Hi, Does anyone know where I can get a tech manual for the GPSMap 235 Sounder. Garmin does not have one. When I turn it on the screen goes black. I have the AC/PC 7 pin adapter but until I get the screen to come on it will not help. Thanks for any help.

It was difficult to find on their site, but here it is:
https://buy.garmin.com/shop/shop.do?pID=65
Then where it says quick links, click "manuals"