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Beogram 4000 malfunction after shipment

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T4000
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T4000 posted on Fri, Nov 20 2020 6:02 PM

Hi!

I have a Beogram 4000 that was damaged in shipment. It was well maintained prior shipment. I initially posted here: https://forum.beoworld.org/forums/t/44481.aspx, but got recommended by sonavor to start a thread here instead.
The [numbers] refers to the Service manual. More pictures and clips can be added upon request.

Mechanical issues found (but now corrected):

a)       The Slide was loose and tilted and the Detection arm was relocated towards the Tone arm (see picture IMG_3629.JPG). 

b)      Pulley [124] came loose during transport and has likely been rattling around freely inside the Beogram. (in this Beogram replaced by a metal version, see picture IMG_3630.JPG). It was found again under the Turntable [4]. The loose Pulley resulted in the free moving Slide.

c)       The Slide threaded rod (Spindle [224]) was hanging loose-ish, also an effect of the loose Pulley.

d)      One of the Slide Contact pins and its plastic holder (Switch E, SO - Switch off/Home position) were knocked off.

Functional issues found (please note that issue #5 is now permanent and overrules the other 4 issues):

1.       Tone arm lowering even if no record is present. Intermittent problem. Happened both on 7" and 12" position. The detector arm bulb is lit up, but something is wrong in the sensor circuits.

2.       Another intermittent problem: sometimes the detection arm function works when scanning an empty platter, but then when the Slide are reaching end position, the servo motor continues to push the Slide to the center. OFF has to be pressed to return.

3.       The Slide stopped over the 12" position, then slowly moving towards the center, then returning back home. This occurred both with and without record. Don't know if this is a normal operation, but it happens intermittently.

4.       When playing a record, the arm lowers, but after 1s the servomotor starts and the arm moves across the record for about 0.5-1cm (my poor Pink Floyd album).

5.       After that I started (in pure frustration) to adjust mechanical bits and pieces according to the service manual. When I came to the step of Tracking force adjustment, I started ON, then pressed Reverse (>) to move the tone arm away from the platter. When I did this, the Slide decided to return to home position. I pressed ON again to repeat the procedure, but the Slide moved ~1 cm, then returning home again (see https://youtu.be/HG-VJ3dCZc0). https I tried a couple of times, but always the same. Also tried to manually push the Slide Contacts, but no reaction. I might have smelled burned electronics, probably for the main PCBA, but I'm not sure on this. The main PCBA [PC 8009012] were inspected visually, no remarks.

Initially I could really need some advice on issue #5, as the other issues can not be reproduced as long as #5 occurs.

Thanks a lot in advance.

 

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sonavor
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Hi T4000

Okay, let's start.

The first step is to disassemble the Beogram to where you can easily observe the tangential arm assembly working.
Also to get cosmetic pieces out of the way so they won't get in the way and won't accidentally get damaged.

Remove the Beogram 4000 dust cover and store it out of the way somewhere safe.
Remove the deck panels and store them away as well. Be careful of the red, plastic indicator piece that moves with the tangential arm assembly to show where on the platter the stylus is pointing. That piece can easily get in the way and accidentally broken. So you need to protect against that.

For now you can also remove the platter and belt and put them out of the way.

This should now give you access and full view of what goes on with the tangential arm assembly.
Post some photos of those areas so we can identify things that are missing and things out of place.

A good start I think.

-sonavor

T4000
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T4000 replied on Sat, Nov 21 2020 11:56 AM

Hi sonavor!

Here we go, se pics below.

Here is also a new try to include the zipped video clip: https://forum.beoworld.org/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.03.05.15.Beogram+4000/IMG_5F00_E3679.zip

sonavor
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sonavor replied on Sun, Nov 22 2020 12:51 AM

Great photos. Just the right size to still view the detail.

From the photos your mechanical parts look like everything is positioned and aligned correctly.

