Bush AC34 volume fault. - UK Vintage Radio Repair and Restoration Discussion Forum

sobell1980 · 12th May 2012, 4:46 pm

Hi, I have a pal of mine bringing a Bush AC 34 over later for me to have a look at. It all works apart from the volume. It's very faint until you apply pressure to the volume control knob then it works as should. As soon as you release the pressure it then goes faint. Any ideas please?

I have a copy of the service data sheet etc but only have this evening to look at it for him. Many thanks.
I'm guessing dirty track or connection to track maybe?

Peter.N. · 12th May 2012, 5:30 pm

Certainly sounds like a faulty volume control although it could be a dry joint on one of the connections or something near it, shouldn't be to difficult to find.

Peter

sobell1980 · 14th May 2012, 7:06 am

Found the fault. Removed volume control, stripped apart the pressed can to reveal the resistive track and track arm. Firstly the nut that held the volume control shaft, resistive track and track arm all together was loose so at times that was causing the volume to be lost to its minimum setting when the track arm lost connection with the track.
This could be regained by applying pressure or wobbling the shaft of the volume control, obviously then making and breaking the connection on the track before the set was dismantled. I e the nut that holds it altogether governs the tension between the resistive track and inner track arm.
Secondly it was very tarnished inside the colume control so a good clean also helped. Upon stripping the chassis out I'm missing most of the threaded screws with washers for the back cover to access the set and two screws that hold the chassis into the base of the set at the front of the base.
They are slottted screws with washers; if anyone could be kind enough to help out with a few of these please let me know. It's a Bush AC34 .

All working now. Beautiful sound, love it.

Nickthedentist · 14th May 2012, 9:07 am

Well done, it's nice to see these increasingly scarce vintage pots refurbished like this, rather than replaced.

N.

12th May 2012, 4:46 pm	#1
sobell1980 Octode Join Date: May 2011 Location: Bromyard, Herefordshire, UK. Posts: 1,241	Bush AC34 volume fault. Hi, I have a pal of mine bringing a Bush AC 34 over later for me to have a look at. It all works apart from the volume. It's very faint until you apply pressure to the volume control knob then it works as should. As soon as you release the pressure it then goes faint. Any ideas please? I have a copy of the service data sheet etc but only have this evening to look at it for him. Many thanks. I'm guessing dirty track or connection to track maybe?

12th May 2012, 5:30 pm	#2
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: Bush AC34 VOLUME FAULT Certainly sounds like a faulty volume control although it could be a dry joint on one of the connections or something near it, shouldn't be to difficult to find. Peter

14th May 2012, 7:06 am	#3
sobell1980 Octode Join Date: May 2011 Location: Bromyard, Herefordshire, UK. Posts: 1,241	Re: Bush AC34 VOLUME FAULT Found the fault. Removed volume control, stripped apart the pressed can to reveal the resistive track and track arm. Firstly the nut that held the volume control shaft, resistive track and track arm all together was loose so at times that was causing the volume to be lost to its minimum setting when the track arm lost connection with the track. This could be regained by applying pressure or wobbling the shaft of the volume control, obviously then making and breaking the connection on the track before the set was dismantled. I e the nut that holds it altogether governs the tension between the resistive track and inner track arm. Secondly it was very tarnished inside the colume control so a good clean also helped. Upon stripping the chassis out I'm missing most of the threaded screws with washers for the back cover to access the set and two screws that hold the chassis into the base of the set at the front of the base. They are slottted screws with washers; if anyone could be kind enough to help out with a few of these please let me know. It's a Bush AC34 . All working now. Beautiful sound, love it.

14th May 2012, 9:07 am	#4
Nickthedentist Dekatron Join Date: Jan 2005 Location: Oxford, UK. Posts: 17,853	Re: Bush AC34 VOLUME FAULT Well done, it's nice to see these increasingly scarce vintage pots refurbished like this, rather than replaced. N.