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Post by jcoutu1 on Dec 7, 2016 8:03:18 GMT -6
I have an SA-3A that is having issues. I didn't build it.
When you fire it up and run signal through, channel 2 only works for about 30 seconds. Starts fine then the level fades to nothing. Channel 1 is working fine.
Any ideas?
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Post by NoFilterChuck on Dec 7, 2016 9:42:11 GMT -6
send a message to Mike Pildis on facebook :-)
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Post by rocinante on Dec 7, 2016 10:17:27 GMT -6
Optical not right? Sounds like something is warming up then dying. Switch the t4bs from 1 and 2.
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Post by jcoutu1 on Dec 7, 2016 10:36:34 GMT -6
send a message to Mike Pildis on facebook :-) I assume that's Serpent Mike? I'll try swapping the cells first and see if the problem follows. |
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dmp
Full Member
https://www.probstelectronics.net/
Posts: 18 
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Post by dmp on Dec 7, 2016 14:00:25 GMT -6
Swapping the cells is a good first test and if the problem follows the cell you know what it is. A few more debugging tips: Pull the t4b completely and make sure the audio goes through. With the cell out there will be no gain reduction. If the audio still goes out, it is not related to the cells. Check for overheating components. there are transistors and regulators that need heatsinking in the circuit. As they overheat they may go into thermal protection (auto shutoff). Here is the groupdiy support thread that has build docs. Worth a read though: groupdiy.com/index.php?topic=42541.0 |
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Post by ChaseUTB on Dec 15, 2016 7:15:26 GMT -6
Can a noob build this? A real noob? I guess I am asking the experienced guys how long does this build take you? How hard do you rank the build? How big of a chance is there to mess up and have to order another kit? Been wanting la3a in my life for awhile. Is everything on the front panel feature wise?
I know Stam is building one but all the important stuff is on the back of the unit where I won't be able to reach during normal use. Even if I make a tray under my desk, I still can't see or use the back panel effectively.
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Post by jcoutu1 on Dec 22, 2016 21:51:44 GMT -6
Optical not right? Sounds like something is warming up then dying. Switch the t4bs from 1 and 2. I popped the T4 out and back in from the channel that wasn't working, pow, good as new. Smooth sailing now. Album with more pics at the link below.   imgur.com/a/F15Fx |
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Post by unit7 on Feb 4, 2017 3:54:15 GMT -6
I've finally started building this. I got the wrong switches though.. Trying to get it right this time I studied the schematics and found none of the SPDT switches have the third pin connected. So why not use SPST switches instead? Asked the same question at GDIY, but the SA-3 thread there seems dead, so I'm trying here too.. If a switch only connects/disconnects one lead, why use SPDT?
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Post by bowie on Feb 4, 2017 12:44:11 GMT -6
I've finally started building this. I got the wrong switches though.. Trying to get it right this time I studied the schematics and found none of the SPDT switches have the third pin connected. So why not use SPST switches instead? Asked the same question at GDIY, but the SA-3 thread there seems dead, so I'm trying here too.. If a switch only connects/disconnects one lead, why use SPDT? Funny you say that, it's was one of the first things I discovered in the world of DIY a few years ago; BOMs asking for SPDT when SPST is all that's required. Not sure why that happens so often. No worries though, just wire the SPDT to work as SPST and you're good to go. |
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Post by unit7 on Feb 4, 2017 13:19:49 GMT -6
I've finally started building this. I got the wrong switches though.. Trying to get it right this time I studied the schematics and found none of the SPDT switches have the third pin connected. So why not use SPST switches instead? Asked the same question at GDIY, but the SA-3 thread there seems dead, so I'm trying here too.. If a switch only connects/disconnects one lead, why use SPDT? Funny you say that, it's was one of the first things I discovered in the world of DIY a few years ago; BOMs asking for SPDT when SPST is all that's required. Not sure why that happens so often. No worries though, just wire the SPDT to work as SPST and you're good to go. Thanks Christian! Good to know. But the fault I did wasn't the SPST/SPDT thing.. I bought ON-(ON) momentary switches and found out just the other day, far too late to return to Mouser. So I'll be ordering switches anyway |
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