Beocord 3500 lacking high frequency in one channel

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grimtim Posted: Sat, Jan 22 2022 2:46 PM

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  Hi all

  New member, first post, so hi everyone :)

  I have a Beocord 3500 that has a lack of high frequency in the right channel. I have ruled out problems with my amp and my speakers, all other sources sound fine and when I try the Beocord through a different amp and speakers the problem persists. 

  I should also mention that I have cleaned the playback head and pinch rollers many times and I am fairly sure that the problem does not lie here...

  I am assuming its an azimuth alignment problem, but before I start fiddling where I shouldn't be fiddling I thought I would check if anyone had any other ideas or advise?

  Thanks for looking :)

  Tim. 

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Pindsen replied on Sat, Jan 22 2022 8:46 PM

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Hi,

I'm more thinking of a capacitor issue in the signal path.
Do you have the same sound level in both channels?

/Pindsen

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grimtim replied on Mon, Jan 24 2022 12:12 PM

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  Thanks for the reply

  I have spent the weekend checking various things to try to get to the root of the problem. Bearing in mind with the following that I have no proper test equipment, everything is done “by ear”, and my ears aren’t the greatest.. Old age and too many loud concerts in my youth!

  It’s a bit strange, as some cassettes seem to have more issues than others. For example, with one cassette there is very little difference between the 2 channels, the output levels seems the same, just a small reduction in the high frequency on the right channel. But with another cassette the difference is quite drastic, the right channel sounds really muffled (quieter) with a distinct lack in high frequency. I tried to tweak the output trimming pot on the right channel with a bad cassette to get the 2 channels to sound similar levels, it didn’t make that much difference to the bad cassette but it made the right channel louder than the left channel on the good cassette. So I adjusted it back down again.

  I tried adjusting the azimuth, just to set my mind at ease, and it made no difference so I put it back to its original position.

  If this helps, the problem also affects recording on the deck. I made a recording on the Beocord and the right channel was very muffled on playback. I played the tape in another deck and it sounded the same, muffled right channel. Using the same tape I made a recording on the other deck which sounded good on the deck it was recorded on, but when I played it back on the Beocord it had a muffled right channel.

  If this sounds like a capacitor problem, would anyone be able to point me in the direction of which one(s) it might be?

  I also thought it might be the record/playback head that has gone, on visual inspection it looks OK but internally it could be totally shot.

  Thanks,

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Dillen replied on Mon, Jan 24 2022 10:12 PM

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Is the problem the same in both tape directions?
Have you cleaned the tapeheads?

Martin

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grimtim replied on Tue, Jan 25 2022 1:12 PM

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Hi

Thanks for the reply

I hadn't actually tried in reverse direction, whoops... But I checked it this morning and I am getting the same issues in reverse direction too.

I have cleaned the head so many times with isopropyl alcohol, but it doesn't fix the problem unfortunately. The cotton bus always comes away clean with no residue at all. 

I wondered if demagnetizing the head might help? I dont know...

Thanks for looking everybody, hopefully I can get to the bottom of this somehow!

Thanks,

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Dillen replied on Tue, Jan 25 2022 1:33 PM

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Demagnetizing is rarely needed - but you could try it.
Else a capacitor somewhere in the signal path could be the culprit.

Martin