Chasing down the problem


Couple of nights ago, I was listening to my mono block tube amps and after about ten minutes the right channel goes silent! What the heck!! So begins the search for the culprit...is it upstream of the amps, or is it the right side mono block that has an issue...and what kind of issue.
Luckily, I own another stereo ss amp, so the first thing to do was to hook that up and see if the problem continued. This would eliminate a few pieces of gear as the culprit...basically everything in front of the tube mono blocks...except the connection from the preamp to the mono blocks...the ic’s.
The system played fine with the stereo ss amp in the chain...therefore leading me to believe that the following components were not at fault...1) the front end digital player and the front end turntable set up ( I did play both to be certain) 2) the tube preamp, 3) the connections between these components...speaker cable and ic’s ( I use different ic’s and sc’s to connect the preamp to the ss amp than with the tube amps).
The next day, I hooked up the tube mono blocks again...and this time after making sure that the connections at the amps were tight and that the tubes were all re-seated. Music played again in both channels ---for about twenty minutes! Then the same issue reared its head again, the right channel was silent. Hmm.

Therefore, unless I am wrong, the only two possibilities left are the right tube mono block...or the right ic feeding that mono block from the preamp. My next thing to do was to change the ic’s for another pair ( could have swapped left for right, but since I have other pairs of ic’s that i know are good, i figured why not try this next) Plan being to check the ic’s and then finally start to move tubes from one mono block to the other and vice versa to see if the issue changed channel.
Last night I listened to the same set up but with just the ic’s changed out between the amps and the preamp....and no problem. ( this after a two hour session).
Hopefully, I have identified the issue..would seem that the original right side ic has a iffy connection somewhere ( a lot easier to address than to have to get the mono amp worked on).
Anyone else have a problem like this that took a little ’work’ to identify?

128x128daveyf
@gdnrbob, Thanks, who knew when we got into this hobby that one had to learn to be a detective as well as everything else, LOL.

@millercarbon  The plug in question is a WBT locking RCA. I suspect that there is indeed a bad solder joint. The cables in question are Nordost Tyr's...which have been very reliable up to now. I am probably going to have to send it back to Nordost for servicing. 
I had a very similar problem recently but in my case the left channel amp would kick out a very nasty hum to my speaker. I opened the amp up and everything looked fine. I ran another pair of  rca cables from my surround sound system which is separate from my stereo system and had the same problem.I was going to take it out for repair but decided to take one more look and again everything looked fine. When I touched the connection to the rca input it moved away from the connector. A little soldering fixed the problem.
@lwin  Your problem was actually at the RCA amp connection..is that correct?
I think mine is the RCA ic's...
@daveyf  Initially I thought it was a poor or problem connection on the cable end and it ended up being the rca connection inside the amp.
@lwin Thanks. That's interesting, although I have never had a hum....just channel drop off.