Hi all, I'm generally a speaker builder so have come over here for some advice. I need to replace the volume pot in my Proton-520 integrated amplifier.
I bought it a while back and it looked as if it had been dropped at some stage as the volume knob had a chunk missing out of it. I tried replacing it with a standard log pot but then realised that the pot has an extra tap (so it has four legs). I'm guessing this is for the loudness button or something. Anyway, the volume is far too sensitive as it is at the moment with a regular three pin pot and the other lead left taped up so I was hoping someone could direct me to a replacement part for the volume pot. Unfortunately I can’t find the original pot so I have no way of determining what the extra leg was connected to at the pot end.
You can see the pot in the bottom right hand corner of the picture. There are two white wires run to it which correspond to each of the channels as the silkscreen on the PCB says x and y next to the pot and also where these wires are connected to the pcb.
I've attached a couple of pics of the amp (not my unit) and the service manual.
Please help me out!
Cheers.
I bought it a while back and it looked as if it had been dropped at some stage as the volume knob had a chunk missing out of it. I tried replacing it with a standard log pot but then realised that the pot has an extra tap (so it has four legs). I'm guessing this is for the loudness button or something. Anyway, the volume is far too sensitive as it is at the moment with a regular three pin pot and the other lead left taped up so I was hoping someone could direct me to a replacement part for the volume pot. Unfortunately I can’t find the original pot so I have no way of determining what the extra leg was connected to at the pot end.
You can see the pot in the bottom right hand corner of the picture. There are two white wires run to it which correspond to each of the channels as the silkscreen on the PCB says x and y next to the pot and also where these wires are connected to the pcb.
I've attached a couple of pics of the amp (not my unit) and the service manual.
Please help me out!
Cheers.
Attachments
It is a 50K dual audio taper(log) pot, with a tap for the loudness control. You can measure this part to determine what are the CW,CCW,wiper,tap terminals.
hard to find original parts, sub difficult because of so many variations. have to find some thing that is electrical equivalent, but can vary mechanically, make it fit, have to deal with shaft length , knob configuration, slot/knurled etc.
Good luck
hard to find original parts, sub difficult because of so many variations. have to find some thing that is electrical equivalent, but can vary mechanically, make it fit, have to deal with shaft length , knob configuration, slot/knurled etc.
Good luck
Unfortunately, that is so for all the old gear fiited with loudness controls and finding a drop-in replacement is now difficult. The extra gain required to make the loudness feature work as intended, has to be dealt with if you just substitute a standard pot - as you found out.
If there is enough distance between the PCB top surface and the volume control centre line, you could fit an available tapped pot like other ALPS types. The RK27 size is large but whether it will fit depends on the length of the original pot. solder tabs. If rotated 90 degrees and using fine extension leads from the PCB holes, you could just save your bacon. You probably only need 14 mm + the lead thickness, centre line to PCB. There are several existing threads here on this problem and sorting out the connections which seems to baffle newbs. Refer to the manufacturer's specification PDFs to get the exact sizes.
At the other extreme, there is this tiny option: RK11K114F30C0B104 WITH CENTER TAP ALPS | Mouser
If there is enough distance between the PCB top surface and the volume control centre line, you could fit an available tapped pot like other ALPS types. The RK27 size is large but whether it will fit depends on the length of the original pot. solder tabs. If rotated 90 degrees and using fine extension leads from the PCB holes, you could just save your bacon. You probably only need 14 mm + the lead thickness, centre line to PCB. There are several existing threads here on this problem and sorting out the connections which seems to baffle newbs. Refer to the manufacturer's specification PDFs to get the exact sizes.
At the other extreme, there is this tiny option: RK11K114F30C0B104 WITH CENTER TAP ALPS | Mouser
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Hi,
I'm new here so already now apologies for anything in will be doing wrong.
I bought a Proton 520 used, but unfortunately it arrived with a broken volume potentiometer. I exchanged it with a standard b50k stereo and it works.
Now my question is about the two white wires that were attached to some extra tabs on top of the old potentiometer, which are missing on the replacement that I bought. In the parts location overview and on the board these are marked with x-x' and y-y'. I also found these extra wires on the circuit diagram, but I am not sure what they're actually there for. From the original parts they looked actually like they were not connected to anything else.
Are these for loudness as described above?
Right now I just left them loose and isolated (and it still works), but it bugs me not to know what they're actually there for and where/what to solder them on to - where do they go?
I wanted to attach some photos showing the old potentiometer with white wires attached and the new one, but they're too big, need to downsize them first
Appreciate your help or advice for other forums, etc.
Cheers.
Christian
I'm new here so already now apologies for anything in will be doing wrong.
I bought a Proton 520 used, but unfortunately it arrived with a broken volume potentiometer. I exchanged it with a standard b50k stereo and it works.
Now my question is about the two white wires that were attached to some extra tabs on top of the old potentiometer, which are missing on the replacement that I bought. In the parts location overview and on the board these are marked with x-x' and y-y'. I also found these extra wires on the circuit diagram, but I am not sure what they're actually there for. From the original parts they looked actually like they were not connected to anything else.
Are these for loudness as described above?
Right now I just left them loose and isolated (and it still works), but it bugs me not to know what they're actually there for and where/what to solder them on to - where do they go?
I wanted to attach some photos showing the old potentiometer with white wires attached and the new one, but they're too big, need to downsize them first
Appreciate your help or advice for other forums, etc.
Cheers.
Christian
No. That particular Proton brand was used by a Taiwanese company that marketed consumer electronics here, many years ago. They used similar electronic designs to Japanese products but were intended for lower budgets and whilst the build quality (often assembled in other SE Asian countries) was not the greatest, they were cheap, looked good and sold well here in Oz.
I believe this is the company: Proton Electronic - Wikipedia
There may be a connection between Proton and the manufacturing of NAD products but I'm unaware of it.
I believe this is the company: Proton Electronic - Wikipedia
There may be a connection between Proton and the manufacturing of NAD products but I'm unaware of it.