grundig: (SO 162 US); Stereo Console SO162US

 I wanted to ask about a problem I am having with my unit, I wanted to see if others have experienced the same or if I really have a problem. My unit works but seems to be a little "hot" when in FM mode. What I mean by this is that the EM84 indicator tube goes full scale on almost any FM station that can be recieved. This does not happen on AM. The most obvious problem compared to the print is that the plate of the EBC41 tube has 76v when in FM and it should only have 34v. The AM and  PU voltage readings are correct.

Could this have anything to do with the changes in FM broadcast standards since this unit was built? If I really do have a problem could someone maybe point me in a likely direction? This tuner is just too sophisticsted for me to analyze and narrow down a fault.

I should add that the unit has been recapped and the problem is not any of the tubes.

Thankyou, Brad.

Attachments:

• schematic (121 kb)

Hello  Brad.

 
As an installation you find a drawing. From that one it is clear how the length of the lighting-beams with the antenna signal is changed.

On a FM radio with strong limitation of the IF-Signal, the advertisement very quickly at the end is.

Thats only a tuning indicator not a fieldstrenght meter. On AM she follows it over a wide range,  the antenna-signal

Please observe this detail.

If you want, read here forlimiting

Attachments:

• FM Limitercurve (23 kb)

 Thank you for the information Mr. Knoll. I can see that the response of the EM84 is very different on FM and my radio may be working correctly.

Would you or anyone else have any ideas on the high anode votage on pin 2 of the EBC41 when in FM.

Brad

Hello Brad.

Íts verry difficult. Only one: test the R35 22 Megohms and R32 1Megohm..

Hans

 I will check those.

Thanks again, Brad.

 I will first apologize to Herr Knoll specifically and the RM community in general if you feel it is in order Herr Erb. However, I would like to defend my actions and suggest that you may have misinterpreted the exchange between Herr Knoll and myself.

 If you read the posts, you can see that Herr Knoll's last post said that my specific problem would be very difficult to diagnose and then directed me to two likley faults. I took this as a polite way of saying the conversation was over because it was unrealistic to expect him to take the time to troubleshoot and diagnose my radio over the internet. I agreed with him. As a new member I was trying to not "wear out my welcome" by asking other members endless questions on specific problems.

 Please be assured that I was only trying to be respectfull of Herr Knoll's time and did not want to be seen as abusing my membership. I hope this will clear up any misunderstanding.

  P.S. I will check the resistors shortly and post my findings.

Yes, please do that ...

We are still waiting for your measurements ...

The resistors both checked fine.

I have reassembled the unit for the moment and it sounds nice to me. If I need to open it up again I may look into this voltage reading a little further.