Beogram TX2 solenoid flatter

[alf]

Hi All,

after fixing the typical problem of a broken string-anker point and re-assemble S2

everything seemed to work fine until I engaged the tonearm lift. After some rattling noise the arm lifted – the noise only happens when lift-up is engaged. A closer look showed a strange flattering movement of the solenoid piston.

In a next step I deoxid-cleaned all contacts on S1,2,3 but to no effect. Next in line was testing of both diodes D3 and D4, but all fine.

Looking at the circuit diagram it would seem the next suspects left are TR4/5/6 – TR6 should be a 92PU51 but is in fact a MPS 51W type.

that of course is if the issue is not of mechanical nature, like a broken off teeth on the gear responsible for lifting and lowering.

has somebody experienced a similar issue – could really do with some pointers here.

thank you for helping out ?

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

[matador]

Hi.

I’m not sure to understand your issue well. But if it is something like “the solenoid makes a scratching noise when activated”, I think it’s a common failure for those decks to have the core of the solenoid, twisted and then seized into the coils. I remember something like that.

Google Beogram 5500 repair, and you should find more info on this.

SOrry if this is not related to your problem.

[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

[Mark-sf]

I would check the 12v supply. You may have bad caps at C3 or C4. Make sure you have a clean 12v at the solenoid. TR6 regulates the voltage to 5v for the motor so it would not cause this issue. There may be 120Hz noise on the 12v line.

[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]

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 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

 

[ummagumma]

Thanks for documenting this, it’s useful information to have.

[Author]

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