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-   -   Replacing 100KAX2 with 100KBX2 (http://www.diyaudio.com/forums/solid-state/229941-replacing-100kax2-100kbx2.html)

svkr2k 13th February 2013 09:43 AM

Replacing 100KAX2 with 100KBX2
 
Hi all,

I have a Kenwood Amplifier KA-32. The volume potentiometer in the amplifier is not working as expected even after lot of cleaning. So, I have decided to replace it with a new one.

The old potentiometer is : 100KBX2 - linear, stereo
The new potentiometer that I have is : 100KAX2 - logarithmic, stereo.

Is it okay to replace the linear pot with a log pot?

Please advice.
Thanks !

DF96 13th February 2013 11:29 AM

It won't actually break anything but you will get a strange law of variation when you turn the knob.

JMFahey 13th February 2013 11:37 AM

Agree.
On "1" it will be like the old one on "5"
"Too loud" in the first 3 or 4 scale points, "do nothing" (or very little) from 5 to 10.
It's worth searching a little more and get the Log/Audio one.

ingo50 13th February 2013 12:25 PM

hi svkr2k
You have already the LOG -version, which will fit. But, as I remember, the old pot has a kontact
at about 50% to do a loudnes. Kenwood did this to make a lin-pot to log-pot and for loudnes.
The log-pot You already got has mybe a poor bal. at low volume and - with the loudnes-kontakt
the input-impedance of the vol-pot is about 50k ohm. Go on solder.....

svkr2k 13th February 2013 04:06 PM

Replacing 100KBX2 with 100KAX2 (updated title)
 
Hi all,
i noticed an error in the title of this thread.

Carification: The pot originally in the amplifier is 100KBX2, which is linear (i hope).

The new pot that I've purchased is 100KAX2, which is log I think.

hope this clarifies.


So ... if i have the log pot instead of linear pot, what would happen?
Hi ingo50, could you please clarify your comment about the pot... sorry, I'm not an expert ...

Thanks,
Raj.

Ian Finch 13th February 2013 04:29 PM

Quote:

Originally Posted by svkr2k (Post 3368274)
......Carification: The pot originally in the amplifier is 100KBX2, which is linear (i hope)......

No, read the replies - volume controls should be Log.
Linear pots are for tone controls, if fitted.

There can be a few types of logarithmic taper pots and this may be be just choosing between two of them. - as with a loudness tap.
However, if you can't see "log" or "audio taper" specified in the catalogue, don't buy it.

DF96 13th February 2013 04:34 PM

Am I correct in thinking that A and B for log and lin (or vice versa) swapped over at some point in the past? I'm sure I saw that somewhere.

Ian Finch 13th February 2013 06:25 PM

Your 100KBX2 pot is tapped as suggested by ingo50. Check the number of terminals. If there are 4, you will be getting the wrong pot, since Ebay stuff is mostly simple "A" format - just 3 terminals. It would solve a lot of problems if you downloaded the schematic and checked this first.
KENWOOD KA-32 Service Manual free download, schematics, eeprom, repair info for electronics

Ian Finch 13th February 2013 07:23 PM

Quote:

Originally Posted by DF96 (Post 3368314)
Am I correct in thinking that A and B for log and lin (or vice versa) swapped over at some point in the past?

I think the Japanese took the "law" into their own hands as far back as the 1960s when it was cussed about a lot in repair shops. Today, every Asian manufacturer has their own version of Japanese convention with only general adherance to those practices. Industrial part manufacturers still seem to keep faith, but then they don't really play in our league with suitable audio replacement parts.

Just for the fun of it, both A & B suffix codes are log. law here but the letters seem only to refer to the connection variations. :scratch1:

wahab 13th February 2013 09:17 PM

Depending on the output impedance of the circuit that precede the pot
you can add 10K to 20K resistors from center taps to ground to somewhat
"logarithmize" the whole thing.


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