B67 rewind not working

[Michael Maurice]

Load the machine up with tape, press << Rew and measure the voltage at Pin 12 of J4 which should be an orange wire.

You should have more than 0.8V but not much more. Now measure the voltage on the base of the motor drive transistor, which is the green wire going off to the transistor.

OR

With the machine switched off and disconnected from the mains, set your meter to ohms and check the continuity between pin 12 of the transport board and the base of the transistor. It should be 0 ohms if it is much more or open circuit you will have to trace the break in the wiring.

There is one other possibility and that is that the transistor itself has failed. You could swap the supply and take up ones and see if the fault goes to the take up motor.

The transistor is a MJ411 but you can use a MJ413

Let us know how you get on.

Michael

[rotoman]

Load the machine up with tape, press << Rew and measure the voltage at Pin 12 of J4 which should be an orange wire(got .1volts)

You should have more than 0.8V but not much more. Now measure the voltage on the base of the motor drive transistor, which is the green wire going off to the transistor (got .1volts)

With the machine switched off and disconnected from the mains, set your meter to ohms and check the continuity between pin 12 of the transport board and the base of the transistor. It should be 0 ohms if it is much more or open circuit you will have to trace the break in the wiring. (Continuity 0 ohms)

There is one other possibility and that is that the transistor itself has failed. You could swap the supply and take up ones and see if the fault goes to the take up motor.(switched the transistors problem still there)

[Michael Maurice]

0.1V is not enough to turn the transistor on.

Now please remove the green wire going to the base of the transistor (~or remove the transistor and repeat the voltage measurement.

I think you should try a new transistor as it looks like its leaky base to emitter.

[rotoman]

Ok I will check tonight.
I can't seem to find that transistor online. Would you know if there is a cross reference number?

[rotoman]

I found a MJ413 on line ordered two.

[rotoman]

I removed the green wire going to the base of the transistor I got .001V
I actually got that last time not .1V in the previous post.

I removed J2 on the right sensor board, and got the the take up motor to work when I press play,in a counter clockwise movement, It will spin for about 4 seconds then stops. The supply does not turn when J2 is disconnected.
Since I got the take motor to work when J2 is removed a fault in the sensor board is a possibility don't you think?

[Michael Maurice]

I've found these people stock the transistor you're looking for

[rotoman]

Thanks, but I ordered 2 MJ413's the other day. What do think about the test I did with the sensor board in my previous post?
The left motor worked in a counter clockwise motion.

[Michael Maurice]

Originally Posted by rotoman

I removed the green wire going to the base of the transistor I got .001V
I actually got that last time not .1V in the previous post.

Where are you measuring it? you should be measuring on pin 12 J4

Originally Posted by rotoman

I removed J2 on the right sensor board, and got the the take up motor to work when I press play,in a counter clockwise movement, It will spin for about 4 seconds then stops. The supply does not turn when J2 is disconnected.
Since I got the take motor to work when J2 is removed a fault in the sensor board is a possibility don't you think?

No the fault lies either on the transport board or the transistor.

[rotoman]

I measured on pin 12, J4 of transport card, and got .001V on rewind, and when at idle. (no change)

The transport card was replaced with one that functions 100%

I swapped the transistors for the both motors, no change

When I receive the new transistor next week, I will try that.

[Michael Maurice]

Then I doubt the new transistor will make any difference.

I've run out of ideas for the moment, I'll take another look at the manual when I get a chance.

AFAIK full power is applied to the supply motor on REW and I cant see what else would affect it.

Did your new transport card come with the sub board fitted or did you swap them over? If you swapped it then almost certainly the fault is on that sub board.

[rotoman]

The sub board was already on the replacement.
I did find a right sensor board, should be receiving it next week, but if you don't think it's that then I will wait to see what you my find when you look at the schematic.
Please look at post #40 to see what voltages I got.

[rotoman]

I replaced the power transistor, and right sensor board, problem still there.
Don't know where else to look?

[whyperion]

Daft question , but , the device is in the USA using USA voltages , has anything in the device been set to expect European or UK voltages ?

[Michael Maurice]

The take up and capstan motors both work only Supply is not working so answer is no.