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Old 11th Oct 2019, 6:34 am   #1
Michael Maurice
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Default Grundig Como 5/GB radiogram

I have been working on this Grundig radiogram.


VHF reception is fine, but on all AM bands, LW, MW, SW, all I get is constant static noise with no stations being able to be tuned in.


Has anyone any suggestions as to why?
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Old 11th Oct 2019, 8:15 am   #2
PJC58-Hythe
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Default Re: Grundig Como 5/GB radiogram

Have you checked to see if the local oscillator is running in the LW, MW, SW frequency changer section, could be a faulty component, valve, broken wire etc.
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Old 11th Oct 2019, 7:03 pm   #3
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Default Re: Grundig Como 5/GB radiogram

Hi Michael

From your previous threads you have some experience in repairing radios so I won't tell you to replace the valve, which of course you would be hard to find!

Looking at the schematic, there is nothing unusual about the am front end.

I don't have picture of the am tuning capacitor but I imagine it would it be an open vane version. No chance a drop of solder has shorted out the oscillator gang?

As short wave is also dumb, the ferrite rod connections won't be the cause.

I guess you have checked the dc conditions on T11/12 so the next thing to do would be to get out your signal generator and work backwards.

Chris
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Old 11th Oct 2019, 11:07 pm   #4
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Default Re: Grundig Como 5/GB radiogram

Its not a valved set, fully transistorised. I'll look at it when I get back in a week or two.
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