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  1. #1
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    Overloaded fuse/broken pin issue- PARTS RESOURCE NEEDED

    Hey all, new here. My buddy and I are working on restoring an old reel to reel to working condition. At the moment, F1, a 1.6A glass fuse blows anytime you turn the power on. And a pin on a connector is broken off inside the port for it. Iíve attached photos for reference.

    We are true novices, so we need help identifying which parts are broken and where to find replacements.

    Any advice on further troubleshooting the issue certainly would not go unappreciated.

    Link to reference photos:
    https://drive.google.com/drive/folde...cb-NwExeQUzCSj


    Many thanks to all who take the time.

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  2. #2
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    Re: Overloaded fuse/broken pin issue- PARTS RESOURCE NEEDED

    i take it the header in 7104 and the connector in 7105 go together
    it looks like the connector (in 7105) has three wires - white on the right, red in the middle and black on the left
    the broken pin seems to be at a position without a wire in the mating connector
    it may be that way to stop the connector from being turned around and inserted incorrectly.

    what are 7106 and 7107 supposed to show? in 7101 the 1.6 A fuse looks blown
    i see fuses, but there is insufficient information to know anything about them
    take them out and examine the metal ends - most manufacturers put size, voltage, current etc ratings on the metal

    are you plugging the device into the power source it expects?
    voltage? frequency?
    without more information, you will likely continue to blow fuses.
    the fuse is there to protect whatever is upstream from a fault downstream
    do you have a schematic or any other documentation?

    who is the manufacturer, make, model, part number, serial number of said reel to reel device?



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  3. #3
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    Re: Overloaded fuse/broken pin issue- PARTS RESOURCE NEEDED

    It seems like it's almost the rule, that people don't get rid rid of working equipment until it develops a problem, then they unload it on someone like you and me.

    * Your photograph shows more than one fuse. Can you determine whether the blown fuse goes to a motor, or does it go to a power supply?

    I have a reel-to-reel unit. From what I can see house voltage goes to the motor, and for the circuitry there's a step-down power supply.

    * Read the volt labels on the fuses. Tell us what you see. It looks as though the good fuse is a slow-blow.

    * Try to turn the motors to see if they spin freely. Seized bearings tend to draw overmuch current which can blow a fuse.

    * In aging power supplies a typical problem is electrolytic capacitors. Did your unit spend years idle? When powering up an unused unit abruptly, inrush current finds a low-resistance path through the capacitors (resulting in a blown fuse). If the capacitors are guilty then you can replace them, although there's a chance the dielectric can be re-formed gradually. A variac lets you increase voltage slowly, over a period of minutes.

    * You might try to open up a connection in the power supply, and attach your own external supply. Apply a few volts while keeping an eye on current draw. See if the unit lights up normally.



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  4. #4
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    Re: Overloaded fuse/broken pin issue- PARTS RESOURCE NEEDED

    So the unit is an old Revox B77 MKII. Manual is here:

    http://www.steampoweredradio.com/pdf...structions.pdf

    It has two glass fuses. F2 (the bottom one) is an 800mA fuse and it is still intact.


    At the current moment, about half of the electronics on the machine work.

    F1 is a 1.6A fuse, and every time you replace it with a new one, it blows as soon as you turn the unit on.

    Hereís my current plan of action.
    -Check for seized bearings
    -Replace the caps
    -Replace the fuse
    -Power up the unit slowly with a variac

    Any other ideas of potential issues to look for?

    Also, if anyone has a good resource for reel to reel parts/fuses/caps that would be a huge help.



  5. #5
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    Re: Overloaded fuse/broken pin issue- PARTS RESOURCE NEEDED

    * Instruction manual: the section about fuses tells of the importance of setting the machine for 120VAC or 240VAC.

    * About capacitors, examine electrolytic (especially the largest ones) for signs of bulging at the end, or oozing of fluid. These are clues telling if one has gone bad.



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