uher: UHER report 4000-S

I have an UHER report 4000 -S in very good condition, except that the motor runs a few percent too fast when I test the recoder with my test tape. I have found a lot of information on the report 4000-S model, but no information on how to adjust the motor speed. It runs about 1,5% too fast.

I would be very greatful for any information or hint.

Bo Sörensson
Göteborg
collector of audio recording equipment

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Dear Bo,

the Uher Report 4000S has no Speed alignement. This motor has, in Germany we call it, “Tacho-Generator”
If You look at the alignement, you see three coils in the Motor. Transistor T10 induced a defined current in the coil signed with +.
The motor makes one short per round with coil at switch K4.
This short induced a voltage at pin K into base of transistor T11.
C34 is making a DC-Voltage from this impulse to base of transistor T12 and T12 makes a lower or higher Voltage at the motor.
You must control this Condensators.

But

1,5 % from 9,5cm/sec is a difference of 1,4mm per second

Do we hear that ?

It´s constructed for report and speach !

Many greetings from Germany

Hilmer

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Dear Hilmer,

thanks a lot for your answer, now I understand the speed regulation :)

You are right, this is a report tape recorder in mono and not intended for recording music or playing pre recorded tapes. I was only curious, because when I had followed all the instructions regarding tuning of the Report 4000 S, I played my test tape. And it was then that I could measure this slight difference between the 3000 Hz tone that the test tape had been recorded with and the playback tone. Sorry to say my old wow and flutter analyser is not working any more, so it is my hearing impression that says me that wow and flutter are OK for an open reel battery driven tape recorder.

I have also bought another Report 4000 S, so now I have a spare part stock. I had hoped that the motor in the second deck would be a little more quiet, but it is also quite noisy. However, I always wanted to have an UHER, and now I have one, or even two!

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Dear Bo,

I have restored already a few Uher 4000 series taperecorders and noticed also that certain units showed a slightly increased tape speed. Inspection of the motor drive pulley and the belt lead to the conclusion that the original 3-sided belt had been replaced by a rectangular or round crossection one. The original belt with 3 times 60° crossection fitted nicely into the pulley groove of the  motor drive. Obviously the different squared or round crossection ones did not enter the Pulley groove completely. The belt speed resulted therefore slightly higher which I guess, is the reason for the higher tape velocity. Maybe You can verify that the rubber belt is of the latter type, which would explain the speed You measured.

These belts are getting loose in almost all cases after so many years of operation and have to be replaced. Unfortunately the original 3-edged type seems to be unavailable. Replacements still available are of the round or square crossection type. Before You work around the motor control I would recommend You to look at this drive belt.

Good luck!

Felix Schaffhauser

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Thanks Felix,

You are absolutely correct, the rubber belt in my Uher is square! I think that I'll have to accept that the old type of 60 degree belts are no longer available. I tested to add a capacitor across the one that is described in Hilmer's answer (above), and I can absolutely influence the speed. Perhaps I'll accept the small difference in speed and use this Uher Report 4000 S for recordings which I'll play only on the same machine.

This week I visited the Radiomuseum in Gothenburg and I was lucky to find yet another Uher Report 4000, this time it is model IC. Of course the power amplifier is dead, and I have already ordered a new. But, this version has a three phase motor, and a very simple way to change the speed, so here I should be able to set the speed so that I can play tapes from other units.

I have looked at more than 10 units of Uher Report 4000, and I have found that in most cases the previous owners have not been careful with the batteries. The have leaked and cause damage to both the electronics and the mechanics - sorry to say. The advantage is that prises for open reel tape recorders are normally very low, with a few exception. The more advanced Uher MONITOR and of course the Nagras are still expensive. I think that I'll stay with Uher model 4000 :)

Thanks for all your help!

Bo Sörensson

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Dear Bo,
please load some pictures from the Museum to the musuemsfinder page.
Pictures from single models are welcome at the model pages with the museum's name in the note.
I need the model-ID to link model-page with the museum.

Greetings,
Heribert Jung
Museumsfinder-Admin

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