A while back i bought a 15w blacklight CFL at a thrift shop. It came nicely in its box and looked good. Back home it turned out that the driver was blown. Two of the lamp connections had arced right through their isolating sleeve and the resulting arc spread to the circuit board, blowing up some transistors and resistors. I was gonna repair the board (it's cheap and simple) but before putting in the effort, i wanted to verify the lamp is still okay.

I replaced it with a Philips SL15 or SL18 choke ballast and a standard starter for a conventional fluorescent tube to see if it does anything at all. But the arc voltage looks tremendously high for a 15w fluorescent tube, compared to linear ones. High enough to keep the starter running dimly, though not enough to cycle it. I'd expected it to be at around 50ish volts. However, at 140mA, the running voltage is 110ish volts (resulting in 15 watts). I have the mains input voltage cranked down to 190ish volts on the variac to reach 15w - at 230v input it'll run at 100v tube voltage and 220mA current, running at 22w which is too much of course. No TRMS meter yet.

The tube is definitely worn out. The tips are purple (rather than deep blue) as if the internal coating was eroded. Even at 22w it doesn't give as much blacklight-light as a new 15w one. Its fate is sealed - off to recycling you go. But i do wonder, what is the correct lamp voltage and current for a 'good' 15w CFL? Are there standards for these, or does every manufacturer just design a specific driver for their custom lamps?

Video (might still be processing): https://youtu.be/F8D7jCG4ezo

For a 230V electronic ballast I would expect that, arc voltages around 100V are quite common (the motivation is to not lose that much power on cathode fall). Better to use a "PL-S 11W" choke and a "xx...40W" starter.
But if the bulb started, it is OK. The starter glowing is not that uncommon with normal lamps either. Plus don't forget this tube is not designed for 50Hz operation, so it won't have enough electrode mass to keep them warm over the current zero cross, so it will exhibit rather large reignition overshoots.

Other common 15W spiral ballast will very likely drive it about right, the lamps do not use to differ that much.

Update: i tried fixing it anyway. Replaced the emitter resistors, the fuse and the transistors. It still doesn't work. It does oscillate - i hear the interference whine on the radio -  but nothing appears to be happening with the tube. Need to do more measurements...