[rockthecatbox]

Yamaha rx-750.  I am not able to get sound from the right speaker channels from both A and B speakers.  I've swapped around speaker cables, different speakers and just can't figure it out. 
Possibly I broke it after testing out an equalizer? I accidentally inverted the "couplers" that bridge the main-in >> pre-out ports, meaning I had them bridging main-in L >> main-in R and pre-out L >> pre-out R accidentally and turned the thing on for a second before I realized.

The Left Speakers for both A and B work so I can power 2 speakers if I only use the Left speakers for both.

The contacts for the speaker wires look clean to my eye - a little dusty - I wiped them with deoxit Q-tips.

Any troubleshooting ideas much appreciated.

[FullRangeMan]

You have not exceeded the impedance limit ?
Did you make these connections while the equipment was on?
https://www.hifiengine.com/manual_library/yamaha/rx-750.shtml

[Doublej]

I think your mis-coupling caused a component failure in either the right channel of the preamplifier section or the right channel of the amplifier section. You could try to determine where the problem lies but unless you are able to repair it yourself, it is better to just take it to a qualified service technician for diagnosis and repair. Given the age of the unit, I am not sure it's worth having it repaired.

You can try unplugging the unit from the wall for an hour to reset it and then plugging it back in to reset the receiver. 

If the unit has internal fuses I would remove the cover and inspect the fuses to see if the right channel has a blown fuse.

You could also swap the left and right channel couplers to see if you have a bad coupler.


 

[Speedskater]

Bridged Mode can be dangerous to the amps output stage if hook-up errors are made.

[rockthecatbox]

Well I've come to terms with the fact that I probably toasted something inside.  I am going to try to fix it myself - I will be asking many questions I am sure.  Thanks all.

[Speedskater]

At least when doing this DIY repair job, you have a good channel to compare to.