Beocenter 7007 - adjust amp voltage trimmer resistors

4 replies
DA
Offline
david.jones
Bronze
Posted January 20, 2025 at 16:53 GMT
#1644386
Hi,

When playing a record and the volume is turned up to about 3.6, the arm lifts off and the unit shuts down. I've been told that the idle current trimmers may need adjusting to give 10mV.

I assume these are the parts arrowed in the image?  Does anyone know where the points of the volt meter should be placed while adjusting the trimmers? Any other information on this would be very welcome.

Thanks in advance, Nick MJ
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filip_kbh
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filip_kbh
Bronze
Posted January 21, 2025 at 12:55 GMT
Edited January 21, 2025 at 21:12 GMT
#1668336
First of all, measure the current idle current. If it is already 10mV, this is not where your problem is. You can measure over the points given in the below screenshot (see instructions below). According to the service manual:
  • The unit must be cold and the volume turned all the way down. Speakers must not be connected.
  • Select P1 to P5
  • Connect a Voltmeter between 3TP200 and 3TP201 and adjust 3R224 to 10mV. Do the same with a Voltmeter between 3TP100 and 3TP101 and adjust R124 to 10mV.
I suggest you either clean the trimpots first with contact cleaner and give them a few turns back and forth (take note of where they were) or that you replace them. They are known to corrode over time. Regarding the instructions to put a Voltmeter between two resistors - it essentially means to put the probes of your multimeter on the outer legs of the two resistors to be measured. I have marked the points with red and green. The two red points are for R124 and the green points are for R224. Be careful that your probes do not slip.
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Location: Copenhagen

DA
Offline
david.jones
Bronze
Posted January 21, 2025 at 16:11 GMT
#1668339
Filip, many thanks for this, very helpful, all working now. I would not have known where the resistors were for meter probe placement. I hope this will help others as apparently this is quite a common fault.

Regards,

Nick
DA
Offline
david.jones
Bronze
Posted February 25, 2025 at 14:03 GMT
#1668946
Hi Filip, I now have another Beocenter 7007 with a similar problem and I wish to change the trimpots you mentioned above. I can't find the specs for these. Could you advise where I might purchase these please?

Thanks in advance, David

 
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