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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment

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Old 18th Oct 2017, 7:37 am   #1
Dave Moll
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Default Another novelty telephone - this time a frog

I recently acquired the telephone pictured below in a non-working condition. After replacing a faulty line cord and open-circuit receiver inset (originally a 2" 100Ω paper-cone speaker), everything works except for responding to a ring signal.

As can be seen from a youtube clip I found, the LED eyes should flash and it should make a chirping sound from a piezzo-buzzer. Neither of these happen, though the eyes do light up when a loop is made. I suspect, therefore, that whatever generates the current to operate the LEDs and piezzo-buzzer isn't working. This time the circuit contains a single IC labelled "YC 2080", but I can't find any data for it.
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Old 18th Oct 2017, 8:43 pm   #2
OscarFoxtrot
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Default Re: Another novelty telephone - this time a frog

It could be as simple as needing a ringing capacitor in the right place. Is the phone 2-wire or 3-wire and do you have a ringing/bell wire at the socket you're using.

Try plugging into a microfilter if you're not sure you have a bell wire at the socket you're using as that will recreate a ringing wire.
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Old 18th Oct 2017, 8:55 pm   #3
Dave Moll
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Default Re: Another novelty telephone - this time a frog

The socket used is a master socket (connected to an extension of my house PABX), but the 'phone is most definitely two-wire anyway. The original cord only had two cores emerging at the 'phone end.

I will try to track down a ringing capacitor within the 'phone and check that it isn't o/c.
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Old 19th Oct 2017, 9:27 am   #4
Dave Moll
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Default Re: Another novelty telephone - this time a frog

Finding the cap. wasn't a problem. It was obviously the "big yellow thing" with one end connected to the "B2 leg of the line. As I got no reaction out of connecting ohmmeter across it, I substituted one which does give the expected flick of the meter needle. Unfortunately the problem isn't going to prove that simple - still no chirp or flashing eyes.
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