Showtec Light Bar 12 Parts

[dmxlights]

Hi,

I would like to know where can you get parts for the Showtec Light Bar 12 (pixel). I know they are cheap bars I have 8 of them and 2 has faults which I have worked out down to a small board thats gone faulty

http://mcgcs.net/lb12.jpg

This is the board that gone faulty (the green one) there is 4 in side the bar and when I move the board around the fault moves with it.

 

[indyld]

Usually for cheap kit like this, we keep them going using donors or fixing the PCB where possible.

 

Out of interest, what are the symptoms of the faulty board?

[dmxlights]

2 of the leds are coming on full as in RGBW all together are coming on when I am just bring on one colour (ie Red or any colour for that matter) at 1%. The other one is the blue on one led does not come on till it at full. I know its not the leds as there is 4 of these board in my bars and if I move them around the problem follows the board.

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I also have been checking thing at component level and I am thinking of replacing the Hex inverter ICs as for some reason I think these may be the fault. I will be checking them more later.

I was just thinking if I could get some of the boards.

 

 

 

[indyld]

Was gonna say, I've found hex inverters to be a weak point on some other fixtures.

 

To get kit out the door, my first move is to take one of the faulty units out of stock to fix others, then deal with the boards at my leisure.

 

Or, at the moment, whenever the chips actually come back into stock... :-/

Edited October 17, 2021 by indyld

[dmxlights]

Hi Rob,

That sounds good that I am on the right track. I am going to check them later with my scope and then order the Hex inverter I can get hem from RS for about 50c each. which sounds like a good place to start.

Thank you for your help as well. I will post back here what I find later

 

[dmxlights]

I have replaced the Hex Inverters that where faulty and now I have one colour on one led stuck on which I found a transistor or mossfet to be the cause.

 

Its has 3 legs and the marking on it which are A2FV. I have looked for info on it but got very little back on it. it a SOT23-3 package.

Edited October 25, 2021 by dmxlights

[indyld]

Is that the ones on the LED board e.g Q4 etc? Or is there a chance that the marked package could be a diode? A lot of the A2xx I found in SOT-23 were switching diodes.

 

Some decent pics in situ might prompt a little more grey matter into action.

Edited October 25, 2021 by indyld

[dmxlights]

Hi Rob,

It is marked Q1. I have removed it from the board. From pinging it out. I think it maybe a transistor or a mosfet but not sure which.

here is what I have pined out..

http://mcgcs.net/lb15.jpg.

.

Here is a pic of the board..

http://mcgcs.net/lb14.jpg

 

Here is a photo of Q1 which I removed

http://mcgcs.net/lb16.jpg

 

Edited October 25, 2021 by dmxlights

[bruce]

Googling A2fv suggests it's a mosfet, taking me to https://www.ebay.co.uk/itm/184370147402

[dmxlights]

Googling A2fv suggests it's a mosfet, taking me to https://www.ebay.co....tm/184370147402

 

Hi Bruce,

I did get that one. I have asked the seller for a datasheet but he can't provide me one. I would like to find more info on it and see if you can find a replacement from RS or CPC for it

I also assume if it is mosfet then this is the pinout

Edited October 25, 2021 by dmxlights

[indyld]

Seems like it could be a MOSFET, although I can't quite work out why your beeping appears to show a ground at both ends.

 

If it tests as a MOSFET off the board (well, one of the working ones does...), then I'd try looking into an available equivalent to the various A2 marked N-channel MOSFETs that seem like a good bet regarding LED supply voltage and current on the spec of that fixture (20v, 2-3A maybe?). I'd guess that in this fixture the Hex Inverter is doing the PWM and the 'thing' is switching the LED supply.

 

Have to admit that I usually have some kind of donor boards to hand that use similar technologies - even if not from the same make and model. A quick hunt around often yields a likely looking part to try. Even better if the same manufacturer as they don't look far for their parts, even in different models.

Edited October 25, 2021 by indyld

[dmxlights]

Hi Rob,

I have been looking at some scrap boards I have even they are not of lights to find a donor none yet.

 

I do know that mosfet only controls the blue of that one led as it is a pixel bar. I am very tempted to put BC547. Also the main power supply is 5v only (had to check this)

 

 

Seems like it could be a MOSFET, although I can't quite work out why your beeping appears to show a ground at both ends.

 

 

 

 

oops. That was meant to be 5v not Ground going to the led

 

[indyld]

Yeah, I guess this unit is a bit smaller and single pixels so a smaller supply makes sense. A lot of what I work on are fairly high power and many use series strings of LEDs.

 

At that voltage and on a single LED, any suitable MOSFET will do the job no doubt. Dunno if a transistor is fast enough tbh.

Edited October 25, 2021 by indyld

[dmxlights]

Yeah, I guess this unit is a bit smaller and single pixels so a smaller supply makes sense. A lot of what I work on are fairly high power and many use series strings of LEDs.

 

At that voltage and on a single LED, any suitable MOSFET will do the job no doubt. Dunno if a transistor is fast enough tbh.

 

Thats what I was thinking about the transistor.

I have a some mosfet from power amps which could be an over kill.

 

[DrV]

Hi Rob,

I have been looking at some scrap boards I have even they are not of lights to find a donor none yet.

 

I do know that mosfet only controls the blue of that one led as it is a pixel bar. I am very tempted to put BC547. Also the main power supply is 5v only (had to check this)

 

 

Seems like it could be a MOSFET, although I can't quite work out why your beeping appears to show a ground at both ends.

 

 

 

 

oops. That was meant to be 5v not Ground going to the led

So you've drawn your LED back to front too. Anode to +5 and cathode to the drain of the MOSFET. If it really is run from only 5V and there is a 30 ohm resistor in series then you can't possibly have more than 170mA flowing through it, even with zero Vf. You need a relatively low Vgsth so something like a BSH108,215 or a DMN6140L-13 are only 15p each from CPC (provided you've got something else to order at the same time) and are complete overkill! I've only picked those as they were at the top of a parametric search and in stock - there are dozens of others to choose from.