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Fixing vintage Radio/Record player for mother and need help with the fuse.

Discussion in 'Power Electronics' started by LanceLane, Oct 8, 2020.

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  1. LanceLane

    LanceLane

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    Oct 8, 2020
    I bought the manual/schematics for a vintage Packard Bell Electronics Corp. RCP-36 cabinet radio/record player that is currently not powering up and after checking the power cord for continuity next i was looking at the fuse. Schematics didn’t give me much in the way of replacement fuse, stated 2ohm resistance fuse but mentioned more specifically that some versions came with a 5A slow-burn pigtail type. the schematic mentioned to maintain 117 volts and labels the power supply as 105-120volts. So my questions are what type of fuse is that in the picture? Also, what are my options for a replacement fuse? 822D4004-F520-41EA-AFA2-C70EF83DC72B.jpeg
     
  2. Bluejets

    Bluejets

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    Oct 5, 2014
    Look wire wound...did you measure the resistance of the shown device..??
    Show the schematics.
     
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  3. LanceLane

    LanceLane

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    Oct 8, 2020
    The schematics are from Howard W. Sams Co. And not sure if I am legally allowed to show them as they have a statement on certain uses without permission.

    No I did not measure the resistance but I suppose I should do so.

    Unfortunately I am by no means educated in electrical engineering regardless of how much I wish I was. I will take any tips and suggestions you have in regards to how to figure such out though.
     
    Last edited: Oct 8, 2020
  4. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    As with any component: Before replacing it verify, if possible, that it is really defect. A fuse can easily be measured using an Ohmmeter. Make sure that the radio is disconnected from mains and any residual charge stored on capacitors internally has been dissipated.
    If the fuse is defect: the statement about a 2 Ω resistance fuse indicates a so called fusible resistor: 2 Ω nominal which is designed to open like a fuse when overcurrent flows. Trigger current possibly around 5 A from the other statement.
     
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  5. LanceLane

    LanceLane

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    Oct 8, 2020
    Thanks to both of you for your responses. They are greatly appreciated.

    I measured the resistance with a multimeter, the two leads have a slight fluctuation between 1.7Ω-1.8Ω, while the fusible resistor has a fluctuation between 3.7Ω-3.9Ω . This would have me assume that it is in fact a 2Ω fusible resistor and possibly still in working order?
     
  6. LanceLane

    LanceLane

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    Oct 8, 2020
    If such is the case that the fusible resistor is fine I am having difficulty figuring out where to go next. Especially since the inside of the chassis is so crazy since it isn’t on a circuit board haha. Power cord appears okay with the continuity test, fuse may be fine, any ideas what may be next in the chain, or likely issue with such an old piece of electronics?

    Do any of the vacuum tubes have anything to do with overall power circuit? I bought a vintage vacuum tube tester regardless in case I need to change one out.

    8A221C1F-B1CA-4095-A9A9-71EF5D4113B7.jpeg DFAAC27C-BAFF-4BD5-86A3-CA871093E1DF.jpeg
     
  7. Bluejets

    Bluejets

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    Oct 5, 2014
    As previously stated, show the circuit diagram so we can follow and advise.
    Otherwise it is akin to getting directions from point A to point B without a copy of your area's roadmap.
    Even more difficult to try to explain to you where to look with your limited knowledge on a common gear basis.
    You will be searching for a variety of positive and negative voltages in the low range area and high voltages in some sections and this can be daunting for the inexperienced.
     
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  8. LanceLane

    LanceLane

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    Oct 8, 2020
    I certainly understand what you are saying Bluejets. The file size in pdf form is way too large and the picture needs to be zoomed into (massively) in order to show the circuit diagram legibly. Even a compressed version at 2.77mb is too large to upload. Therefore I cant really chop it up in screenshots in an adequate manner. I started a private conversation if you are open to looking at the entire schematic. I apologize for this inconvenience and truly appreciate your help Bluejets.
     
  9. Bluejets

    Bluejets

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    Oct 5, 2014
    Start at the power cord.
    Check you have both conductor continuity from the wall plug to the terminations in the unit terminal strip.
    Check continuity through the on off switch to the transformer primary.
    Check primary winding for a circuit, could be 40r more or less depending on many things.
    Check secondary windings for a circuit, smae only much lower readings.
    Should have a high voltage output, an output for the valve heaters and perhaps a split outout for other.

    All above should be unpluged, no power.
    See how you handle that first.

    Was there any sign of life what-so-ever..??? heaters in the valves glowing red..??
     
  10. LanceLane

    LanceLane

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    Oct 8, 2020
    While in the process of checking the primary winding, I re-soldered the power cord and resistor fuse back into their places and low and behold, the device is powering up perfectly. Vacuum tubes all seem to be glowing a healthy color. Thanks all for your input. 41F749E3-7CF5-4D51-B54A-A8B54ED325ED.jpeg 283A3BB7-2B4B-4307-9CEB-37E7A4443522.jpeg
     
  11. Bluejets

    Bluejets

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    894
    Oct 5, 2014
    And you have output..??
     
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