Conn Strobotuner faulty

[Esppse]

Hey guys,

Does anyone know what may be wrong with this Strobotuner ST11? I turn it on, and the light works, it lights when I play a note, or stays lit in calibrate mode, but does not spin.

[ElectricDruid]

Does anyone know what may be wrong with this Strobotuner ST11?

Someone's left a can of tuna inside it!

(Sorry, no real idea)

[PRR]

Of course there is tuna in a tuner.

Does it spin when GENTLY pushed with a finger? Or is it seized up?

Blind luck: press all the chips into their sockets with your thumb. I used to fix Apple][s that way.

I'm sure the service manual is out there.

(Last Strobo I had used vacuum tubes.)

[Yazoo]

In case this helps - there is a video on Youtube of a repair on this model

Uncle Doug also has a video on the repair of a valve/tube-based model.

[Rob Strand]

Service manuals and schematics (solid-state)
http://home.grandecom.net/~garybrookshire/files.html
http://home.grandecom.net/~garybrookshire/files/ST11_Manual-Schematic.jpg

You can see the motor drive at the top center (after rotating for humans) of the schematic.
Looks like a 2-phase synchronous motor.

If you have an oscilloscope: Follow the signal from pin 10 of the 72185-001 then through the 4k7
and then to the collector of the first transistor.  After that check the motor output where the two
emitters join.   Probably worth checking the 100uF and 5u6 caps haven't dried-up as well.
You can also check the DC resistance of the two motor coils.

Without an oscilloscope you will have to use DC measurements to guide you along.

[PRR]

Just to be sure, check power supply. We know the Neon works, but I don't know if the logic and motor rails have been ruled in/out yet.

Also the thing may be 40 years old and may have been left un-powered a very long time. I'd want to look for ripple at the two thousands-uFd caps or, if not convenient, just replace them on suspicion.

[Esppse]

Ok ill try out the suggestions thanks, I know it's not worth much, if I can't get it to work, it makes one darn good night light.

[Rob Strand]

Ok ill try out the suggestions thanks, I know it's not worth much, if I can't get it to work, it makes one darn good night light

Short of the motor being fried I think it's fixable.