B&O Beogram 1200 Turntable Renovation / Service

B&O  Beogram 1200

B&O Beogram 1200

In order to raise some funds for this project, I’ve been buying various vintage bits and pieces; amps, turntables, speakers, receivers and fixing them up for sale.  This blog shows some pictures of the inside of a Bang & Olufsen Beogram 1200 with SP14 cartridge.

I took the thing apart and cleaned all its contacts, replaced the tonearm wire with silk covered, pure silver conductors.  All pulleys, rubber rollers,  belts and rubber bands have been thoroughly cleaned and the main bearing oil for the platter has been cleaned out and replaced with Van den Hul “Special Turntable Spindle Oil” which is “doped with microscopic Zirconium ceramic balls”.  Over the years, the pulleys, belts, bands and rollers get little lumps of black dirt stuck to them.  I don’t know what its constituents are but I should image it contains fluff, dead skin cells, grease and moisture.  The effect of it being there is to add a tiny little bit of wobble to the smooth running of the platter.  Maybe it cannot be heard, maybe it can but bear in mind that the variations in groove size and shape, that makes up the sound you get from an LP, are absolutely tiny.  I’m not going to quote figures as I’m sure you can imagine just how blooming small they are so any help in getting a fixed reference for movement of the platter and arm will be a good thing.

Changing the oil made a massive difference to the friction of the bearing.  The bearing oil in a vintage TT like this will be thick, even sticky, dried out, moisture laden, dirt laden and some will have evaporated.  With the old oil, turning the table off when at consistent speed, it would spin for about 3 revolutions and then stop.  With the Van den Hul oil, I got bored timing it still spinning after what seemed like 20 minutes, it just went on and on.

To my ears the change over to the silk covered, solid silver tonearm wires made a distinct difference also.  I won’t go into trying to describe the sound change because hearing that from others leaves me dry but I will say I much preferred the new silver wire, by far.

There was no plastic cover with this turntable, it probably got thrown away when the previous owner couldn’t stand the site of it being all scratched and cracked.  Plastic gets very brittle as it ages, I think it’s something to do with UV light decomposing it.  Plastic from this ear was also very scratch prone as opposed to the polycarbonate used now (a well know version of PC is used as bulletproof glass).  There are companies around that can make a new cover for you and they are surprisingly inexpensive – I always thought it would be prohibitively costly, apparently not.

But the main point of this blog is to upload all the photos I took (so I knew how to put it back together again) in case others find them useful.

Silk covered, solid silver, tonearm wiring.

Silk covered, solid silver, tonearm wiring.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O tonearm wiring connections to the SP14 cartridge.

B&O tonearm wiring connections to the SP14 cartridge.

B&O Beogram 1200 switch mechanism.

B&O Beogram 1200 switch mechanism.

In the pictures below, you can see some of the grime I’ve been talking about, black deposits on the pulley wheel:

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

Removing the circlip spring washer using round nose pliers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

Sulphur corrosion to the silver plate on the Moving Coil pre amp PCB:

B&O Beogram 1200 silver plated connections for moving coil preamplifier board.

B&O Beogram 1200 silver plated connections for moving coil preamplifier board.

B&O Beogram 1200 insides.

B&O Beogram 1200 insides.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 insides.

B&O Beogram 1200 insides.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

Silk covered, solid silver, tonearm wiring.

Silk covered, solid silver, tonearm wiring.

To replace the original tonearm wire, I soldered the new silver wire to it and pulled it through, pulling the new wire along with it:

B&O Beogram 1200 turntable wiring being replaced.

B&O Beogram 1200 turntable wiring being replaced.

B&O Beogram 1200 turntable wiring being replaced.

B&O Beogram 1200 turntable wiring being replaced.

The entire inside sub assembly:

B&O Beogram 1200 insides.

B&O Beogram 1200 insides.

Connections to the tonearm cartridge socket showing which ones go where:

B&O Beogram 1200 turntable SP 14 cartridge connections.

B&O Beogram 1200 turntable SP 14 cartridge connections.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

The two pictures below show the switch that controls the auto return mechanism, the large cob wheel with the groove in it is part of that mechanism.  What is missing from the shot is a small half-circle spring device that flips the switch contacts.  At the time it had fallen off and I only found out when the auto return did not work.  This spring clip comes off easily!  Not a great design.  I will put another image at the end of these showing where the clip should go – it won’t be of the clip itself as the turntable has now been reassembled and I’m not opening it up just to take another photo so will draw it instead:

B&O Beogram 1200 switch mechanism.

B&O Beogram 1200 switch mechanism.

B&O Beogram 1200 switch mechanism.

B&O Beogram 1200 switch mechanism.

The Beogram 1200 motor assembly:

B&O Beogram 1200 insides.

B&O Beogram 1200 insides.

Drive belt pulley and drive wheel:

B&O Beogram 1200 pulley wheels and rollers.

B&O Beogram 1200 pulley wheels and rollers.

A cog wheel on the main bearing to drive the auto return mechanism:

B&O Beogram 1200 turntable bearing gear.

B&O Beogram 1200 turntable bearing gear.

B&O Beogram 1200 turntable.

B&O Beogram 1200 turntable.

B&O Beogram 1200 turntable main platter bearing.

B&O Beogram 1200 turntable main platter bearing.

B&O Beogram 1200 turntable platter switching mechanism.

B&O Beogram 1200 turntable platter switching mechanism.

The spring clip that falls off easily is under this brown insulating sheet which is held on by a single nut:

B&O Beogram 1200 turntable platter switching mechanism.

B&O Beogram 1200 turntable platter switching mechanism.

B&O Beogram 1200 turntable platter switching mechanism.

B&O Beogram 1200 turntable platter switching mechanism.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable connections for MC preamp.

B&O Beogram 1200 turntable platter.

B&O Beogram 1200 turntable platter.

B&O Beogram 1200 turntable platter drive pulleys.

B&O Beogram 1200 turntable platter drive pulleys.

B&O Beogram 1200 turntable platter, spring-loaded centre.

B&O Beogram 1200 turntable platter, spring-loaded centre.

B&O Beogram 1200 insides.

B&O Beogram 1200 insides.

A picture of where the auto return mechanism switch has the spring clip that falls off if you look at it too firmly:

Distant view of automatic return switch spring clip.

Distant view of automatic return switch spring clip.

View of automatic return switch spring clip mechanism.

Close up view of automatic return switch spring clip mechanism.

 

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About Matal

Hand made HiFi, photos, a friends poetry.
This entry was posted in Finance, Vinyl and tagged , , , , , , , , , , , , , , , , , , , , , , , , , , , , . Bookmark the permalink.

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