Hello,

I've read that topic-thread and I downloaded the manuals. Thanks!
But, there is no voltage at the main board. I tried every Netzteil pin, but there is no any voltage in the Grundig 2x4. I checked all the mainboard and netzteil pins it looks good, the're no oxyded/bad soldered pins. Very strange! Maybe the trafo is broken. (the trafo gives not a relais "sound") The power buttons are still good.

Berrie

Hello Berrie,

the power transformer does not make a sound at 50 or 100 Hz - it´s a switching power supply, that works at a frequency of a few kHz, so you can not hear it.

Also check the fuses, pos. SI 422 (primary fuse, 1,25 A) and pos. SI 431 (secondary fuse, 500 mA).
And then, you must check one thing after another, in a systematic way.
- Check the voltage on C 431 (150 µF/385 V).
- IC 401 can also be bad, so that no voltage goes into the power transformer.
- If there are all voltages on the primary side of the transformer, check the voltages on the outlet side of the transformer as shown in the service manual.
- If you still guess, that the transformer is bad, you must put it out from the printed board to check the coils of the transformer for breaks.

ATTENTION: Be careful! All parts on the primary side of the transformer are live area, mains 230 Volts!!!
For checking and reparing always use a isolating transformer!
And also very high voltages are present at the primary AND the secondary side of the power board!

Best regards and good luck!
stego

_________________

Hello Berrie,
i got an 2080 (it's the same model with longplay) and the powersupply doesn't work (like yours). The primary fuse SI422 (T1,25 A) was blown.
one of the 2,2nF capacitors around the diode bridge got a short.
After replacement, the powersupply works.

Good luck and never give up

ST3026


An Stego:
herausgefunden habe ich den Fehler ganz leicht, Netzteil ausgebaut,
Sicherung 422 eingesetzt und Sicherung 431 entfernt. Netzteil mit Trenntrafo betrieben und Spannung langsam hoch gedreht. Bei ca 30V hat's dann "zisch" gemacht. Und der defekte Kondensator war leicht zu finden...

Vielleicht kannst du es mal ins englische übersetzen, meins ist da nicht so gut.

@ST3026:

Danke für diesen Hinweis!
Ich habe Berrie schon geschrieben, er soll beide Sicherungen prüfen. Wenn wir das Ergebnis hier lesen, geht´s weiter. Wir müssen hier systematisch vorgehen, da nicht alle Netzteil-Ausfälle genau die selbe Ursache haben. Wobei dieser Fehler natürlich durchaus möglich wäre.
Wir wissen außerdem noch nicht, ob Berrie einen Regel-Trenntrafo zur Verfügung hat. Daher auch der Sicherheits-Hinweis in meinem vorangegangenen Posting.

@Berrie:

ST3026 wrote, that he has found the failure in his power supply very easily: He took away the fuse at pos. SI431 (500 mA) and replaced the blown fuse at pos. SI422 (1,25 A) with a new one. Then he plugged the power supply to his variable isolating transformer and increased the voltage, beginning from 0 V. And - at approx. 30 Volts the fuse SI422 has blown again!
Now it was very easy to find the defective capacitor, as he wrote.

Best regards!
Viele Grüße und Danke @ST3026!
stego

_________________

Thanks for the reply's!
I will try the anwsers tomorrow.

Berrie