grundig: Gundig Satellit 600 repair - No LW/MW/SW/FM

The radio gradually became intermittent on A/C mains, then a year or so later became intermittent on batteries.  Finally it would function only as an audio amplifier.  The clock worked, but none of the reception bands functioned. The problem was finally traced to an internal board leakage that I surmise is caused by contamination.  The problem was repaired by isolating the circuit line connecting pin 1C on the power switch to resistor R832.  This connection is routed through connector STV603 pin 2. 

The failure was evident by the presence of a voltage ( +9 volts if used on batteries, approximately 20 volts rectified DC when running on A/C mains)  on power switch pin 1C with the power switch in the ON position.  In this position, the voltage on pin 1C should be zero.  When the voltage rises above about 3 volts on this line, transistor T811 is turned on which activates the uProcessor IC802 IRQ line, which stops the uProcessor.  It appears this feature was included in the radio design in order to quickly mute the receiver and return the display to the clock function.  The radio will operate properly if R832 is completely removed, however it will take a few seconds for the clock display to return. 

After repairing this set, I have had two other associates report similar symptoms on their Satellit 600 sets.  This might be expected if manufacturing process contamination on the circuit board is just now beginning to surface.   I hope to report that they have also been successful with this repair. 

 

Attachments:

• Satellit 600 Power Switch (80 KB)
• Satelllit 600 uProcessor halt circuit (55 KB)

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Auch mein Satellit 600 zeigte die Probleme wie von Herrn Weigel beschrieben.

Bei mir bestand die Lösung im einseitigen Auslöten von R832. Seither funktioniert das Gerät wieder einwandfrei.

Besten Dank an Herrn Weigel für die hilfreiche Dokumentation!

Freundliche Grüsse, Walter Haring

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