Fish finder question

I won the OK T15 at PIF and was wondering if anyone knows what Head unit was on it before. I’ve got a 688ci HD on there now and it works, just not the down imaging. Any advice would be appreciated. Thanks.

Hi Jim, and congrats!
I think that base will accept a Humminbird Matrix series or 500 series or 600 series head unit. The transducer is most likely dual beam (200/83 khz), so that’s the limiting factor in your 688 unit. If you want to use the DI function, you’ll have to upgrade the transducer. I’ve had really good luck with the oldschool 500 series—they seem to last longer than the fancier newer models (esp compared to Lowrance).
Pat

Thanks. I was pretty sure it was a transducer issue.