I believe you said that the fixed arm had come loose during shipping so you had to fix that.
There isn't too much adjustment in mounting the fixed arm but there is some.
The Beogram 4002 manuals say that the fixed arm should be perpendicular to the rear rail that the tangential arm assembly travels on.

Check if that is so. It looks good in the photo. The tonearm also looks nice and parallel to the fixed arm so that looks really good too.

In your initial photos of the Beogram 4000 it looked like the tonearm was not in parallel when it was lowered.

You can check that by pressing here (in the photo below) and observing how the tonearm lowers.

Pressing in on this point simulates the lowering solenoid operation.  You should see the arm lower straight down.  Releasing the lever should result in the arm raising straight up. If that is what you see then that part is good.

The connecting bar outlined in green dots here positions the tonearm in reference to the fixed arm.
The resting spot for the tonearm is where the point of the lifting arm rests in the "V" of the connecting bar.


The two screws outlined in green dots allow that bar to be adjusted slightly to set the tonearm parallel and the "V" channel lined up with the lowering bar.

Again...you arm assembly looks good in your photos so hopefully everything will function good in the manual lowering and raising test.

If that is the case then we can move on to check the platter height to the fixed arm and some other arm position checks like the lowering limit of the tonearm and the tracking force calibration.

-sonavor

 

 

T4000
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T4000 replied on Sun, Nov 22 2020 1:56 PM

Hi sonavor,

To make it more easy to share the videos, I have now created a YouTube channel.

Error #5 as described in previous posts can be seen here: https://youtu.be/HG-VJ3dCZc0

 

Check 1:

When I initially adjusted the detector arm, I made it perpendicular with the backside of the Beogram, not the rear rail. Now I realized that the whole dance proofing assembly can not only move, but actually stay in different positions (https://youtu.be/wkWiJtY7kEs). With that new knowledge, I loosened the 2 screws again and readjusted the detection arm from good to very good, now perpendicular with the rear rail. The 2 arms are now completely aligned, with 8.5mm in between (0.334645669 inches).  

 

Check 2:

When lowering the tone arm, it looked like it makes a little move to towards the detection arm, just before it reaches its lowest position. I made some adjustments according to your excellent guide.

Lowering the tone arm (before adjustment) - Top view: https://youtu.be/zk0ySXD82ew

Lowering the tone arm (before adjustment) - Side view: https://youtu.be/XL1-PwqyaC4

Lowering the tone arm (after adjustment) - Top view: https://youtu.be/6GC_-PpWplw

Lowering the tone arm (after adjustment) - Side view: https://youtu.be/9A3ws5rjHpc

 

A briefly mentioned in my first post, I initially adjusted the following according to the Service manual and/or Beolover's instruction videos:

Thanks a lot for your kind help!

Per

sonavor
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Hi Per,

The lowering doesn't look too bad as an early adjustment. It will need to be rechecked later.
It kind of looks like some of the lateral movement you are seeing is from the floating chassis. I typically do those initial adjustments with the floating chassis and tonearm assembly completely removed but I would not recommend that here. Especially because it appears that your Beogram 4000 is pretty close to being correct.

One thing you could do is tighten down the floating chassis as if for transport to it doesn't move while you are manually pushing on the arm lowering.

One other thing to note is the distance between the fixed arm and the tonearm. 
My Beogram 4000 manual does not state anywhere (that I can see) what that distance should be. 
In the later 4000 series (Beogram 4002 and 4004) their service manual states the distance between the arms as 7.7mm.
For now I would leave yours alone. The main thing right now is to get everything where it will function.

The next step I would make is checking and adjusting if necessary the platter height to the tonearm/fixed arm.
You can do that by putting the platter back in place but without attaching the belt. You don't want the motor turning the platter during these tests.

Did you say you did or do not have a service manual for the Beogram 4000 ?

I don't see one in the Beoworld service manual section. We need to get one added there.

I will post a picture of the platter height adjustment so you can check that.

