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!
I have a Beogram 4000 that was damaged in shipment. It was well maintained prior shipment. I initially posted here: https://archivedforum2.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.
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
Hi sonavor!
Here we go, se pics below.
Here is also a new try to include the zipped video clip: https://archivedforum2.beoworld.org/cfs-file.ashx/__key/CommunityServer.Components.UserFiles/00.00.03.05.15.Beogram+4000/IMG_5F00_E3679.zip
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.
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
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.
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.
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?
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.
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
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.
Normal 0 21 false false false SV X-NONE X-NONE
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.
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?
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.
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.
T4000: 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
I opened up one of my Beogram 4000 turntables and ran a couple of tests.When I press "On" and the Beogram starts to move the arm assembly forward I can use the "<"/">" to stop and position the arm.After stopping the arm over the area of record play I unplugged the Beogram.Next, I plugged the Beogram back in to power.Like yours the Beogram remains in the "Off" state.Unlike yours however, when I press "On" my BG4000 knows where it is and continues forward to the first record set down spot it finds. It does not return home.I also checked this out on a second Beogram 4000 and get the same result.
So it appears your Beogram 4000 has a blocking signal from somewhere in the control logic.There is a nice BG4000 Training Notes manual in the Beoworld service manual section that details the control logic of the Beogram 4000.I recommend getting it. You need to have a Beoworld Silver membership or higher to access it. I will read through it myself to see if I can get some hint on what to check next. Maybe someone else on the forum will have an idea as well.-sonavor
One more quick thought...it occurred to me that your Beogram 4000 symptoms are like the logic for the "Off" button is always engaged. -sonavor
Yet one more possibility :-) ...After talking to Rudy he suggested that it might be a problem with the ">>" button/signal from the control panel.-sonavor
Hi sonavor and Rudy,
Tonight, I opened up the control panel to measure the button switches. They are all according to spec. I paid extra attention to >> and OFF, but no remarks. Did not have time to clean them from potential oxide today, but might revisit for that.
I also visually insected the electronics of the two PCBA. No remarks.
Okay, I was hoping something would be revealed there.
I think there still has to be a problem where the Beogram control logic is being told there is an end stop (ES) event or a fast reverse (>>) event.Please download the Beogram 4000 training notes from the Beoworld technical information page. You will need to get familiar with the control signals.-sonavor
Today I finally had some time to look at the logic circuits described in Service Manual, section 3-1, Diagram 1. I focused on the ES and OFF signals. Those signals feed into the NAND gates in 3IC0, 3IC1 and 3IC2. After pressing ON, I measured as follows:
Is looks like 3IC1 is defective.
What does the jury say?
On those NAND logic devices it only takes one input to be a logic "0" in order for the output to be a logic "1".3IC1, Pin 1 has a 1.2KOhm pullup to +6V so it appears to me that one of its inputs must be a logic "0". So 5.6V would be reasonable for the output.Those NAND logic devices do not fail very often and should it turn out you do have a failed NAND device it would bring into question whether you Beogram was a working unit prior to shipping. It seems unlikely the shipping event would have damaged a none moving part like that.While strange things are possible I think it is more likely that your fault is in something that sends voltage signals to the logic controls.The question to check is what should 3IC1, Pin 1 be when you press "On".According to the Beogram 4000 Design Notes I pointed you to 3IC1 is the logic for the tonearm Lift so I don't believe it is a problem here.Check the 3IC0 logic device and the flow diagram in section 5-4 of the service manual.According to the Design Notes, 3IC0: Automatic Slide Transport In, is the logic device that starts the Beogram. Monitor the SI signal that starts things off.
This diagram shows the logic board and which logic gates relate to what Beogram 4000 functions.
Regarding the logics:
I have now read the document you recommended, BG4000 Training Notes manual. I will leave 3IC1 be for now. I focused on section 3-25 (3IC0). I measured the voltage of pins, but I'm a bit hesitant to draw any conclusions anymore, so I'll just present the results below. As you also pointed out the Fault-finding diagram 5-4 in the Service Manual, I'll present the measurements for these signals as well.
