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ARCHIVED FORUM -- April 2007 to March 2012
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This is the first Archived Forum which was active between 17th April 2007 and 1st March February 2012

 

Latest post 12-28-2008 1:05 AM by Folke. 8 replies.
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  • 12-21-2008 2:07 AM

    • Folke
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    • Stockholm, Sverige/Sweden
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    BG 4002: no Volts to arm motor

    BG4002_PCB1.JPG
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    New problems surfacing in my Beogram 4002... First the pickup arm motor, now this.Sad

    All of a sudden, the pickup arm motor isn't fed any voltage whatsoever. When I press START, STOP or hold down < or > and measure the pins on the edge of PCB1 leading to the motor, zero Volts (actually 0.3V after pressing STOP). It used to be 5,5 and 12 Volts.

    Everything else works - platter motor, all lights, pickup arm down/up. I haven't replaced any components, but I have removed, cleaned, oiled and re-installed the arm motor. No short-circuit in the soldering job for the motor wires.

    I can see that PCB1 has heat discolouration around TR20, where the board gets warm.

    Maybe I need one of Martins upgrade kits...Hmm

    Again, any help greatly appreciated! I hope it's a "normal" problem...


    BG 6000 Quad (two!), BM 3000, BM 5000 (2005), BV S45, BV M70 with trumpet stands

  • 12-25-2008 11:33 PM In reply to

    • wongss
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    Re: BG 4002: no Volts to arm motor

    Reply Contact

    u manage to solve the problem?

    All the e-cap in your TT still the old original cap? If yes then suggest you to chnage all the e-cap and tantalum cap.

  • 12-26-2008 4:46 AM In reply to

    • Folke
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    Re: BG 4002: no Volts to arm motor

    PIC00027_49p.JPG
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    Hi, Wongss!

    Haven't replaced any components, I'd better leave that to someone who actually knows what he is doing! Embarrassed


    BG 6000 Quad (two!), BM 3000, BM 5000 (2005), BV S45, BV M70 with trumpet stands

  • 12-26-2008 8:46 AM In reply to

    • Dillen
    • Top 10 Contributor
    • Joined on 02-14-2007
    • Copenhagen / Denmark
    • Posts 5,008
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    Re: BG 4002: no Volts to arm motor

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    What type number is your deck ?

    (53xx or 55xx)

    Make sure you have all connectors on correctly, they will easily mount 1 pin off. Check also the soldering of the edge connectors, they are often found cracked.

    Martin

  • 12-26-2008 1:34 PM In reply to

    • Folke
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    Re: BG 4002: no Volts to arm motor

    PIC00029_40p.JPG
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    Hi, Martin!

    First my apologies for starting two threads on my BG4002! I saw it as two different problems...should have stuck to one thread for one machine, I guess.Embarrassed

    It's a BG4002 Type 5511. Here's what happened... Before I did anything, I made sketches and took pictures, just to be sure! I just got this unit, and the pickup arm motor was very noisy. I de-soldered the motor wires from the board and cleaned the motor. I also removed all connectors from the main board and cleaned all the pins, removed the board, visually inspected the components and attached everything again. All connectors were in place, just like in my reference pictures. All pins correctly inserted in the sockets, nothing sticking out on the sides. I was very thorough and checked that the colour-coded wires corresponded with my pictures.

    When I installed the motor again, it ran backwards! When I pressed STOP the arm would move towards the platter centre spindle, and vice versa. And I hadn't mixed up the black and red motor wires. I re-checked my pictures several times: black-left, red-right. I noticed that the motor wasn't getting 12V any more, but 8-9V. So I resoldered the motor wires to the board, but reversed this time, and the arm moved correctly for a couple of minutes - and then the board stopped outputting any voltage at all to the tone arm motor. Everything else seems to be getting correct voltage, platter motor etc.

    I have removed the motor again. No change, minimal voltage from the main board when I use the controls (typically 0.5-1.5V). The motor will run on a 9V battery, but is very noisy.

    If I would venture to guess, I'd say that:

    1. I did something to the motor that made it run backwards (but all I did was remove the rear plastic cap, clean the tiny contacts and re-assemble, making sure that the contacts were positioned on each side of the motor spindle).

    2. I did something to the board that I just can't figure out.

    3. One or several components on the main board failed in the process, causing the problem.

    4. ...or something I can't think of!

    I have removed the main board again and inspected it under a loupe for loose/cracked solder joints. I found three suspicious looking ones at the control panel connector, and resoldered them. But no change.

    I'm sure you can tell that I'm just an adventurous amateur, and that I'm feeling my way forward here...Unsure

    Again, any help greatly appreciated!


    BG 6000 Quad (two!), BM 3000, BM 5000 (2005), BV S45, BV M70 with trumpet stands

  • 12-26-2008 4:35 PM In reply to

    • Dillen
    • Top 10 Contributor
    • Joined on 02-14-2007
    • Copenhagen / Denmark
    • Posts 5,008
    • Founder

    Re: BG 4002: no Volts to arm motor

    Reply Contact

    I noticed you wrote that when you put the motor back together... "the contacts were positioned on each side of the motor spindle"

    Obviously, these need to go to their correct sides respectively of the commutator or the motor will rotate backwards and/or short the driver circuit, depending on the motor windings timing and start position for each motor activation. Check this.

    Then check the transistors in the motor driver H-bridge. I don't have the manual at hand but I seem to remember that they are the ones in the group near the power resistor and speed changing relay in the above photo. There are 8 in total, 4 smaller (plastic house) and 4 larger (metal house).

    Martin

  • 12-26-2008 5:11 PM In reply to

    • Folke
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    Re: BG 4002: no Volts to arm motor

    PIC00034_42p.JPG
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    Thanks, Martin!

    It's very possible that I didn't reassemble the motor as it should be, I'll see what I can do. The transistors is this lot, I presume? I guess I've got to call in professional help here...Embarrassed


    BG 6000 Quad (two!), BM 3000, BM 5000 (2005), BV S45, BV M70 with trumpet stands

  • 12-27-2008 9:55 AM In reply to

    • Folke
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    • Joined on 10-24-2008
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    Re: BG 4002: no Volts to arm motor

    Reply Contact
    Martin, you have a PM.

    BG 6000 Quad (two!), BM 3000, BM 5000 (2005), BV S45, BV M70 with trumpet stands

  • 12-28-2008 1:05 AM In reply to

    • Folke
    • Not Ranked
    • Joined on 10-24-2008
    • Stockholm, Sverige/Sweden
    • Posts 30
    • Bronze Member

    Re: BG 4002: no Volts to arm motor

    Kondensator.JPG
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    Picture for Martin. Main capacitor.

    BG 6000 Quad (two!), BM 3000, BM 5000 (2005), BV S45, BV M70 with trumpet stands
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