LED driver

I have a 6W ceiling light with 30x 2835 LEDs in series, the driver is externally mounted and is on the blink (flashed for a while, now mainly nothing, occasional flicker) no bulgy looking capacitors, PCB seems to be a reference design for a bright power BP3133A chip.
So I need a replacement CC driver that will provide 60mA @ 90V, but I don't seem to be finding such a thing, anyone?
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On Saturday, 21 April 2018 16:28:44 UTC+1, Andy Burns wrote:

Fairly trivial to make a CR ballast.
NT
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snipped-for-privacy@gmail.com wrote:

would that be non-isolated from mains? if so I wouldn't fancy it for the lamp part itself ...
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On Saturday, 21 April 2018 18:12:09 UTC+1, Andy Burns wrote:

yes they're not isolated. I take it your LEDs are touchable then.
NT
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snipped-for-privacy@gmail.com wrote:

not touchable, but the LED strip (unusually all in series) is only separated from the aluminium case by a strip of some tape, the LED part is 3m distant from the driver, with just two single insulated cables for + and - to it, no earth available ...
The other thought is to replace the LED strip with more conventional 12V LED strip that's cuttable every nth-LED and use a more easily obtainable driver.
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On Saturday, 21 April 2018 18:44:04 UTC+1, Andy Burns wrote:

You can make isolated CR PSUs by starting with 2 mains transformers back to back. But really if it runs on 90v it should use earth & proper insulation.
NT
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snipped-for-privacy@gmail.com wrote:

I hadn't appreciated what voltage it must have been running at until it died and I dismantled it (30 white LEDs in series at ~3V each) no markings on the PSU, but I notice the output smoothing cap is only 50V rated, so probably explains why it only lasted a couple of years.
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What makes you think the LEDs are a single series chain? Often there are two or more series chains on the tape, connected in parallel, so the driving voltage is lower (or variations such as adjacent LEDs paired in parallel).
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Andrew Gabriel
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Andrew Gabriel wrote:

Well ... I thought I'd looked closely enough to see it zig-zag as a single run (this tape has no cut marks or resistors) but looking more closely they are in series runs of 5 LEDs, with 6 groups in parallel.

Yes, even still constant 60mA @ 15V drivers seem rare ...
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Andy Burns wrote:
Oh silly, of course now I'm looking for 300mA and there seem to be plenty of those ...
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I had a GU10 LED explode. It was definitely series wired.
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Andrew Gabriel wrote:

Apart from the zig-zag track, the other thing that fooled me, was that unlike other tapes which have + and - connections at both ends, this one has + at one end, and - at the other ...
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I was just thinking the same. 90 v that is a little odd. Are we sure the leds all still work and that a short somewhere in this sticky insulator is not what has done for the psu in the firs place? Lossless droppers using capacitors are generally only used in cases where you cannot actually touch the cable at all, I used to have one in a pifco torch that was rechargeable, eventually the capacitor went leaky and filled the room with orrible smelling smoke. Yuck. Brian
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Brian Gaff wrote:

yes, the LEDs give the occasional flash and flicker

It's one of your favourite SMPSUs, and I've ordered a replacement 300mA 12 to 24V constant current one for it, the 90V was a red herring.
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On Saturday, 21 April 2018 21:05:06 UTC+1, Andy Burns wrote:

If the herring had 90v across it I'm pretty sure it's a dead herring now
NT
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On Sat, 21 Apr 2018 16:10:06 -0700, tabbypurr wrote:

Whereas a Torpedo fish would simply have claimed it was recharging its batteries. :-)
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On 21/04/18 18:04, snipped-for-privacy@gmail.com wrote:

C plus a FW bridge is all thats really needed.

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On Saturday, 21 April 2018 19:10:07 UTC+1, The Natural Philosopher wrote:

If your name isn't bodgit & scarper you need a series R to limit inrush current to a value the LEDs will survive, and to act as a fuse when/if the C shorts. You'll also want a discharge R across the C.
NT
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