The mechanical part of the volume potentiometer on my Cambridge Audio A1 Amplifier has broken, and I'm currently trying to see if I can superglue it back together etc, but I'm not sure this will be successful, so it may be better/safer to purchase a new one.
I don't have a schematic so can't check what value it is, but hopefully the attached pics may help someone more knowledgeable advise what part I need to buy.
Thanks, Rob
I don't have a schematic so can't check what value it is, but hopefully the attached pics may help someone more knowledgeable advise what part I need to buy.
Thanks, Rob
Attachments
I think the A denotes it's logarithmic, and the 104 means 10 followed by 4 noughts, so 100K resistance. And it's dual operation.
Rob
Rob
It may take some searching, but it should be possible to find a replacement. The biggest challenge will be to find a replacement that'll fit mechanically. If everything else fails, you can probably fit an ALPS RK097 in there and hook it up with wires.
A104 is indeed 100 kΩ, audio taper.
Tom
A104 is indeed 100 kΩ, audio taper.
Tom
Does anyone know who has made the component in my pictures by looking at the manufacturers symbol on top of it?
I can't see VR3 listed on the parts list from the materials list. It's probably just listed under of one of the boards.
This might help me track down the exact thing - so I don't get anything that is mechanically shorter, or doesn't align correctly.
I've still not given up on repairing the original (this may be the best route - if it works reliably). I will give it a go tomorrow, I have to go out now.
Rob
I can't see VR3 listed on the parts list from the materials list. It's probably just listed under of one of the boards.
This might help me track down the exact thing - so I don't get anything that is mechanically shorter, or doesn't align correctly.
I've still not given up on repairing the original (this may be the best route - if it works reliably). I will give it a go tomorrow, I have to go out now.
Rob
In which way is the pot currently broken?
You may not need an exact match, though that would be nice. If it fits, you could upgrade to an ALPS RK271 "blue velvet". Mouser has them... As does RS.
Tom
You may not need an exact match, though that would be nice. If it fits, you could upgrade to an ALPS RK271 "blue velvet". Mouser has them... As does RS.
Tom
As close as you can get, I guess :
https://eu.mouser.com/ProductDetail...22LjZM5f3rIH2Eiagt8zDXkOZ5RUnIpKsks3UxwNsCA==
Bourns PDB182-B230K-104A
Patrick
https://eu.mouser.com/ProductDetail...22LjZM5f3rIH2Eiagt8zDXkOZ5RUnIpKsks3UxwNsCA==
Bourns PDB182-B230K-104A
Patrick
I don't know, but my eye thinks the bushing is busted from the flange.
Attachments
Correct. Nothing wrong with your eyesight.
I've stripped it completely down and superglue it back in exactly the correct orientation, then a tiny bit more each side. Today I will try and reassemble it. The fun will be getting the sliders and knob in the correct orientation to the markings on the front panel, and not disturbing the sliders too much during assembly.
I'll do some meter tests as I go along, and if it doesn't work out I'll buy one of the devices mention and use one of them. Physical properties rather than electrical may be the main issue with getting a good replacement though.
I've stripped it completely down and superglue it back in exactly the correct orientation, then a tiny bit more each side. Today I will try and reassemble it. The fun will be getting the sliders and knob in the correct orientation to the markings on the front panel, and not disturbing the sliders too much during assembly.
I'll do some meter tests as I go along, and if it doesn't work out I'll buy one of the devices mention and use one of them. Physical properties rather than electrical may be the main issue with getting a good replacement though.
Golly, I didn't think this would be so hard!
I got the potentiometer back together, and in the correct orientation etc, but once some force was applied to the locking nut that holds it in place the superglue didn't hold, so back to really wanting to replace it.
There are so many designs of potentiometer out there. I've looked at RS and Mouser, and when I think I've found something it's either linear (I need logarithmic) or the shaft is the wrong type or too long etc.
I did find ALPS RK09L1220A1B, but I couldn't really work out if it was what I wanted. The fact sheet was interesting and showed you how the part No breaks down and describes what you are ordering, or you could do it the other way round.
I've found something on Ebay (Item No 123868039337) which seems about right, or could be made to work/fit. It has a round shaft, so no flat part. However I think if I'm careful I may be able to cut/file one onto it - worth a try anyway.
I got the potentiometer back together, and in the correct orientation etc, but once some force was applied to the locking nut that holds it in place the superglue didn't hold, so back to really wanting to replace it.
There are so many designs of potentiometer out there. I've looked at RS and Mouser, and when I think I've found something it's either linear (I need logarithmic) or the shaft is the wrong type or too long etc.
I did find ALPS RK09L1220A1B, but I couldn't really work out if it was what I wanted. The fact sheet was interesting and showed you how the part No breaks down and describes what you are ordering, or you could do it the other way round.
I've found something on Ebay (Item No 123868039337) which seems about right, or could be made to work/fit. It has a round shaft, so no flat part. However I think if I'm careful I may be able to cut/file one onto it - worth a try anyway.
I've also ordered an ALPS 402148, as that sounds/looks like it might do the job as well. I didn't go for that at first as the title listing I was looking at said 100K, but in the listing it said 10K.
This way I will have a choice of two to play with. I may have to do some stuff mechanically (orient it to line up with the front panel correctly), and electrically (use long wires to connect to the board), but hopefully there will be a solution here somehow.
This way I will have a choice of two to play with. I may have to do some stuff mechanically (orient it to line up with the front panel correctly), and electrically (use long wires to connect to the board), but hopefully there will be a solution here somehow.
I don't understand WHY anyone thinks "superglue" is a magic fix, I suppose they still think it's worthy.
It's not...
Epoxy, twin-tube epoxy, is a much better alternative if used properly, so is JB Weld.
