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Thread: Hello, I need help with a "hum" problem.

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    Default Hello, I need help with a "hum" problem.

    I have a Pioneer CT-F700 cassette deck and every now and then when I am playing a tape-all of of a sudden, I get a loud continuous HUM sound. I have to turn the deck off and on again and it goes away. It is grounded to a metal source. The music still plays and comes out of the speakers okay but the hum is loud and doesn't stop! Can anyone give me some advice? I have demagnetizes the heads and it still does it on nearly every tape I play! OWWW! Help please.....

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    Default Re: Hello, I need help with a "hum" problem.

    It is grounded to a metal source.
    I am not sure what you mean by this. Have you tried removing the grounding?

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    Default Re: Hello, I need help with a "hum" problem.

    Hi, yes at first this loud hum started and i did not have it grounded. I then grounded it and it still does it occasionally. The other thing that is quite annoying is that the deck will shut off the tape playing while it's playing. Any ideas why these two things may be happening? Thank you for your help!

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    Default Re: Hello, I need help with a "hum" problem.

    Hum is almost always some sort of grounding issue. I would suggest that you skip the extra grounding, and search for problems with the motor of the player.

    But I guess there are more knowledgeable members here...

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    Default Re: Hello, I need help with a "hum" problem.

    Sounds like you have an intermittent switch contact on your controls. This could cause both the hum and the motor stoppping while the tape is playing. If you feel up to it, try this: Get yourself a can of De-Oxit (You can order cans from Amazon). Take the tape player out of its case (carefully!!!). Find the switch(s) that control play and give them a LIGHT squirt of De-Oxit and work the switches through their entire range. While you have the deck open, go ahead and treat any other controls likewise. Be VERY CAREFUL not to get any of the De-Oxit on the belts and other drive parts of this unit. Let the De-Oxit dry, run a clean cloth over the interior to clean any overspray and put the unit back together.
    Grounding: All the components of your system should be grounded back to a common ground point, usually the ground lug on you amplifier. From the ground lug, you can then connect a lead to a good ground source, like a cold water pipe or other good ground. "Daisy Chaining", which is connecting one unit to another and to another, etc, is not recommended.
    Hopefully, between the cleaning and grounding, you will have a quiet well performing system again. I am sure other forum members will also chime in with good recommendations.
    By the way, welcome to the wonderful world of Quad.

    MTGC (Michael)

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    Default Re: Hello, I need help with a "hum" problem.

    I will try that. I have a can of De-Oxit at home. I will let you know if that is the problem.
    Thank you all for the info!

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    Default Re: Hello, I need help with a "hum" problem.

    Thank you, I will try that.

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    Default Re: Hello, I need help with a "hum" problem.

    If memory serves me right (er ... what was I talking about? ... oh, yeah) the Pioneer CT-F700 is what, 30 years old?

    I don't believe you mentioned where the hum is coming from? Speakers would usually be a grounding issue (as mentioned) and the solution is a common ground between all your components and your electrical system. Then again, if you've been using the same setup for years and it's just started, that may not help much. Maybe an easy fix would be moving it to another tape loop if one is available. I'd also try swapping out RCA cables if those aren't hardwired into the player, or at least twisting the connectors to break any corrosion that could degrade the signal. If it's out of the player itself, try picking the player up when it's humming and see if it stops. Fairly common as these things age for the caps and diodes on the AC side of the power supply to weaken. That can cause the transformer to vibrate some, and that will cause a humming sound thru the cabinet and your equipment rack. Holding it up reduces the resonance. Might help at least to eliminate that from your list as the cause.

    Of course, the real solution would be for you to transfer all your cassettes to digital ... this IS the nineties, you know ... <G>
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    Default Re: Hello, I need help with a "hum" problem.

    Thank you all with the help. I will try all your suggestions and see what happens. Stay thirsty my friends

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    Default Re: Hello, I need help with a "hum" problem.

    I'm just wondering if you ever found a solution. I also have the same deck with the exact same issue. I've noticed it will happen soon after you record a song and play it back.


    It doesn't seem like a grounding humm because it will just happen shortly after or in the scenario I stated above. To help identify the problem: the left channel VU will be way more sensitive than the right (will be at a higher db) and sometimes the sound is muffled but goes away.


    To remedy, temporarily, I'll turn the deck off then on again and it'll kind of fix itself. Need help.

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    Default Re: Hello, I need help with a "hum" problem.

    Pioneer CT F700 (Medium).jpg

    In the photo you will see a slide switch with a string or wire pull. This slide switch controls playback and record modes. De-oxit. The one in the middle of the photo between the two vertical PC boards.
    Last edited by The Bushmaster; 04-30-2017 at 04:52 PM.

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    Default Re: Hello, I need help with a "hum" problem.

    Quote Originally Posted by aspataro View Post
    I'm just wondering if you ever found a solution. I also have the same deck with the exact same issue. I've noticed it will happen soon after you record a song and play it back.


    It doesn't seem like a grounding humm because it will just happen shortly after or in the scenario I stated above. To help identify the problem: the left channel VU will be way more sensitive than the right (will be at a higher db) and sometimes the sound is muffled but goes away.


    To remedy, temporarily, I'll turn the deck off then on again and it'll kind of fix itself. Need help.
    No, unfortunately, I haven't. I put the deck in my closet and don't use it anymore. Sorry.

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    Default Re: Hello, I need help with a "hum" problem.

    Other possibilities are old capacitors, which tend to fail when power is applied (especially electrolytics in power supplies so they don't supress the mains ripple), you can get increased impedances in other capacitors which can pick-up/let through mains hum. The other is 'dry' solder joints where again you get a higher impedance into which mains frequencies can 'leak'. Dry joints would most likely have the most effect in the most sensitive i.e. high gain circuitry so around the playback heads etc. Unfortunately neither are easy to find unless you've some test equipment, a good eye, and a lot of patience.
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    Default Re: Hello, I need help with a "hum" problem.

    Sadly, my friend I have two words of advice for you; garbage-can. You can pick up newer 2channel decks than that one with far superior specs for $50. Or less if you look around. Hell I've seen the nakamichi dragons going on ebay for 25$. In fact I think I still have one sitting in my basement, if you come over I'd give it to you.

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    Default Re: Hello, I need help with a "hum" problem.

    I have two CT F700 decks. I much prefer them over the so-called newer ones. Specs? Better then most. And I have much more control over the recording process.

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    Default Re: Hello, I need help with a "hum" problem.

    Okay, well I sprayed the pulley system and it was still doing it. So I thought maybe I didn't get it enough so I tried again and I also sprayed the heck out of the pots for the input and output knobs.

    After about a half hour of letting things settle I turned it on recorded played and it hasn't hummed at me, yet. I'll keep playing and hope it doesn't come back. If this is fixed it probably just comes down to thoroughly spraying everything with Deoxit.

    It's too nice of a good looking deck to trash.

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    Default Re: Hello, I need help with a "hum" problem.

    also. put Ferrite chokes on the power and audio cords. They help with RF noise and EMI noise

    https://www.amazon.com/s/ref=nb_sb_n...ferrite+chokes
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