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Audio Research LS25 MKII Problem

I'm wondering if anyone has any experience with the ARC LS25 MKII. I just bought one used. Soon as I got it I put in new tubes, it run fine for the first day. After about 2 hours today it would mute it self, I would get up and unmute it and again 5 minutes later mute itself. After it did this a few times it would become unresponsive and I'd have to power it off for 10-15 minutes. I turned it off and about an hour turned on again, it run again for about an hour and guess what, muted itself again. So far it hasn't become unresponsive since but obviously something is a miss. I read the manual and it states this.

"RESETTING THE CONTROLS" To avoid discharging static to the LS25 controls, contact another surface (Such as a metal equipment rack) to drain away the charge before touching the LS25. If a static charge should "lock up" the microprocessor, making the front controls inoperable, put the LS25 in mute and power down the system and turn off the LS25 and unplug from the receptacle blah blah blah."

Apparently the LS25 shares the same control system as the REF1 so could share same problem.

Anyone with any experience of this problem or any ideas?

Thanks!

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dweller's avatar
dweller
3,780 posts
 

Where are you located? There may be a technician close to you that can check the tubes. The alternative is to send the unit to Audio Research for a checkup (think $600 and up).

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bulbous_blues OP
8 posts
 

I'm in San Antonio TX. There is a guitar place in town that sells tubes, maybe he can test them. They are 6H30s though so I think I read they don't test on your average tester. I could just buy another set of tubes and keep as spare. There is a couple of technicians in town who I could ask about looking at the unit, one is more vintage radio/cb radio I think he was Vietnam era military radio engineer, I'll start with him. If anyone knows a good technician in San Antonio or Austin area?

 

Thanks

bilyeauxbrew's avatar
bilyeauxbrew
28 posts
 

Sorry to hear and I hope you get resolved soon, and post back the problem and fix! I added the same amp a few months back and it has been great with no issues.

dweller's avatar
dweller
3,780 posts
 

You may want to return the tubes and have thetubestore test and certify. If they come back good, think about returning the LS25 to seller and let them get it fixed.

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bulbous_blues OP
8 posts
 

Okay, well I think I found out the problem! Our house is old and has shoddy electrics, I did my best to fix some of it when we moved in. The outlet the pre-amp was plugged into has an intermittent earth problem. I now have it plugged into a different line, and was just running for 3 hours with no problems. Thanks to everyone is offered some help.

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