Tandberg 9000x Blowing Fuse

Discussion in 'Tape' started by GregPerugini, Feb 24, 2018.

  1. GregPerugini

    GregPerugini New Member

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    Hello All;

    Just got me a Tandberg 9000x that wasn't powering up. Opened it up, cleaned the switches, and noticed that the central motor was indeed turning - all the rest was not powering up. Checked the fuse - saw that it was blown. Put in another one - it lit up and engaged briefly, and then blew that fuse.

    Any ideas on where to troubleshoot first? I will Deox it again and work the switches, and thanks in advance for any input.
     

     

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  2. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    I'd check for shorted Frako filter caps, starting at the power supply board. Those are the larger gold-colored caps, and they tend to short out with age.

    Also make sure the mechanism moving parts aren't frozen: pinch roller arm, braking mech etc. You might have a solenoid trying to move one or the other of those and popping a fuse because they're frozen with old grease.

    John
     
  3. GregPerugini

    GregPerugini New Member

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    Thanks, John. I checked the Frako's on the power supply board. They seem to check ok. I have checked all the linkage connections for movement - It all looks like it wants to move. I found a 9000x power regulator board on ebay that I will try. I will let you know.

    Greg
     
  4. GregPerugini

    GregPerugini New Member

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    OK John, Here is where I am at on this Tandberg 9000x.

    I thought that the regulator board (where the fuse is) might be bad, and replaced it. Perhaps it was burnt out by one of the motors being frozen. Replacing the board allows it to power up, but pressing rewind just gives a hum on the motor that removes the pinch roller against the capstan (tb3.jpg, motor with the red dot). My guess is that motor throws a rod that moves the lever away from the capstan for rewind and engages the switch below the motor that activates the right spindle. That switch works, and the spindle turns, but the motor does not throw against it as I think it is designed to do. I did find this spring loose in the machine when I opened it (TB2.jpg). That spring holds the throw-rod part somehow onto the level engaging the pinch roller - I think, but I haven't figured out how. TB1 shows where I think the spring goes, linking the level to the throw rod somehow (I think).

    So on the good news side, the regulator board is fixed and I do have power and lights, and the capstan turns. Rewind will work with a fixed throw motor on that side, and the stop button lights and seems to function. tb3.jpg TB2.jpg tb1.jpg

    All is quiet.

    On the bad news side, in addition to the rewind throw motor the play or forward wind buttons don't show any action, and they don't light up.

    But I am getting closer to getting this working. I will clean the boards, but any suggestions or help would be appreciated. I will most likely also take out that rewind throw motor and see if I can get it working, or find a replacement. I am also looking for a donor machine for parts.

    Thanks for the Help!

    Greg
     
  5. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    Those cylinders are solenoids, not motors. They used a small motor on the TD 20A/20A SE to move the brakes and headbridge but on the 9000-series and the 10X/10XD they're using solenoids, essentially a large electromagnet.

    Do any of the brake or headbridge mechanisms move if you apply manual force? The #1 cause of failures on this series is gummed up old dried grease, and the solenoids are never going to be able to move them if they're sticky. That could explain the hum, if the coil inside the solenoid is being powered but it can't move mechanically.

    The lack of lights on the buttons may or may not be serious. Could just mean the little lamps under the button covers are blown (I have some of those if so). The bigger concern is whether the IC-based logic has failed somewhere. The IC's that are used in these as a form of gated logic are known to be fragile & finicky and they're also long since obsolete. Finding replacements and troubleshooting that complex gated logic is usually a deal-breaker, as it's way easier and cheaper to find another deck that doesn't have those problems, and part out the deck with the bad logic.

    John
     
  6. GregPerugini

    GregPerugini New Member

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    Ok, I am getting somewhere.

    Found a unconnected wire from the big canister capacitor under the left spindle motors. OK, so now I see rewind works well, and forward wind/play would work if that solenoid plunger would work to move the head carriage and engage the switch that turns the right spindle. I think I will try to see if I can fix that solenoid, and make sure there is enough power going to it. Looks like a few bulbs might be blown in the switches, but I will get there when I get there..

    Thanks again for all your help. Any suggestions would be great.

