Bench inspection lamp- replacing with LED

[Cornboats]

Decided to change broken flourescent ring with an led alternative bought off Ebay. It came without any details of required supply. The supplier
does not have this information, just that its been stored in warehouse for 10 years. I want as bright a light as possible but am concerned that at too high a voltage will burn out the led's.
There are 90 led's each with a small yellow spot in the centre of the inside of each led lens. Could these be mains tolerant led's. I've put 9-14v DC on the circuit and lamps glow but not to their full luminance. How much voltage can I apply without fear of burnout?
If I'm reading the circuit correctly the lamps are configured in sets of 5 with a resistor of 15 ohms. Each set supplied in parallel.

[stj]

those are straw-hat leds, probably 3v and 20-30mA max
so how exactly are they wired again? 5 in series per resistor or 5 in parallel?
https://ohmslawcalculator.com/led-resistor-calculator

if they are in series try 12v

[CapLeaker]

Change the resistors to a led driver that limits the current to 20ma. Put on 24vdc PSU and don't worry about the LEDs. That's how I fixed a whole auditorium that was full with these LED lights that burnt out.
Take all LED strips out, replace every LED on the board and change the resistor to current limiting LED driver 20mah, correct new voltage adjustable DC power supplies instead of transformer to get them to dimm. Then installing teverything again. Still works perfect 12 years later. Easy fix. But it was a lot of work.

Back then I used NSI45020… but now much better things are available like NSIC2020JBT3G.

[Cornboats]

The leds are in banks of 5 wired in series with a15 ohm resistor. Theres 18 banks all supplied in parallel.

[stj]

needs atleast 15v then - maybe 18