Asides from that, the only successful solution to this broken pot is to replace it.
There are web sites out there that supply various pots - guitar sites, etc.
Google is your friend.
It's not...
Epoxy, twin-tube epoxy, is a much better alternative if used properly, so is JB Weld.
Asides from that, the only successful solution to this broken pot is to replace it.
There are web sites out there that supply various pots - guitar sites, etc.
Google is your friend.
> linear (I need logarithmic)
Are the *wafers* in perfect shape? You may not need to change these, not even desolder them, if you can find the mechanical nose-part and swap it over. Ah, I may be mis-remembering how the shaft fits the rotors.
Are the *wafers* in perfect shape? You may not need to change these, not even desolder them, if you can find the mechanical nose-part and swap it over. Ah, I may be mis-remembering how the shaft fits the rotors.
This is the potentiometer you require.
100K Logarithmic Stereo 16mm Potentiometer D Shaft | Switch Electronics
The faulty potentiometer has longer legs and was supplied to CA as an OEM part so unavailable.
You will need to cut the 6 legs off the existing potentiometer and solder them to the new potentiometer this will ensure exact alignment when refitting in terms of height from the tone board to the front facia location hole.
100K Logarithmic Stereo 16mm Potentiometer D Shaft | Switch Electronics
The faulty potentiometer has longer legs and was supplied to CA as an OEM part so unavailable.
You will need to cut the 6 legs off the existing potentiometer and solder them to the new potentiometer this will ensure exact alignment when refitting in terms of height from the tone board to the front facia location hole.
Measure these with a machinist's ruler or slide calliper:
It looks like the distance from the top of the PCB to the centre of the shaft could be the common 12.5 mm. In that case, you may be able to squeeze in an Alps RK271.
I wouldn't bother buying parts on eBay unless all other options are exhausted. Just shop at Mouser, DigiKey, RS, etc. You get genuine parts and don't get ripped off. I know you can buy good parts on eBay, but you can also get royally shafted. The SNR is not great there.
Tom
- Diameter of potentiometer shaft
- Pin spacing (in both X and Y directions)
- Distance from top of PCB to centre of pot shaft.
It looks like the distance from the top of the PCB to the centre of the shaft could be the common 12.5 mm. In that case, you may be able to squeeze in an Alps RK271.
I wouldn't bother buying parts on eBay unless all other options are exhausted. Just shop at Mouser, DigiKey, RS, etc. You get genuine parts and don't get ripped off. I know you can buy good parts on eBay, but you can also get royally shafted. The SNR is not great there.
Tom
Thanks for all the extra info (I will start a list of good sites to use), but the two potentiometers I've ordered have arrived, so I will see what I can do with them. The ALPS model I ordered looks tiny, so that looks to be no good. The other one looks like the one Audio Service has suggested in his link, but mine is a vertical pot rather than a horizontal one, but I think with some bending and soldering I can get it electrically to work (I will test its operation before fiddling with it). It doesn't have a flat spot which is good and bad. Bad means I'll have to try and file one, good means I can file it in the place to give me good orientation. I would have probably ordered the Audio Service one if I'd known about it. Being in the UK though can mean big postage from US companies though. I will post some pics of how I get on (after Christmas - she who must be obeyed won't let me fiddle for the next few days, don't blame her). If it doesn't work out I'll order the one with the flat.
The ALPS RK271 all seem to come as motorised when I've looked.
Also I've now ordered some JB Weld and some Deoxit for future jobs.
Happy Christmas all, Rob
The ALPS RK271 all seem to come as motorised when I've looked.
Also I've now ordered some JB Weld and some Deoxit for future jobs.
Happy Christmas all, Rob
It's fixed 🙂
Please see pics below.
The first two pics are the original (broken metalwork) potentiometer, the next pic is the two different potentiometers I ordered (I used the Alpha VR63ST), then the original below the new one I'm going to use, then the new one modified, then lastly the modified new pot on the board.
I probably should have spent more time to find exactly the same one as the original, but I spent a fair bit of time, and when I did find (for sale) what I thought was correct it would turn out to be linear, a different resistance, or different mechanically (especially the shaft shape - D shape required). In the end I found a 104K dual logarithmic with the same shaft and mounting dimensions (roughly) , but a round shaft rather than a D shape made by Alpha (VR63ST) - on Ebay. However to get this to work/fit, I had to bend and shorten the long legs, solder the old long legs on the rear 3 (shorter) legs, file a flat (in the correct orientation) on the round shaft, and file the round shaft down from 6.3mm to 6mm to get it to fit.
This was quite a bit of work, but the good news is electrically and mechanically it looks good, and more importantly works.
I'm chuffed, and have learnt lots from this - which I am keeping a note of.
Thanks to all, Rob
Please see pics below.
The first two pics are the original (broken metalwork) potentiometer, the next pic is the two different potentiometers I ordered (I used the Alpha VR63ST), then the original below the new one I'm going to use, then the new one modified, then lastly the modified new pot on the board.
I probably should have spent more time to find exactly the same one as the original, but I spent a fair bit of time, and when I did find (for sale) what I thought was correct it would turn out to be linear, a different resistance, or different mechanically (especially the shaft shape - D shape required). In the end I found a 104K dual logarithmic with the same shaft and mounting dimensions (roughly) , but a round shaft rather than a D shape made by Alpha (VR63ST) - on Ebay. However to get this to work/fit, I had to bend and shorten the long legs, solder the old long legs on the rear 3 (shorter) legs, file a flat (in the correct orientation) on the round shaft, and file the round shaft down from 6.3mm to 6mm to get it to fit.
This was quite a bit of work, but the good news is electrically and mechanically it looks good, and more importantly works.
I'm chuffed, and have learnt lots from this - which I am keeping a note of.
Thanks to all, Rob
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