Sign in   |  Join   |  Help
Click here to tell us about your new email address

Beogram 4002 Opto-tracking adjustment

rated by 0 users
Not Answered This post has 0 verified answers | 24 Replies | 0 Followers

Krolroger
Top 500 Contributor
London, UK
61 Posts
OFFLINE
Silver Member
Krolroger posted on Mon, May 1 2017 1:09 PM

Hello All,

I'm fixing up a BG4002 (type 5514) and trying to adjust the tracking mechanism.

The available adjustment seems to be a little bit crude, frankly, to the extent that once you think you've got somewhere, when you tighten up the set screw, it goes off again.

I note that Rudy with his very tidy LED alternative adds a trimming pot to adjust the light source for fine tuning after you have got the basic adjustment.

My question is would this sort of set up work with the standard 24v 40mA (?) incandescent bulb?  Say a 250 ohm 500mW single turn trimmer?

Or would this introduce unintended consequences?

Regards,

 

 

All Replies

Krolroger
Top 500 Contributor
London, UK
61 Posts
OFFLINE
Silver Member

One more question, if I may.

There is quite a lot of slop in the platter spindle bearing so should one take the 23mm detector arm measurement as if the platter is under slight tension from the drive belt?

Regards,

Krolroger

sonavor
Top 50 Contributor
Texas, United States
2,712 Posts
ONLINE
Gold Member

I don't take that measurement with any belt tension on the platter. Because the spindle has three adjustment screws for its horizontal position I move the arm over the platter and take three measurments - One nearest the outer edge, one near the spindle center and one towards the back of the platter.  When all three points have 23mm then you know you have a perfectly level platter. It usually takes me several iterations of adjustment and measuring to get it set right. It is also another one of those adjustments that you need to make sure your starting point isn't already near the limit of one of the adjustment screws.

Regards,
sonavor

Krolroger
Top 500 Contributor
London, UK
61 Posts
OFFLINE
Silver Member

I'm guessing that the set screws for the rails are as the factory set them - quite a variation from one end to the other relative to the base of the floating chassis - so my instinct is to leave them alone.  I don't think the deck has suffered any massive trauma other than misadjustment and years of neglect so I am assuming the rail adjustment is ok.

My latest challenge is to reproduce the 5 cabinet guiding washers, the awful clear plastic ones having disintegrated. Currently making a silicone mould, with a view to making a resin casting or maybe using a low temperature alloy instead as these washers are nearly always missing or unobtainable. Luckily I had a spare set to make a mould from.

Has anyone had a go at this - other than 3d printing?  Here's a picture of another use for a hummus pot.

Regards,

Krolroger

 


sonavor
Top 50 Contributor
Texas, United States
2,712 Posts
ONLINE
Gold Member

I believe Søren Mexico made some out of aluminum a while back.

Regards,
sonavor

Søren Mexico
Top 10 Contributor
Mexico City
5,934 Posts
OFFLINE
Bronze Member

made these and it worked out good, no need to adjust the trim on mine, but maybe other decks may need adjustable eccentrics, the original  square ones gives 4 positions as the center hole is off center

Collecting Vintage B&O is not a hobby, its a lifestyle.

Krolroger
Top 500 Contributor
London, UK
61 Posts
OFFLINE
Silver Member

The saga continues.

I wasn't happy with the downward set of the detector arm, so, noting Beolover's tip to flip over the set screws for the tangential carriage rails so they are adjustable from on top,  I have done this.

The back rail is easy, but the front rail on my turntable appears to have the bottom of the set screws drilled out or peened so that they are not adjustable or removable.

I suppose therein lies a clue.  I will just have to content myself with the available adjustment on the back rail.

 


sonavor
Top 50 Contributor
Texas, United States
2,712 Posts
ONLINE
Gold Member

Krolroger:

The saga continues.

I wasn't happy with the downward set of the detector arm, so, noting Beolover's tip to flip over the set screws for the tangential carriage rails so they are adjustable from on top,  I have done this.

The back rail is easy, but the front rail on my turntable appears to have the bottom of the set screws drilled out or peened so that they are not adjustable or removable.

I suppose therein lies a clue.  I will just have to content myself with the available adjustment on the back rail.

You are referring to my posting of a Beogram 4002 Type 5513 on the Beolover Blog. I should add that while it makes it easier to work with the rail adjustment that adjustment should be a last resort. If you raise the set screws for the rail height too much then problems crop up for other mechanical adjustments. When these 4002 series turntables do require adjustments like this you just have to prepare for a long ordeal. Sometimes you get lucky but most of the time there is quite a bit of iteration in the adjustments. If things get too far out of adjustment I have to revert to the zero starting position and make very small adjustment steps. I think I went over the adjustments on that Type 5513 Beogram about ten times. It is quite rewarding when it is all complete though so take a break every now and then to recharge. Then keep on keepin' on :).

sonavor

Krolroger
Top 500 Contributor
London, UK
61 Posts
OFFLINE
Silver Member

Hi, thanks for reply.

The situation was that my back rails had been adjusted high which I think was contributing to the downward tilt of the detector arm.  I know by how much I've wound in the screws in case I have to revert.

 

 

sonavor
Top 50 Contributor
Texas, United States
2,712 Posts
ONLINE
Gold Member

With the back rail set screws set high, is the metal plate that fits on top of the rail at an angle? It does make sense that the source of the slope is due to that back rail setting. 

sonavor

Krolroger
Top 500 Contributor
London, UK
61 Posts
OFFLINE
Silver Member

Exactly.  You can just about see it in the photo I posted in this thread on May 4th.

Page 2 of 2 (25 items) < Previous 1 2 | RSS