ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi all,
I am currently restoring three machines (2 * 8500 and 1 * 9500). On the 9500 the cassettedeck is completely dead. It doesn't do anything. When I press the cassette function the lid wil open and that is about it. Nothing else is happening. The motor doesn't turn on, the head does not engage, nothing happens.
This is a deeper problem than a few belts because if that were the case then at least the motor would be spinning. But that isn't happening. Simply put: it is completely dead.
Now, question is whether or not this is something that is even remotely fixable?
Any pointers would be welcome :-)
Kind regards,
Bert
Check supply voltages.
Martin
Hi Martin,
I would love to but the service manual is rather convoluted, I can't make heads nor tails from it.
The motor is not getting any voltage that is for sure.
PCB20 appears to be the primary PCB for the cassettedeck, right? I already removed the front panel.
Measured several areas and there are voltages in there, can't be 100% sure if they are correct.
I am wondering if the primary CPU is dead? This seems to be the control point.
Pressing the TAPE function opens the slide and then: nothing.
Can anyone help me out tracing the PCB?
Where to start?
What points to measure?
Help me make some logical steps tracing the route :-)
THANKS!!!!!
Nobody?
I have checked many things on PCB20, can't find any fault in the transistors. There is power going into the PCB. I can measure voltages and they seem OK. That said: I cannot say for sure because the voltages can be dependable on certain IC states.
But the "schematics" are very B&O. Meaning: unless you know what you are looking for: tough luck. It doesn't say anything about the flow so I don't know where to start. It doesn't say anything about the states of the IC's and their voltages in operation. Some transistors can simply not be found in the service manual. They are there but not in the schema. So to me this is a black box. As I said: press "Tape 1" = slide door opens; then absolutely nothing. No motors will run. The tape deck heads do not engage. Please help me trace thsis fault. Where do I start? What steps does it normally take? What voltages should I have at critical points? Otherwise this one is likely going to the parts bin (very sad).
Do you have any DC across the motor, when you press TAPE on the panel?
To test that I would need an extra pair of hands ;-).Let me see if I can juryrig something with wires.
But as far as I can see there is no voltage on the motor, it is dead as a doornail Chances of this motor being dead are very slim, i've only seen that happen a scant few times. Also nothing happens, it as if the command to start the tapedeck is never sent. I can't seem to access the components for the motor on PCB20 without removing a big soldered slab of something.
As far as I can see the power supply board outputs the right voltages. That said I did not remove it because I simply don't know how. It is wedged between the cd-player and the transformer somehow.
Regards
there are 4 (four) connections on the motor, I did not dare bridge them with my multimeter. There is a resistor + what I think is a thermistor that accounts for 2 (two) points of the four. Across these there is roughly 4.8v DC.
On the other entry points there was 9v and 3v. The 9v would be enough to turn the motor (even though it is on the low side). But again nothing happens aside from the voltages being injected.
I removed the tapedeck from the housing. The PCB of the cassettedeck was in bad shape, I reflowed the solder. No effect. I can see the main belt is missing though I can't see how to get at it.
So basically "some" DC voltage is going in, but nothing happens.
Can you give me some DC voltage readings:
- on the emitter pin of transistor 20TR31- on connector P42 pin 7- on connector P42 pin 8
All with reference to ground?
I would love to check that transistor but it does not exist. It is in the schema but it is not on PCB20 (neither the adjacent transistors).
Today I dismantled the back of the deck. The belt had completely disintegrated on the spindle. I cleaned the hell out of it. Then I replaced the belt At least I think I did it the right way.
Now there is some progress. When I press 'TAPE1' the motor will try to spin. I can see that the secondary belt is moving. This is the small belt.
But the mechanism doesn't move (with the large belt). Also it seems as if the heads do not retract / activate.
Perhaps I have installed the belt incorrectly. I could not find any usable instruction so had to guess. It is around the black disc, then the second wheel. The first wheel is last and only touches the belt on one side. Then it goes to the pulley (which goes to the motor).
When I press TAPE-1 I can see it wants to rotate but it's stuck. Or something to that end.
Any ideas?
Regards,
Make sure the belt runs between the components on the small PCB without rubbing on any.
I checked the belt and the big flywheels. As far as I can see it is on correctly.
But I can only rotate the flywheels about half a rotation (left or right).
After that they become 'stuck' as if they are locked.
I have absolutely no idea what would cause this.
From your shop i've seen the 9500 belts you have and will order them. I am now simply using belts to test the device; they will work for that purpose.
One thing I am unclear of is that your set has three belts. I can see two belts, yes. But the third belt is unclear to me, where does it go? It might be that this missing third belt is what is causing the current issue?
final update for now.
I have removed the large flat belt. The two big flywheels can spin freely. It is the big black plastic wheel that is the problem. That one can spin half it's rotation (left or right) and then blocks.
Is this because the third belt is missing? Or is there another mechanism that causes the block?
The service manual I have is for the 1st iteration, this is the second. I've not been able to find any service manual for the 2nd iteration with details about the mechanism.
Ok, last for today. Was up early so had some spare time.
I traced where the third belt had to go and inserted one from stock. Still no luck. Odd. Then I checked my reflow work. Lo and behold, a tiny solder bridge almost invisible to the naked eye.
After reworking the pcb, it starts. Heads are retracting / advancing. Motor pulleys are all good, flywheels are good.
I can insert a tape and it will play. Obviously I need to redo the work with 'real' belts (these are just for testing).
So. It appears that the mechanism in this B&O simply won't work without belts. This gives the appearance of a fault outside of the tape mechanism. Based on experience I would expect the motor to turn even without a belt. It does not. All of this is likely because of the IC's governing the "boot-up behavior" etc.
Had some spare time while waiting in the lab.
It seems that at least some of the issues were because the previous owner tried to swap the belts (or something to that effect).
When I reinstalled the housing it did not work. When I had it in hand, it worked. Really odd. On further notice it became clear that the black upper housing should be screwed to the platform. These screws were missing of course. Luckily I had B&O screws of the right type.
Now it is playing, finally. Haven't tested the sound quality because these are testing belts. Likely it sounds wobbly. Will let my test tape run a full course to see if it holds up.
Of course now the sliding door is not working right. Back to cleaning and lubing it seems. Always something with these B&O machines.
Nope. Still some issues.
--> First of all; the STOP does not work.
--> Secondly; the autoreverse reverses the tape before it has ended.
@Martin, are these common issues with these machines? I can remember that the two 8500's also had this issue, that STOP did not work in any way.
Perhaps you can shed some ideas?
So,
repaired the stop function; it was a transistor acting up in the chain.
Now to work on that auto-reverse problem, need to dive into the circuit
Hi
Just had a similar problem, tapedeck worked so far played both directions but fast forward only one direction.
The culprit was a junk belt I bought on the big auction house.
That was absoloutly the last belt I bought there, the belt seems to fit but for the last pice of turning the gearwheels it's not enough even that the capstan wheels did not stop or going slow visible.
For testing I took the old belt, cutted a piece about 1,5 cm out reglued the belt and voila the tape worked again.
Lesson learned...don't buy on e....
Ordered a belt set at Beoparts DK that worked without any problems.
Kind regards
Christian
Hi Christian,
Okay that seems to make sense, I was using test belts because I wanted to discover if the mechanism was faulty (as it seems). I've now ordered 'real replacements and am hoping to install them next week.
That said, the mechanism is rather finicky ;-)