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Beogram 8000 random pre-mature tonarm lifting

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ALF
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ALF Posted: Tue, Oct 4 2016 2:42 AM

Greetings all,

My BG8000 came up with some strange surprises:

Records end pre-maturely, tonarm lifts and moves  back to its resting position.

This happens randomly and does not occur at the same position.

Using the << or >> function shows a freely moving carriage.

Did anyone experience the same or similar problem and was able to find a solution ??

Thank you for advice, help or pointers :-):-):-)

Cheers ALF

Dillen
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Dillen replied on Tue, Oct 4 2016 8:13 AM

Capacitors, capacitors, solder joints, solder joints.
Solder joints and capacitors.
Capacitors and solder joints.
The CPU socket, capacitors and solder joints.
And the CPUs solder joints and capacitor.

Martin

ALF
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ALF replied on Tue, Oct 4 2016 10:31 AM

Ok ok, understood.........well, almost !??

All caps were replaced a couple of months ago with Martin's cap-kit,  together with a thorough inspection of all solderjoints under the magnifier.

I kind of expected a 'terrible' reason for that problem, but does it really help ?

Yes, it could be the processor socket.......or.........shame it is not just a lub-problem with the carriage !

As I see it temperatur-variations must play a role in it, as the problem hardly ever appears when the table is 'cold'.

But as it is not something simple I won't get around another inspection !

Anything more specific would naturally help :-):-)

Cheers and thanks for 'trying'

ALF

Dillen
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Dillen replied on Tue, Oct 4 2016 11:08 AM

If you replaced all caps in the kit, we can rule out caps.

The deck will stop and park the carriage if the CPU receives a reset (bad power supply, bad connections/solder joints).
It will also stop if, while playing, the threaded shaft hasn't rotated for a certain number of seconds (dirt on the threaded shaft/bushing,
bad servomotor (lubrication), too tight servomotor belt, bad tracking lamp/opto, blocked carriage movement, bad shaft opto or an electronic fault.

Martin

ALF
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ALF replied on Wed, Oct 5 2016 1:28 AM

Thank you for trying to help Martin, mucch appreciated :-)

Yes, I would rule out the caps.

If the servo-belt is too tight the problem should present itself more often or perhaps most times ?!

With 'threaded shaft' you are referring to the spindle that is driven by the servo-motor, right ?!

I will investigate and clean and lubricate once more to be on the safe side.

Tracking-arm light is present and clearly visible and as said earlier, both fast forward and reverse function moves the carriage freely.

Yes, there is the unpleasant possibility of an electronic fault or bad connection.......

I am still hopeful it is something mechanical .

Cheers - ALF

ALF
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ALF replied on Thu, Oct 6 2016 5:49 PM

cleaned and lubricated the spindle after another close inspection of the solder joints -

no suspects discovered though !

table seems to work fine now :-))

back to other projects

cheers

ALF

ALF
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ALF replied on Fri, Oct 21 2016 3:17 AM

Well well well......never doubt Martin's expert advise Whistle 

As a lub-service seemed helpful at the time, I am not sure why my eyes have failed me so badly when inspecting the solder-side of the main board Confused

In short: the problem returned after a lengthy fault-free performance !

I opened the table again and discovered cracks on the some connector-joints incl the power-connector.

How I could missed those beats me ??

All conector-joints were re-soldered incl the PCU-socket joints and IC3 - this times I really took my time

And inspected every solder joint on the two boards !!!

At the same time I was also suspecting one of the servo-drive involved transistors......??

but so far everything seems back to normal.......and I am catiously optimistic it stays that way......

At least for anwhile :-)

Thanks to all problem-interested fellows 

Cheers -ALF

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