Hi All,
I am over my Beogram 4000 now for a considerable time and can not find the problem.
what happens here:
activate ON, the platter starts at 45 !!
The carriage does not automatically move in to the drop-down point, however I can manually switch to 33 and move the carriage forward, activate arm lowering and it plays as normal.
i have been through the training manual and fault-finding flowchart in the SM.
the SI circuit had a wrong BC183B fitted which is wrong - why and how that got in….no idea.
i felt unsure about the correct replacement: BC184 or BC149 ? i chose the BC184 typ and it was working fine.
now its back to the previous issue described ?? i have checked as per flowchart but obviously missed something fishy in there……but what ?
can someone provide any other pointers than the fault-finding chart suggests ?
as always, thanks for your help
ALF
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Beogram4000 start issues
11 replies
Hi,
i revisited the adjustment of the platter motor as the table seem to have 45rpm locked in ?
yes, I can operate a speed change manually, but….
adjusting the motor as per SM I set all trimmers - 4VR1/2, 1VR1/2/3 - in their center position.
I can adjust the corresponding 33rpm voltage at about 15V at 42Hz, 45rpm at about
15V at 53Hz - not 59Hz as the training manual suggests.
checking the SI signal I should see 6V after a 10ms delay…..what I am getting though
is just under 2V which is obviously far too low……but why ????
6V are present at the suppy, 1TR20 measures fine 1C15 is 10uF / 16V - no 6V cap at hand.
the 24V supply is on the low side at about 23.4V ?!
would really appreciate some input
thanks guys
ALf
If I read the schematics correctly, the fault could be between 1TR2 and 1TR3. So start by testing those two transistors.
Location: Copenhagen
Thank you for your input, I will test those two transistors.
just a brief recap:
i verified 6V at The C of 1TR20, but when measuring the SI on the mainboard the max I see is 2V ?
i assume this is the signal 3IC4 is receiving ?
it seems the logic has locked-in the 45rpm as the platter starts only with 45 when ON is activated.
the components of the SI circuit are working ! The. Platter motor adjustment is another matter but should not interfere with the start-up of the carriage, moving in !
i hope my explanation didn’t lead to misunderstandings here.
any help is most welcome ?
ALF
Tested the mentioned transistors - off board ! - and both tested fine.
obviously one other (or more) component(s) is faulty as this issue was not a gradual decline but appeared suddenly.
at this stage I want to rule out a contact issue as the table performs normal once the carriage has moved in via FE to its drop-down point.
ALF
Hi Alf
Do I understand right? You are measuring 6 V at C of 1TR 20 and 2 Volt at SI on the mainboard?
If so it seems that you have a broken trace between these points.
SI is connected to several IC's on the logic board under the button plate.
Have already had broken wireconnections b etween mainboard and logicboard, maybe you have a closer look there.
Kind regards
Christian
Hello Christian,
thank you for your reply - very sorry to say you just missed out on a 10/10,
But a 9/10 for inspiration isn’t too bad either I thought ?!
I did check that 1cm track under the magnifier, than clean that short track with a fiber glass pen as well and still did not see any damage…..which sidetracked me.
assuming that there may be a wire issue further on stopped me for now but thanks to
you I simply connected a short wire jumper between SI and C of 1TR20…..success ??
and now the platter starts at 33rpm as it should.
many thanks again ?
ALF
Congrats, issue solved
Nice!
Location: Copenhagen
Thanks Filip,
my thoughts precisely - nice to see the carriage moving correctly again.
always interesting how many challenges this table can throw at you……
ALF
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