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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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h1npw
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h1npw replied on Sun, Jul 12 2020 5:54 PM

One down...Laughing

I've just noticed that the cartridge is a SP15 which I don't think would have been originally supplied with the turntable.

If I've researched it properly these were only ever supplied with the Beogram 4000... could be nearly 50 year old...Surprise

Craig
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Craig replied on Sun, Jul 12 2020 8:19 PM

Nigel
the SP15 belongs to me, your original is on test in a working deck and sounds great 😉 

h1npw
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h1npw replied on Mon, Jul 13 2020 10:06 AM

It just keeps on getting better!

Thanks Craig

Craig
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Craig replied on Mon, Jul 13 2020 11:12 AM

I could do with a service manual for the 4004 actually......looking in the products library throws up a 4002 with some references to the 4004......its a little confusing trying to follow, anyone got anything better than this? or am I missing a trick here?

Craig

Craig
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However.....this small detail aside i have now replaced all the connectors into the main PCB and the current pulled stays reasonable until I replace the connector P8 on PCB8......the current goes high very quickly. Closer inspection of PCB8 reveals a scorched 8D11 diode....


Craig
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Testing reveals a dead short across the diode, however I cant find any reference to this diode in the circuits i am looking at........


Craig
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Craig replied on Mon, Jul 13 2020 12:22 PM

Ohh....and its a type 5527 

Dillen
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Dillen replied on Mon, Jul 13 2020 1:01 PM

Shorted 8C14?

Martin

sonavor
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I emailed you the Beogram 4004 schematic for that board 8 output board. It shows that remote control circuit you are referencing with the burned out 8D11 diode.

John

Craig
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Great stuff John!

I can now see I need a IN4148 and our man from Denmark is bang on the money once again.........shorted 8C14 2.2uf tantal, looks like this circuit is only required for remote control of the BG4004 via a hardwired link on the PHONO DIN connector....I believe I have both components to hand so will push on, thanks guys......as always I appreciate your help ;¬)

Craig


Craig
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Replaced the two offending components and re-installed the PCB8 complete with all connectors...powered up and was pleased to see the unit pulled no more than 10mA at the fuse point.


Craig
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I imagine the 10mA was the power ON diode at the front of the cabinet glowing......put the platter and belt back in place and run a disc and was rewarded with what I think is a flawless operation..........


Craig
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Hooked up to a BM4000 and the sound is excellent too......went after a 45rpm test and this was equally flawless, I think.....the pickup dropped nicely onto the 45 disc and played...however it didn't change speed automatically like the BG4000 would and I had to change speed manually...still worked fine but as I have no user manual I dont know if this is normal operation or not?

 


filip_kbh
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It’s not. The speed should change to 45 automatically. 

filip_kbh
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It’s not. The speed should change to 45 automatically. 

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