There's another Audiokarma thread about a guy who had cycling protection relay issues with an SX-980 after relocating to a new dwelling. Not sure how that turned out - I believe the thread ended with him taking the receiver to a repair shop.
Another interesting thing I've discovered this morning. I started wondering if there could be a small mod made to the protection board to accommodate slightly-weird line voltages like I seem to have here. What got me to thinking about this was that, many times when the relay would stay engaged on its own using normal line voltage, the relay would let go as soon as I put my DMM probe on pin 7 of the PA3004 to measure the AC voltage there.Don't feel dumb, everybody has different experiences, which bias their point of view. AK members share their different skill sets to help each other!
Okay, I'll give that a try. It would be easier to piggy-back another resistor on top of R8 to achieve a lesser resistance value. Now that we're talking about that, I'm thinking I may have already tried piggy-backing R8 - possibly with another 470K-ohm resistor. I think I saw a voltage increase on pin 7 of the PA3004, but the relay kept cycling. Not sure if I posted that or not. Anyway, I'll give it a try.
I reconnected R11 and R12. Then I piggy-backed R8 with another 470K-ohm resistor, then worked my way down to a 270K-ohm resistor, which got me at 0.76vac on pin 7 of the PA3004. I didn't want to increase the voltage any more than that. Relay still cycling, but did latch for a few seconds from time-to-time. Again, putting my DMM probe on pin 7 of the PA3004 always caused the relay to let go.
Probably not a bad idea. I found an older meter-based socket tester. Everything checks out fine. But, since the receiver doesn't use a ground lug on the power cord, I'm not sure how much good this would do me?i would be testing the mains supply with one of these .
I show no voltage whatsoever between neutral and ground. I'm in a brand-new science building on a large college campus, so the electrical work was recently installed and inspected. But still, it's like there's something funky with the power..... although I can't see what.
You should't read any voltage between neutral and ground, If you did you would have a problem.
In that thread the poster had moved to a new apartment building that had arc-fault detecting circuit breakers as mandated by recent building codes. His receiver worked fine until he moved in there, if I recall correctly.
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Thanks for the link! I read through most of the posts. That guy had the same symptoms with his 1280 as I've had with two 980s. Odd that his receiver still had the relay cycling problem even after taking it back to the location where it worked before. That's on my list - I'm working on getting the second SX-980 cleaned up and upgraded to LED lamps. Once that's done, I'll take it home and see if the relay cycling goes away (hope so).
Will do. It'll be interesting how this turns out. I have a friend that worked for the electrical contractor who did the work here - I'll get in touch with him, as well.In that thread the poster had moved to a new apartment building that had arc-fault detecting circuit breakers as mandated by recent building codes. His receiver worked fine until he moved in there, if I recall correctly.
Check with your building Maintenance Dept to see if your NEW building has Arc-Fault detecting circuit breakers in their distribution panels. That may be your issue.
I looked for that post, but could not find it
Yes, it does. The whole ground plug thing seems a little silly, considering the ground wire and the neutral wire are both tied to the same buss bar in the breaker panel.