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Beogram 4004

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Craig
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Craig posted on Fri, Jul 10 2020 11:05 AM

Nigel....a member of the site returned a BM4400 to my "workshop" for some attention, I sold this to him some years back and it had stopped receiving FM transmissions......the front end and IF section where fine and I just needed a slight adjustment to the stereo decoder fortunately.....there remains a slight issue with the headphones jack as Nigel reported it didn't work, I haven't got any headphones to check it but the output at the connections to the socket show good on my scope.......however I digress....Nigel also dropped off a BG4004 he picked up at a car boot for £30!   


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Craig
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The two lamps within the rpm indicators fitted next, the original lamps had no markings to indicate voltage or current, the service manual says 24v at 40mA. The covers for these lamps where very tightly attached and with safety in mind I decided to butcher the starlock washers (or locknuts) and remove the whole assembly, I don't know of a way to get starlock washers off without snipping through them....they will of course be replaced with new on completion.

 


Craig
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The new lamps soldered in nicely.......


Craig
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Main PCB complete.....all components in Martins kit match this board with no exceptions.

 


Craig
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With regards to the lamps I have two remaining, the plug in lamp I believe would be required if a CD-4 switch was installed, this deck doesn't have one therefore the lamp is now a spare, the other lamp is for the detector arm....I have replaced these in the past with LED's supplied by Rudi the Beolover...its a bit tricky and when installed one has to make sure the light is falling in the correct place or the sensor has problems picking it up, so I'm reluctant to replace the existing fully functioning lamp with another lamp just for the sake of it (cop out I know) Sad

 


Craig
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New belts installed and gave it a run......I have downloaded coolterm terminal software for windows and the relevant driver for Rudys RPM device, im getting hexidecimal and asci  but cant remember how to get a sensible reading to paste into excel so I can trend the motor over a period of time...I have done this before by following a thread from here....anyone know where it is Crying

 

 

 


Dillen
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Dillen replied on Thu, Jul 30 2020 7:28 PM

The wedge-socket lamp is for the tracking (interrupter) system at the foot of the carriage.
The small lamp is (correctly) for the record detection system in the sensor arm.

Martin

Craig
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Martin.....thanks for the clarification, This is the lamp I think your talking about, sits in a lamp box and shines through a slot as the arm is drawn toward the centre of the platter and activates the servo motor.

 


Craig
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If so I shall leave it in situ as its epoxy glued in place, if the lamp was blown I am sure I could remove it and fit the new lamp into place by straightening the wedge wires....however as its not I will leave well alone, sorry about the size of the picture ;¬)

 


Craig
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All boxed up and ready to go, new belts and platter fitted along with Martins kit.....got it sitting alongside its BM4400 which is also now fully functional, the earphone socket just needed repositioning and now works fine as does the FM reception.....demodulator adjustment was all that was needed.

Craig 


chartz
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Well done Craig 👍🏻

Mmm... rings a bell or two Wink

Jacques

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