Suche Kenwood Stroboskoplampe

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yawara
Stammgast

#1 erstellt: 02. Jul 2007, 09:40

Hallo!
Ich habe einen Kenwood KD 5033AF Dreher, bei dem das Stroboskop nicht mehr richtig läuft. Also mal geht es, dann wieder nicht....wenn ich den Pitcher etwas drehe, geht die Lampe dann wieder an....dann fängt der Dreher aber etwas an zu leiern. Möglicherweise zieht dann der hohe Stromberbrauch die Motorleistung kurzzeitig etwas gerunter. Ist die Lampe hin? Oder deutet das "Hin-und-Wieder geht sie" auf einen Defekt im Netzteil oder sonst irgendwo hin?
Gruß Janko

tri-comp
Stammgast

#2 erstellt: 02. Jul 2007, 10:42

Hi,

This is just a guess, because I don't know the KD-5033:
Older turntables have a NEON lamp as stroboscope light.
When the lamp get's old it will start to flicker much like the ordinary neon-lamps you know for lighting of the house.
You then have two options:

1)
Replace the lamp (NE-2 is most likely what is used here) Take a look at:

http://en.wikipedia.org/wiki/Neon_lamp

2)
Lower the series resistor. In most cases a resistor between 470K-Ohm and 1M-Ohm is used. It should be safe to lower it to 100K-Ohm which forces more current through the lamp stabilizing the glow (But also accellerating the wear)

....of course your turntable may NOT use a NEON-lamp in which case all the above should be disregarded entirely

Kind regards,

/tri-comp

yawara
Stammgast

#3 erstellt: 03. Jul 2007, 14:08

Hi Tri-comp!
Thank You for support! I*ll have a look inside my turntable at the weekend....maybe it is a NEON-Lamp....but the Lamp needs about 100V!?!
Bye J

tri-comp
Stammgast

#4 erstellt: 03. Jul 2007, 17:46

Yes, it needs from 90-110V. That's why it has a series-resistor to limit current. 220V AC directly will kill it instantly!
Actually it functions like a kind of Zener-diode.
When you apply voltage slowly from zero and up, the lamp will fire (turn-on) at around 100V. If you apply more voltage (through a current limiting resistor, of course) the lamp will conduct more current to keep the voltage across it stable @ 100V. This ability is used in old Tube-amplifiers where the power-supply can be stabilized. Here the Neon-lamp is used as a zener, or in case higher current is needed, some specialized tubes like the OA-2 / OB-2 were used. They work much like the simple neon-lamp.
When you connect a NEON-lamp to AC, both electrodes light up.
When it's connected to DC, only one is lit.
Flickering light & black coating of inside indicates end-of-life