Hi all,
This is my primary Beocenter in the living room. Suddenly the right speaker cut out, I repaired the mute relay and presto there is sound again. Then I thought let's spin a cassette as I had aquired some nice prerecorded ones. All is fine, cassette spins and music comes out nicely when suddenly: nothing.
Symptoms are that, when a tape is loaded and play is pressed, the play array comes up. This is good. But that is it. Nothing moves. If I repeat this process without a tape in it I can see that the right take-up reel moves slightly back and forth (a notch).
I thought I could smell something burning, no smoke or anything. Just that smell. So, off the unit goes and onto the workbench (again). I can't find anything that is actually burned on any pcb (I would expect a burned resistor). Nothing seems out of the ordinary.
Tape belt is intact but likely a bit too slack. That said it worked before without a hitch on the same belt. I haven't ordered a new belt just yet because I need to work out if the deck can be saved first.
Any ideas if this is mechanical (in the tape deck) or electrical?
Thanks!
BB
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Beocenter 8500 - Cassettedeck stopped working
21 replies
Hi BB
Hardly could remember but there was a kind of smell in a Beocenter 9500 came from Resistor R131 on Board No. 20.
The PCB was burned, scrached it all away and coated it with some Nailcoating from my wife ( be quiet don´t tell her ;-))
It´s a 22 Ohm Resistor and in my opinion the resistor should limit the Current through the Motor.
As in your case there was nothing wrong with the belt or drive, mounted a new Resistor on "higher legs" so the PCB is not blackened anymore. Mounted a new belt, Member Dillen has the right ones, don´t buy somewhere else some work some don´t, belts from Dillen working always.
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Hope you´ll have success
Kind regards
Christian
Hi Christian,
I'll be damned, exactly the same resistor is burned to a crisp on mine. I'll replace it with one that can handle a bit more power. And i'll also put it on 'legs'. I have a Beoparts belt which is the best I know, so i'll put that on as well.
Let me see if this will fix the issue :-).
Bert
Hi Christian,
replaced the resistor but unfortunately no success. When I load the tape the array comes up and then flips itself (direction change) and then disengages. It never starts to run. Fast forward and reverse are fine so it's not the new belt.
Something must have bitten the bullet when the resistor died in flames. Oddly I can't find any transistors that are dead in the water in the circuit.
Bert
The resistor in question is in series with the motor and is there to allow the safety circuit to monitor the motor current.
A too high current will cause a high voltage drop across the resistor (that's ohms law), again causing the
monitoring transistor to issue a signal to the tape controller to stop the drive (in some Beocords/Beocenters take it into standby).
The resistor will also double as a safety fuse in severe cases, so DON'T fit a higher wattage resistor unless you want a house fire!
The resistor is not the problem - it merely indicates a problem.
Check the motor in the tape drive - seized?
Check the reel tables - seized?
And if the drive is the one-belt type, check the small idlerr at the extreme corner of the drive - seized?
Take apart, clean and relubricate accordingly.
Finally, check the power supply voltages - is the motor running at all?
The resistor is not marked as a safety component in all manuals, but it really should be.
Fit a good fusible (or at least flameproof) type of resistor.
Martin
(Apparently there is no longer a member called Dillen).
Good morning Martin,
Yes the burning resistor is indicative of a larger issue. I replaced the resistor with a 250mW metal film resistor, it should be fine. The rest of the mechanism is all ok, nothing seized and has a new Beoparts belt. It is a one belt drive. It was playing fine when suddenly it slowed down pretty fast and then stopped altogether. This coincides with the burning resistor.
But. It seems there is no power going into the drive. The motors in there are fine, I can turn them on external power, nothing is seized. This must be the reason why the drive isn't spinning. At least the capstan motor isn't getting any juice at all. I expect the other motor to be down as well (I'd rather not muck around with that one even on low external voltage because it drives a lot of gears.
I need to check these B&O schematics on where the power to the motors is actually coming from and if there are any dependencies on that.
Bert
Hmmm. The main motor should get 13.8v when engaged but is getting 0v.
As is usual with these B&O schematics I can't find where this 13.8v is coming from. It just magically appears in the schematics (see the red circle).
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BB
I tried tracing the 13.8v line. In the end it comes to a connector which is called C32 in the schematics. Sadly that line can't be found anywhere in the schema. I really, personally, hate B&O schematics. They are always so damn faultridden and overcomplicated. That said I expect that line to lead to a voltage regulator or something that is busted because there is 6v on the input line. Not 14v as the schematics show. Now where to find that doohickey......
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The connection is named C32, which means that it can be found on diagram C with number 32.
On diagram C, it is named F32 because the connection goes to diagram F.
Nothing strange about this.
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In other words TR17, C12 and F2. Check for cracked solder joints.
Martin
sorry it is very busy over here. TR17 was busted, replaced it with one from stock but that did not solve the issue. I need to analyse this further as it seems there has been a cascade somehow. That BD435 would not blow quickly at all.
- The voltage regulator (IC3) is good.
- The 2200uF cap is also good.
- F2 fuse is good
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