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!!!!!

Bert

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). 

Bert 

Do you have any DC across the motor, when you press TAPE on the panel?

Martin

Hi Martin, 

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 

Bert

Hi Martin, 

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. 

Bert

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?

Martin

Hi Martin, 

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, 

Bert

Make sure the belt runs between the components on the small PCB without rubbing on any.

Martin