Telefunken M5 tube

[Vladislav81]

Hallo, ich habe ein Telefunken M5, Röhre, monophon, mit den Geschwindigkeiten 19, 38 und 76.

Ich habe es vor kurzem von einem Handwerker nach der Restaurierung erhalten, aber es gibt einige Missverständnisse.

Ich habe einige Magnetbänder mit Musikaufnahmen, die in den 1950er bis 1960er Jahren für Rundfunkgremien produziert wurden. Die Aufnahmen wurden mit Geschwindigkeiten von 38,1 und 76,2 cm/s gemacht. Eine große Vielfalt an Musik. Die Bänder sind meist auf Triacetatbasis.

Als ich den M5 kaufte, wollte ich ihn folgendermaßen einsetzen: die oben genannten Bänder abspielen und meine eigenen Aufnahmen auf neueren Bändern mit einem Röhrenmikrofon-Vorverstärker und einem Mikrofon machen. Die älteren Bänder sind bekanntlich 50 Mikrometer dick. Im Gegensatz dazu beträgt die Dicke des Bandes, das ich für meine neuen Aufnahmen gewählt habe, etwa 48 µm.

Es stellte sich heraus, dass es unmöglich war, alle diese Bandtypen auf einem M5 zu verwenden, da es unmöglich war, das Spannsystem so einzustellen, dass es sowohl mit Acetat- als auch mit neuen Bändern richtig funktioniert.

Zumindest ist dies die Meinung.

Dennoch hat sich ein Problem ergeben. Das Tonbandgerät hat, auch nach der Reparatur, eine sehr schlechte Wicklung auf der rechten Seite bei 38er Geschwindigkeit. Das heißt, das Band, auf das es eingestellt ist, wird ziemlich locker aufgelegt, und vor allem schwingt der rechte Schleifenwähler auf den ersten 200 Metern des Bandes. Danach ist alles mehr oder weniger normal.

Ein Handwerker sagt, dass es so sein sollte. Ein anderer sagt, dass die Kupplung am Wickelmotor verschlissen ist. Der dritte sagt, dass die Lager ausgetauscht werden müssen.

Wer von den beiden hat Recht?


Ich danke Ihnen.

P.S. Leider kann ich kein Deutsch, deshalb kommuniziere ich über den Übersetzer DeepL. Ich kann Englisch, kann ich bitte in dieser Sprache kommunizieren?

[sensor]

Ich vermute das es an der Bremse beziehungsweise an der Einstellung der Bremse liegt. 

Wenn der Bandwickel bei vollständig gelöster Bremse ordentlich zieht könnte man den Wickelantrieb als Fehler ausschließen.

[Frank Stegmeier]

Hallo,

meine Englischkenntnisse reichen leider nicht aus, um das Folgende in Englisch zu schreiben.

Die Auskunft, daß es gewollt sei, daß die M5 zu locker aufwickelt, ist falsch: bei richtiger Funktion wickelt sei stramm auf, und das ist auch nicht von der Dicke des Bandes abhängig. Ich setze voraus, daß das Gerät elektrisch in Ordnung ist.
Die M5 hat ein 2-Motorenlaufwerk, d.h. nur einen Wickelmotor. Im Gegensatz zu M5A/B/C sitzt die Kupplung auf der Achse des Wickelmotors.Daß diese Kupplung verschlissen ist, kann ich nicht ausschließen. Ich würde aber zunächst die Spannung des Riemens zum rechten Bandteller prüfen. Sollte der falsch eingestellt sein, kann man den Abstand der Achse vom Umspulmotor durch die 3 Schrauben, die sichtbar werden, wenn man den Mitnahmeteller dreht, korrigieren. Du hast die Service-Anleitung??? In der ist die Einstellung beschrieben. Wenn die Riemenspannung in Ordnung ist, würde ich den Bandzug rechts überprüfen. Dazu muß zuerst der Bandzug links eingestellt werden, siehe Vorschrift im Service-Manual. Danach kann der Bandzug rechts am Widerstand "Betriebsspannung rechts" eingestellt werden., auch hier: siehe Manual.