IC0
Pin Function Voltage (V)
1/2 NAND (/Q0) 0.06
5 SI 5.85
7 +6V 5.85
8/9 NAND 5.75
10 ES 1.93 (a bit lower this time, 2.6V last time I measured)
11 OFF 1.93 (a bit lower this time, 2.6V last time I measured)
12 /Q1 5.57
13 Input fr.3IC9 2.32
IC1
5 WO 5.8
13 "Is SI missing" 0.77
IC7
2 DR 5.87
5 BL 5.88
The detector arm light = On
Regarding SI:
I studied the Start Impulse (section 3-11 in the Training Notes manual). I don't have an oscilloscope at hand, so I'm not quite sure I can observe the 10ms pulse we are talking about here. I can buy one if needed. Can transistor 1TR20, that generates the SI, give some hints? Any ideas what to look for in that case?
Regarding what happened during transport:
As far as I was told, the Beogram was in good shape prior shipment. Please note though: issue #5 was not present when I received the Beogram. That error appeared a couple of days later. The "only" failures the first week after arrival was issue #1 -> #4:
4. When playing a record, the arm lowers, but after 1s the servomotor starts and the arm moves across (and scratches) the record for about 0.5-1cm.
I'll try to describe (and remember) exactly what was going on when #5 first appeared:
I was moving the Slide from Position [ D ], first groove of the record, slowly to the right pressing ">" with several, short intervals. (Purpose: to get the stylus over the aluminum plate for tone arm weight check). I pressed ">" a few times, and then the issue #5 appeared, causing the Beogram to switch off. After that I removed the Slide Contact Spring assembly to reach the Slide Contacts. I pressed the contact pins, probably from the right to the left, and then I might have smelled burned electronics.
Just looking at your IC0 logic -
If my memory serves me correctly...Your Beogram 4000 appears to be in the "On" state according to the IC0 flip-flop pins 1 & 2 state.The IC0 flip-flop circuit is latched where /Q0 is a logic "0" (or "L"). Maybe someone else who has gone through this recently can confirm.So it appears that your IC0 logic is saying the Beogram is on and can move the arm transport forward. Since that isn't occurring then something else must be stopping the tangential arm assembly.When you are in this state do you see the platter motor pulley turning? Can you feel the tangential arm assembly motor turning (or trying to turn?).You mentioned that the spindle and spindle pulley had come off earlier.In re-assembling that are you sure the spindle is correctly positioned now?See if you can manually turn the pulley and move the tangential arm assembly with the servo belt removed. Is it easy to move or do you feel a lot of resistance?
I decided to go over the Beogram 4000 control circuit to refresh my memory.The logic "Low" ("0") on the /Q0 signal that comes from the 3IC0 flip-flop circuit, will turn on 1TR25 to drive the tangential arm assembly (the slide assembly) forward. The same control over 1TR25 occurs with the "FF" control panel button is pressed.So mechanically, check the spindle movement that drives the slide and make sure it moves correctly. As I mentioned earlier, you can test it manually by disconnecting the servo pulley belt and turning it by hand.Electrically, measure the DC voltages around 1TR25 and see what they are when the /Q0 is a logic "0".
Hi sonavor,Today when I started up the Beogram, Error #5 was gone. I decided to screw the spring assembly back in place, but then Error 5 reappear. And disappear. Error #2 and #3 could be reproduced when #5 was gone (caught #3 on tape: https://youtu.be/4FmXFWzZDfk). And I might have a new issue. Error 6, the tone arm seems to be stiff, it doesn't lower (this stiffness can also be seen in the Error #3 video). And then.... Error 7, I broke this plastic construction:
The below text was written before the Beogram (and I) went all erratic (I never got to measure 1TR25, let me know if it still makes sense):
There is nothing mechanically stopping the Slide. I can however not electrically run it forward due to error #5. When I remove the servo belt and manually turn the pulley it runs smoothly. The manually turn the pulley is what I have been doing so far to move the Slide for the various tests/adjustments.The Slide servo motor is running when the Slide is returning home. The Slide moves back home at ON. If it is already at home, it moves 0.5cm to the left, then back home and turns off. Error #5.
