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SOS on Audio Research SP-9MKII

99.237.131.60

Posted on February 28, 2015 at 10:56:24
dd168168
Audiophile

Posts: 207
Location: Canada
Joined: December 18, 2004
I was listening to it today for about 2 hours. All of sudden, the sound shut off. I went to the system and saw SP-9 LED turned to green. It was like in mute mode. Then I turned off and turned it back on. The machine seemed working fine, then it shut off again in 5 minutes. What went wrong? Is it the tube or something else? Please help.

 

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Perhaps , posted on February 28, 2015 at 11:01:23
E-Stat
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Posts: 37463
Joined: May 12, 2000
Contributor
  Since:
April 5, 2002
it is a problem with the muting circuitry. I had that issue with mine years ago. The culprit was a bad TI sourced NE555 timer.

Irritating, but that has been the only trouble I've had with mine in twenty years.

 

RE: Perhaps , posted on February 28, 2015 at 11:22:43
dd168168
Audiophile

Posts: 207
Location: Canada
Joined: December 18, 2004
Thanks. How difficult is it to replace it? It seems a quite inexpesive part if that is the problem.

 

RE: Perhaps , posted on February 28, 2015 at 13:27:26
Blackdog
Manufacturer

Posts: 1505
Location: Ontario
Joined: March 20, 2006
Not too difficult if you have decent soldering skills,and can get at it easily. Note there are two of those IC's in the timing circuit. Best thing is to replace them both.



Dan Santoni

 

RE: Perhaps , posted on February 28, 2015 at 14:01:32
dd168168
Audiophile

Posts: 207
Location: Canada
Joined: December 18, 2004
Thanks. Which brand shoul I get?

 

RE: Perhaps , posted on February 28, 2015 at 17:08:31
Blackdog
Manufacturer

Posts: 1505
Location: Ontario
Joined: March 20, 2006
The 555 timer is pretty generic. TI and Fairchild are probably the most popular.
Dan Santoni

 

RE: Perhaps , posted on February 28, 2015 at 17:32:21
dd168168
Audiophile

Posts: 207
Location: Canada
Joined: December 18, 2004
Thanks for the quick anwsers. I have not opened the cover yet. But from the pictures online, it seems that NE555 was installed on the socket. It might be a lot easier job, just take the old ones out and insert the new ones.

 

RE: Perhaps , posted on February 28, 2015 at 20:15:59
Blackdog
Manufacturer

Posts: 1505
Location: Ontario
Joined: March 20, 2006
I've seen them with and without sockets. If you have the sockets then it's a five minute job. Make sure you orientate the IC the right way.
One other thing to look at if the IC's still don't work is C24. It is a 33ufd 16V capacitor. If that's failed the timer will think it's muted. The value controls the time it takes to un-mute.


Dan Santoni

 

Well..., posted on March 1, 2015 at 13:07:36
E-Stat
Audiophile

Posts: 37463
Joined: May 12, 2000
Contributor
  Since:
April 5, 2002
I had ARC perform the service so I can't tell you how easy the task was. I just remember the failed parts.

 

RE: Perhaps , posted on March 2, 2015 at 10:23:35
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
Given the age it might be prudent to replace it if it is an electrolytic.

Dave

 

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