UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Audio (record players, hi-fi etc)

Notices

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

Closed Thread
 
Thread Tools
Old 20th Jan 2021, 12:12 am   #1
Minster97
Pentode
 
Join Date: Nov 2013
Location: Essex, UK.
Posts: 103
Default 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?
Minster97 is offline  
Old 20th Jan 2021, 9:20 am   #2
Cobaltblue
Moderator
 
Cobaltblue's Avatar
 
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
Default 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
__________________
Invisible airwaves crackle with life or at least they used to
Mike T BVWS member.
www.cossor.co.uk
Cobaltblue is offline  
Old 20th Jan 2021, 10:18 am   #3
Minster97
Pentode
 
Join Date: Nov 2013
Location: Essex, UK.
Posts: 103
Default 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
Minster97 is offline  
Old 20th Jan 2021, 10:52 am   #4
Cobaltblue
Moderator
 
Cobaltblue's Avatar
 
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,823
Default 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
__________________
Invisible airwaves crackle with life or at least they used to
Mike T BVWS member.
www.cossor.co.uk
Cobaltblue is offline  
Old 20th Jan 2021, 11:06 am   #5
snowman_al
Octode
 
snowman_al's Avatar
 
Join Date: Dec 2018
Location: Llandeilo, West Wales, UK.
Posts: 1,092
Default 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
__________________
Never Leave Well Enough Alone...
snowman_al is offline  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 7:42 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.