Problems with my Tri-Vista 300--Need some help

I want to thank everyone once again for your replies on this thread. I managed to get my amp back today with new tubes. Indeed, the original trivistors were faulty and are now replaced. Probably the first instance of bad tubes on this gear.

Secondly, there is indeed a big problem with the source selector on this machine now. Wasn't when I initially took it into the shop, but I don't doubt the repairman's integrity. I brought it back home and when i turn it on, it travels the circuit around the sources, but rather than settling on the most recent source, as normal, it starts to click repeatedly against either the top or bottom of the source array. I finally grabbed the selector and tried to forceably put it on the proper source. Finally, it stopped this strange behavior and I could listen to music again. I'm going to have to get a new selector chip and replace it in the amp. Has anyone else had a similar problem with this amp? Thanks.

Washline,
My Denon does the source selector thing! The most annoying thing! I had been extremely busy, and then very tired, and then when I felt up to dealing with it it stopped as mysteriously as it started. Funny thing- I thought I would be relieved to read that someone else had this problem, and I am in part. But it is frustrating not to understand how my amplifier works- as it must be for you, especially when everyone must seem miles out of reach and real information a real commodity. It puts my situation in a new light, and I thank you for that. I wish I could tell you I had your amplifier( for all sorts of reasons) and that I knew why the source selector behaves this way and what to do about it. I would love to tell how to deal with that. I would love to be of some help! All I can really do though is admire the intelligence and patience you have displayed in sorting out your problems. The input selector chip seems a reasonable quess. Hopefully others here have had this problem and will be able to help you figure it out, and that MF will offer some insight too. In the meantime, even as my lowly, but much beloved Denon is behaving itself I am resolved I will learn something about these amplifier related quirks, and if I learn anything soon enough and reliably enough I will try to pass on what I have learned. I am sorry you have to put up with all this ( my long post included) and I wish you luck.

check that. Inexplicably, the source selector has started to work properly again. Don't know why. Who can figure out the idiosyncrasies of circuits and electricity. I'll keep my fingers crossed in hopes that the selector continues to work properly. In any case, what a gorgeous sounding amp.

Timf, I thank you very much for your post. It seems as though our problems are very comparable both in development and solution. Like I said, who can truly grasp the strangeness of circuits and electricity. Even the best equipment can develop such strange, seemingly uncaused problems.

Washline
Glad your problem is solved.
Chris