flutter in the speed of the brushless motor under load. With no load ie; pinch roller disengaged, the speed of the motor is consistent.

When the motor flutters, it does cause voltage loading , ie the meter bulb flutters, too.

The motor runs simply by hall type position elements & really no servo to speak of. Normally the drag on the motor is mostly from the pinch drive as the tape presents very little drag.

I cannot determine if the issue is work bushings in the motor causing excessive drag when the pinch roller is engaged or if it's the circuit that is having difficulty driving the motor.

If I load the motor with just my finger to take the pinch drive out of the picture, the bulb still shows fluttering, so I don't think the pinch drive is the culprit here.

Does anyone have any experience with this issue? I seem to recall a site I visited a few years ago where a guy was claiming to be quite the whiz on these units up to providing 'rebuilt' motors...can't find it now.

Thanx, glen

[stokes]

Glen,I am not familiar with this specific unit,but some reel to reels I've experimented with had "motor run capacitors" in the power supply to the motor.If the Space echo uses these they could be suspect.

[Enzo]

Brushless motor.

Let the motor run free. Now rap on the chassis. DO the lights pulse when you do that? I am wondering if the bulbs are responding to the vibration of a bogged down motor.

With the pinch roller away, spin it. Does the roller spin free? The tape drag is not a lot, but hard grease on the roller shaft can offer a load to the motor.

Grasp the capstan, can you stall it? Or is it still strong?

Is this circuit the same as the one in the RE201? If so or similar, then there are like four coils in the motor, each driven by its own drive circuit comprising two xstrs apiece. Like a car with one dead cylinder, the thing will run with one bad drive but under any load, it balks. Scope all four drives where the coil wires take off. Basically ther are four powr xstrs on the motor drive board, scope their collectors. All look the same? Each drive is one of them, plus a smaller xstr, and a handful of small parts.

If this is a different brushless motor, then never mind.

[Enzo]

I bet the motor bearings are OK, but grasp the capstan with it not running, wiggle it side to side to see how much slop is in the bushings.

[Mark Black]

Also as I remember (it's been quite a while since I worked on one of these) you might take a hard look at the electrolytic caps in the motor drive/control circuit. Seems like I recall a similar problem related to those drying up and/or changing value. For sure they are all getting old in that and other parts of the circuitry...

[Mars Amp Repair]

Flutter in re-150

In reply to all the great responses;

1. you can see the loading on the power supply line translated as ripple that mirrors the motor fluttering, so it's not a mechanical response of the bulb. I was using the bulb as a convenient indicator.

2. I realized early on that the pinch roller bushings were worn, so I disengaged the pinch roller & loaded the motor with my fingers.
a. it is very strong
b. it still flutters when I load about what a good pinch roller would
c. the motor shaft rocks a little bit, but the top has an acutual bearing in it...I dont' know what is down below as I can't get the armature to come out...it doesn't seem like this loading is bogging down the motor.

3. I'll have to check to see the individual drive signals to each of the 4 motor drive windings. From the schemo, it looks like it has 2 hall elements for position sensors.

4. I individually jumped the 4 drive dampening capacitors (1uf), but perhaps I should just replace them all as all of these electrolytics are old. I can recall having similar fluttering issues with VCR direct drive capstan motors circuits back in the day.

I'll follow up....thanx, glen

[Mars Amp Repair]

Yeah,
The slight wiggle in the motor that I experienced turns out to be bushing wear...I put pressure on the capstan on the opposite side of the Pinch roller & it sped up & the flutter stopped.

I disassembled the motor to the point of removing the top bearing to see that the bottom is a bushing & it's worn.

I cleaned it out with alcohol & put some light motor oil in there...just a drop. Reassembled the motor & reoriented it on the chassis so the pinch roller pressure would not be bearing down like it had.

No it's obviously not the best way to go about it but in light of there being no replacement for the motor, it's the next best thing to using it as a doorstop!

The flutter has stopped & even if I put extra pressure on the motor, it stablizes itself with no flutter.

BTW, I did end up replacing the motor smoothing caps & a few filters....pretty much to no avail, however I'd replace them in the next one with the same motor wear as it might have allowed the relubed motor to run not so close to the fluttering range..

Thanx all, glen

[oc disorder]

accurate simulation of a japanese Tape Echo machine

Saw this recently

http://www.soundfonts.it/?a=read&b=26

Couldnt help thinking while Glen is trying to remove the wow and flutter
programmers are putting it back in..!

GS-201 is an accurate simulation of a japanese Tape Echo machine of the early seventies, featuring:
Distinctive dynamic range and frequency response
Realistic response to the panel controls
Motor "wow and flutter"
Sound degradation and distortion at high feedback levels
Very natural hum and background tape noise
Three different kinds of magnetic tape models
Ultra-low CPU usage

[gscontr]

space echo question

I bet the motor bearings are OK, but grasp the capstan with it not running, wiggle it side to side to see how much slop is in the bushings.

have an old re-101 with a bad pinch roller. Any suggestions on where to find one?

[Enzo]

Not offhand, but it needs to fit the shaft. The actual diameter doesn't matter as long as it is large enough to make solid contact with the capstan, but not so large as it hits stuff. Tape speed is determined by the capstan, not the pinch roller. Yuo might see if MCM has any in your size.

If the rubber is hard, you can try to rejuvenate it. Wipe mineral spirits on it. DOn't drop it in and soak it, the thing will swell up like a tumor. Just wipe it down repeatedly and see if it helps. Actually gasoline would work too - most volatile hydrocarbons rejuve rubber - but gasoline is a lot more dangerous to have open in a shop. If that doesn't help, oh well, you were going to replace it anyway.

[Mark Black]

Somebody turned me on to this guy a while back:
http://www.srdpc.com/witt/
He actually has a picture of one he did for a Space Echo on his website and it looks really good!

I haven't done any business with him, but it's nice to know someone is filling that very niche market.

Good luck!

[gscontr]

thanks

You both have been very helpful, it seems that the balance of the tapedrag, and the capstan pressure are crucial to this old unit working correctly. I can get it to start rolling again by either bumping the pinch roller or easing the tension on the tape. Too loose, and the tape flutters over the heads, too tight, and it locks up. I'll try mineral spirits on the roller, and continue to try adjusting the tape feed side of the loop. Hope i can be of some use to the members of the forum in the future. Know anything about wurlitzer 200 e.p.'s got a lot of distortion on my re-transistor output fix.......thanks, and God bless you guys for being so helpful

[Enzo]

And make sure the roller spins freely on its shaft. Pull it back so it is not touching anything and see. Gummy old lube will bog down a motor. FOr that matter, how strong is the motor. Can you stall the capstan with your fingers?

[gscontr]

thanks again

the capstan is rolling along pretty well. so, the motor seems pretty strong. when i got the thing, around 10 years ago, the capstan pinch roller had a ton of gunk around the bearing surface, so i cleaned it out and got it running for about an hour. The pinch roller has some slop in the inner surface, even after polishing it, so i think i need to install a sleeve to tighten it up. i even thought of replacing the post and roller with something that would be more reliable, but with all of the bearing companies i've tried, all of the solutions are just a bit off. I really appreciate all of your help on this thing, and hope that i can be as helpful to others on this forum. Have a great Xmas and new year.

[Liam]

I wish I'd read this thread BEFORE I sold my RE201 so cheap...ah well