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BM 6500 noise on datalink

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skolesen
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Hvidovre, Denmark
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skolesen posted on Sat, Dec 16 2017 3:49 PM

Hi Beoworld,

I've been following the forum a couple of years and have learned a lot by the good discussions. Thanks for that.

 

On my workbench I have a white  BM 6500 type 2336. I've recap board 4 and 9 to solve IR range problem and put in a new backup battery. So far so good, but when I tested the BM with my BL Penta mk. 3 I found that the display wouldn't turn on with the BM. Only if I switch to AUX the Penta display comes alive.

As a note the Penta work perfect with a BC 9500 I've previously had on my workbench.

Put the scope on the datalink port and discovered that there was a perfect 1.2V/143KHz sine wave noice on the datalink.

Does any have a clue what is causing this or where to look.

Any help is appreciated thanks.

 

Steffen

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Dillen
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Copenhagen / Denmark
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Dillen replied on Sat, Dec 16 2017 4:29 PM

Bad decouplung of the voltage regulators would be my guess.

Martin

skolesen
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Hvidovre, Denmark
19 Posts
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Bronze Member

Thanks Martin,

That was the trigger I needed. The 5V power supply was ok. Then I started looking down the line and stopped at the AUX datalink protection circuit. Replaced the BC 547 and the 12V zener and puff the Penta display started act normal.

 

Thanks again Martin your the best :-)

 

Steffen

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