Replacing potentiometer for remote gain control

[Sizzlechest]

My amp came with a remote gain control which is housed in it's own little box. I took it apart and inside is the circuit board with a potentiometer. I would like to install a potentiometer in my dash somewhere for the bass control, without using the clunky box that came with the amp (for a cleaner look). I'm just not sure of the exact potentiometer to buy, or how to wire it.

The pot has B203 printed on it, which I read online may mean it's linear, but I'm not sure what the 203 represents. The number should represent the impedance?

The box connects to the amp with a phone wire (6-pins). Is the wiring standardized, or is each manufacturer unique? Can anyone help me out with doing this?

The amp is new, it's a Soundstream RUB1.1000D

Click to read more...

 

[Umbra]

You can use one of these if you turn it all the way up, set your gains appropriately, then turn it down. That way you can't accidentally send a clipped signal.

Either way, I think your best bet is installing it behind a panel and just make a hole big enough so the knob protrudes through.

 

[Sizzlechest]

I already have one of those that connects to my amp, what I'm aiming for is just the potentiometer dial that I can cleanly install in my dash. I was hoping to use the Soundstream one that came with my amp but it has a circuit board soldered to it.

The functionality is perfect, the remote ranges from 0-gain to my set-gain, instead of 0-gain to max-gain.

 

[maylar 10+ year member]

My amp came with a remote gain control which is housed in it's own little box. I took it apart and inside is the circuit board with a potentiometer. I would like to install a potentiometer in my dash somewhere for the bass control, without using the clunky box that came with the amp (for a cleaner look). I'm just not sure of the exact potentiometer to buy, or how to wire it.
The pot has B203 printed on it, which I read online may mean it's linear, but I'm not sure what the 203 represents. The number should represent the impedance?

The box connects to the amp with a phone wire (6-pins). Is the wiring standardized, or is each manufacturer unique? Can anyone help me out with doing this?

The amp is new, it's a Soundstream RUB1.1000D

A potentiometer is a variable resistor. The center terminal is the moveable connection (variable), and the 2 outside terminals are either end. If you take an ohmmeter across the 2 end terminals you can measure the value of the pot. If the number B203 has any reference to its value, it probably means 20,000 ohms (20K) but measure it to be sure. Every manufacturer is different on the wiring, so you'll have to trace from the pot wires to the RJ11 connector and duplicate the connections. Since the amp is mono, you're probably only dealing with a single section pot and 3 connections total.

Mouser, Digikey, or Parts Express will have pots with different mounting options. I'm sure that even a 1/4 watt size will be adequate.

 

[Sizzlechest]

Thanks maylar

I tried to determine what is going where by looking at the circuit board but it's hard to tell. If I snap a picture do you think you can determine? The pot has 6 solder points, as does the phone wire jack.

 

[bbeljefe]

If that knob is attached to the case with a nut, which I think it is, you can remove the whole thing from the case and mount it in the dash through a hole the same size as the one in the case. Your only consideration with that would be that you have ample room behind the dash for the PCB and plug.

 

[Sizzlechest]

If that knob is attached to the case with a nut, which I think it is, you can remove the whole thing from the case and mount it in the dash through a hole the same size as the one in the case. Your only consideration with that would be that you have ample room behind the dash for the PCB and plug.

Plenty of room behind the dash for this, but the turning part sticks out about an inch beyond where the mounting threads are on the pot. I want it to be more flush.

 

[CSCStang]

Try to get a second nut of the same size and then you can set the depth you want, or drill the hole just a little smaller than the post and twist the pot through creating a tight thread in the plastic, or add washers to the post before you pull it through the hole. If you're saying the internal post is sticking out too far, use a hacksaw and cut it down some.

 

[Sizzlechest]

Bbeljefe, it is not secured with a nut. There is a lid on the back of the case secured with two screws that keeps the board in place. You slide the board in knob first, then put the back lid in and secure with screws. I can't cut the rod because I wouldn't be able to use the black knob since the entire shaft does not have the same form to accommodate the knob. This is why I think I need to re-wire a potentiometer.

Here is what I'm working with, if anyone has any ideas please share

 

[Sizzlechest]

Fixed above picture url. If anyone can give me pointers on finding the correct potentiometer and how wire it I'd appreciate it.

 

[ummduh 10+ year member]

Fixed above picture url. If anyone can give me pointers on finding the correct potentiometer and how wire it I'd appreciate it.

Why not probe it, figure out which wire does what, and then desolder that one from the board and use it? It'd take about 5 minutes max with some solder wick to get it off.

Hard to tell from the dark pick, but you can follow the traces and see where they go.

135

246

Looks like Pin 1 on the jack goes to Pin 2 on the Pot, 3&5 on the jack go to 4 on the Pot, 6 on the Jack goes to 6 on the Pot, 2 on the Jack goes to maybe the LED? 4 on the Jack, possibly paired with #2 ? Probe it with a DMM and write it down, then duplicate it. Cut the end off an old phone cord to use as a breakout to make it easier to follow.

 

[Sizzlechest]

Why not probe it, figure out which wire does what, and then desolder that one from the board and use it? It'd take about 5 minutes max with some solder wick to get it off.
Hard to tell from the dark pick, but you can follow the traces and see where they go.

135

246

Looks like Pin 1 on the jack goes to Pin 2 on the Pot, 3&5 on the jack go to 4 on the Pot, 6 on the Jack goes to 6 on the Pot, 2 on the Jack goes to maybe the LED? 4 on the Jack, possibly paired with #2 ? Probe it with a DMM and write it down, then duplicate it. Cut the end off an old phone cord to use as a breakout to make it easier to follow.

Thanks for the reply, I'll go with this approach.

With my DMM it is reading 19.5 when I test the lower outside posts on the pot; when I use the middle post in the test with one on the outside it does go up and down accordingly depending on the pot position. Can I assume this is a 20k pot or is it actually a 19.5? And since there are 6 posts on this pot, is one for the left channel (top set), one for right (bottom set)?

I was going to follow the below site for re-wiring once I figure out what wires do what in the telephone jack. Are pots consistent with what each pin does? I couldn't find a telephone plug so I'm going to pick one up. For now I was testing directly on the circuit board.

Potentiometer

 

[bubbagumper6 5,000+ posts]

Well if you know how to solder just remove the pot from the board and solder 6 little wires from it to the board. Then you can mount the pot wherever you want and have the board hidden behind the dash with a few inches of wire between...

 

[Sizzlechest]

The problem is the pots shaft is too long, and it extends further out if you push it in. I cant't saw it down because it extends when pushed, and I also wont be able to install a knob on it. I'm buying one with a shorter knob that has a constant length as a replacement. I'm trying to replace this separate gain control box with a knob built into my dash to clean up the install.