Philco radio in 1971 Ford truck only works on warm days.

Discussion in 'General Electronics Chat' started by sel55, Nov 2, 2012.

  1. sel55

    Thread Starter New Member

    Nov 2, 2012
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    I have Philco D1TA-18806 radio in my 1971 Ford F-100 truck. It works fine on warm days but when it gets cold it loses the signal. I'm guessing there is a connection that contracts when cold and becomes disconnected. What is the best way to determine what the problem is? I don't know anything about radios.

    Thanks in advance.
     
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Open it up and find the cold solder joint.. Good luck.
    Or just buy a new radio
     
  3. crutschow

    Expert

    Mar 14, 2008
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    If you can operate the radio on the bench with the chassis open, then you can spray various parts of it with a can of cold-spray to try to located the bad area. But as mcgyvr said it's likely easier just to buy a new radio. It would likely work much better with improved sound as compared to your old one anyway.
     
  4. sel55

    Thread Starter New Member

    Nov 2, 2012
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    Thanks for the replies. I'll try your suggestions. I know buying a new radio would be much easier and be better quality but it's interesting learning about the old technology.
     
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Get the back off and get soldering!
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Just reflow every solder joint in there.. :)
     
  7. KJ6EAD

    Senior Member

    Apr 30, 2011
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    Also look for corrosion on the antenna connector and the body feed through.
     
  8. sel55

    Thread Starter New Member

    Nov 2, 2012
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    Thanks for all of the suggestions! I'll remove the radio in the next few days and give an update. It has to come out through the glove box.
     
  9. HonT

    New Member

    Oct 25, 2012
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    The cold weather can cause an already loose solder/wire lose contact due to contraction. That may be one of the causes
     
  10. ScottWang

    Moderator

    Aug 23, 2012
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    You should separate two parts, one is antenna, and another is the radio itself, from the connector to the antenna as the others said, if the problem is in the radio, then you can use hairs dryer to spread the hot air to check where the problem is.
     
  11. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Try working all the buttons, switches and pots without taking it out. It could just as likely be a corrosion issue in one of the controls.
     
  12. sel55

    Thread Starter New Member

    Nov 2, 2012
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    I've tried different antennas so have eliminated that as a possible problem.

    I bought some cold spray as suggested by crutschow. I warmed the radio up so I was getting a signal. I was in a metal building so there was a constant humming noise but I was getting a good signal. I sprayed one part at a time until I got results from a resistor that is built kind of like the spring on the barrel of a ball point pen but a lot smaller. The ends were held by metal holders like cups on their side. When I sprayed the "cups" the signal would go away and when I heated it with a heat gun the signal would return. I used a pair of pliers to crimp the ends to tighten them and put the radio in a refrigerator for a couple of hours. While it was still cold I connected it back up and could get a weak signal but I attributed that to the metal building so I thought it was fixed. I installed it in the truck and it acted like I hadn't done anything.
    I read your post after I had reinstalled the radio but I did as you suggested and moved the dial all of the way both ways as far as it will go and pushed all of the buttons and it didn't help. While moving the dial I get some high and low sounds that I usually get between stations but no signal. Thanks for the idea. Everything is worth a try.

    Around 50 degrees F. is it's cut off point. That's what temperature it is now and I'm getting a very faint signal. When it warms up the signal gets much stronger. Now I'm wondering if I should have moved the resister back and forth in the "cups" to wear down any oxidation that may have been on the wires.

    I spent a couple of hours on the project and won't don't have time to work on it again for a while. It hasn't worked in a long time. I remember my wife sending a portable radio/cassette player with me on a road trip in the truck from Montana to Texas in 1985.

    Thanks for all of the suggestions.
     
  13. KJ6EAD

    Senior Member

    Apr 30, 2011
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    That part may be a resistor or it might be a fuse or inductor. If it's a resistor, you should measure it before it falls apart. Some pictures would help.

    Electronics of that age will inevitably have some age and environmental damage including dried out capacitors. I'd clean the board and controls then replace all of the electrolytic capacitors and anything that's corroded or heavily oxidized.
     
  14. sel55

    Thread Starter New Member

    Nov 2, 2012
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    Thanks for the reply. I thought about taking pictures but my camera wasn't handy, however, I'm attaching a scanned page from Sams Photofact no. 94, April 71 It's hard to read...

    Item no: R5 Rating: .68(PTC) MFGR. Part No. 3L0-0004-4

    It looks like I have my work cut out for me with replacing the the capacitors.
     
  15. ramancini8

    Member

    Jul 18, 2012
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    Buy a kero heater for cold days.
     
  16. MrChips

    Moderator

    Oct 2, 2009
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    Bad advice. You will kill yourself with carbon monoxide poisoning.
     
  17. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Caps with bad ESR will get better as they warm up. It was an old trick in TV repair to hold a soldering iron NEAR the body of an electro cap, and if the set started working you knew that cap had an ESR fault.

    That trick might help you locate a cap (or other component) that goes from bad->good when it gets warmer. Other temperature faulty parts in old 70's audio gear are small transistors, notably 2SA PNP types. They often crackle and/or fail when hot or cold.
     
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