Substitution pot value

[Randall]

I have a Laney acoustic amp in with no sound. I tracked it down to a failed master volume pot, VR6. The pot in question is an Alpha B5K 16mm knurled shaft pc mount. As far as I can tell it is no longer available. I can however get the same series pot in B10K. Looking at this circuit, is there any reason this sub wouldn't work? It looks like maybe the taper would be different, but I dont THINK it would hurt anything.

Or do I need to strap a 10K resistor across the outside lugs?
image_51262.pdf

[Enzo]

Schematic calls for 4.7k, so it doesn't matter electrically, but for search reasons, 4.7k might turn up something where 5k doesn't..

But to answer your question, the pot is just s simple voltage divider, I see no reason a 10k wouldn't work fine there. I see no potential impedance problems from it.

I have a big collection of 16mm pots, and I seem to recall 5k among them. Yes, knurl shaft. But I am sure you can get them faster from your normal suppliers.

[Chuck H]

https://www.mouser.com/ProductDetail...Sllsb0qA%3D%3D

[Randall]

Chuck H, correct value, and could probably be made to work in an end days situation, but wrong shaft type, length and lugs.

[Chuck H]

Well you did say "B5K 16mm knurled shaft pc mount". Which is what that pot is. A split shaft opposed to solid/knurled shouldn't make any significant difference. More specifics might make it easier to find the pot in question. I guess you must have a special shaft length and staggered or bent pins then?

[Enzo]

A photo of what you have/meed would be helpful.

[Randall]

Actually Chuck H, no. The picture looks exactly like what I have, but as we know the pics are often just approximations. If you look at the model no. yours is a solder lug, 21 detent, d shaft, 20mm length shaft. I need a pc mount, knurled shaft, 15mm length.

I have ordered the right type in a 10K.

[Chuck H]

Actually Chuck H, no. The picture looks exactly like what I have, but as we know the pics are often just approximations. If you look at the model no. yours is a solder lug, 21 detent, d shaft, 20mm length shaft. I need a pc mount, knurled shaft, 15mm length.

I have ordered the right type in a 10K.

Haha! That's funny. I specified pc pins in the search and there's no mention of detents prior to that page. I don't think I've ever seen a stocked 21 detent 16mm pot anywhere, but sure enough it's indicated in the part number data. I'm suspicious that that pages indications of solder lugs may be an error. But better to play it safe.

[Chuck H]

Well I know you already ordered, but...

Shaft length is .53" which would be about 13.5mm. It's probably the same shaft in reality.

https://www.amplifiedparts.com/produ...ll-linear-16mm

[Enzo]

Most catalog pictures have a note somewhere that the picture is for reference only, not necessarily the exact part.

[Randall]

The B10K pot came in (damn the mail is slow these days). It is installed and working just fine. Thanks guys.

[pdf64]

The stage that the master vol feeds looks to have an input impedance of 2k7; I think that will affect the effective taper of the pot, more so as its value increases.
eg a 100k pot may result in the taper being a problem.