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Ekco CR280 valve/tube car radio

A long time since looking at such a radio to check-over/repair as no known history and not powered up in any way

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Took apart section by section with bits in separate labelled bags I will test the valves later today ECH42, EF41, EBC41,EL42 Seems surprisingly good condition inside. Will have to replace the 12V (-ve supply) lead and speaker lead as perished and the on/off switch is ohmic. The vibrator had obviously been removed at some point (putty-stuff is split) in the past. what to look out for when testing these and how to remove that putty-like goo if necessary, warming with hot-air?. I assume test with load attached but what to do if a problem within the vibrator.?

What ohmage speaker? 2.5, 3 or 4 ohm ? Could measure primary R of the output matcher more accurately if any help but primary 692 ohm and secondary between 0.1 and 0.2 ohm

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook
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3 of the valves tested fine but the ECH42 was very C/H leaky but I happened to have one of these valves lying around

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

On 2008-06-14, N_Cook wrote: ...

...

I doubt there's much chance of finding a replacement vibrator these days, if its contacts have gone. I wonder if anyone has come up with a design for a solid-state (plug compatible) replacement?

Mike.

Reply to
Remove _ for valid address

split)

that

load

I have some schema for similar Ekco CR... radios and the vibrator would seem to contain a valve or 2 inside as well as coil and bell-mechanism.

If you can get inside the can , do they have oil or anything inside ? under that goo would there be a contact adjustment aperture ? A long time ago I seem to remember trying to deal with one where the contact make-break was very irregular and I never could make it work properly

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

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Reply to
N_Cook

There are no adjustments inside a vibrator. No oil. The "putty-stuff" that you saw is likely to be an asphalt or tarry substance used to seal the mechanism from outside air. Vibrators were purged and filled with nitrogen to reduce the possibility of oxidation of the contacts.

If you can open the vibrator casing, and get to the innards, you might be able to repair the contacts (if that's the problem) and reseal with epoxy. Not much else to go wrong inside, other than the coil burning out. Oh yeah, the leafs that the contacts are on might lose their temper (springiness) and cause the contacts to have inadequate contact pressure. If that happens, the vibrator is wasted.

There are still sources for vibrators (not cheap!!!).

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Antique Electronics Supply

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has solid state replacements for $30 USD.

--
Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in the 
address)

Experience: What you get when you don\'t get what you want
Reply to
DaveM

I've only ever taken one radio vibrator apart. It looks just like a small relay inside a soundproofed can (foam inside). There's a mass sprung on the arm, to make it mechanically resonant, plus two changeover contacts and one contact in series with the coil. Total 6 connections (one terminal is common on both changeover contacts and the contact in series with the coil.

There is a mechanical adjustment screw for the NC contact to the coil.

It has no "goo" or "oil" or anything like that, just a crimp at the bottom of the can onto the paxolin base on which the pins mount. Surprisingly, the foam rubber stuff looks as good as new, this one must be at least 50 years old. I could imagine some other rubber compositions could turn to "goo" by now.

Mike.

Reply to
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Reply to
sparky

Yes.. absolutely correct.. Been so long since I've been inside a vibrator I had forgotten.

--
Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in the 
address)

Experience: What you get when you don\'t get what you want
Reply to
DaveM

Very poor selection of solid state vibrators at Antique Electronics Supply better to go to the people that actually make them. They have pin out diagrams and all sorts of these things available.

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Or Direct to the vibrator page.

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John k9uwa

Reply to
John Goller, k9uwa

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