Armstrong 526 Receiver Volume Pot - UK Vintage Radio Repair and Restoration Discussion Forum

Still hoarding · 29th Oct 2020, 7:58 pm

Hello,

After unsuccessfully trying to sort out the volume potentiometer for the last 3 days I finally decided it's gone. Sprayed Deoxit, turned the knob till my fingers hurt and eventually took the thing apart. It's still rough.

Has anyone here replaced the pot and are they still available? Tried to google the numbers stamped on its body, 100k ΩS/LG 2DB AB F2 C1S. Of course, I can't find anything with those numbers.

I would greatly appreciate any suggestions.

vidjoman · 29th Oct 2020, 8:19 pm

Have you replaced/checked the capacitors connected to the pot. Any DC leakage will cause it to be noisy

Herald1360 · 29th Oct 2020, 9:41 pm

Sounds like it's 100k log which should be available unless it's some unique special for the application.

Still hoarding · 30th Oct 2020, 1:42 am

Quote:

Originally Posted by vidjoman

Have you replaced/checked the capacitors connected to the pot. Any DC leakage will cause it to be noisy

It's mechanical noise. The pot sounds as if it's scraping. I had one channel lower than the other, tapping the unit brought it back up. Took all the boards out and cleaned them, eventually worked out the volume pot sounded rough. Deoxit didn't work, taking it apart made no difference. The dimple in the wipers looks worn.

Chris, I wondered whether someone here swapped the pots and could recommend a drop in replacement.

snowman_al · 30th Oct 2020, 9:31 am

Yes it is a 'Stereo 100k ohm Log pot'. No chance of getting an original.
Try and get an Imperial one with a 1/4 inch diameter (rather than 6mm) metal shaft. You will have to file the flat for the control knob in the correct position.

The electrolytic caps immediately before and after the control are numbers 249 and 257 on the schematic and component layout. They will be leaky by now.

PaulR · 30th Oct 2020, 10:04 am

Before you scrap it try dismantling it and smearing Vaseline or silicone grease on the track and wiper. It sounds counter intuitive but it has worked as a long lasting solution for me

Cobaltblue · 30th Oct 2020, 10:05 am

I don't know what your Pot looks like but it may be worth visiting Blore Edwards

They do a pretty comprehensive range

https://www.blore-ed.com/product-pag...-gang-availabl

Cheers

Mike T

dazzlevision · 30th Oct 2020, 12:21 pm

Quote:

Originally Posted by Still hoarding

Hello,

Has anyone here replaced the pot and are they still available? Tried to google the numbers stamped on its body, 100k ΩS/LG 2DB AB F2 C1S.

I would greatly appreciate any suggestions.

That looks like an AB Metal Products pot, so Blore Edwards should be able to help you.

I think C1S is actually CTS.

Still hoarding · 31st Oct 2020, 8:00 pm

Thank you for all your suggestions, it is CTS, but it's made in England.

As you all pointed out, a drop in replacement might be hard to find.

Took the damn thing apart again and polished the wipers with 2500 grit paper, it's no longer noisy. After putting the receiver together, one channel is down in the tuner section, oddly, other inputs work fine on both channels.

The CD is playing through the tape input okay, but sometimes the tuner section can be selected at the same time as the CD is playing. This results in music from both channels but the tuner is also playing, albeit on one channel only.

If no inputs are selected the tuner sometimes is heard at normal volumes but with obvious distortion.

Please correct me, could it be that flushing the potentiometers resulted in grease from the selector buttons running into the contacts? It's a bl..dy mission.

Cobaltblue · 31st Oct 2020, 8:37 pm

Quote:

Originally Posted by Still hoarding

Thank you for all your suggestions, it is CTS, but it's made in England.

As you all pointed out, a drop in replacement might be hard to find.

Did you look at the Blore Edwards parts?

2-45 Dual Gang Series 45 Potentiometer

Available in a wide range of resistance values

Solder or PC terminals

1/4" or 6mm Diameter Aluminium shaft

Variety of standard lengths to choose from

Custom shaft lengths available (also flats, slots etc)

A hard working 1" diameter old school pot

As far as I know that's whats fitted in the Armstrong

You just need to go to the web site and put the values in

Cheers

Mike T

Still hoarding · 31st Oct 2020, 9:06 pm

Mike,

I have had a look at the site, very useful, thanks. Looks like the pot is now smooth and works well with an exterior input, I tried plugging a CD machine in, but the internal tuner is only working on one output. Not sure whether it's a mechanical contact in the switches or something has failed in the tuner section.

