I'm playing a video game called 善人シボウデス, and I noticed some grammar I'm not familiar with:
ところでこのラジオ、電源ケーブルにつないだはいいが、この後どうすればいいんだろう?
This was said by the main character, who generally speaks in Standard Japanese. But I didn't know you could say 〜た+は like this in Standard Japanese, so I tried looking it up. I mostly looked under た and は, but I couldn't find a dictionary that covered it.
Later, in another part of the game, I noticed the same character saying a very similar sentence:
電源を入れたはいいが、こいつでなにをスキャンすればいいんだ?
So I started to wonder if this 〜たは was part of a larger pattern. For example, is this 〜たは always followed by 良い and some kind of contrastive conjunctive particle like が・けど・ものの? I searched online and saw similar examples:
【子役事務所】に入れたはいいけど。。。どうしたらいいの?
Can anyone explain this pattern?