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Citation 17 preamp - in use, no output for about 5 secs every 10 minutes or so
Citation 17 preamp - in use, no output for about 5 secs every 10 minutes or so
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Old 20th August 2018, 04:52 PM   #1
donberry is offline donberry  United States
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Default Citation 17 preamp - in use, no output for about 5 secs every 10 minutes or so

Citation 17 preamp - a previous owner has re-capped it, looks like they did a nice job. Sounds very good only about every 10 minutes or so the output just stops for about 5 seconds as if it were shut off but after the approximate 5 seconds, sound can be heard again and it's as though nothing happened.
My thoughts was the output board so I took it out and examined it but as mentioned, someone has re-capped it and everything looks good. This has the boards that are attached to the chassis with connectors, you basically just pull them out , makes them really easy to work on, and I did find one of the solder pads on the connector had a poor connection so I fixed it but everything else looked fine.
I thought the problem would be in the power supply board or the output boards, but examined them thoroughly, looked fine to me. I did only give the other boards a cursory look.
If you flip it over there are test points for all of the boards and the voltages are printed right on the chassis and I went thru them all and all of the voltages were pretty much right on which wasn't surprising - I'm guessing a component heats up and gives an intermittant failure - for about 5 seconds -
wondering if anyone might have any ideas, could tell me what to check etc ?
I really enjoy this preamp, especially when mated with a Counterpoint SA-12 amp but this intermittant failure really ruins a good listening session
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Old 20th August 2018, 05:06 PM   #2
rayma is online now rayma  United States
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Quote:
Originally Posted by donberry View Post
the output just stops for about 5 seconds as if it were shut off but after the
approximate 5 seconds, sound can be heard again and it's as though nothing happened.
The relay driver Q1 is triggering the output mute reed relay. Replace capacitor C3,
check related resistors for values, and look for bad connections in the muting circuit.
Harman Kardon Citation 17 - Manual - Professional Solid State Preamplifier / Audio Equalizer - HiFi Engine

Last edited by rayma; 20th August 2018 at 05:09 PM.
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Old 20th August 2018, 06:26 PM   #3
donberry is offline donberry  United States
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wow, awesome doesn't begin to cover it. Thank u so much. Will do that and report back
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Old 3rd September 2018, 08:19 PM   #4
donberry is offline donberry  United States
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Finally updating you on this. After replacing the cap it was still doing it. I didn't have enough to do them all but tho they were still in spec, I did have the right values to replace the resistors in that immediate area so I swapped them in - was still doing it. I was ordering some other stuff from Mouser so I went ahead and ordered a new Q1, a MPSA13, thought maybe it was breaking down when it heated up.
Swapped it in yesterday and now I'm not really sure what's going on. At 1st I thought it fixed the problem but of course right after thinking that, it went silent for about 5 seconds. Before, once it started it would happen , guessing, like every 30-45 minutes. Now, after replacing Q1, it did it the 1st time after I'd been listening to it for about 2 1/2 - 3 hours but then it didn't happen again for a long time - guessing it was like 3 hours later. Today I fired it up again, after about an hour it went silent for the 5 seconds but it's been a couple hours now and hasn't done it since.........
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Old 3rd September 2018, 08:24 PM   #5
rayma is online now rayma  United States
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Quote:
Originally Posted by donberry View Post
Swapped it in yesterday and now I'm not really sure what's going on. At 1st I thought it fixed
the problem but of course right after thinking that, it went silent for about 5 seconds. Before, once
it started it would happen , guessing, like every 30-45 minutes.
Check the muting circuit operation to determine if that is turning the audio off.
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Old 6th October 2018, 05:08 AM   #6
donberry is offline donberry  United States
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Join Date: May 2009
sorry so long for the update. Makes me feel even more stupid but the problem is solved....turned out that there is a window a/c on the same ac line and every time it kicked on and off, it muted the stereo for some reason. Color me stupid.
I do thank u for your time trying to help me.
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Old 6th October 2018, 06:07 PM   #7
jaycee is offline jaycee  United Kingdom
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Location: Norwich, UK
The AC is probably causing enough line dip to make the amp think it has lost power. Try increasing the value of C12 to 10uF and see if it helps.
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Old 11th October 2018, 04:28 PM   #8
donberry is offline donberry  United States
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sincerely appreciate the tip and will give it a try but pretty sure the problem is the computer. Just moved it to a OneAC medical line conditioner I have but still doing it and am renting so re-doing ac lines is out of the question. Easy enuff to try so will swap in the cap and see what happens.
Do know, time u have taken to help me out is sincerely appreciated, especially keeping it simple enuff even I can understand
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