Home Theater Questions? Ask a Technician for Answers ASAP
Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, bear with us; re-confirm and post back with the complete model number of the AVR.
Appreciate the additional information.
How is the Infinity Alpha 1200S connected to the Sony STR-DE875 using what kind of connection(s); LINE LEVEL (RCA) or HIGH LEVEL (speaker wires)?
And is this a fresh/new install? ...or the pair has been working as expected before and this issue just recent?
Can you please disconnect the RCA plug to the Sony's SUB WOOFER jack? Lightly touch the tip/center pin of this RCA plug. With the Infinity Alpha 1200S turned on, LEVEL up, there should be a thump/humming sound from the subwoofer.
Please post back results / observations of the above once tried.
Yes, lightly/momentarily touch the tip of the RCA plug of the coaxial cable connected to the Sony's SUB WOOFER jack.
Touch the RCA tip with your finger.
If the Infinity Alpha 1200S is turned on, LEVEL up and other settings set, then there should be a thump or humming sound when the RCA tip is touched. That there is none would make the Infinity Alpha 1200S suspect rather than the absence of a "...signal from my AVR..."
Would you consider a alternate connection? It would serve as both a TEST and as an attempt of a fix.
Connect the Infinity Alpha 1200S's HIGH LEVEL IN R & L terminals to the Sony STR-DE875's FRONT L & R speaker terminals (parallel to the existing speaker/wires connected).
I understand; no prob.
It would appear to be an internal hardware issue.
Are you then considering a DIY (do-it-yourself) repair approach? If yes, do you have access to and familiar with a multi-meter and even a soldering iron?
Based on the results of the above tests, it would most likely be a faulty sub.
Still, do you have a CD player, or portable MP3 player or even just a 3.5mm-to-RCA plug cable?
Actually, I was hoping to validate if not confirm (more) the likelihood of a failed sub by connecting the sub's R & L jacks LINE LEVEL IN to the AUDIO OUT jacks of a CD player, or portable MP3 player or even the earphone/headphone jack of a phone.
Yes please; any connection/means that can feed another sound source to the sub's R & L jacks LINE LEVEL IN. The idea is to try make any sound come out of the sub without connecting/using the Sony STR-DE875.
Any device that has red & white jacks for AUDIO OUT such as an old cassette deck, a CD player, DVD player, cable box would serve the purpose.
When able; thanks.
Any length of electrical wire would serve as an FM antenna. If available, then the Onkyo could test the sub while in FM mode.
What's the Onkyo's model number please?
Please connect the sub's R or L ***** *****NE LEVEL IN to the Onkyo's MONO OUT (SUB WOOFER)
Just 1 cable please...
Sorry but not phono out but MONO OUT (SUB WOOFER) to the r or L jack of the sub's LINE LEVEL IN.
Re-check with the Onkyo tuned to an FM station, sound playing on the speakers, Infinity Alpha 1200S turned on and controls set to MAX GAIN
I checked the repair / Service Manual for the Infinity Alpha 1200S and yes; there is a separate circuit for detecting incoming audio signals that then triggers fully turning on the built-in amp for the sob speaker.
This would confirm the internal hardware issue.
Are you then considering a DIY (do-it-yourself) repair approach?
If yes, do you have access to and familiar with a multi-meter and even a soldering iron?
To my understanding, both offers multi-meters of different brands/models. Nothing in particular as long as it can read resistance, AC and DC voltage.
Then I can provide troubleshooting steps; i.e. which part to test.
Great on the DIY!
Sorry for the delay; mobile with sluggish Internet if at all.
Still, please post back with clear pictures of the internal circuit of the subwoofer. Click HERE.