Platter motor is running.
My logic circuit measurements in previous posts were made with the servo belt removed, otherwise I would not have time to measure before it tuns off again. So, my measurements are under that condition; Slide moving back home (I stop the condition by manually pressing SO).Regarding the spindleThe Slide Spindle seems move as intended, and I also confirmed the alignment seems to be according to Service Manual 4-6 "Adjustment of Spindle". See also video the Spindle when Slide is returning home: https://youtu.be/53YIdLNQb6g
New observation:
This PCBA seems bent (red) and the conductor (blue) seems to be damaged. I think I read something about this (blue) being normal when the trim pot was installed, though.
It is a little confusing regarding the exact status of the Beogram 4000.If I read your post correctly you are saying the "Error #5" (where the Beogram won't start) is now intermittent, right.Regarding your video of the Beogram 4000 starting, stopping at the first set down point, then continuing on to the end stop....That looks normal to me. The tonearm will not actually drop if there is no cartridge mounted. It requires some weight to go with the arm balancing to drop freely.When the Beogram continued forward to the end stop did you click FF to cause that to happen or did it do that on its own?-sonavor
Hi,
That makes us 2.
Error #5 is now intermittent, yes. Sadly.
The tone arm is not balancing anymore, it is stiff, regarless of solenoid position (error #6). Somethign might have happened when I reinstalled the cover a few days ago.
In the Video I only pressed ON, the rest was done by the danes.
Okay, then what must be happening with the Beogram travel across is the result of the tangential tracking sensor being out of alignment.That would make sense based on the Beogram components that were out of place when you received the Beogram shipment.What is happening there is most likely the Beogram sensors are telling it that the arm is free and should be playing a record.The tangential arm sensor thinks the arm is not in the correct tracking position so it instructs the servo motor to advance it forward to catch up.It never catches up because the sensor is out of alignment so it just continues forward until it hits the end stop.We don't need to mess with that just yet but will obviously have to come back to it soon.The good thing is that a portion of the tangential arm control logic appears to be working fine :-).For the stuck tonearm you need to carefully observe the tonearm movement mechanics.If the arm does not freely move when the arm lowering lever allows it to drop then there has to be some physical thing blocking it.First try it with the Beogram unplugged.Manually move the lever that the solenoid would engage to release the arm lowering damper and watch the arm lowering lever action.Checkout how the lever is engaging and disengaging with the horizontal bar that releases the tonearm itself.Is there contact?Is the arm lowering damper working?Make sure the arm lowering limiting screw isn't preventing the lowering.Did someone move the tonearm counterweight too close to the tonearm base so it won't pivot down?Like I said, there has to be something mechanical there causing a problem and the mechanical components are all right there at the back of the tonearm.-sonavor
sonavor:Did someone move the tonearm counterweight too close to the tonearm base so it won't pivot down?
Hi sovanor,
Me and my Beogram needed a break from each other. Now, I'm back.
The tonearm counterweight was the issue. Someone (me) adjusted it a while ago to obtain zero force adjustment ('Static balance' according to the Service manual and Beolover's video https://youtu.be/j3KNUQIsTG4). The result at the time was good, but I must have been reckless lately, because now I noticed that the tonearm base was too close to the counterweight. It's adjusted and moves freely again.
What would you recommend me to look at next?
So that was the source of the stuck arm problem, right?Now that is resolved.You will have to post a reassessment of what is not working at this point so reorganize and see what the next step is.-sonavor
Correct. Perfect balance is unfortunately very close to whenthe tonearm base is too close to the counterweight. Slightest move of the adjustment screw, and the arm is stuck. Anyway...
Well, current status is that error #5 is back again.
Same as in my very first post here, I was about to adjust the tracking force using the tracking force gauge. I pressed ON, tone arm moved to 30cm position, and lower. Then I used > to move the tonearm back for the adjustment. It was possible to start moving it back, but not stopping it. When pressing forward (>), it just stopped for a split second, end then continue back home. And after that Error #5 seems to be permanent again.