29th Oct 2020, 7:58 pm	#1
Still hoarding Triode Join Date: Feb 2019 Location: London, UK. Posts: 12	Armstrong 526 Receiver Volume Pot Hello, After unsuccessfully trying to sort out the volume potentiometer for the last 3 days I finally decided it's gone. Sprayed Deoxit, turned the knob till my fingers hurt and eventually took the thing apart. It's still rough. Has anyone here replaced the pot and are they still available? Tried to google the numbers stamped on its body, 100k ΩS/LG 2DB AB F2 C1S. Of course, I can't find anything with those numbers. I would greatly appreciate any suggestions.

29th Oct 2020, 8:19 pm	#2
vidjoman Dekatron Join Date: Jun 2013 Location: East Sussex, UK. Posts: 3,326	Re: Armstrong 526 Receiver Volume Pot Have you replaced/checked the capacitors connected to the pot. Any DC leakage will cause it to be noisy

29th Oct 2020, 9:41 pm	#3
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Armstrong 526 Receiver Volume Pot Sounds like it's 100k log which should be available unless it's some unique special for the application. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

30th Oct 2020, 9:31 am	#5
snowman_al Octode Join Date: Dec 2018 Location: Llandeilo, West Wales, UK. Posts: 1,092	Re: Armstrong 526 Receiver Volume Pot Yes it is a 'Stereo 100k ohm Log pot'. No chance of getting an original. Try and get an Imperial one with a 1/4 inch diameter (rather than 6mm) metal shaft. You will have to file the flat for the control knob in the correct position. The electrolytic caps immediately before and after the control are numbers 249 and 257 on the schematic and component layout. They will be leaky by now. __________________ Never Leave Well Enough Alone...

30th Oct 2020, 10:04 am	#6
PaulR Dekatron Join Date: Oct 2003 Location: Southport Lancashire, UK. Posts: 3,236	Re: Armstrong 526 Receiver Volume Pot Before you scrap it try dismantling it and smearing Vaseline or silicone grease on the track and wiper. It sounds counter intuitive but it has worked as a long lasting solution for me __________________ Paul

30th Oct 2020, 10:05 am	#7
Cobaltblue Moderator Join Date: Dec 2010 Location: Exeter, Devon and Poole, Dorset UK. Posts: 6,875	Re: Armstrong 526 Receiver Volume Pot I don't know what your Pot looks like but it may be worth visiting Blore Edwards They do a pretty comprehensive range https://www.blore-ed.com/product-pag...-gang-availabl Cheers Mike T __________________ Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk Last edited by Cobaltblue; 30th Oct 2020 at 10:07 am. Reason: spelling

31st Oct 2020, 8:00 pm	#9
Still hoarding Triode Join Date: Feb 2019 Location: London, UK. Posts: 12	Re: Armstrong 526 Receiver Volume Pot Thank you for all your suggestions, it is CTS, but it's made in England. As you all pointed out, a drop in replacement might be hard to find. Took the damn thing apart again and polished the wipers with 2500 grit paper, it's no longer noisy. After putting the receiver together, one channel is down in the tuner section, oddly, other inputs work fine on both channels. The CD is playing through the tape input okay, but sometimes the tuner section can be selected at the same time as the CD is playing. This results in music from both channels but the tuner is also playing, albeit on one channel only. If no inputs are selected the tuner sometimes is heard at normal volumes but with obvious distortion. Please correct me, could it be that flushing the potentiometers resulted in grease from the selector buttons running into the contacts? It's a bl..dy mission.

31st Oct 2020, 9:06 pm	#11
Still hoarding Triode Join Date: Feb 2019 Location: London, UK. Posts: 12	Re: Armstrong 526 Receiver Volume Pot Mike, I have had a look at the site, very useful, thanks. Looks like the pot is now smooth and works well with an exterior input, I tried plugging a CD machine in, but the internal tuner is only working on one output. Not sure whether it's a mechanical contact in the switches or something has failed in the tuner section.