ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi everyone. And thanks for this great resource. I've just gotten a Beogram 4002. Most everything seems to work and it sounds terrific. But I have a question concerning whether or not it is in fact working as it is intended. When I press the start button the arm moves correctly to the start of the record (a 33 rpm lp in this case). The arm appears to start to lower in the correct position above the record. However, as the arm drops it continues to move laterally as well so that when it finally reaches the record it is slightly inward from where the start of the record actually is. Usually after the actual start of the record. Is it normal that the arm continues to move laterally while the arm is dropping? And if so is there an adjustment to make it start dropping a little sooner? I have been able to adjust the rate of the arm dropping to approx. 1 second which is what I understand is the recommended rate. Thanks for your help. Mike
Hi and welcome to Beoworld!
Tell us, does the arm 'drop' (it shouldn't) or does it take too long to go down?
Normally, the arm takes about one second or less to reach the groove. Now it is not clear to me whether the arm fully stops before descending, or if it continues to move to the left before it has touched down.
Jacques
Sounds to me that the arm is not quite straight so is encouraging movement inwards - the arm moves by working any deviation from straight causing the arm to move. Once on the record, the stylus is correcting this. Needs adjustment but no doubt an expert can tell you how - the service manual is on site!
Peter
Sounds in need of adjustment to the opto at the carriage base.
Martin
mjlisz: Is it normal that the arm continues to move laterally while the arm is dropping?
Is it normal that the arm continues to move laterally while the arm is dropping?
No, that is not normal. That is, assuming my BG4002 is normal: press start; platter begins to spin at essentially the same time the tonearm moves into position over the lead-in groove of the record; once over the record, the tonearm will stop moving laterally and gently lower into the lead-in groove.
The experts above will know far more than me how to adjust/fix.
Folks, thanks for your help. Perhaps "drop" was not the right word. "Lowered" would better describe what the arm does once it reaches the lp. As I believe it is being controlled by the damper. The arm appears straight. And once the needle reaches the record the tracking system takes over and everything works wonderfully. If I understand the replies by Rich and Dillen, what I describe is not normal and in need of adjustment. Is there anything more you can tell me about the opto at the carriage base? I see an LED down there that I thought was related to the tracking system. Any specifics on where exactly this opto is and how to adjust would be appreciated. I downloaded the service manual from vinyl engine and will be searching it for reference to this opto as well. Mike
The procedure is descr5ibed in the service manual, down-loadable form this site. You are looking at the paddle attached to the bearing at the base of the arm. This should first be in line with the cueing arm. It can be knocked out of line although unlikely. If not straight, do so first.Then, you need to first loosen the locking screw on the base of the opto detector assembly, and then adjust the adjusting screw (found on the opposite side), so that while straight, the sled remains stationary, but upon any deviation the servo motor should immediately correct this. (BTW Don't let the arm drop all the way (i.e. below platter level) as it has a habit of moving slightly, and will not allow for best adjustment; I usually remove the linking spring between solenoid and damper, so that the arm remains up, but this assumes both arms have previously been setup and are dead straight!) Once this is achieved partially set the locking screw, then check and re-adjust if necessary. You want this as sensitive as possible whilst allowing accurate cueing. Finally lock the screw and check again!
Olly
Folks, I hate to be dense. Perhaps its just terminology. But I am having trouble determining exactly what and where the paddle is. I have the service manual but cannot find the corresponding section. Is it called something else there? If it is could you please let me know how it is referenced in the service manual?
Is the opto detector assembly referenced above the tracking assemble or is it another opto detector located on the arm?
I feel like this is just a hump I need to get over and then all will be clear. Thanks - and I know it can be frustrating trying to tell a newbie like myself something technical of which I have no idea. So I am very grateful.
OK. Is the paddle called the shutter in the manual? If so, I may be understanding this. But this seems to adjust the tracking of the needle once it is lowered onto a record. My beogram tracks fine once the needle is lowered onto the record. Again, my problem is the lateral movement of the arm while the needle is being lowered. Which as I now understand it now should stop once the needle starts to be lowered onto the record and started again (tracking) once the needle lands in a record groove. I repeat all this to verify my understanding of how the beogram works and verify the above procedure would fix this. But perhaps I still have it all wrong yet.
Yes, I believe the paddle is called the shutter in the manual. The device that interupts the light beam is paddle shaped, hence coloquialy it is called the paddle!
The paddle will control the servo, which controls the motor that turns the screw drive, that drives the carriage which carries the tone arm both inward, when the record is playing and, via switched override, outward at the end of play.
