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GELÖST - STUDER B67 MkI : kein Aufnahme

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Beitrag Dienstag 5. Juli 2016, 14:43
Thierry Jungspund
Jungspund

Beiträge: 5

Hello there,

Sorry for writing in english but I don't really master Deutsch.

A friend asked me to overhaul his Studer B67, which I did : all electrolytic and tantalum capacitors have been replaced on all of the audio boards, stabilizer and oscillator boards.

On the Tape Transport Control Board 1.67.761 I also had to replace one of the spooling motors control ICs (one TCA561 was dead, and it costs a fortune).
After the base revision was completed I started the calibration process as per the Service Manual : demagnetization, playback head azimuth, output levels, frequency response etc. And then I wanted to start the record amplifiers calibration but, and it is a big BUT, the machine doesn't record anything on tape !

Of course I first suspected something wrong in the record amplifiers, so I swapped them with my own B67 record amplifiers, to no avail.

I also checked voltage at pin J3-10 (Y-REC) on board 1.67.761 to find that when RECORD function is engaged by pressing RECORD and PLAY keys together, it drops from 12V to 0V. So I assume that Q12 base conduction is activated by IC1 (SC10429), concluding that it is alive and working. When machine is running in recording mode, tape is normally erased and the oscillator frequency is exactly 150KHz, so there are no issues there. All other functions are working normally.

This B67 has no VU-meters nor control panel. Of course I verified correct jumpers position on interconnection board, and I also visualized with the oscilloscope and 1KHz generator that input sinusoidal waveform arrives intact on the record amplifiers inputs.

Now I'm lost and I don't know where to look for fault, could someone put me on right tracks please ? I am running out of ideas...

Thanks for your help !

Thierry
Zuletzt geändert von Thierry am Samstag 9. Juli 2016, 22:33, insgesamt 1-mal geändert.

Die hier gezeigte Werbung wird nicht durch "Das STUDER und ReVox Forum" bereitgestellt, sondern automatisiert durch Google. Grundlage sind die verwendeten Schlüesselwörter in den Beiträgen. Besucher dieser Links werden gebeten sorgfältig mit den angebotenen Produkten/Seiten umzugehen.
 
Beitrag Donnerstag 7. Juli 2016, 21:12
studer289 Trippel As
Trippel As

Beiträge: 133
Hello Thierry

Welcome in the Revox and Studer forum....oder so ähnlich ;-) ;-)

Warmly ;-)

Clemens

Beitrag Freitag 8. Juli 2016, 09:28
Thierry Jungspund
Jungspund

Beiträge: 5

Danke sehr Clemens !

Beitrag Freitag 8. Juli 2016, 21:00
Bricksounder Haudegen
Haudegen

Beiträge: 243
Wohnort: "ländlich" - zwischen Bodensee und München
Hi Thierry,

I have no B67 myself, but isn't there an enable switch ???
on the later Studers you have to switch from save to ready
this enables the record mode
look after this and check how that works on your machine

best regards
Ralf

Beitrag Freitag 8. Juli 2016, 21:08
Thierry Jungspund
Jungspund

Beiträge: 5

Hi Ralf
Thanks for the suggestion but it's a "no Vu_meter" B67, hence no ready/safe switch.
Regards
Thierry

Beitrag Freitag 8. Juli 2016, 21:27
Bricksounder Haudegen
Haudegen

Beiträge: 243
Wohnort: "ländlich" - zwischen Bodensee und München
hmm,
the A810 without VU have still a ready save switch
are you sure there is no "enable" Signal for ready, which has to be
switched or hard wired ???
sorry for haveing no better idea

Ralf

Beitrag Freitag 8. Juli 2016, 22:44
cavemaen Benutzeravatar
Lebende Forenlegende
Lebende Forenlegende

Beiträge: 2455
Wohnort: 34582 Borken / Hessen
Wenn der Bauteile tauschte, könnte er 'n Kondenser falsch rum verlötet haben oder so, falls das Luder vorher gelöscht haben sollte.

Wenner da noch nie inner Maschine gelötet und Erfahrungen hat, kommt er da nit weiter.

Da musser das Manual auf 'n Schoß nehmen und logisch bei der Fehlersuche vorgehen, oder das Luder jemanden bringen....

Beitrag Samstag 9. Juli 2016, 08:32
Thierry Jungspund
Jungspund

Beiträge: 5

Hello,

Thanks to posters for trying to help.

To make things clear this is the B67 exact model I am working on :

Bild

As you can see there is no "Ready / Safe" switch, only the usual red RECORD pushbutton.

The jumpers on the Basis Board (1.67.700) are in positions I and L, as per the Service Manual :

Bild

@ cavemaen : all audio boards are perfectly working, after the revision I installed them into my own B67 and they work flawlessly, so the problem is definitely not a consequence of the overhaul.

This is my B67 : (https://lh3.googleusercontent.com/-esiUSY9kKZM/UYZkyctvsHI/AAAAAAAAdBI/YxGYa-huyrkm_Nb2gSuqYaOYYB4tuEHUACCo/s800/P1030158.JPG)

Thierry

Beitrag Samstag 9. Juli 2016, 22:32
Thierry Jungspund
Jungspund

Beiträge: 5

Problem solved ! Issue was down to some bad (corroded) solder joints on the Basis PCB 1.167.700.

Special thanks to Ernst (Pievox) who guided me toward unexplored tracks so far. Always better to have an expert advise.

Thierry

Die hier gezeigte Werbung wird nicht durch "Das STUDER und ReVox Forum" bereitgestellt, sondern automatisiert durch Google. Grundlage sind die verwendeten Schlüesselwörter in den Beiträgen. Besucher dieser Links werden gebeten sorgfältig mit den angebotenen Produkten/Seiten umzugehen.
 

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