Chinese Mini LED Moving Heads Fault

[DJ Pippa]

I’ve been running two Mini Led Moving Head Units for around two years. On setting up a few weeks back one of them for want of a better description just twitches, the condition stepper motors, cooling fans and also the led on the power board.

 

 

After watching, 10W LED "blunty" moving head disco light teardown on YouTube, I used boards from the good light that I had to locate the fault area, and arrived at the power board being the culprit. Thing is at this point It’s pinning down the likely faulty component, a touch out of my depth, since when I was last employed in electronics was in the days of valves back in the 60s. Has anyone any ideas on this?

 

 

[erik10_4]

This appears to be a switch mode power supply (SMPS) and the symptoms you describe suggest to me a malfunction of the SMPS 'feedback circuit' (just my guess). A fault in this portion would cause the supply to keep trying to start up, failing and trying again. The bad news is that it can be very difficult to identify/test faulty components in a SMPS unless there is visual evidence of failure (e.g bulging capacitors, blackened components etc.), particularly without a PCB schematic. In the picture as presented I can see nothing obvious. Sorry I can't give you any specific help.

[timmeh2]

Hi

 

The best advice I can give you is to throw it away and buy a new one. Sourcing spares is nigh-on-impossible and the components and specifications can change with every batch that leaves the factory.

 

What I can tell you is that its a dual-voltage regulated PSU that kicks out 24v for the steppers and 12v for logic and the LED chips, which is pretty common for this kind of kit. You might be able to find a generic board that fits, but they come in many shapes and sizes.

 

If its failing to start it could be a shorted component causing the polyfuse to constantly break and reset. Can you fire it up on the bench to see what happens? Usual precautions about line voltage applies.

 

All the best

Timmeh

Edited September 7, 2019 by timmeh2

[bigclive]

That hiccup effect usually points to two areas. The electrolytic capacitors on the low voltage side (must be low ESR types) or the bootstrap circuit on the mains side. Check the solder connections on the transformer first and then look for a diode going from one of the primary side windings to a capacitor near the control chip. There may be a bad solder joint, diode or capacitor there.

[DJ Pippa]

Thanks so much guys for your replies and help. Looks very much like I'm out of my depth with this, perhaps you are right "Journeyman" I should just bin it, The closest I can seem to get with sourcing is this "

TIPTOP YC-LED-95W Led Moving Head Light Power Supply 7x10W 24V+12V Output Bare Board YC-100-12-24 Voltage Transformer From China " from " https://www.dhgate.com/store/product/tiptop-yc-led-95w-led-moving-head-light-power/407644438.html" trouble is my lamps appear to be 7x20w. Problem is my lamp is the 150w version which I take to be 7 x 20watt. Just can't beleive these Chinees can do such a great job with building these cheap lights and not have spares to support them. May just have to hope someone puts up one they've drop of there rig or something on ebay for spares. Take care you lot, and thanks again.

 

 

 

[Don Allen]

Although Chinese power supplies can sometimes have labels on them that are not accurate, as they use one board for several different version outputs, the power supply in your picture has a 60W power supply label on it. The Gigertop power supply you provided a link to is labeled a 95W power supply. Do you have a power meter such as a HOPI to see how much power your working mover draws on full output ?

[musht]

Aliexpress brings a few results for Led+Moving+Head+Light+Power+supply

 

Just need one that will physically fit and deliver 24V @ 1.5A and 12V @ 2A

[bigclive]

I'd recommend sticking to an original power supply in the exact same format as the existing one. These units are space optimised to the hilt.

 

My own approach to repair would be to start by looking at the back of the PCB and probably reflowing the solder connections on the transformer.

For a simple repair approach with no test equipment I'd suggest swapping out those two big round capacitors next to the output connector. They will be low ESR capacitors. After that the prime suspects would be D1 and the round capacitor at the top right hand side of the PCB. All those components have to be installed in the correct polarity.

 

If not confident in electronic repairs then consider buying a new light and keeping this one as a source of spares.

[indyld]

As Clive suggests, these power supplies are often quite fixable depending on availability of components and tools plus a bit of common sense. A multimeter set to diode test and a known-good PSU for reference is a great starting point to pin down areas and components after the usual examination of the board for obvious damage, magic smoke and dry joints.

 

Getting individual components can be a bit of a faff or seemingly disproportionately expensive for a one-off, so having a donor board to hand isn't a bad idea. Don't suppose you can get hold of a cheap busted fixture from somewhere else and use the PSU from it?

 

E2A: Of course, assuming that these fixtures were mega-cheap and you've had two years from them one might argue that they have done their job. But I'm a fixer at heart.

Edited September 10, 2019 by indyld

[Richard CSL]

https://www.ebay.co.uk/itm/AC-DC-Switching-Power-Supply-Module-AC-110V-220V-230V-to-5V-12V-24V-Dual-Output/253654775400?hash=item3b0f00b668:g:vLkAAOSwSK1a~k8F

[Jivemaster]

Chinese disco kit isn't usually long life kit. I'd guess that perhaps a fan or just a vent accumulated two years worth of dust and then the internal cooling became poorer to the point of something cooking to destruction. Maybe you can get an alternative psu board, maybe it will fit or not, some kit is tight for internal space. Maybe it's time to retire some units to the spares or repair pile and use something else.