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AaronWil

Spider Valve MKII - troubleshooting help please

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Hello.  Have a SV 112 MKII that I bought new years ago, and have used only on very rare occasion.   It's in mint condition and has likely seen less than 3 hours of use.  Fired it up last night to find it making horrible scratching noises mixed with an overall terrible sound, and big uncontrolled volume swells even with master volume at zero.  Tried all the obvious fixes, including a reset.  Even tried a different cord & outlet, with and without it's switchboard attached.  Let it sit powered up for an hour and found everything to appear normal.  No excessive heat, no tube noise, and all the buttons, switches & knobs appear to be normal.  If anything, the master volume knob sets off the noises when touched, but not every time I try it.  It's a "scratch, scratch, scratch, EXTREMELY LOUD GUITAR, scratch, scratch, SEMI LOUD GUITAR..." sort of thing.  And that's with the master volume at ZERO.

 

Have had lots of other tube amps and this initially made me think tubes, but these are so new that I'm doubtful that's the case.  Pulled and inspected all four tubes and sockets anyway and saw nothing unusual.  Cleaned leads and reinstalled.  No improvement.  Tried running out to a 4x12 cabinet too.  I have HD100 heads that have been used & abused almost daily for years and still work like new.  I have no idea why this combo would go mental on me now.

 

When not in use, it's been kept unplugged with a cover.  It's never even left the room it's in since I got it.  So it's not a handling or power surge issue.

 

I don't live anywhere remotely near an amp repair place, let alone a service center.  I'm thinking one of the two main boards has failed.  Are spares available?  Not wanting to spend a fortune on fixing it, but it's a true shame to let it die.

 

Any suggestions?

 

Thanks!

Aaron

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If its not the tubes - then sitting forever probably has oxidized the master volume pot probably some jacks as well. DeOxit usually can clear that up. But P-Sark is better equipped to point you in what to look for.

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http://line6.com/support/page/kb/_/general-faq/cleaning-pots-and-faders-r816

 

A Knowledge Base posting on the subject.

 

Use a cotton swab, do not spray directly into it. And for heaven's sake, don't touch anything

on the inside, or heaven is where you'll end up. Really embarrassing in heaven, telling them

all that you ended up there because of something clumsy with a 200+ Volt line on an amp.

Even more embarrassing when you tell them the amp was unplugged. Capacitance discharge

into you really hurts, and it can kill, especially if you have a heart condition.

 

The shock hazard is too great. Got zapped myself the other day pulling a circuit board out of one,

bumped my elbow against the wrong thing. It hurt. Been doing this 40+ years, I still get zapped every

now and then.

 

So be careful applying contact cleaner in a valve amp (tube amp).

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Thank you both!  Appreciate the ideas.  Tubes are original, with just a few hours on them.   I swapped out the 6550 and 12zx7's with a newer set from one of my HD100's and found same issue.  Will try the pots next.  Loud & clear on not touching the caps.  Thx!

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Use only specified tubes.

 

These are not all analog tube amps of yester-years (a la circa 1960's and 1970's). Can't go doing

tube swaps like that. The analog and digital section need to play nice with one another.

 

Do not do tube swaps with anything other than the specified tubes. I see way too many come across my

repair bench because of that. Don't do that.

 

Use the specified 5881WXT (preferably Sovtek) power tubes and 12AX7 (preferably Sovtek). Check the

Knowledge Base for bias instructions, should be +35mV(dc), +/- 2mV.

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I've had my Mk ii 112 for about three years now... gigging on average twice a month. I've never changed the tubes. The amp is starting to act up on me. Clean tones are dirty and dirty tones are difficult to control. I am thinking that problem is not related to the tubes though because it is an intermittent problem. The last gig it worked great. I will tap a few pots and it starts working a little better, though still not as well as it should. Should I be looking to change the tubes?? Would that be an appropriate trouble shooting step given that the symptoms are intermittent?? Can't be having amplifier issues on stage!!!

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Take it to a Line 6 authorized service center and have it serviced.

Yes, definitely needs tubes changed out. Don't do it yourself, shock hazard is too great.

They will know what to do and how to do it if it's one of the authorized service centers.

Someone other than that and they might make some incorrect assumption about the amp.

 

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