Author Topic: Ghost in the Machine?? Item turns back on after being turned off. Panasonic  (Read 1312 times)

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Offline gooseEL34Topic starter

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Hey guys
I am handy with a VOM, oscilloscope and soldering iron but I mainly work on non-micro-component devices (guitar amps and pedals).
I have a favorite CD/Tape/Tuner unit in my shop.  It is a Panasonic SA-PM39D and here is the symptom:

A few seconds (10-15) after I turn it off (hit the soft push button), it will restart in demo mode.
I hear a relay click when I turn it off and again when it turns back on spontaneously.

I really do not know how these type of units do their switching on and off.  I am assuming that I might have some issue in the circuit whereby a relay is not holding open or closed based on a voltage dropping or being applied due to a bad cap.

Might I be in the ballpark?  Also, with no online schematic, I am just guessing at this point.

Any help would be appreciated.  You can talk in EE terms as I am aware of the basics (I understand resistor, capacitor, electrolytic cap, relay, short to ground, etc...).  Digital logic and solid state design is my weakness as my stuff is generally basic (take 120v wall voltage, step it up to 390v and then filter it and supply it to the various tube stages).

Thanks



Tim
 

Offline singapol

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From pg.9... Look at the pg.9 link.  Picture is worth 1K words. :)

When the unit is first plugged in, a demonstration of its
functions may be shown on the display.
If the demo setting is off, you can show a demonstration
by turning on the demo.
The display changes each time the button is held down.
Demonstration
(demo on)
@
A
  NO DEMO
(off)
You can reduce the power consumed in standby mode
by turning the demonstration off.

Note
You  cannot  turn  the  demo  function  on  and  off  when
the unit is on


Page 9:
http://www.datasheetspdf.com/PDF/SA-PM39D/635951/9

User manual-
https://support.panasonic.co.nz/docstore/SC-PM39%20Operating%20Instructions.pdf
« Last Edit: September 20, 2016, 04:37:30 pm by singapol »
 

Offline Len

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It's not the only haunted radio to turn up recently:
https://www.eevblog.com/forum/blog/eevblog-922-mailbag/
 :scared:
DIY Eurorack Synth: https://lenp.net/synth/
 


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