Regarding the video where your Beogram 4000 tries to start, then immediately stops...we may have to look at what is causing the analog control logic to fail there.
Typically there is a poor connection somewhere and/or a problem with the button/actuator alignment. You posted a couple of photos of the buttons and actuators. The alignment of those is very critical to the Beogram 4000 operating correctly.

-sonavor

 

sonavor
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Hi Per,

One other thing regarding the Fixed Arm and Tonearm positions you currently have...
The arms looks close to where they need to be and they are parallel. 

Recheck the arm lowering with the metal covering for the Fixed Arm and Tonearm back on.
I am wondering if it will fit properly with the distance between the two arms you have it set to (8.5mm).
It may have problems with that in which case it will have to be re-adjusted.

-sonavor

T4000
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T4000 replied on Mon, Nov 23 2020 4:15 PM

Hi sonavor,

Regarding the distance between the fixed arm and the tonearm, I measured the drawings in the Service manual and each arm is as wide as the space between them. I then measured the actual arms. They are 8.25mm. So, the space between my tonearm and fixed arm is 0.25mm wider than on drawing (+/- deviation from me measuring a paper drawing with calipers). A video of the arm lowering when the metal cover is back on can be found here: https://youtu.be/wfPYzpx7R58

I measured the height between the platter and the fixed arm = 13mm. Same as stated in the Service manual, section 4-1. By the way, I send you a copy of it by e-mail.

I great way to fall a sleep at night is to ponder about what is wrong with the Beogram (being slightly ironic here). But I did get a Eureka moment. What if the Slide connector pins (the red, plastic ones) are not lubricated enough?! This turntable seems to have been at a B&O service center in 1999, so everything is well lubricated, but now when I revisited the Slide connector pins, I noticed that the first 3 from the right did not run very smoothly.

What lubricating would you recommend for these?

 

Per

 

sonavor
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Hi Per,

I wouldn't trust making measurements off the service manual diagram. Unless the diagram specifies the distances any measurement would be an approximation. From your video it is difficult to tell how well it is operating. The cover appears to fit fine. It should easily slide on. The important thing is that none of the moving parts of the tonearm are touching the cover when the tonearm moves (vertically and horizontally). 

That is good that the platter adjustment is correct. So far it appears that the Beogram was set up correctly when it was shipped to you and your reassembly of the pieces that came loose are good.

For now continue to operate the Beogram with the fixed arm/tonearm cover removed...until you have the record play working.

I'm not sure I follow what you mean regarding the red, plastic slide connector pins.
Are you referring to the tonearm assembly position switches here (in your photos)? -

....and the metal bars that actuate them?


Those shouldn't require any lubrication.
The adjustment of those bars is critical though.
They have to engage the switch actuators just right so the switch engages but doesn't interfere with the arm assembly travel. 
If those are out of adjustment they require a lot of patience to set correctly. 
I would not try to adjust those yet. They should already be in the correct location.
You should check if any of the bars that actuate the switches are loose though. Everything should be tight in its place.

-sonavor

chartz
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chartz replied on Mon, Nov 23 2020 5:14 PM

Nice photos Per.

John you are the best. I wish I had some free time to help. I’ll be watching with great interest though 👍🏻

Jacques

T4000
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T4000 replied on Mon, Nov 23 2020 5:39 PM

Hi sonavor,

 

I don’t trust it either, but it gives you an indication. Pictures online also indicate this ratio. Anyway, the metal cover slides on easily and the tonearm does not touch it, neither vertically nor horizontally. I noticed the tonearm moves smoother away from the fixed are than towards the fixed arm, though.

The dotted yellow circles in your picture are the one I mean. The switches, not the bar. The first two (counting from the top of the picture) are very easy to press, no friction what so ever. The next 3 (one yellow and two red) can be pressed, but have quite some friction, they don’t go down smoothly. There are some old lubrication on both the switches and the bars. Unknown pedigree. Thus my question. The switch #5 from the top (Switch E, SO) is the one that was knocked off in transport, by the way.

The bars are all screwed tight in place.