Sollte tatsächlich die Umspulkupplung verschlissen sein, sollte ein guter Mechaniker sie wieder instand setzen können. Wenn alle Stricke reisen: ich hab noch einen kompletten Umspulmotor inklusive Umspulkupplung der M5 hier....

Falls Du die Service-Anleitung nicht hast, findest Du sie hier im Download-Bereich:
https://download.tonbandforum.de/index.p...andgeraete

Du mußt Dich hier allerdings neu anmelden.

Viele Grüße und viel Glück mit dieser Maschine

Frank

[bitbrain2101]

Hello Vladislav81,

welcome in our Forum for taperecorders. We talk to each other member by the first name, so please tell us your first name and where you are located. You used the german word "Handwerker", we use the word "Techniker" for people doing work at taperecorders, technician in English. Can you do work at the recorder by yourself or do you need a technician to do the work ? The tape tension system of the M5 is very tricky, but adjustable. The brake bands can be a problem at this recorder. Service manuals are available, but in German language only.

Best regards, Tobias

[Vladislav81]

Hello Tobias,

My first name is Vladislav, I'm from Russia.

I apologize, I think I'd better write in English.

Yes, I need a technician to do the work. I'll contact a technician that lives in Moscow, he specializes in repairing tube M5 recorders.

So, if the tape tension system is set up correctly, the M5's tape drive would play 45 micron tape as well as 50 micron tape without readjustment?

Does it really have one average tension setting for all three speeds?

Do all tubes need to be shielded, not just the 804?

I cannot download any part of M5 SM. Do I have to register at Download section separately?

[AKRETA]

As far as I know you have to login separately with the same credentials for this forum you already have.

[bitbrain2101]

As far as I know you have to login separately with the same credentials for this forum you already have.

Thats wrong ! You have to register separately with username and password for the download section.

Regards, Tobias

---

Hello Vladislav,

Engisch is much better than German through translator. What kind of problem occurs with the different tapes ? In what condition is the pinch roller of your M5 ? If the rubber has become hard (they do it all), you can get problems with the tape run. The pressure force of the pinch roller against the capstan axle is also very important for a smooth tape run with different tape. Adjustment is explained in the service manual.

Regards, Tobias

[Vladislav81]

Hello Tobias,

The problem is as follows. I use pancakes and approx. 45 micron tape wound on standard AEG hub. I put a roll of this tape, thread it and start play or record at 15 ips. The tape doesn't lay on takeup hub well, it lapses fast or slow. One cannot predict how the tape would lapse. The tape is hitting the receiving roll, and this affects the sound because the tape is twitching and apparently pulling slightly out from under the pinch roller. I thought I could record a classical music concert the next month using this M5, - I couldn't do it. And the right tensioner oscillates almost constantly.

When I try to manually pull the right tensioner to the left, the tape twitching is greatly reduced, almost stops. As soon as I pull the lever back to the right and leave it to tension the tape, it starts all over again. The situation improves when about 1/3 of the roll is on the right. At almost half a roll the problem almost disappears. All this is at 15 ips, at 30 ips it is much worse. I'm talking about 45 micron tape.

By the way, when I first got my M5 from technician it already has this problem. So I called the technician and asked how to readjust the tension system. He told me there's a adjustment shaft on the right side under the tensioner, and that I need to loosen the screw, rotate the metal stick-regulator clockwise or counterclockwise and see what that does. So, I... broke the regulator cord or what is it called. I brought the M5 to another technician, he repaired this cord. Because I wanted my M5 working.

And now I have a question. If the right tensioner is in the far right position, the brakes on the right side brake the right reel holder? And if the right tensioner moves to the left, the brakes on the right reel holder are loosened?

One more question: is it true that the M5 tape mechanism can be optimally adjusted for one particular thickness of tape? I was planning to use thicker tapes on it, but I see that it does not work well with them.

Can you please tell me what you think the problem might be here? Well, other than myself of course?

