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BeoSystem 2500 - FM reception

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krkn7
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krkn7 posted on Sun, Mar 3 2013 9:58 PM

Hi all,

I have a BeoSystem 2500 (type 2606) which does not tune fm stations very well. The symptoms are:

Very low volume in FM only, in AM mode the volume is normal.

Not detecting any stations with automatic scanning. If i search manually, i hear the station but at low volume)

Not detected stereo in any radio station.

 

I have the fm antenna connected, the fm board in service position, and do not see any bad capacitor or visibly bad component,

I measured the voltages and appear to be correct (+5 V, +15 V, +30 V).

 

I appreciate if someone guide me to other tests, to find where is the fault.

 

Thanks in advance.

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Keith Saunders
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A Very Warm Welcome to Beoworld..

Your "Problem Statement" suggest that the problem is related to the aerial input and/or aerial components in the unit.

What kind of FM aerial are you using and have you checked it using another FM receiver if you have one ?

Regards Keith....

krkn7
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krkn7 replied on Mon, Mar 4 2013 10:08 PM

 

Thanks for your reply, Keith.

The FM antenna I am using is the original BeoSystem 2500 (awful dipole).

Yes i'm have another fm receiver, I tested the antenna and works fine.

I've also tried to skip the rf connector of the beosystem and put long piece of wire directly to the pcb connector with the same result, best reception but sounds at very low volume,  there is not stereo in any station and the automatic search does not find anything.

As additional data, the BeoSystem always been at my parents' house since 1991 (I have not bought used). Since year 2000 aprox. has been used a few times and has been a long time power off.

The thing is when i switch to AM mode the volume increases and automatic search works, so I understand that the problem must be in the fm tuner front end or near this. But i have limited knowledge in electronics and do not have oscilloscope Sad

Regards. Enrique.

 

 

Dillen
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Dillen replied on Mon, Mar 4 2013 10:13 PM

Those tuners are highly integrated and very difficult to service.
Find a replacement tuner board from a donor.

Martin

marexy
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marexy replied on Wed, Jul 15 2015 9:26 AM

Hi

I have exactly such problems as written above

3 faulty tuner boars and need to be serviced asap.

It seems that this type of error is very common.
I am convinced that it can be corrected.
please if anyone can help.
All have the same error!
It would be pointless to destroy all 3 tuner board.

marexy
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hi

Someone already corrected the error on tuner board ?
I have 3 such units with the same problem.
Please help.

Thanks

marexy
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still looking for a solution.
I do not believe that it is so difficult to repair.
At least 20% of these units ( 2500, 2300, Overture.....)  have the same problem.
I am convinced that it can be repaired.
Please advice and solutions from anyone

Weebyx
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marexy:

still looking for a solution.
I do not believe that it is so difficult to repair.
At least 20% of these units ( 2500, 2300, Overture.....)  have the same problem.
I am convinced that it can be repaired.
Please advice and solutions from anyone

I have also seen this problem in a BM4500, and I also have a defective 2500 tuner board.. 

I would guess that the change of all the caps would be a first solution, but since the whole tuner is adjusted from the factory with precise settings, then the whole tuner might need to be re-adjusted again, and it is not something that I know how to do.

Some time ago I had a BC2300 where the tuner thought it was japanese, and didnt receive any stations, that was an IC on the board that was defective (I looked at the schematics and decided to try), and after that was changed, the unit worked again, but I don't think this is an issue with these boards..

/Weebyx

 

GERTAP
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Hi ...

YES , this problem sems to be common, i have 2 pcs of overure with exactly this problem.

Sound on FM is a bit low and distorted and the overture it is not able to find any stations when a search is performed.

I dont think the fault is the tuner module , thus the sensivity is ok,  it must be the the detector curcuit , it should not surprise me it is a faultu capacitor around the LM1865 FM IF detector,,

I am shure other has meet this problem , and somebody could have the solution

Please write !!!.

BR GERT

 

solderon29
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These pcb's did suffer from leaking electrolytic capacitors,particularly the tiny ones used to allow the close fitting,but it's fairly obvious if this has happened.

The tuning and muting is controlled by the central computer,and I think you will need to check voltages around IC1 (LM1865)which may provide further clues.

Also,both am and fm demodulated signal's are processed by the stereo decoder chip IC4(LA3401).

If you can connect an external audio amplifier to pin 2(fm) or pin1(am)you should be able to hear the stations.If you can of course,this rules out the tuner and it's control,and points towards IC4 and it's associated circuitry?

Nick

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