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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment.

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Old 14th Jul 2020, 2:20 pm   #1
Mr Etronic
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Location: Caernarfon, Wales, UK.
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Default No sound on Columbia

Hi, picked one of these up to go with my radio. Using it with a HMV 1106 set to gramophone and wires pushed into the pin sockets in the back. I got the motor running OK for now but I'll rebuild it later. My problem is the is no sound at all when a record is played. Tone arm looks OK, it then goes into a pot for volume and on off, then to the radio. Do the tone arms fail? Seems very little in there to fail, no loose wires.
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Old 14th Jul 2020, 3:07 pm   #2
Edward Huggins
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Default Re: No sound on Columbia

Well, these old tone arms most certainly do fail. The magnetic head on this could be over 70 years old or far more. By touching the PU/Gram sockety on your radio are you getting a loud buzz on the radio? Have you checked for continuity of the signal wires and the pot's connectivity from the pick up head? If it turns out that the head has failed, then careful dis-assembly will be needed. What skills do you have with vintage electroncs, do you have a voltmeter?
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Old 14th Jul 2020, 3:10 pm   #3
Heatercathodeshort
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Default Re: No sound on Columbia

If you have a test meter I would suggest you check continuity across the pick up lead. It should read around 1500-2000 ohms. You may well find that the coil is O/C.

This comprises thousands of turns of hair like wire that is extremely difficult to rewind. [See my thread 1935 GEC radiogram]

If the coil reads OK it is possible the damping rubbers that support the needle armature have hardened or collapsed preventing the armature from moving in the magnetic field.

These rubbers can be replaced but it is a tricky job even for the experienced. check the continuity first. John.
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Old 14th Jul 2020, 4:19 pm   #4
Mr Etronic
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Default Re: No sound on Columbia

Quote:
Originally Posted by Edward Huggins View Post
Well, these old tone arms most certainly do fail. The magnetic head on this could be over 70 years old or far more. By touching the PU/Gram sockety on your radio are you getting a loud buzz on the radio? Have you checked for continuity of the signal wires and the pot's connectivity from the pick up head? If it turns out that the head has failed, then careful dis-assembly will be needed. What skills do you have with vintage electroncs, do you have a voltmeter?
Many thanks for the reply.
Yes getting a large buzz when one of the gram sockets touched.
Yes voltmeter
Basic skills with radio, fair theoretical knowledge but applying to these old sets is a learning curve. Just learning my way around these things. Vintage is a whole new ball game that is the idea of doing it myself to gain knowledge from guys who know about these sets.
I'll check all that now.
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Old 14th Jul 2020, 4:20 pm   #5
Mr Etronic
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Default Re: No sound on Columbia

Quote:
Originally Posted by Heatercathodeshort View Post
If you have a test meter I would suggest you check continuity across the pick up lead. It should read around 1500-2000 ohms. You may well find that the coil is O/C.

This comprises thousands of turns of hair like wire that is extremely difficult to rewind. [See my thread 1935 GEC radiogram]

If the coil reads OK it is possible the damping rubbers that support the needle armature have hardened or collapsed preventing the armature from moving in the magnetic field.

These rubbers can be replaced but it is a tricky job even for the experienced. check the continuity first. John.
Checking now.Many thanks.
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Old 14th Jul 2020, 4:25 pm   #6
PsychMan
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Default Re: No sound on Columbia

While it is hard to rewind them to exact spec, you can make something usable with a DIY wind.

I did something on a similar arm, where I used the thinnest magnet wire Maplins (at the time) stocked. Which was thicker than the original stuff. I wound as many turns on as I could get, and replaced the rubber pieces in the pickup with bits of silicon strip cut from silicon cupcake holders.

It worked, it but wasn't as high output as the original. A simple opamp pre-amp did bring it up to acceptable levels though.

I didn't extensively check the fidelity of this solution but it certainly worked good enough for me at the time. Worth a consideration if you have no better options

EDIT: also, while a break will almost certainly be corrosion inside the winding, do check for other connection issues on the wires connecting to the coil, you never know
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Old 14th Jul 2020, 5:43 pm   #7
Mr Etronic
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Default Re: No sound on Columbia

Ok if I took the measurement right (Disconnected one of the wires from the pick up to the pot, and attached voltmeter to that wire and the other pick up wire still on the pot....so only resistance of pick up is measured) I get infinite resistance. So I take it the is a break somewhere?
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Old 14th Jul 2020, 10:10 pm   #8
Mr Etronic
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Default Re: No sound on Columbia

I'll get this done by a pro as it looks delicate. I think you have a section to request paid help. Its too nice to mess up.
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