Regards, Vladislav

[bitbrain2101]

The tape is hitting the receiving roll, and this affects the sound because the tape is twitching and apparently pulling slightly out from under the pinch roller.

Hello Vladislav,

there is a problem with the pinch roller or the pinch roller pressure force. The tape at the right side of the capstan should never influence the playback sound !

Regards, Tobias

[Magnettonmanni]

Hello Vladislav,

I also have an old 3-speed M5.

A report exists about a really professional repair of a M5. I still have to look for it.

To get you in the right mood, here's a film of how your M5 should run when it's working fine.

https://www.youtube.com/watch?v=GKQWzdeJArU

I would like to point out this film by Peter Ruhrberg because the tape running functions are presented and tested particularly well here.
It is not very important that the device has a different capstan-motor and that the tape platters are decoupled from the drive belts during the time they are not in use.

If your device doesn't work like this, it's not OK. It's not normal then. 

I have a question:
When rewinding,is the tape wound up quickly and tightly in both directions?

Best Regards
Manfred

[Vladislav81]

Today I found the cause of the problem. It turned out to be... the pinch roller cover. The technician before last, who had never repaired tape recorders before, had lost the spacer washers that were supposed to be on the pinch roller axle. As a result, the cover prevented the roller from moving freely and, consequently, the tape from being tensioned correctly and consistently. Truly - the devil lies in the details.

So, dear Tobias, it seems you were right!

However, I haven't run the M5 this new way enough yet to state it definitively, but if there are no problems during rewinding, and the tension problem on the right side occurs only during the working mode (or whatever it is called in English), it's definitely in the pressure roller assembly. But I didn't expect it to be that primitive! The pinch roller cover!

I'll shoot another video tomorrow to show how it (or she?) works now. Would anyone be interested in watching and listening?

[bitbrain2101]

Congratulations Vladislav,

one of the most important things with tape recorders, rollers must rotate freely. Sometimes its good to get your fingers at the rollers and turn them like a child, but with the feel of a technician. Video will be interesting, of course. I assume that you talk about playback or record mode as "working mode" ? Did you check the surface of the pinch roller contacting the tape ? Often the rubber got hard and slippery because of aging. In most cases it does not help to clean or grind the rubber to get more "grip", even if you could find new pinch roller, the rubber has the same age. Next task is to check the pinch roller pressing force in playback mode.

Regards, Tobias

[Vladislav81]

Dear Tobias,

I had to turn the pinch roller by the finger to see if it rotates freely, first of all. But somehow I didn't realize to do it, because I'm fixated on the tension system.

Yes, I just cannot find a correct word for the main working mode of the tape mechanism. Is it the "playback mode"? The mechanism itself doesn't play back or record, it's the tape recorder as a whole. The mechanism simply pulls the tape through the tape path. If the mode should be called "playback mode" in English - OK.

Yes, I've checked the pinch roller surface, it's not too hard and not too soft. However, the pressure roller could still be replaced as a preventive measure; it is not necessary at this time.

Regards,
Vladislav

[Vladislav81]

Dear Tobias,

Alas, it helped, but not a lot.




Great sound, though, IMHO. The tape here is 45 microns approximately. The M5 is calibrated to it. The source is 96/24 WAV played back through SSL 2.

Regards,
Vladislav

[bitbrain2101]

Hello Vladislav,

Sound is pretty good. For the right tension arm, it looks like something is uneven turning. Did you take the belt for the tape counter away and check if the tension problem is still there without the counter belt ?

Regards, Tobias

[Vladislav81]

Hello Tobias,

Thank you so much.

No I have not tried yet. I'll check today.

It might be worth replacing the pressure roller?



Regards, Vladislav

[bitbrain2101]

It might be worth replacing the pressure roller?

Hello Vladislav,

I can not tell you, did you check the pressure force of the pinch roller against the capstan wheel ? It is very important for proper tape run. What kind of pinch roller do you have/get for replacement ?

