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Author Topic: Randall Warhead volume pot  (Read 3375 times)

TolerBear01

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Randall Warhead volume pot
« on: October 17, 2015, 07:49:51 PM »
Hey there. I use the Randall Warhead and I love my amp but my master volume pot is giving me problems. I'd say it's worn out because it's an old amp. My amp is also doing something and I was gonna try to trouble shoot it. Does the master volume control act really abruptly from low volume to high in these amps as a part of their nature? Mine does it between 0-3 on the volume knob. At low volume it has hardly any good usable sound and the tone just drops out. It still has tone but it sounds more like fuzz than distortion and it sounds muffled and it loses most of its bass. You turn it up past 2 or 3 and it gets really loud really quickly and it sounds awesome. There's a dead spot on the volume pot where the sound goes dead abruptly but you can still barely hear it. Before it developed this it sounded the same way. It just recently developed the "dead" spot. I'm an electronic technician but this amp is really complex and I want to get an idea of what other Warhead users are experiencing to see if I'm heading in the right direction. Thanks. I hope you see this and respond. I really need to take it apart and check for a cold solder joint in the volume pot. I just took it apart and cleaned all of the pots out as a preventive maintenance. Also I would love a schematic of both original versions of the Warhead. The combo as well as the 300 watt head.

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J M Fahey

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Re: Randall Warhead volume pot
« Reply #1 on: October 17, 2015, 10:28:34 PM »
If there is a "jump" at a given point in a pot scale , as opposed to, say, "a lot of variation between 3 and 6" then the pot track is probably cracked or chipped there.
Replace it, no big deal, just pamper the PCB if it's PCB mounted, meaning use a good hot iron, melt and suck solder quickly, don't twist and squeeze pot legs needlessly, at molten solder temperatures adhesive between copper pad and PCB base insulating material is ***very*** weak and it's easy to pull the pad.
Old fashioned and almost forgotten solder wick is excellent to pull last remaining solder from a joint , by its own capillarity, so I recommend you get some.

People stopped using it because it's disposable and *seems*  to be a waste, the piece which absorbs solder must be clipped off and discarded, but here what we are trying to do is pamper the PCB itself, which is irreplaceable.

Of course, if the pot is connected through wires, like old Fender/Marshall/Randall it's easier and safer.

Enzo

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Re: Randall Warhead volume pot
« Reply #2 on: October 18, 2015, 12:04:41 AM »
And it never hurts to try and clean it first.

The amp may be complex, but there is nothing complex about a volume control.   There are really only two ways most volume controls function, and they are the same in most amps.

TolerBear01

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Re: Randall Warhead volume pot
« Reply #3 on: November 05, 2015, 12:45:11 PM »
Does anybody know what kind and where to buy the original type of volume pot?

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DrGonz78

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Re: Randall Warhead volume pot
« Reply #4 on: November 05, 2015, 05:41:41 PM »
You got some pics? Is it a 50k dual gang pot? Here is a thread to another web site that has most or all of the X2 schematics.
http://www.rig-talk.com/forum/viewtopic.php?p=192826
“A person who never made a mistake never tried anything new.” -Albert Einstein

TolerBear01

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Re: Randall Warhead volume pot
« Reply #5 on: November 05, 2015, 06:09:59 PM »
Mine is a first generation. I'll have to check it to see.  It's hard to do that because I use it to practice with my band. Thanks. I'll check that link too.

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TolerBear

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Re: Randall Warhead volume pot
« Reply #6 on: November 18, 2015, 01:11:22 PM »
Ok. I took my amp apart and was surprised to find a dual rotary split shaft 100k potentiometer made by Alpha. I couldn't tell if it was an audio taper or linear but the one I ordered was an audio taper. I ordered one off of Mouser but they only have the "D" shaft. I found one on ebay that said it was made by Alpha but it looks a little different than the one in my amp. The original one has a full Metal casing with the word Alpha stamped on it then the value. I was afraid the one from Mouser I ordered wouldn't work with the original volume knob so I turned to Ebay. I ordered ones on there under the description "3 pcs Alpha 100KA / A100K Dual Audio Pot Potentiometer 15mm 1/4W Volume Control". I added a picture of it. I hope it shows up. Do y'all think I did right by my amp? Thanks.  :dbtu:
« Last Edit: November 18, 2015, 01:12:47 PM by TolerBear »

DrGonz78

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Re: Randall Warhead volume pot
« Reply #7 on: November 19, 2015, 12:04:19 AM »
Yeah if the original pot was for volume control then Audio Log is probably the best bet. Strange that the old one did not say A100K or something like that on it. Anyhow post a picture of the original pot if you can.
“A person who never made a mistake never tried anything new.” -Albert Einstein

TolerBear

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Re: Randall Warhead volume pot
« Reply #8 on: November 20, 2015, 06:21:03 AM »
I looked more closely at the volume pot and it appears to be a linear pot. It says B100k. I never did like the way the volume went from 0 to 4 abruptly when was working right. I think an audio pot will fix that but I don't know what it'll do to the tone. Right now the tone at below 2 sucks but at almost 2 and greater it's awesome. I hope it fixes that too. What do y'all think?

J M Fahey

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Re: Randall Warhead volume pot
« Reply #9 on: November 20, 2015, 08:11:25 AM »
If it's a gain pot and value is the same, it will NOT affect tone at all.
Different taper will "spread" its effect along the scale in a smoother way.

TolerBear01

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Re: Randall Warhead volume pot
« Reply #10 on: December 15, 2015, 07:58:38 AM »
It's the master volume.

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J M Fahey

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Re: Randall Warhead volume pot
« Reply #11 on: December 15, 2015, 08:37:53 AM »
Same thing.