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Beogram 4004 never turns off

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burnerxp
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burnerxp posted on Tue, Jun 16 2015 4:03 AM

I have a Beogram 4004 that has been in storage for many years, it was fully functional at time of parking, however I recently took it out of storage, only to discover it has become having problems, I have been able to correct most of the common issues (Tone arm would not lower automatically, this was a problem with the damping/solenoid arm becoming stuck/sticky) I was able to remove the arm, clean with a pipe cleaner saturated with goo-gone and lubed and re-installed, I also lubed all known areas, now I can play a record, however when I press "STOP" the table continues to turn and I have to unplug the unit to get it to stop, all other controls and functions seem fine.

I have searched a fair amount but it seems like most of the articles are repeats and I have not heard anyone specifically say they could not get one to turn itself off.

I am hoping someone here might be able to shed some light on this, I keep thinking something is just stuck from sitting. The unit has low hours on it, when I had it in use I kept having PowerAmp probems and I got discouraged/tired of sinking money into the system so I sold off all the good stuff (Originally had B&W 801's) Really cool speakers, they sold off easy, the power amp/preamp/level indicator and EQ where all Alpine/Luxman and are all gone now, I am either going to restore this so I can play some of my old Vinyle or sell it off.

Thanks for any help someone can give.

 

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Dave Farr
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Welcome to Beoworld.

You may need to remove the control panel and inspect the switches underneath.  Oxidation can cause problems or the contact pin may have a problem. Try pressing the stop control repeatedly to see if anything 'frees itself'.

Dave.

Steveric
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Welcome burnerxp,

Another thing you could try, clean the contacts of the operation panel 's connector plug into the main board. Wink

 

burnerxp
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burnerxp replied on Mon, Jun 29 2015 12:36 PM

Thanks for the info, I may have missed providing some relevant info, I have already disassembled and clean all of the control panels switch contacts (I am a retired master auto tech, plus I am currently active in the computer service industry for over 20yrs so I have some technical background), when pushing the stop button the tone arm lifts as expected and then returns all the way to right past the record, however the platter continues to spin and never stops, which suggests since they are SPST momentary contact switch's that the they are doing what they should, have I misinterpreted the way they work?

I have noticed a large number of items relating to the upgrade/replacement of the Replacement of the Tracking Sensor Light Bulb with an LED on the internet however it seems like this would only be relevant to the Toner Arm movement and Tracking, am I wrong?.

sonavor
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Hi,

I think you will need to locate the "SO" signal in the turntable per the schematic and monitor the components that signal passes through. It sounds like that signal is not functioning somewhere in your turntable. I take it that you have to unplug the turntable right now to get the platter motor to turn off?  When you plug the turntable back in, the motor initializes in the off state (not turning), right?

-sonavor

burnerxp
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Turns on by it self as soon as the cord is plugged in, like something is stuck, maybe a relay somewhere, I am really not sure, like I said worked until it was parked so something has to be gummed up or stuck I would think.

sonavor
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Here is the circuit area I would look at. The "SO" switch and the "ES" switch (not in the picture) are on the tonearm carriage.
I don't have a BG4002 or BG4004 opened up on my bench right now so I'm not in position to give you actual measurements from a working turntable. I believe the schematic diagram shows a condition where the turntable is running.  The "SO" switch is open and so is the "ON" switch.  There is 21V from the power supply transistor 1IC1 going to the turntable platter amplifier. 

When the "SO" switch closes, the power to the platter motor should turn off.  If the 33 RPM button is held down, the 21V should be supplied to turn the platter but goes away when the 33 RPM button is released. Note that other logic in the turntable, when the 33 RPM button is depressed, prevents the tonearm carriage from operating.
When the "ON" button is pressed, 21V goes to the platter and the tonearm carriage operates.  I believe that action opens up the "SO" switch so when the "ON" button releases, the turntable is able to continue and play normally. Since your turntable always has power on the platter motor, maybe there is a problem with the "SO" switch or transistor 1TR1. If 1TR1 isn't switching it would make "SO" not have any effect on turning the power off.


sonavor
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Also check the P5 connector that connects the "SO" switch to the circuit.

Steveric
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Hi burnerxp,

Did you solve the issue ?

mac1929
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Suggested by mac1929

My 4004 had same problem. I found 4 wires broken on mine, which were suppose to be attached to the control board in front of the arm mechanism, probably from transporting the unit. Also, if you stop (unplug the TT) once the arm is nearest the spindle, two switches will be exposed. One switch controls returning the arm, the other shuts off the arm and spindle motor. I sprayed deoixt on the switches, and now it works like it should. If you still have the TT and the issue. let me know, and I can give more details.

Fateus
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Fateus replied on Sat, Jul 30 2016 11:39 PM

I believe I've got the same problem you had, four wires are brokem off just in front of the switches you mentioned.  The wire colors are black, red, grey and white.  I can see the solder spots that they broke off from but don't know what color gets soldered to which spot.  Would you be kind enough to either tell me the order they get soldered back looking at them from the front of the turntable or if possible, send a picture?

Kromer
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Kromer replied on Fri, Apr 27 2018 1:03 PM
Thanks for the suggestions in this thread, it solved the problem on my bg4002. I’ll just show you a couple if pictures of the wires in question. On mine it was red, gray and White that were broken.

Arta
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Arta replied on Sat, May 29 2021 3:58 PM

Hi. I have Same issue being the plater not turning off. I checked these wires are OK and TR1 seems switching fine. There seem to be a residual voltage around 10 to 12 v all over the place in the circuit that causes the motor to vibrate or sometimes rotate resulting in non stop operation of the platter. Also the bulbs light faintly as a result of this voltage. Could this be some sort of grounding issue? SO switch has 0.1 Ohm resistance so it should be OK. 

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