Regards, Tobias

[Ferrograph]

Эта ошибка не будет на прижимном ролике или приводном валу.
Я не слышу никаких колебаний высоты звука.
Подозреваю проблему с приводом правого ремня.

Привет, Ян.

An der Andruckrolle oder der Antriebswelle wird dieser Fehler nicht liegen.
Ich höre keine Tonhöhenschwankungen.
Ich vermute ein Problem beim Antrieb des rechten Bandtellers.

Gruß Jan

[Magnettonmanni]

Hallo Jan,
Du bist ja perfekt in "auswärts". Großartig!

Hello  Vladislav,
The right feeler lever must not move. It must be mechanically pushed inward by the play or record button to release the brake band.
If the fast-forwarding works properly, the drive plate is still OK. (see my first message)
Then everything is fine when the mechanic will work again.

It looks like your M5 is set up for 76.38 and 19 cm.

Best Regards
Manfred

p.s.
Look at Page 9, third Paragraph of the service-manual.

[Vladislav81]

Hello Manfred,

Thanks a lot for pointing at SM. I understand almost everything, but I don’t have new old stock brake ribbons.

Yes, fast-forwarding and rewind works good. Can FF a whole roll of Quantegy 478 without much notice, only it slightly slows down at the end of the roll, if using the first FF speed all the way through. Is it correct? The roll is tight after M5.

I took off the tape counter belt, tried running the M5 without it. Getting better, but not too much.

I've noticed that when the tape recorder was shut off for a whole day long, it starts almost very well. Then I FF and rewind the tape, then change it for 50 microns tape, and it starts doing that again.

I have no tools to measure the pinch roller pressure forse.

Regards, Vladislav

[bitbrain2101]

Hello Vladislav,

the pressure force of the pinch roller will probably not be the reason for the tension arm problems. You can test at playback mode to press the pinch roller arm with your finger and see if the swinging of the tension arm changes.

Regards, Tobias

[sensor]

wo rot eingekreist, kann man das Ansprechverhalten des Hebels und der Bremse verändern

aber man sollte auch sicherstellen das sich der Wickel geschmeidig dreht auch wenn er leicht gebremst wird , das der Riemen in Ordnung ist

[Frank Stegmeier]

Hallo Ulf,

ein Bild zeigt die Unterseite eines M5B/R oder M5C- Chassis. Hier geht's aber um die M5, und da werden die Bremsen anders eingestellt....

Viele Grüße

Frank

[sensor]

wenn man sich mein Bild genau anschaut sieht man da auch rot eingekreist die Bremse für den linken Wickel. dicht daneben ist auch vorbei 

habe gerade mal geschaut ob es im WWW ein Bild von der Unterseite des Cassis der M5 gibt, leider nichts gefunden

[Vladislav81]

Hello, Tobias, Manfred, Jan,

This was digitized by starting the M5 “cold”, after idling for a day.



Regards, Vladislav

[bitbrain2101]

Hello Vladislav,

here is a link to a  report of repairing the brake at M5A https://tonbandforum.de/showthread.php?tid=15367
You will have to translate it, its in German. 
The problems of your machine are at the underside of the deck, so video from the upper side does not help that much. You can only see the symptoms, but not the cause.

Regards, Tobias

P.S. Big thanks to Peter Ruhrberg for the report and to our moderator Andreas for repairing the link to the report

[Vladislav81]

Hello Tobias,

Thank you so much for the link.

I'll try to make a photo of the underside of my M5 today, if anyone is interested.

Regards, Vladislav

[bitbrain2101]

I'll try to make a photo of the underside of my M5 today, if anyone is interested.

Hello Vladislav,

try to make a video from the underside if the machine is in running playback mode. It is possible to run the machine in opened position. Foto is static only, you can not see any motion.

Regards, Tobias

[Vladislav81]

Hello Tobias,

Yes, big thanks to Peter Ruhrberg and Andreas.

Yesterday I've made a photo of the underside of my M5, I'll try hard to make a video within a few days.

https://disk.yandex.ru/d/19Tye5fh0NjsyA

I don't know if it's available in Europe.

