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B&O 4002 turntable issues

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bbrandt
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bbrandt posted on Tue, Apr 4 2017 4:33 PM

My 4002 turntable sometimes makes loud squeaking noises while playing (from motor area?).

Also the arm sometimes squeaks when moving, especially at the ends of travel. Sometimes it doesn't come to a full rest when returning to the right and will only park and shut off if I give it a gentle shove.

And lastly, it makes a tremendous rumble at the end of LPs before lift off.

I lubricated the areas around the axle pivot between solenoid & damper, the ends of the solenoid, and piston of the damper. Also the long threaded shaft that the mechanism runs on.

I used Zoom Spout high quality turbine oil, which is paraffin based and non-gumming.

How taught should the drive belt be? Mine seems a bit loose.

What else should I look for?

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Søren Mexico
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Welcome to the forum. This thread may help you a little, but get the manual and a set of belts from Martin (Dillen)

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

sonavor
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What type of Beogram 4002 do you have? There are several versions of that turntable. The type number is usually on a sticker underneath the turntable. Squeaky platter motor sounds are a symptom of the motor bearings drying out. That goes both for 4002 versions with the AC platter motor and versions with the DC platter motor. Member Beolover has a process to lubricate those bearings. You cannot just put oil on the motor shaft. The link I posted explains how the bearings have to be re-infused with oil. I have had him restore three of my Beogram motors so far and they work great now.

On your other problems oil is probably not the solution. You could have a bad pulley on the tonearm transport. Check for cracks on that pulley. Metal (aluminum) replacements are available. The belt on tangential arm motor should not be too tight. You will need the correct belts though. Dillen on this forum supplies those. 

These Beograms are now around forty years old and require some well deserved restoration if they are to be back in service again. Once restored they perform beautifully when paired with a good MMC cartridge (the last and most important part). 

-sonavor

bbrandt
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bbrandt replied on Mon, Apr 10 2017 10:33 PM

Thank you Sonavor. I am not able to get under the turntable at the moment to check the type. Here are a few things that have happened or been discovered:

- The TONEARM TRANSPORT pulley is not loose and the belt is new. I was told to check that the screws are not loose: the two on the left of the pulley (looking at the turntable form the front) are tight. There is NO screw on the pulley itself. Should there be?

- I replaced the motor drive belt.

- I ran it without a record on the platter. The arm now most times goes to the end and returns. But sometimes it gets stuck at the end and won't return. I can only get it to return if I hit the stop button

- Listening carefully with the platter removed, I don't hear any noise or squeaking from the motor. The squeaking sound occurs at the end of travel for the arm in both directions.

- With an LP on the platter, I did notice that the arm will travel too far, taking the stylus into the label area!

I love the 4002 and hope to be able to rectify these issues. I have a 20CL cartridge on it.

Thank you, Brian

bbrandt
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bbrandt replied on Mon, Apr 10 2017 11:35 PM

I played a few more LPs watching at the end to lift the arm before it gets to the label. But the last LP played, the arm did not go fully to rest, stopping before it did with a grinding noise. I gave the assembly a gentle tap to the right and it turned off.

It seems the arm has problems at both ends of travel.

Thank you

Brian

sonavor
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sonavor replied on Tue, Apr 11 2017 12:22 AM

It is too hard to provide any advice without knowing what type of Beogram 400x you have and not seeing anything. Can you take and post some pictures of the Beogram insides?

sonavor

bbrandt
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bbrandt replied on Tue, Apr 11 2017 12:43 AM

This is the tag underneath. If you need inside photos, let me know what you would like to see.

When I last reassembled it, the panel on the right, behind the buttons, seems to have gotten stuck. I don't want to have to force anything, so if anyone has hints on how to free it...

bbrandt
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bbrandt replied on Tue, Apr 11 2017 12:46 AM

The photo was pasted in, but it looks like it didn't post. Is there a trick to posting photos?

The info on the tag is:

GR 4002

SLUTAFRØVNING

No. 1189015

TYPE 5513

Thank you

Brian

 

sonavor
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There are two ways to post images.

One way is to use the "Options" tab of the message post screen (just to the right of the "Compose" tab). From there you use the Add/Update button which launches a popup dialog to upload a file from your computer. 

Another way is to go to your Beoworld user profile screen and from there to your "My Files" section. From the "My Files" section you can create some personal folders that you can name and upload images to. When you have pictures uploaded to your "My Files" folder you can use the "Insert Media" option of this message posting tool. You just browse in that popup to your image in your "My Files" folder and it will add it to your post.

