You can use the Onkyo RC685M as a replacement but make sure it has all the functions you need. We do guarantee it to work.
The Integra RC835M Receiver Remote Control is originally supplied with Audio/Video Receiver models: Onkyo DTR-20.4
Battery Required : AA Battery 2 pack
Frequency Type : IR
Dimensions: 2.00 x 6.00 x 1.00 (W x L x D, inches)