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Biasing the MKII HD100 Head
by raed6 on 2011-11-20 18:18:53

Hello,,

My Question is Simple,,

How Do I bias my MKII HD100 Head,, is there any detailed guide for that? any picutres/videos - any links? and is it dangerous even if i pull the plug of while changing tubes!!?? What is the Procedure followed in changing tubes and biasing the head,,I LIVE IN EGYPT AND THERE IS NO LINE6 QUALIFIED SERVICE HERE!!!!!!!!!!!!, Please Help ASAPPP!! Thanks



Re: Biasing the MKII HD100 Head
by Rowbi on 2011-11-21 02:17:23

well for starters yes it's very dangerous, as some of the pins in the tube sockets can still be live when the plug is disconnected (it depends on the amp and the standby switch wiring and position).  Also when you bias an amp, the amp has to be powered up and running, and that's very dangerous.  Touch the wrong thing and it could kill you.

So I seriously advise you to get an amp tech to replace the tubes and bias it.  any amp tech will do, as the tube amp part of this amp is just like any other tube amp.  the bias setting is 35mV +/-2mV.

If you're really serious about doing it yourself, then google for tube amp safety and biasing guides.  they will show you what you need to know.  there's no official guides from Line 6 because this work should be done by a qualified amp tech (who would know how to do it).  but there are plenty of general guides and videos, and once you get inside the amp it's obvious if you've seen a few guides/videos.

Be safe

Rowbi



Re: Biasing the MKII HD100 Head
by raed6 on 2011-11-21 06:59:44

First of All Thanks For your Safety Advice,,,I already knew that but I'm really desperate to find any tech amp here in Egypt...We barely have guitar techs...and since tube amps aint so popular here...consequetivly no AMP Techs!!! All I need to know is from where do I tweak the THING (Button/Screw) to adjust the bias to 35....Is it beneath the tubes? beside the resistor? Dont Worry Im Planning To buy the Bias King Product It makes things MUCH safer...check it out http://www.youtube.com/watch?v=YRg-eT6JKrk&feature=related HOWEVER NOW MY MAIN PROBLEM IS FINDING THE TWEAKABLE SWITCH TO ADJUST THE BIAS...Thankssssssssssss....Please Help ASAP because I'm One Step Away of Buying/Keeping This Amp for this STUPID biasing issue...(YES Stupid; beacuse randall managed to make a friend;y biasing/tube change solutions in their amp...Thanks Again



Re: Biasing the MKII HD100 Head
by raed6 on 2011-11-21 12:26:54

Please Any one I want a PICTURE of the POT that I Tweak for biasing!! and How do I tweak it??



Re: Biasing the MKII HD100 Head
by spaceatl on 2011-11-21 17:19:54

The pots are blue...you will see wire where they were...

http://line6.com/support/message/121299#121299

However, this link is a mod that puts the pots on the back of the amp with the test points...It's fairly easy to do and less than $10 USD in parts...Any compentent tech could do it for a bench charge (1 hour labor)...

Please be careful...




Re: Biasing the MKII HD100 Head
by raed6 on 2011-11-21 21:00:07

Can I PLEASE ASK you to copy this pic and in paint brush POINT with an arrow to the POT and from where its tweaked!!! and one more thing will it look the same on hd100 head?? and where EXCACTLY please where i'll find and a pic offcourse if possible or a vid maybe ??!? Please consider my bad situation where i cant find the right tech for it and i seek your guidance guys cuz i really like this amp and am about 2 sell it 4 that issue im facing!! I just need a simple guidance for changing and biasing my hd100 SAFELY if possible EASIEST METHOD...and by the way with God's willing if i keep that hd100 & manage to bias my self..i'll buy the bias king product, i guess life would be easier measuring directly and not touching and holding wires !!

You Got My Point:

1-Where is the pot on hd100?

2-How to tweak it (Clockwise/anti-clockwise) or generally how?

3-Should the amp be powered on?

Pics or vid for hd100 or similar if possible,,

Please Explain and if i find that i might not be able to do it and dangerous for me i might stop,,,,,,



Re: Biasing the MKII HD100 Head
by raed6 on 2011-11-21 21:04:51

the blue wwire is everywhere cant find z pot



Re: Biasing the MKII HD100 Head
by spaceatl on 2011-11-21 21:26:49

At the point that you find you are unable to do it, you might be dead...really man, I can't help you with this...Even with a Bias tester, you are not safe because the pots are in the amp and very near the plate voltage feed...It is very dangerous as this has to be done while the amplifier is on...

A TV repairman can do this for you as the voltages inside conventional TV are just as deadly and have similar bias adjustments...I suggest you find someone...They will know exactly what they are looking at it will take them all of about 15 minutes to do it and the best part is that you won't be dead...Sorry man, if you were here in Atlanta, GA I would gladly do it for you but I can't instruct you on how to do it this way...



Re: RE: Biasing the MKII HD100 Head
by Line6david on 2011-11-22 09:58:31

Hi,

 

   At this point I am inclined to agree with spaceatl. It does not sound like you have enough electronics experience to bias the amp. 

 

  This is VERY DANGEROUS even for someone who is trained to work on electronics.

 

  I would suggest that you take the amp to a TV repair shop or store that services electronics and get them to help you.

 

  It's really not worth getting hurt over.

 

  Thanks,

  David

  Line 6 Customer Support



Re: Biasing the MKII HD100 Head
by raed6 on 2011-11-27 07:29:09

I AM BUYING AN ANTI-ELECTRIC SHOCK GLOVES...AND I AM TOTALLY RESPONSIBLE FOR MY ACTIONS....PLEASE PLEASE SOMEONE GUIDE ME (PICTURES MUCH MUCH PREFERD) TO CHANGING AND BIASING THE TUBE OF MY MKII HD 100 HEAD....

HERE IS A LINK TO THE GLOVES IM BUYING http://www.utilitysafeguard.com/Gloves/Special-Purpose-Work-Gloves/electrical-gloves/150-0-11/

DONT WORRY 4 MY SAFETY.....PLEASE HELP AGAIN ANYONE IM ALL CAPS IN LOUDDDD VOICE PLEASE HELP ME TO LOCATE THE BIAS POTS AND HOW TO ADJUST THEM (PUSH/PULL/TURN RIGHT OR LEFT) AND WHEN...PLEASE I REALLY NEED THIS



Re: Biasing the MKII HD100 Head
by raed6 on 2011-11-29 09:07:13

Will Someone help me or What People?!?!



Re: Biasing the MKII HD100 Head
by Line6Tony on 2011-12-02 10:59:21

You are getting into dangerous territory with trying to do this yourself. We will not walk you or anyone else through a bias procedure. If need be, ship your amp to a service center so it's done right. We are locking the thread.




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