Can this engine (DCC on board)come with a speaker and can it be easily upgraded to sound? It's the 0-6-0 USAR Penn. with a slope tender
It's easy if you get a tech to do it.
Did it come with a speaker installed? If the Decoder is in the tender then it maybe a standard Steam loco installation. But if the decoder is in the boiler area them a profession tech will be the best option to have a sound decoder installed.
I have not installed a decoder into a Bachmann HO 0-6-0 any version. Now I have installed decoders into the Bachmann N scale 0-6-0s.
On our newest DCC Sound Value 0-6-0s, the decoder is in the tender, but in the earlier versions (analog and DCC On Board), the decoder is in the locomotive, and there are no electronics in the tender. For adding sound, I would agree to talk to a DCC installation specialist.
I concur. Despite what lots of people say about a decoder just "plugging in," that's only with certain newer "DCC ready" engines that have the plug to do it. I highly suspect that your engine does not have it. That means you have to back feed circuits to see what is what, then you have to install the speaker and solder it to the leads from the decoder, and possibly install a baffle.
There's this myth that persists that converting a DC locomotive DC and sound is incredibly easy, but it's only in "DCC ready" situations and you still have to solder the speaker in.
At the point you appear to be in with Model Railroading, I strongly urge you to find a tech to do this install for you. Google is your friend, there are many out there. It ain't cheap though. You may find that the cost of purchase and DCC installation may be almost equal to just buying a new locomotive with DCC and sound already installed.