In Dec 1 you suggested Electrically, measure the DC voltages around 1TR25 and see what they are when the /Q0 is a logic "0".
So now I did:
C: Varies each time I press ON. I got 16V, 2V, 10V, 5V, 1.3V.
B: 0.6-0.7V
E: 0V
It is curious that this error comes and goes. That makes me think there is something mechanical, something moving that causes the problem. I am also thinking about the fact that the turntable supposedly was in working condition and something during shipping caused the failure. We will eventually figure it out. You might have to dig into the Beogram button control panel.When you press ON and the Beogram starts you should see a constant voltage on the collector of 1TR25 that would be instructing the servo motor to drive forward until the first set down point. It still sounds like there is a signal telling the Beogram that it is supposed to be turning off or telling it to be in fast reverse mode. I believe you said that when you manually move the tonearm where it would be over the platter and then turn power on that the Beogram immediately returns the arm to the stopped/home position. It would be interesting to monitor the collector voltages of both 1TR25 and 1TR34 at the same time with an oscilloscope. Regarding the tonearm balance though. The counterweight should not interfere with any movement of course. A couple of questions about your adjustment.Were you making the zero balance adjustment with the tracking force knob set to zero? Were you making the zero balance adjustment with a phono cartridge attached?A cartridge has to be mounted on the tonearm and the knob with the spring tension for the tracking force needs to be down at zero when starting the adjustment.The result should be a balanced arm that has freedom of movement within the range that the Beogram would be playing a record. Horizontally and vertically.
I may be barking up the wrong tree, but I noticed on the last picture (marked in red) where the PCBA board is lifted, would it be possible for the diaphragm be out of adjustment and forcing the tone arm to run backwards, as it was made to do on the 4000?
Keith.
Hi Keith,
From what has been described about the failure it doesn't sound to me like a problem with the tracking sensor diaphragm. I say that because the problem happens before the tonearm lowering event occurs. The signal from the tracking sensor shouldn't be a factor at that point.
If it is somehow related then there is also a problem with the Beogram logic not knowing what mode it is in.
I still suspect the problem is related to one of the items that came loose during shipment of the Beogram.
Hi sonavor and Keith,
Happy new year! And thanks for your interest in my Beogram! I'm very grateful for this, I can tell you. I hope the below information can give you some clues. Please let me know =)
I manage to borrow an oscilloscope today. Collector of 1TR25 is on Channel 1, and 1TR34 on Channel 2. The short minus voltage at the end of each reading is when home position is reached and the relay shuts the Dane off. 1TR25 seems to be active when the Slide moves to the left, and 1TR34 when the Slide moves to the right.
Regarding the tonearm balance:
Were you making the zero balance adjustment with the tracking force knob set to zero? -Yes, I did. Were you making the zero balance adjustment with a phono cartridge attached? -Yes, and without the protection. After adjustment the arm is again free-moving. Just very close. See picture:
Regarding the tracking sensor diaphragm.
Would it be possible that error #3 and #4 is related to it?
All the best,
I am afraid it has been too long away from this problem that I can't remember the problems by their number. Please restate the problem when referring to it so it is in context with each post. Otherwise it is too much back and forth looking up what the numbers go with in the thread. It is probably easy for you to remember but many of us are working on multiple projects. Thanks.
I would like to see the activity on the transistor base leads. In addition it would be good to use both of your oscilloscope probes to look at the forward and reverse signals on the motor itself...nodes where the emitters of 1TR28 & 1TR29 connect along with the nodes of 1TR31 & 1TR30.If you see signals trying to drive the motor to reverse and stop then you need to track down what is driving those control signals.
On your tonearm and counter weight. The weight assembly is away too close to the back of the tonearm. It has hardly any room to move.
Here is what my Beogram 4000 tonearm counter weight looks like from the side. It is balanced and calibrated so the tracking force knob is at 1 gram with the mark shows that it is at 1.
OK, I'll include the error descriptions in each post from now on.
Tonearm counter weight
I don't know what I will do with that information.
* Error #5: At ON, Slide moves ~1 cm to the left, then returning home again (https://youtu.be/HG-VJ3dCZc0).