Jockey Larry Cassidy admits he was sceptical when Brian Smith steered him into an unusual aid to try to help with his crippling knee pain.

Cassidy rode his first winner after a lengthy injury lay-off aboard the Smith-trained Sony Legend at Doomben on Saturday.

Smith has played a big part in Cassidy's comeback, in particular urging him to try a "Wellcell" which is now his constant companion.

The trainer has been a champion of the Wellcell, attributing it to getting him over a major health scare several years ago.

It is a small plastic device which emits electromagnetic light frequencies and is advertised as a treatment for everything from pain to poor sleep.

"Larry was complaining about his knees and the trouble he was having so I kept telling him to get a Wellcell and he finally did," Smith said.

Cassidy said he was not really sure if it worked or not but said he now took it everywhere.

"I'm not exactly sure what it's meant to do, but I know I lost the damn thing for a week. It was in the bottom of my bag or something," Cassidy said.

"My knees got very sore again. Perhaps it was a coincidence, but after I found it again I carry it with me except when I am riding."

Sony Legend was Cassidy's his first winner since he steered Winx to victory in the Sunshine Coast Guineas 16 months ago, the beginning of the champion mare's unbeaten run which now stands at 10.

It has been a long and painful comeback for Cassidy whose weight soared during his enforced lay off.

"When you are sitting around all day and eating that will happen," he said.

"But I have a strict exercise regime in place and walk 60-70 kilometres a week.

"Of course that means using your knees and at times the pain was crippling. But I have my weight down and I should be able to ride 54 kilograms in a few weeks."

"I'm still not 100 per cent there but the timing is coming back."