Hi,
This is not a well-known amplifier, so here is a review I wrote years ago about it:
http://www.musicgearreview.com/reviews.php?man=Montarbo&cat=Guitar_Amplifiers&mod=165%20NR (http://www.musicgearreview.com/reviews.php?man=Montarbo&cat=Guitar_Amplifiers&mod=165%20NR)
And Schematics I had directly from the company:
(http://img34.imageshack.us/i/montarbo165schematics.jpg/)