In order to clearly see what is happening on the left (relatively to the upperside, that is on the right), I'll need to turn the upper part of M5 upwards at almost of 90 degrees. In this case, the top part (with mechanics) will hang only on the hinges. Won't the hinges break in 1-2 minutes while I'm shooting video? Or is it better to try to unfold the M5 and put it vertically on the chairs?

Don't know why, but my M5 works better (relative to the tension on the right), if I FF the tape at approximate of 100 meters and then rewind it to the start. And it can mishandle the tape after half of roll is done. Works better with 50 micron tape (EMTEC PER 528, for instance). Works worse with acetate based tape.

Regards, Vladislav

[bitbrain2101]

Hello Vladislav,

I can see the Foto, never seen the underside of the first M5 series. For running the M5 with open chassis, there is a bar to put under the chassis, like for the motor hood at a car. The chassis is in aproximately 45 degrees position then, what does not make problems. You can see it here on the 2nd Foto. Don´t be afraid, nothing will break in the open position.
http://www.tonbandmuseum.info/magnetophone-m5.html    
https://reverb.com/de/item/65336287-tele...el-tu-reel

Regards, Tobias

[Vladislav81]

Hello Tobias,

I know about this bar, but if I install the upperside on it, nothing could be seen on the left side of the mechanism (right side of the face). So I think I'll put it on the floor and open both sides at 90 degrees, so as to see what's happening there.

UPD: I made two videos today showing the M5 working from the outside and inside. The second time I managed to catch the moment when the winding problems started. Both videos are in the cloud, 4K / 60 fps.

https://disk.yandex.ru/d/x_KOJl90f-vkyQ

https://disk.yandex.ru/d/6vTRa49Ulk2JtA

Regards, Vladislav

[Magnettonmanni]

Hello Vladislav,

You have a very nice machine with a small mechanical fault.

Please do not attempt to operate the chassis vertically!
This is very dangerous and can result in serious injury. Apart from damage to the device.

The fault is probably in the axis of the drive pulley for the belt drive, possibly in connection with an incorrectly adjusted brake.


We'll see.

You need to approach the matter systematically and I will be happy to help you. This takes some time because I can't always react quickly.


At the very beginning,
I would like to ask you to re-enact the operating states, as in the first Peter Ruhrberg film I recommended. (Peter is one of the greatest magnetic tape specialists in the world, which you can count on your fingers.)

It doesn't have to be so perfect or fast, but all operating states should be run through with a test tape.

Short note:
The fact that the tapes behave differently is due to their different elastic moduli and not to the difference in thickness of 2 µm.
Belt, tape, winding core, feeler lever and belt drive form an oscillating system and the tape properties influence the oscillating circuit. 

With Best Regards

Manfred


With best regards

[Magnettonmanni]

Hello Vladislav,

Unfortunately I've only been able to see the films now.
The chosen position of the machine is a good idea.

But for the tests please use the normal operating position.
Please don't make the films so long
I have to pay for every bit. 5-10 seconds are enough for each operating state.
And then we'll see what happens next.

Regards

Manfred

[bitbrain2101]

Hello Vladislav,

thanks for the video clips. A little more light in the corner could be helpful. I have written to Manfred, that he will become the first supporter, because I know nothing about this old version of the M5 brakes.

Regards, Tobias

[Vladislav81]

Hello Tobias and Manfred,

I found out today that this fault is independent of the brake system. I moved the spring on the bar from the last hole to the penultimate hole. It didn't work. Then I loosened the brakes on the right side altogether. Again, almost no effect. Yes, there was less tape oscillation, but it didn't disappear completely. In my opinion, as a preventive measure, the bearings in the coaster coupling and in the rewind motor coupling should be replaced.

Regards, Vladislav

[bitbrain2101]

Hello Vladislav,

you can check bearings by hand and ear, feel that there is easy movement and listen that there is no noise by turning. If you wind the tape forward with lowest speed, does the oscillation of the tension arm occur too ?

Regards, Tobias