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Post subject: HotRod Deluxe Bias Pot won't turn clockwise???
Posted: Wed Jan 23, 2008 9:52 pm
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I'm trying to bias my Hot Rod Deluxe right now, but the pot won't turn clockwise at all. The highest reading i can get is 62mv. theres a little notch coming out of the pot that doesnt let me turn past a certain point. how do i bias hotter?!


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Posted: Thu Jan 24, 2008 11:56 am
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I'm not too technical when it comes to amps. But maybe that safety notch is there to keep the amp from being biased too hot. In that case, the notch may need to be removed.

Whatever you do don't take my word for it. I was more or less just guessing.

Now I'm interested to see if my DeVille is the same way, most likely it is.


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Posted: Thu Jan 24, 2008 12:21 pm
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Are you sure you are measuring correctly? Are you sure you know what your doing? If you bias an amp wrong you can make it run very hot and degrade the components and shorten your tube life greatly...if you have any doubt in what your doing i would just bring it to a certified Fender tech...thats what they are there for

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Post subject: Re: HotRod Deluxe Bias Pot won't turn clockwise???
Posted: Thu Jan 24, 2008 12:27 pm
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d4niel wrote:
I'm trying to bias my Hot Rod Deluxe right now, but the pot won't turn clockwise at all. The highest reading i can get is 62mv. theres a little notch coming out of the pot that doesnt let me turn past a certain point. how do i bias hotter?!


Heres a good website i found on how to do it...hope it helps since you probably have your amp all torn up...haha

click on Hot Rod biasing instructions...seems like he knows what hes talking about...check it out

http://studentweb.eku.edu/justin_holton ... l#letsdoit

-stratdude83

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Posted: Thu Jan 24, 2008 1:27 pm
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Yeah the website listed above is a great site for biasing the HRD. Sounds like your saying it will turn but not any hotter than 62mv. You really need to take the plate voltage into consideration too though.


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Posted: Thu Jan 24, 2008 5:06 pm
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Yep, without knowing the plate voltage the measurement is useless.
You should get a Bias Rite and do it properly.


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Posted: Thu Jan 24, 2008 8:52 pm
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hrmm well i mean i've read that website thouroughly before i attempted to bias my amp. and he's using an HRD also. the thing is...the first time i ever tried to turn the pot clockwise, it could only turn about 1 mm. theres a plastic notch that comes out of the edge of the bias pot that prevents me from turning the knob clockwise..and in the pictures of other hrd bias pots, i dont see anything limiting them from turning the knob in any direction. i literally never opened the back of my amp until i researched alot about biasing and tubes, etc. when i tried to turn the knob for the first time, i couldn't turn it. as for plate voltage, more knowledge would be greatly appreciated. I'm not doing anything thats out of the range of what a normal hrd would/should be able to do. that website also gives clear instructions as to what should work. thanks for the help so far though.


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Posted: Fri Jan 25, 2008 6:45 am
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It sounds like the pot is at the end of its travel. It could be your tubes or possibly bad solder joints on the tube sockets. Are both tubes glowing?
The same thing happened to mine.


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Posted: Fri Jan 25, 2008 8:20 am
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Is your amp used? Perhaps someone was tinkering with it and turned the bias up way to high and cracked some solder joints in the tube sockets from running it to hot...might be a possibility

Did you check the plate voltage rating for the tubes that you have? You should set the bias for your specific tubes

-stratdude83

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Posted: Fri Jan 25, 2008 8:22 am
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i dont think its the tube's
should i just cut the plastic piece off? if i do so then i think i could turn the knob. i was just wondering if anyone else's hrd has that plastic piece sticking out of the bias pot


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Posted: Fri Jan 25, 2008 10:41 am
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That tab is there to prevent the trim pot from rotating 360 degrees. If you cut the tab, you'll destroy the trim pot. More than likely,there is another problem with the amp. Fender usually uses a drop of paint to keep the pot from moving. The problem could be cold solder joints or fractured joints on the power tube sockets, or a bad resistor. The Hot Rod Deluxe is notorious for shoddy solder joints.If the amp is under warranty, if you mess with the tab, you'll void it. I would take it to a tech.


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Posted: Thu Feb 07, 2008 8:56 pm
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what kind of tubes r u using?jji bet! some tubesare on the cold side,i got 2 pair of jjs that i cant bias higher than 33ma the hot rod ahs a small bias range to boot!with almost all NOStubes you can bias where u want to and still have room left on bias pot.but not so with current production tubes!you will have to have the bias resistor changed which will give the bias more range then you will be able to bias any tubes.if you dont know how to do this.take it to an amp tech the voltages in the amp can kill u sodo not try an change any resistors if u dont know what ur doing!changing the bias resistor will solve your problems! ...good luck


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Posted: Thu Feb 07, 2008 9:14 pm
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i have the same problem with JJ tubes i bought from eurotubes and they wouldnt take them back if u deal with them tell them you want a hot pair 65 or higher! but they will just send u what they have if they dont have'm and then he'' blame it on ur amp! and ull have to have the bias resistor changed to use their tubes! which will cost you another 40 or 50 dollars just to use their tubes and they wont tell u this before u buy them and they wont takem back either! has anyone else had this exp. with them? my advice is avoid erotubes all together!Bob is a real as hole trust me! if u want JJs buyem from some one else! they'll never get another dime from me! peace!


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Posted: Fri Feb 08, 2008 6:27 am
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Hi Jimmy,
There is probably nothing wrong with your tubes. I also bought tubes from Bob at Eurotubes. Blues Option #1 for my HRDlx. I had the same problem. It was my amp not the tubes! I had cold solder joints where the tube sockets are soldered to the boards. I also had a couple of bad resistors too. My amp was only a month old. After the repair, I could bias almost up to 100mv.
Eurotubes warrants their tubes for 6 months. I've never had any problems with JJ's or Eurotubes service. I would get the amp checked out before you start bad mouthing someone and his company. Bob told me to get the amp checked out and if it still wasn't working out send them back for a refund.
The problem I had was that only one tube would operate because the of the sockets and resistors. I too would only max out at 33mv. Look around the internet and you'll find this is a common problem with the Hot Rod series. You should also be using a Bias Rite to adjust the bias. When I put the tubes back in it shot up to 85 mv after the work was done.
My work was done under warranty.
Eurotube is still one of the best sources for JJ's. Do yourself a favor and take the amp to a tech because it seems like you may not know your way around the inside of an amp and that can be lethal.


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Posted: Fri Feb 08, 2008 6:28 am
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Hi Jimmy,
There is probably nothing wrong with your tubes. I also bought tubes from Bob at Eurotubes. Blues Option #1 for my HRDlx. I had the same problem. It was my amp not the tubes! I had cold solder joints where the tube sockets are soldered to the boards. I also had a couple of bad resistors too. My amp was only a month old. After the repair, I could bias almost up to 100mv.
Eurotubes warrants their tubes for 6 months. I've never had any problems with JJ's or Eurotubes service. I would get the amp checked out before you start bad mouthing someone and his company. Bob told me to get the amp checked out and if it still wasn't working out send them back for a refund.
The problem I had was that only one tube would operate because the of the sockets and resistors. I too would only max out at 33mv. Look around the internet and you'll find this is a common problem with the Hot Rod series. You should also be using a Bias Rite to adjust the bias. When I put the tubes back in it shot up to 85 mv after the work was done.
My work was done under warranty.
Eurotube is still one of the best sources for JJ's. Do yourself a favor and take the amp to a tech because it seems like you may not know your way around the inside of an amp and that can be lethal.


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