Both methods take a little bit of getting used to but they work. Note that there is a size limit to the image files. I always try to crop mine down from the original high resolution file to the area I want to include in the post. Then I resize that cropped image to a width of between 650 and 1200 pixels. 750 pixels seems to work best on this site.

sonavor 

sonavor
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bbrandt:

The info on the tag is:

GR 4002

SLUTAFRØVNING

No. 1189015

TYPE 5513

Thank you

Brian

 

Type 5513 is after the AC platter motors so it has a DC platter motor and it has an optical sensor to determine the position of the tonearm carriage. It is still just guessing without actually seeing it but it is possible that you have a problem in the position detection. Since it appears to be intermittent the problem could be a weak signal due to a lamp going out or a bad light sensor. Start with simpler things first though. Check to make sure that area is clean and free of dust/dirt. Check solder and wire connections. Also keep exercising it with the platters (top and sub-platter) off so you can see what is going on with the stop detection. With the platters off the Beogram will think there is a record present and lower to play. If you gently tap the arm towards the center to simulate a record playing the tangential drive should move the arm to keep up. See what happens when you do that at the point the end of record should be detected.

sonavor

 

bbrandt
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Today the problem has worsened. The arm will not move to the edge of the record to begin play. I have to send the arm back to rest by using the Stop button, but even then it doesn't go completely to rest and turn off. I have to give it a gentle push to the right to turn it off. So, not possible to play records now.

The turntable was serviced a few months ago by Analogique here in NYC but is out of warranty. They service B&O from back in the 1980s (or 1990s) and know the units. They lubed and went through the 4002 and it worked beautifully for a while until these new problems began. I hoped that I may be able to fix it myself, but...

I am not certain what you would like me to photograph or what exactly I should look for. Everything looks clean and in order inside to me. If you tell me specifics I will check and report back. If I can figure out how to post photos, I will do that too.

Thank you for your help and patience.
Brian

sonavor
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sonavor replied on Tue, Apr 11 2017 10:02 PM

Did you try some more testing with the platters (and belt) completely removed so you can just observe the tangential arm activity?  The things to look for would be if the motor stops turning or the belt is slipping. Also checking for any squeaking sounds you heard before.

If nothing mechanical is causing the problem then it could well be electrical. I always exhaust the mechanical and connection trouble-shooting first. Are you the original owner or did you buy it used and had it serviced there in NYC? Do you know if any service on the Beogram involved the electronics? 

sonavor 

bbrandt
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Hi Sonavor

The Analogique service was in August 2016, because the arm didn't move (it was a broken belt), and here is what was performed:
Replaced belts
Replaced lamp(s) and/or LED(s)
Replaced capacitor(s)
Traced located and repaired electronic problem(s)
Reconditioned and lube bearings/carriage/cam
Cleaned and lubricated as necessary
Tested and ra
n

I have owned the turntable since around 1990. The last service before 2016 was in 1997! At that time, Technetron in NYC did:
Replaced belt drive
Replaced arm belt
tip 141 transistor x2
tip 146 transistor x2
BC 156 (?) transistor
10 MF 16V cap (?)
Relay

The items with (?) are due to unclear handwriting. But perhaps this gives you an idea of some upgrades that may have happened.

I took all the platters off and can see what is a clear problem:

Sometimes the arm moves all the way along the path. Sometimes it gets stuck part way. Sometimes it gets stuck at the very end of the play or before returning to full rest.
When this happens, the pulley and belt for the arm is still spinning BUT the gold threaded shaft which turns with the pulley stops turning. This is when the squeakiing sound happens.

If I give it a nudge the shaft will begin turning again and the arm continues to move.

The belt on the arm pulley is new and appears to be tight. The pulley has two screws to the left of it which feel tight to me. The pulley also has a small hole on its right side, near the end of the shaft. There is nothing in this hole. Is that correct or should it have a small screw there.

When it gets stuck at what would be the end of the LP, the only thing that makes it return is to hit the stop button.
The pulley seems to have some lateral movement on the shaft (left to right). When the pulley is hard left on the shaft, a very small amount of the shaft protrudes on the right. During the course of the arm moving, when it gets stuck (at this point the shaft stops spinning) the pulley seems to have shifted slightly to the right and there is no longer any shaft protruding. If I push the pulley to the left, the shaft and the arm begins to move again.


FYI, it had been suggested to lube the 4002 as a first try at fixing it. The threaded pulley shaft had some grease on it. As I didn't have grease, I used "Zoom Spout Oiler" Highest Quality Turbine Oil, paraffin based non-gumming (the same oil I used on the other lube points). Now there is really no grease on the shaft, only that oil. However, the arm was already getting stuck before I applied the oil. What type of grease should be on the shaft (which can be easily obtained)?

I took photos of all of these things but I don't know if they tell you much. I can try to upload them if they help you.

Thank you
Brian

Søren Mexico
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bbrandt:
When this happens, the pulley and belt for the arm is still spinning BUT the gold threaded shaft which turns with the pulley stops turning. This is when the squeakiing sound happens.

The pulley is loose on the gold threaded shaft. (missing screw ?)

The belt should not be tight but nearly loose to the feel of it, get a correct set of belts from member Dillen, 2016 original belt didnt exist and member Dillen is the only one we know to supply the correct ones

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

bbrandt
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Hi Søren

The belt for the arm appears correct to me. The tension is as  you described. If I push down in the center, the belt compresses to almost the top of the shaft of the motor pulley post (sticking out of the black motor). Doesn't this sound correct?

What does look odd is that the belt has a slight twist to it when it goes around the black motor shaft/pulley). It is not absolutely flat, but it is flat on the big pulley wheel. Is this correct?

I will purchase a belt from Dillen if needed. Just want your opinions first.

Brian

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