I have a problem with the tape deck on this kit. Originally, when I got it, the tape didn't work. When I removed the deck it was clear the drive belts had changed to black goo. They were so bad it was impossible to see where they fitted.  I could only find two sets of drive belt pulleys so I got new belts for these. I did check the motor by switching on and from memory I am sure it actually spun.

When I reassembled it there was a big let down. Selecting tape with cassette in place and the heads moved into place but returned after about a second. The symptom is almost as if there is a tape sensor that has detected the end of the tape. 

My first question is :- Have I missed something? because I have come across a tape deck somewhere that had a tape motion sensor driven from the feed spool. I don't know where to look next as it is not easy to check the power to the motor if that is faulty so I would be glad for any suggestions to get me started.

Thanks

John

Hi John,

There is a motion sensor but check first that the right tape reel actually
rotates when the tapeheads engage at play.
If it doesn't, the problem is not with the motion sensor but could instead be a
seized reel spindle or, more likely, something mechanically incorrect (maybe
the belts are not correct or not mounted correctly or both).
Could also be a dry spot in the clutch mech.
When play is activated, the tapeheads are supposed to engage and the capstan is
supposed to start rotating. At the same time, the right reel will start rotating to take up the
tape as it gets played (and also catch eventual slack).
On most of these lovely machines, the capstan will actually continue to rotate
even if other sources are selected and first stop again when the Beocenter is
put into standby.

There are two belts in the tapedeck section. New belts are available as a set
(worth grabbing a set if you are unsure if yours are correct) and mounting
instructions can be included.

Note, that if you don't lift up the turntable section and free the tapedeck
cables while servicing the tapedeck section, you may easily pull the
tapedeck cables hard enough to cause their respective plugs to lift off
their pins where they connect to the board under the turntable section.
Depending on how many - and which - pins got lifted, the
resulting symptoms vary but it's always worth checking that all plugs
are correctly seated here before diagnosing elsewhere.
This applies to Beocenter 5000, 7000, 7002, 7007 and 7700.

Martin

Thanks for the information Martin. It is reassuring to learn there are only two belts. I must have a more serious problem, when I select any function neither of the spools rotates nor do I see any signs of the capstan rotating. I had wondered whether the motor had failed but I am still certain that it worked before I took the deck out

I did unplug the deck to clean the mess from the belts but the main multi plug was very stiff to remove and I might have done some damage there. I will have to look at that very carefully before anything else.

Regards

John

I have looked again at the workings with all opened up and a tape in the holder. The connector is properly seated but there was no sign of movement anywhere except for the heads. 

I removed the belts and the motor showed no signs of life. There is indication of power to the deck because when switching on the supply there was a click from some relay and a light under the tape lit briefly.  After standby when TAPE is selected this orange light lit under the cassette and the heads moved into position for about one second then retracted. The light now stays on until the supply is switched off.

  I am still puzzled why the heads retract again and this makes me think there is some interlock that has been disturbed and the motor may in fact be O.K eve though it never spins. I can not think of a way of checking the motor without removing it completely and this seems a bit hazardous.

I hope these observations might help someone to tell me what to do next.

Regards

John

Best thing to do is to measure the voltage to the motor after pressing play.

Martin

Thank you Martin,

I think I have found the points to measure the motor supply and have no voltage. Just to confirm that I measured the right place, a black and a red lead come out of the motor sub-assembly. They go to a small pcb near one of the solenoids and the red lead connects with an orange lead from the wiring loom. This is where I made the measurement.  I assume the orange lead goes back to the multi plug and socket on the board under the record deck.

I intend to trace the orange lead back to the plug and then disconnect the plug and see what appears on the appropriate pin if this seems sensible. At least at this stage it seems I have not a problem with the motor.

As a matter of Forum practice would it be better if I restarted this thread in the Vintage section or is it O.K. here?

John

I have traced back the orange to the connector and the voltage on the orange pin is about 3v and the black pin about 0.5v. I had assumed that the black lead would be returned to the common chassis but there is no connection between the relevant pin and the chassis so perhaps I am wrong.

John

There's a transistor (11TR13) between the motor negative lead and ground so don't
expect the motor negative lead to be at 0V. About half a volt seems correct.
With reference to ground, you should have something like 13-15 Volts on the
motor positive lead, that'll be on plug P2 pin 11.

If you don't have this voltage, you will have to trace backwards towards the supply,
which is at plug P11 pin 1 (regulator output).
Still no voltage, check the fuse F2.
Check also plug P24, the voltage goes through that one too.

The schematics are downloadable from our main website for silver and gold members, easily
worth the small membership fee.

Martin

I think I have found P11 but the printing is obscured. The plug I measured is close to the tape deck. Pin1 which is next to the space on the socket and has a green lead shows 5.6 v.

I am not sure where the fuse is located but I have found one on the same board with no label but marked as 1A slow blow. This is sound.

I am assuming that the motor is probably O.K. and the problem is elsewhere. I have difficulty in finding my way around the diagrams in the service manual so I will have to be helpless and ask where to look next. I am not sure that I checked the right fuse but I can only see the one. I am not very confident about this, I have previously had a fuse problem and found although I checked the two obvious ones there was another hidden away.

John

The fuse, I am referring to, is on the large board near the cooling fin that also
holds the amplifiers etc.
The board coordinates are B2, again referring to the printed "squares" on the board.

Martin

Thank you Martin for your reply. Yes it was the fuse I checked and it is O.K. There is another fuse at the other edge of the board near a two pin connector. This is marked 4A slow-blow and this too is sound. 

Did you check the voltage at the regulator output ?

Martin

Yes Martin, I have rechecked the voltage  on pin1 of P11 and there is voltage there but it is only 5.5v. The plug I checked is a brown one near the tape deck and across the boundary between sections C and D on the pcb. The plugs are not easy to identify on my board but I think I have got it right.

When I checked it originally I had thought it was a 6v line and so would not be serious. Looking back at your earlier replies I now think I should expect to see about 13v. 

I have now got the downloaded service manual but struggle to follow it as the drawing convention is not familiar to me.m No doubt this will get easier with practice.

John

I have come back to this Beocenter after a break and checked measurements again. On plug 24 I checked the voltage on the brown lead coming from pin 1 and this is 13v.  I am assuming this means that the power unit is working O.K. I must be misunderstanding the wiring diagram because it looks to me as if there should be 13v also on pins 2 and 3 but this is not so. The fuse F2 is sound but there is no voltage on it . These measurements were made with the tape unit unplugged.

Does the  c shaped symbol represent the socket of the plug/socket combination?  I am also assuming that the thick black line with triangular arrows represents the wiring loom but I find difficulty in finding the other connected plugs are placed.