Grundig RPC 2500-2 Radio DEFEKT

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Tolis_athens
Neuling

#1 erstellt: 27. Dez 2011, 19:13

Hallo from Greece.
Sorry i don't speak German, I just joined and i need all the help i can get from the forum.
I have an Grundig RPC 2500 which worked great all those years.
Suddenly the radio stopped to function and i hear nothing but a FFFZZZZ and no stations all over the scale, either in FM or LW or MW. When i try to change stations go only 0,05 MHz up or down and then everything "locks".
Cassette and Turntable works great.
I found a topic with the same problem but i cannot understand the internet translation and how our friend fix the problem with his stereo.
Its a great looking compact stereo. Please if anyone can help me email me at: t.tsakmakis@gmail.com or give an answer to this forum.
Thanks in advance.
All the best from Greece,
Tolis

anymouse
Inventar

#2 erstellt: 27. Dez 2011, 20:38

You mean

this thread?

Sounds really like the same situation -- luckily there is also a solution given. I do not have the device, just translating the other post.

Do you have a voltmeter? Can you measure the 32V-rail-voltage (this should be printed on the board)? For axel.jahr this voltage collapsed to 0V, due to a defect in the PSU.

If this is true, check the following: in the PSU there should be a (now maybe defective, maybe not) Zener-Diode (seems D322). Parallel to this Z-diode is a tantal-capacitator, which developed a short.

axel.jahr replaced the capacitator with a electrolytic capacitor with a sufficient high voltage strength, and the Z-Diode with a 33V new one.

------------

Translation of axel.jahrs post:

I'm having problems with a cult Grundig RPC 2500-2 compact system! Everything works, except for the tuner. It just produces produces static noise, the memory channel can be adjusted manually, the frequency can be adjusted manually only once for 0.05 MHz and then the tuner locks up.

In any case, the 32 V supply is defective. I hope everything else is secondary error. I measure 0 volts, where on the circuit board is printed 32 V. In the power supply sits a charred (!) Z-diode and a suspicious (perhaps defective=) transistor next to it (may be already replaced once before my time?). The Zener diode is certainly defective. Unfortunately I have no service manuel for the device and on the diode nothing except "ITT" is left readable.
Has anyone here a schematic diagram of the device or can tell me what are the diode D322 and T322 Transitor for parts? Perhaps also the values of R465 (560 ohms?), R466 and R380 (4.7ohm?)? That would be great.

Hi all,

Problem solved: It was probably once an electrolytic capacitor in parallel to the Z-diode replaced by a too tight tantalum electrolytic capacitor. This was a short circuit. Now I have a Elko with higher voltage strength and provisionally two 15V zener diodes in series in it and the RPC works just fine! :-) I measure at the 32V-rail now 29 V, therefore the two Z-diodes should be replaced by a 33V-Z-diode (which I don't have here of course).

To calibrate the tuner, the service manual for the R500 should be sufficient.

regards
Axel

I hope, this helps.

[Beitrag von anymouse am 27. Dez 2011, 20:39 bearbeitet]

Tolis_athens
Neuling

#3 erstellt: 28. Dez 2011, 17:34

Hallo to the Forum.
Thanks to the answer given by our friend anymouse, problem SOLVED!!!!!!!
I just finished the repair and everything its perfect.
Radio stations loud & clear. Up & down search (both manually and automatic) works fine.
My German friend i have no words to express my gratitude.
Thanks for your time and effort for the accurate translation.
All the best and Happy New Year,
Tolis