[alf]

I would not call this working – when play is activated the display comes on for a few seconds and a very faint click (as something tries to engage) is heard…then came over, display out, nothing further……

as mentioned earlier, feels like a protection is kicking in ?

quite obviously something is shutting down the deck very quickly.

ALF

[alf]

I checked all components in question off-board:

C9 = 21uF, TR3 and TR4 all hfe near 290.

I wonder if the protection kicks in as the deck shuts down shortly after play is activated because of a different fault elsewhere or too sensitive ??

ALF

[alf]

Obtaining those voltages was  a bit tricky because the deck shuts back to standby

fairly quickly after PLAY was activated:

TR1:  B = 5.8 VDC,  C = 15.8 VDC,  E = 5.3 VDC

TR2: B = 15.8 VDC,  C = 5.9 VDC,  E = 16.1 VDC

are these voltages consistent with  proper functioning transformer  ?

ALF

[alf]

Well, back on the BC7000:

sadly no change after replacing LM272 – that drawer motor worked fine before.

i replace the BD435 with a BD437 but what I can not get is the 12V supply for the capstan motor.

the fuse resistor has also been replaced !!

as said before, the motor works as been tested with my  benchtop VDC supply.

i begin to wonder if the transformer got a hit during the “accident” ? It would be good

to know what its typical VAC voltages are before hitting the rectifier diodes ?

other than that I am stepping in the dark right now without progress.

just such a shame that lovely deck doesn’t work.

anyone, anything ?!

ALF

[alf]

The following parts are gone:

uP board, display board, big alu cover – anything else is available ?

ALF

[alf]

Right ?, just been there…nice shop.

good to know the BD437 would work – I can get that one even here.

the l272M are most likely chinese origin, sold in the UK, US and of course CHN

the order is out !

ALF

[alf]

I look into it, but first I have to restore the 14.8VDC supply.

the L272M mot control could still be fine but without the supply I couldn’t test.

the BD 435 has to be ordered, unless I could use a BD437 as alternative ??

the same question is in regards to an alternative for the no longer available

L272M chip ?? Any suggestions ?

ALF

[alf]

Yes, the safety resistor was dead and has been replaced.

sorry, I meant of course 22VDC !!
Correct, the 27-28VDC are in Stand-By – ok, thats cleared up….when play is activated

i get just under 22VDC.

still missing the 12VDC for the drive as well as the 14.8VDC at P6-pin9 ??

i had the motor running on 12VDC with the benchtop power supply – no trouble.

difficult to imagine the motor is at fault.

i will look into the BC-435 and BC-136…other than those will cause a headscratch.

ALF

 

[alf]

Hi Martin & Glitch,

thank you for helping out – sadly my BM has turned into a salvage operation……

to explain: I had indeed solved the start-up by using a much more suitable AC-AC adapter providing 120VAC instead of the ordinary step down, delivering only 110VAC, with a defacto output of only about 100VAC.

after reassembling I noticed no tuner signal – all the preset stations were still on display but no sound …… I  verified all plugs / connections are properly connected which was the case.

one fatal mistake occured – I forgot to put back that insolating cardboard protector which sits over the small stand-by transformer. Putting all down, obviously something touched where it shouldn’t – all hell broke loose, smoke coming from the power transistor assembly…….the end ?

so, whats left for me to do is to check what I can salvage – very sad, that BM had a full recap !!!

once again, thank you all for stepping in and offer to help – very much appreciated.

ALF

 

[alf]

Hi Christian,

just had a suspicion the BM may actually not getting the required VAC ?

it is a US model, type 1903 (120VAC !) and its been operated using a step-down transformer (110VAC output).

that BM had always had some trouble with the start-up and so far it worked just ok.

i decided to measure the actual VAC it is getting, showing only about 97VAC.

using my variac and cranked up the mains voltage to about just under 120VAC…..and

surprise – no trouble with the start up ! It is a power-hungry beast. So I used my other AC to AC adapter which is delivering 120VAC output.

right after reassembling I noticed the tuner “is gone”, meaning it wont pull any stations

in ?? Of course I checked all connections, nothing suspicious to detect.

could that pre-scaler chip have died in the process ?? The other inputs work.

regards

ALF

[alf]

Hi Christian,

no !!

i do not measure 23.xVDV at P51-pin2 but just under 20VDC, same as at the 7RL2

the voltage is only present when I try to start up the BM – it is not present by just connecting to the mains.

same appears at 6TR18-C – at start up I see about 20.xVDV.

interestingly enough I can not find +/-55VDC either ??

nor can I verify the voltages at P48 in ON status as the BM does not switch on !

ALF

[alf]

Hi Christian,

the red dot is present.

the 19.8VDC were measured at P51-pin2 connecting the 7RL2 directly.

At this point I should see at least 23.8VDC as per circuit diagram – should I not ?!

just taken out PCB6 and replaced BD676 with a higher Hfe reading than the old one.

have not checked the other points.  The BM has seen a complete recap !!

the voltage at 6IC9 – collector is about 23,x VDC – have not yet checked 6IC10.

will get back with more findings…..

ALF

 

[alf]

Hi Craig,

it worked before the original bulb went dead.

The “replacement bulb” has a different filament type – it lights up but does not produce

the correct light circle.p through the lense.

the correct bulb has been ordered from Beoparts shop yesterday – now its the waiting game until it arrives.

ALF

 

[alf]

Hi Christian,

thanks for the input, very much appreciated.

R30 measured 14.9 ohm !

i revisited that detector bulb, definitely not lighting up, so I put a “replacement” that lit up straight away as expected when 6.3V are present.

However that “replacement” is not the correct bulb – my hope is Martin (Dillen) can supply a correct one ?!

ALF

[alf]

Hi All,

I played not too bad, scored some nice goals but you can not beat the

“team of knowledge & experience”.

A big thank you to Martin who pointed out a potential problem with the white tumbler bar and its free movement. One small spring, kind of embedded in the chassis, attached to that bar was obstructed in its free movement by a particle and so was the bar’s movement.

the solenoid”s piston had to work overtime and only just overcame that extra force after some rattling forth and back.

all is well now, everything is recapped, lubricated and ready for playing some nice records again ???????

thank you also to all interested followers – it was a great new chapter to learn.

ALF

 

[alf]

Hi,

well, C3 and C4 on #2 board have been replaced but no change in the lifter issue.

i like to exclude the lifter/lower gear wheel as it performs basically the same task at the run-out groove of a record without any drama – no stuttering or rattling of anything!

same thing goes for the piston of the solenoid – leaves me with testing TR4/5.

As I see it : when the lifter function is activated a fluctuating power supply is fed to the solenoid……what else could it be ?!

ALF

[alf]

Hi Mark,

I  can verify 12.1 VDC at P3-2 and 12.09 VDC at the solenoid. So far I haven’t checked

C3 and C4 which are easy enough to replace. It had been suggested to replace those two caps but am almost certain both are fine  ?!

will repirt back once they have been replaced. Thank you for your contribution ?

ALF

 

[alf]

Hello,

no, its not what you are referring to !
A bit tricky to describe but the piston moves freely when it moves.

what however happens when the lift is activated is that the piston moves forwards and backwards very quickly which generates a rattling noise via the lever arm “connected” to the gear wheel that operates the up/down lift.

does that explain it any clearer ?

ALF

[alf]

hi,

perhaps a better word to describe the solenoid issue is ‘solenoid rattling’ ?!

which only occurs when the lift is engaged (< or >)

ALF

[alf]

Hi John,

yes, I will do that after all those turntables are off the workbench and will repost the findings – wish me luck ??

ALF

 

[Author]

Posts