    Greg
     

     

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  7. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    That's a motor run cap, probably. Sounds like maybe someone else has been in there before you, which really multiplies the things you may have to check.

    You can try disconnecting the solenoid mechanically and see if it snaps in crisply when it gets power. Watch your fingers while doing that.

    John
     
  8. GregPerugini

    GregPerugini New Member

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    You are right about that. I will pull it from the machine and test it. How much power does it need to snap?

    Greg
     
  9. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    I'd leave it connected and select an operating mode that should engage it, let the deck supply the voltage for that initial test.

    John
     
  10. GregPerugini

    GregPerugini New Member

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    So, if I trace the wires back to the board, this is what happens if I monitor the the yellow/green set that supplies power to the play solenoid.

    1. constant 34.5 Volts when powered on.
    2. when stop is pressed, it lights up, the brake solenoid engages, and the voltage drops to 30 Volts. After a second or so it disengages the brake solenoid, light goes out, and the voltage goes back to 34.5.
    3. when play is pressed, it does not light up, but voltage drops to 30 voltage. nothing moves, or makes a sound anymore, on the play solenoid (which engages the heads)

    When I monitor blue green combination, on startup I get 4 volts, and when I press play that doesn't change. But when I press stop it goes to zero, light goes out, and in a second the voltage goes back to 4 volts.

    I hope I am explaining this properly. It does seem like I am getting power sent to that solenoid, but nothing is moving at all. I do have a power supply that I can adjust to feed current to that to test the solenoid to test it, and I am not sure what the results mean, but there is power going to that solenoid, and it is not moving. By drawing power, perhaps that signals something to other parts in the circuit - I don't know. Any help in this would be appreciated. At this time I am thinking of taking the play solenoid off and stripping it down, but if there is something else perhaps wrong by my diagnostics, or something else to try, let me know! Thanks again for your help.

    Greg
     
  11. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    Blue is the common (+) side of the solenoid, which has two (-) inputs. IIRC, they supply grounds (via Q to both yellow and green to engage and only one of the two to stay engaged. Watch blue+yellow and blue+green and see what's being supplied across those two combinations 1) at rest 2) after pressing play, and 3) after 1 second or so.

    You can get a description of that circuit and a legible schematic for the 9000x in this later service manual: http://sportsbil.com/tandberg/9100x-9200xd-sm-2.pdf

    Start reading around section 2 (pg 7) and then look at the schematic that follows pg. 20.

    John
     

     

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  12. GregPerugini

    GregPerugini New Member

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    Thanks for that, John. What a great manual.

    On Yellow/Blue:

    On PowerUp and Rest State, 29.5V
    On Stop Pressed,29.5V. Brake solenoid engages and button light engages for about a second, then back to Rest State.
    On Press of Rewind Button, 29.5V. Left motor engages, but only as held down - once released, it turns off.
    On Press of Play Button, 29.5V.

    On Blue/Green:

    On PowerUp and Rest State, 0.4 for about a second, then steady at 4V
    On Stop Pressed, Voltage drops to 0.4V for about a second, then steady at 4V Brake solenoid engages and button light engages for about a second.
    On Press of Rewind Button, 4V steady. Left motor engages, but only as held down - once released, it turns off.
    On Press of Play button, 4 volts steady. No other changes visible.

    FYI, when the play solenoid switch is pressed manually, the right side spindle turns.

    In short (hopefully not a pun) the buttons only seem to act on engaging, and don't stay on unless I hold them pressed. I am hoping that these diagnostics point to only the solenoid as the problem, and nothing deeper. The manual states that the hold phase only will stay when the hold winding receives current.

    Thanks again for your help. This seems to be a well built unit, and easy to work on - the logic boards in particular can be easily taken out to bench test, and the bottom board is easily accessible from the rear.

    Greg
     
  13. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    Not sure about easy, the logic section usually causes people's heads to explode and parts for it are really hard to come by unless you can find a stash at some obsolete parts distributor and fork over enough to cover their MOQ.

    If it's just the solenoid, will definitely be a lot easier. Not convinced of that from the troubleshooting so far, though.

    I may (or may not) have spare used parts for that... LMK if you want me to check.

    John
     

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