Per

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sonavor
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Hi Per,

I understand your question now.
I can see in the photos that there is a little bit of grease to help the actuating bars engage the switches. I don't know if that is a regular part of the maintenance or not. That isn't called out in the service manual with the other BG4000 lubrications. A tiny bit of grease to prevent the actuating bar from catching might be okay.

I guess I missed your information regarding the shipping incident being knocked off in transport.
So you have to reinstall that one? 
Are the others okay?
You are correct in thinking that the switches that don't operate smoothly are suspects to being a problem.
The red and yellow buttons just transfer movement to the leaf type actuators underneath. 
This Beolover Blog post has a good photo of those switch contacts. 

FYI - The red colored switch actuators are for switches that are normally open and get closed when the arm position actuating bar presses them. The yellow colored switch (the "17" position indicator) is a normally closed switch and actuating the switch opens it.

Before diving in check the switch contact operation manually with the platter removed and everything opened up. 
It is a little tricky and you will have to manually hit the ES and SO switches. If you can actuate the switch manually but not with the actuating bars in place then the problem is most likely an alignment problem with the actuating bars. I you cannot actuate the switch manually then the problem is probably with the leaf contacts.

-sonavor

T4000
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T4000 replied on Mon, Nov 23 2020 9:15 PM

Hi sonavor,

I will try to put some silicone grease on these tomorrow and see if I can get a smoother operation of these.

The SO switch was reinstalled, and tested OK with a buzzer. All of the 5 switches seem to be working, maybe a bit slow buzzer reaction on switch [ B ] (second from top of your picture). Potential root cause of one of Error #1-4 (in my initial post)?

Regarding the suggested manual switch contact operation, I did not quite understand what to do here. Shall I press ES and SO simultaneously, and if so, what is the expected movement from the Beogram?

Per

 

sonavor
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Manually operating them was just to verify the underlying switches operate. If you have already verified that then no need.
On the manual operation of the switches you have to actuate the ES switch before the end of travel to get the Beogram to reverse and you have to make sure and hit the SO switch to get it to stop. Same for the stylus set down points "30" and "17".  One thing it will check is if your "Start" button will initiate the Beogram correctly. 

-sonavor

T4000
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T4000 replied on Tue, Nov 24 2020 8:59 PM

Long story short. The Slide Contact Springs actuate the 5 contact pins correctly. This is not the root cause of issue #5.

The long story to conclusion:

To exclude the possibility that there was something wrong with the Carriage Position Switches, I today cleaned all 5 of them according to Beolover's instruction video https://beolover.blogspot.com/2015/04/beogram-4000-cleaning-of-tone-arm.html. I also cleaned of sticky grease from the pins (as mentioned in previous post). I relubricated the plastic part with silicone grease, so now there is no friction left. Big difference.

Plugged in and tested, but Error #5 is still present.

After that I checked that the springs were in correct position over each switch.

Method: I placed a tape on the platter, marking each of the positions [ A ], [ B ], [ C ] and [ D ] ([ E ] is home position, off the platter, so only estimated), measurements according to Service manual 4-2. Then I removed the Slide servo belt off the pulley to manually move the slide at the same time as placing a buzzer at the switches. As soon as the buzzer came on (or off for switch [ B ]2) I compared the position of the stylus on the platter with the tape marking. Switch [ E ], [ D ], [ C ] and [ B ](2) was measured. [ B ](1) and [ A ] was not accessible, but I estimated the position visually. Position [ E ] was 1mm off, the rest were within tolerance.

Service manual, section 4-2

 

Position [ D ] was 1mm off tolerance.

 

Position [ C ]

 

Position [ B ]2.

 

Position [ B ]1, right in the middle between [ A ] and [ B ]2.

 

Position [ A ].

 

Observation: When I was done with the test above (Slide at position [ D ], I placed the servo belt on the pulley again. When connecting the power and pressed "ON", the Slide return to home position. Same as before, regardless of previous position on the platter.

Per

 

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