I want to move my receiver to a cabinet that would require it to stand vert instead of horizontal. Would that be a problem? Cooling slots would be open and it would be controlled by remote (cab door open).
Well I would imagine that there are heat sinks built in to help cool the electronics. These depend on heat rising through them when horizontal. If placed vertical then the air flow would be restricted and possible overheating may occur damaging components. A possible fix would be a low volume type of computer fan with a variable speed control mounted on or near the unit would take care of this. My opinion would be to mount it on place it near the bottom of the unit to move the air as it was designed to work. Just my opinion but other than this it should not be an issue.
How powerful is the receiver? Does it seem to run hot when it is horizontal?? Do you often play it loudly for extended periods or run more then 2 speakers with it???
It was originally engineered to be used in a horizontal orientation and most likely any heatsink layout was done to aid convective cooling. But if it runs pretty cool normally it is likely no problem at all.
Odds are it doesn't matter if you aren't using it hard. I have run/tested many receivers and amplifiers standing on end some for days.
One time years ago I was acting as a sound/light tech for a local band. One of our amplifiers had failed and I had to borrow an amp from the local music store. I got the last thing they had, a dreaded Phase Linear 400 but it did work. We were running 4 stage monitors on it and it was running hard at a few hundred watts/channel. It would go about 10 minutes at a time then cycle out on a thermal protection. A fan near it helped but still cycled. I went into the kitchen and got a low pan and filled it with ice and a little water. I set the amp on it's inadequate heatsink fins in the pan of ice. Ice was replenished between sets, worked perfectly!