When solenoid activation causes the tone arm to drop to the record from the lifted position, the servo is activated. Thus, any movement of the tone arm towards the centre of the record, will cause the motor to turn the screw and the carriage to move accordingly. Thus, during the movement of the stylus towards the record, it must drop as near to vertically as possible and not be dragged towards the record centre by some friction or balance misadjustment in the system.
Assuming the needle drops with minimal tone arm deviation from vertical, it should, if the shutter (paddle?) is adjusted correctly, not cause servo activation to move the carriage. If the carriage does move as the stylus is dropping, you need to adjust the position of the light source/slit relative to the paddle, such that activation of the servo stops, until the arm is moved inward, towards the record centre, by the stylus following the groove in the record.
The opto system can be found in a black,box like structure, the position of which is locked/adjusted by 2 screws. One screw locks the small box in position and the other is an eccentric, movement of which will change the position of the box. The adjustment is very sensitive!!!!
I believe that the procedure is covered under the section called "servo adjustment" in the manual.
There you are, clear as mud!!!!!!
Regards Graham
Sorry to confuse I couldn't quite recall the official name given to the part. Yes the shutter is what I was referring too!
Got it. Did it. It works! HOORAY! I apologize for expressing any doubt. You all had it right from the start. My Beogram works and I am so happy. :) (All smiles)
THANK YOU!
Well done!
Could you please expand on what you did and how you did it?
Any photos?
And you know how to thank the Beoworld! * * *
chartz: Well done! Could you please expand on what you did and how you did it? Any photos? And you know how to thank the Beoworld! * * *
Pics, or it didn´t happen
Collecting Vintage B&O is not a hobby, its a lifestyle.
Folks, specifically what fixed this problem was "adjustment of the shutter" as it is referred to in the service manual or adjusting the "opto" as referred to above. I have to admit that at first this did not seem intuitive to me as this procedure seemed to apply to tracking the record. Tracking worked fine in my case. But, obviously, this adjustment affects more than just tracking. As I adjusted to opto, first the wrong way, the needle, as it lowered, moved laterally further than before. But as I went the other direction it moved less and less until it finally stopped moving laterally alltogether and than just lowered to the record without any lateral movement at all.
I read many posts here and elsewhere pertaining to dried oil on solenoids and linkages causing the needle to drop slowly or not at all. But all of this was fine in my case. However, I did end up adjusting the damper in order to get the needle to drop in about a second as specified in the service manual. I also rebalanced the tone arm while I was at it.
I applaud all of you for not only your knowledge and experience, but also your willingness to share. Especially with newbies like me. Cheers! And I am embarrassed to say that, yikes, I don't know how to thank you all at Beoworld. Any hints?
mjlisz: Folks, specifically what fixed this problem was "adjustment of the shutter" as it is referred to in the service manual or adjusting the "opto" as referred to above. I have to admit that at first this did not seem intuitive to me as this procedure seemed to apply to tracking the record. Tracking worked fine in my case. But, obviously, this adjustment affects more than just tracking. As I adjusted to opto, first the wrong way, the needle, as it lowered, moved laterally further than before. But as I went the other direction it moved less and less until it finally stopped moving laterally alltogether and than just lowered to the record without any lateral movement at all. I read many posts here and elsewhere pertaining to dried oil on solenoids and linkages causing the needle to drop slowly or not at all. But all of this was fine in my case. However, I did end up adjusting the damper in order to get the needle to drop in about a second as specified in the service manual. I also rebalanced the tone arm while I was at it. I applaud all of you for not only your knowledge and experience, but also your willingness to share. Especially with newbies like me. Cheers! And I am embarrassed to say that, yikes, I don't know how to thank you all at Beoworld. Any hints?
As a thank you, why not consider signing up as a silver / gold member if you can afford it :)Regards your comment above, the opto is just for tracking. A difference between earlier and later units was that B&O omitted a switch that disabled tracking until the arm was on the record surface, later 400x decks had no switch, and so the tracking circuit is turned on as soon as the solenoid activated. Hence, if the shutter (I still prefer paddle :-P ) is allowing light to get to the opto sensor, the arm will start moving right away!Anyway, glad you were able to fix the deck. It is highly recommended that you do lube the mech. A note of caution regarding the damper - never over tighten (and I mean sinking the screw below the casing!!) otherwise permanent damage will result! It will have needed adjusting possibly because it had dried out a bit, so a good clean, and then application of some good quality machine oil will be best.