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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 hood could do with a polish though on initial inspection there are no deep scratches, the hood is loose and i discovered that one of the securing bolts to the rear is missing the male part of the assembly....I suspect its only a machine screw but will investigate further in due course.

The internal alluminium trims are in very good condition too and the cartridge has a stylus still connected...all good signs


Craig
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Unfortunately someone has tried to polish out a mark of some description from the platter resulting in a horrible mess....I thought I didnt have one of these platters laying around, however I do so thats another piece of good luck.


Craig
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Keypads are also in very good shape......


Craig
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Opened her up and had a look inside......the belt was off as you would expect and there where bits of suspension damper all over the bottom of the set.


Craig
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Otherwise the insides look remarkably intact and clean, The tone arm was found to be seized and wouldn't respond when the solenoid arm was pulled in, will require removal and freeing up.   


Craig
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Craig replied on Fri, Jul 10 2020 11:44 AM

There was also a cute little brush lying on the bottom with the B&O logo.......for the stylus i expect, I will power her up once i free off the solenoid and damper mechanism with my variac, providing the current doesn't go through the roof, and see what functionality we have. There will remain the usual capacitor change out and replacement lamps I expect, new belts and anything else that's past its best. Overall this looks like a very nice find .......   

h1npw
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h1npw replied on Fri, Jul 10 2020 12:21 PM

Hi Craig

Thank you for starting a thread on it!

You have a platter???  I'm going to have to rent a van to get all the wine I'm going to owe you! That's fantastic!

It's amazing how many of those stylus brushes find their way into the innards of Beograms...

The person I bought it from said her father hadn't opened the lid on it for the last 30 years or so which explains how clean the innards are.

Cheers

Nigel 

Craig
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Ok removed the pickup arm lowering lever and spring assembly to lubricate and ease it back to life......


Craig
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cleaned up and ready to be reassembled........


Craig
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Craig replied on Sun, Jul 12 2020 12:23 PM

The arm replaced i have taken a look inside the internal fusebox and discovered one of the 125mA fuses has been destroyed.......so replacing the blown fuse with my multimeter i connected up my variac and slowly powered up whilst watching the current flow....at 150mA I stopped as there is clearly something amis.......I will start with the transformer and move on to the power supply side of things.....

Craig
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Removed all the connectors from the main PCB and powered back up slowly and measured 24vac delivered by the transformer with around 10mA load....so reconnected the power supply to the PCB and read around 20mA 


Craig
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Popped a fuse in and connected the supply to the main PCB and was able to measure a healthy 30vdc at the reservoir capacitor......fair enough.


Craig
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Reconnected P7 to the main PCB and measured no increase in current pulled.....


Craig
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Reconnected P6 and two things happened when I powered up again.....the drive motor kicked into life and the 33rpm display came to life.....I wasn't expecting that to happen and operation of the keypad switches failed to stop the motor spinning.....there was however no significant increase in load measured at the fuse box...so I powered down and, as ever in times like this, opened a bottle of sauvignon blanc............. 


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