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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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20th Jan 2021, 12:12 am | #1 |
Pentode
Join Date: Nov 2013
Location: Essex, UK.
Posts: 103
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Volume control not working
I have a 1930’s HMV radiogram model 542.When on radio the volume control works perfectly but on gramophone the volume won’t adjust.
It’s the same knob so I don't know what’s wrong. Any advice please? |
20th Jan 2021, 9:20 am | #2 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
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Re: Volume control not working
Hi there is a separate volume control for the radiogram I don't know about this particular Gram but I seem to recall on one of my HMV's it's on the front so you can adjust the volume with the lid closed.
Certainly the circuit shows 2 separate volume controls. Cheers Mike T
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20th Jan 2021, 10:18 am | #3 |
Pentode
Join Date: Nov 2013
Location: Essex, UK.
Posts: 103
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Re: Volume control not working
Many thanks.You are quite right. It works from the knob on the front. It doesn’t have much effect though. The volume just goes up and down a little bit. At least it works though. May be dirty contacts?? Gary
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20th Jan 2021, 10:52 am | #4 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
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Re: Volume control not working
I haven't used mine for a couple of decades but I do remember that I had to re-build the "cartridge" pickup head. The rubber goes hard and the magnet goes weak, which reduces it's output.
Is it that the volume is low? if so I suspect the pick up head. I will try to find a thread on a re-build I am sure there have been a few. Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |
20th Jan 2021, 11:06 am | #5 |
Octode
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
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Re: Volume control not working
It may help if you know the set this is based on did (does) not have a conventional volume control, i.e. one that works on/in the audio frequency (AF amplifier) section.
Instead it has an RF/IF gain control which increases or decreases the radio signal. As this is before the gram input to the AF amplifier it cannot control the gram volume. Because of this another separate 'gram volume' control is needed. This controls the gain of what becomes the first AF amp valve when gram is selected. Alan
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