Thursday, 28 March 2013

Whacking Danish Moles

B&O beauty

Bang & Olufsen. One of those companies you have to love and hate.

They make beautiful audio equipment that is as much about lifestyle as it is about quality sound. The quality of construction is impeccable and the design aesthetic is outstanding. It might not be everyone's cup of tea but it does impress MOMA enough that they have 12 pieces in their collection designed by Jakob Jensen. I have owned one of them (the Beomaster 3000), and have recently been working on and listening to another, the Beogram 4002 turntable.

However as great as it is, the stuff does have complications that go along with it. The engineering and design is very much proprietary. Many parts are not shared with other companies or even other B&O models and are not available any more without wide and long searches through ebay and the audio geek forums. For example turntables use cartridges that can't be sourced and must be re-tipped at great expense, or you take a chance at ebay.

The good thing is that the Beogram 4002 I am listening to Santana on right now did come to me me with not one but 2 good original cartridges. In other areas it was not so great.

B&O 4002 1

Cosmetically the biggest problem was the paint wear on the switch plate. The different sections depress switches for start, stop, left, right, cueing and speed. They obviously don't have good paint in Denmark as they were very worn looking. Or the original owner had very acidic skin oils...
Actually it seems to be a common problem with these. I did not want to spend time on issues like that however until I made sure it worked well.

The table came to me with reports of the tonearm not dropping to the record when it was supposed to, or at best only doing it sporadically. A little internal investigation and web searching lead me to the relay and solenoid that operates the linkages which lower the arm. The solenoid and other moving parts have old lubricants on them that can get hardened or gummy over the years. After cleaning & oiling these, though not fully disassembling, I was able to get much more consistent tonearm dropping. I went down a few of the wrong paths first but once it did seem to be going in the right direction I went for the cosmetic treatment.

B&O 4002 switch plate

It is a bit of a jigsaw puzzle, figuring out how to take this table apart but I worked it out. The switchplate is actually stainless steel glued on to machined aluminum parts. It did not take long to sand it down with fine wet sanding paper and a final pass with a 4000 grit pad. I clear coated it with 3 coat of satin Tremclad.

B&O switch plate painted 2

It looked great so I put everything back together after doing some other internal cleaning such as switch contact points. Oh yeah I also polished the lid with wet sanding and Novus polish.

There are numerous little dovetail and notchy kind of fittings that I had to reshape a bit or add some washers to in other places as some small plastic pieces had broken or gone missing. Once back together, it worked. Sort of...until up popped another mole to whack.

The motors now refused to shut off once the arm returned to it's standby position at the far right. the platter would spin and the motor that moves the tonearm was also spinning. It was even smelling a bit hot inside probably due to belt slipping. So it came apart again.

B&O linear track switches

B&O linear track off trigger

The first picture above highlights the 2 switches that control the motor and arm return points. I determined that the one on the right was not being activated when the tonearm came to rest, and by bending slightly the piece highlighted in the second image I was able to get that happening again. So it went back together...and the next mole popped back up.

This time the tonearm hesitated a bit at the beginning and end of the records before either getting to the music or heading to the leadout groove and shutting down. It would skip a few times before moving inward. After a bit of extra stylus pressure was added at the adjustment point (to just over 1 gram; these track very light) it seems fine again. I have now listened to several records and it is playing nearly flawlessly everytime. Very infrequently it seems to need an extra push of the up/down button to cue properly but that seems to be less frequent with more use. It could be that the lubricant is working its way into where it needs to be as things move it around.

In any case Glen Gould sounds pretty good right now!

B&O Beogram 4002 2

B&O Beogram 4002


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