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Re: icar 100K pot
Posted: Sun Aug 25, 2013 3:37 pm
by Haze13
I have built a marshall JCM 800 2204 and my presence pot is Ok. Try a better quality pot like CTS. I always say that they are way better than Alpha.
Re: icar 100K pot
Posted: Sat Aug 31, 2013 11:15 am
by michele
appetite4distortion wrote:6.2M seems me crazy (or shot), possibly you measured in the wrong way? did you measured when the pot was desoldered and alone?
BTW, yes, it's normal for them to drift from nominal 100K to two or three times..mine (68) is around 300k, don't remember exactly.
Unfortunately it is also normal for it to be a bit scratchy..all of them are like that more or less..it's something you have to live with, like the presence pots of marshall. That is due to design of the carcass which leaves too much gap and dust enters too easily in the traces. Surely you can clean it , but after 2 or 3 weeks it starts back again. I dunno if there are some tricks to mitigate that.
I have tried too to replace it with aftermarket pot (200K), no scratch, but in noway it sounds the same anymore ..sounds weakier, just like you said. Poor us vintage nuts!
Hi,
I measured with my tech, it was on him bench. It was alone and desoldered. As you say, its normal they drift up in value to three times.
But 6.2 M is far away from it. My tech has a theory...
according to him...the pot has never been 100k. It was made to deflect competitors. My wah is one the first i guess 67. The circuit was engraved in epoxy to hide it.
With that pot it sound perfect but the scratch... I tried a 200k Rmc pot and it died...really died.
Re: icar 100K pot
Posted: Sat Aug 31, 2013 11:45 am
by michele
Haze13 wrote:Can you post some pics of this wah with a 6.2 M ohm pot?
Wah does not need all that range of a pot, It uses actually some small portion of the "trace" of the pot. May be the 6.2 M Ohm pot is a special LOG type or something like it, and when the Wah at max, you get only like 200k-300k of a resistance? Can you check the resistance when the wah on the max?
These are the pictures
https://plus.google.com/photos/10671900 ... jPbY0p-jNw" onclick="window.open(this.href);return false;
Re: icar 100K pot
Posted: Sat Aug 31, 2013 5:18 pm
by V8
Pot looks like a stock 100K ICAR, got a close up picture? FWIW I have two here that measure around 290K
For really scratchy pots I have carefully taken them apart to clean them.
Re: icar 100K pot
Posted: Sun Sep 01, 2013 2:38 am
by michele
V8 wrote:Pot looks like a stock 100K ICAR, got a close up picture? FWIW I have two here that measure around 290K
For really scratchy pots I have carefully taken them apart to clean them.
I'll post other pics..
Did you open it?! Would you sell one of it?!
Re: icar 100K pot
Posted: Sun Sep 01, 2013 4:49 am
by V8
Yep took the cover off, cleaned then replaced the cover,sorry the pot is back in its home.
BTW nice looking Clyde you have.
Re: icar 100K pot
Posted: Sun Sep 01, 2013 10:35 am
by michele
V8 wrote:Yep took the cover off, cleaned then replaced the cover,sorry the pot is back in its home.
BTW nice looking Clyde you have.
Thanks a lot, what did you use to clean it?
Re: icar 100K pot
Posted: Sun Sep 01, 2013 11:25 am
by V8
I followed this
http://www.diyguitarist.com/DIYStompbox ... ebuild.htm" onclick="window.open(this.href);return false;
the patient
http://i270.photobucket.com/albums/jj10 ... 7a42b8.jpg" onclick="window.open(this.href);return false;
Re: icar 100K pot
Posted: Sun Sep 01, 2013 6:22 pm
by michele
Thank you again.
Re: icar 100K pot
Posted: Sun Sep 01, 2013 7:14 pm
by V8
more info on rebuilding pots
http://brawer.com/2012/02/rebuild-a-vin ... ntiometer/" onclick="window.open(this.href);return false;
and a must read, btw there could be a break in the conductive wafer on the pot measuring 6M
http://www.geofex.com/Article_Folders/p ... tscret.htm" onclick="window.open(this.href);return false;
