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Hello, will somebody help me fix a Sony TC-250A Reel deck?!

 
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Paul A.
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PostPosted: Sat Jan 21, 2006 11:27 am    Post subject: Hello, will somebody help me fix a Sony TC-250A Reel deck?! Reply with quote

Hello world, I am an amateur DIY-er, and I am trying to fix a Sony TC-250A Reel-to-Reel deck! (A poor man's R2R deck -only one motor, two-head!) Here's The Problem: It works PERFECTLY... except that there is a colossal amount of HUM present as I play back tapes!! How do I fix this?? What is the most likely cause of the hum? Oh yeah: I have the original Service Manual for this deck! But I don't have formal training in electronics... although I can use a digital volt-ohm meter and I have a soldering iron! Any suggestions will be ETERNALLY appreciated!!!
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sparky



Joined: 18 Nov 2005
Posts: 98
Location: U.K

PostPosted: Sat Jan 21, 2006 10:52 pm    Post subject: Hello, will somebody help me fix a Sony TC-250A Reel deck?! Reply with quote

Been many years since I saw a reel to reel. Is the hum motor hum or mains?
First thing would be to obtain a can of switch cleaner and clean by spraying the switches (including pots like volume control) and at the same time continuously moving them to free up hardened grease and clean the contacts. Secondly if still producing fault symptoms you may have dried up electrolytic capacitors particularly in the power supply area and thirdly ensure all earth connections are sound.
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Paul A.
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PostPosted: Sun Jan 22, 2006 12:50 am    Post subject: Sony 250A Reel Deck Hum Reply with quote

Thank you for answering!! Pardon my ignorance, but since I'm new here, I'm not even sure how to reply to you!! do I click on this "postreply" button, is that the correct way of doing it?...

Power supply hum!!! That rings a bell... I was thumbing thru some of my cassette Service Manuals in search of clues (Pioneer CT-5151 and CT-4141A) and BOTH of them have "Faulty power circuit...Check and repair" listed under "Excessive hum" listed under "Poor signal-to-noise" ratio, listed in the "Troubleshooting" section... I guess that could be it! (By the way, er... HOW do I check if "all earth connections are sound"? (I'd be studying electronics engineering right now if I had the money!!)

Now, what's interesting is that I hear the hum ONLY when the lever is in "Play" position... there is no hum if it's in the "Stop" position, although the motor is continuosly running, and the motor runs all the time, as long as the POWER button is on! So, what can you glean from these facts?? (and thanks again!...)
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sparky



Joined: 18 Nov 2005
Posts: 98
Location: U.K

PostPosted: Sun Jan 22, 2006 4:08 am    Post subject: Hello, will somebody help me fix a Sony TC-250A Reel deck?! Reply with quote

Yes this may be an indication that the record switch may be in limbo rather than making proper contact and the switch cleaner may help this particularly if hiss can be heard from the speaker before any buttons pushed indicating the amplifier is in operational state.
With regards to the earth connections well I just meant things like chassis screws with wire attached etc are tight and making a good connection.
I take it you are a keen hobbyist with a desire to learn electronics.
You don't need to be rich to learn this and you are currently doing as I did (and probably most others) many years ago and will learn as you go along. The advantage you have now is the Internet with a vast amount of information to hand including free courses and you pay for examinations only. Good luck with this and I along with other members will encourage and support you if you choose this path.
With regards to posting I can read it o.k so is fine but registering is usually better.
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Paul A.
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PostPosted: Tue Jan 24, 2006 10:58 am    Post subject: Sony 250A Reel Deck Hum Reply with quote

Thank you for your help, it is truly appreciated! The 250A is a stand-alone deck- it doesn't have built-in amplifier or speakers, so it needs to be plugged into a stereo system to work! And now, i will proceed to extract and test all electrolytic caps on the Power Circuit board -there seems to be seven of them- and that will probably take me a few days, but will keep you posted! Thank you again!!!
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