Eurolite TG-5 : No DMX response

[LUCASSARAGOSA]

Hi, just got a eurolite TG-5 second hand. Seems to work normally, however with DMX mode it cant recognise any signal coming in. The controller and cable work 100% as it works on another light. address is set to 1 which matches. It goes only to stand alone mode. I have a 120ohm terminator fit in, and the polarity is pin 3 is hot. Ill link the the pdf of the manual. Any help is appreciated 

https://www.manualslib.com/products/Eurolite-Tg-5-4242804.htmleciated 

Edited November 3, 2022 by LUCASSARAGOSA

[indyld]

If the device otherwise works in local mode or standalone (and you have cycled the power between different states - some cheap devices seem to need this) then the issue is either with the physical connections of the DMX ports or the DMX chip in the unit.

[LUCASSARAGOSA]

Just replaced the DMX in and out with a different on reconnecting to the main pcb, same thing. I guess its a problem with the PCB then. Do you think its possible to get a new one? Seems like a waste of the light.

[indyld]

Locate the DMX chip on the board and swap it out for a new one. Much easier to find a chip than than a whole PCB.

[LUCASSARAGOSA]

Quite new at DMX, which is the DMX chip? Here is the PCB:

https://ibb.co/Khk9Lp3

[indyld]

8 pin package connected to the DMX ports. Look up the number marked on the chip to confirm what it is. As they are socketed, you can easily swap one in from a working unit.

[LUCASSARAGOSA]

The two 8 bit chips near the DMX connector are 

LM358P - low power dual operational amplifier

SN75176BP - differential bus transceiver

And one which has no writing on it 

Would any of those be the DMX ones?

I dont know if this is relevant but just noticed the PCB has 3 wires going to “DIM” this other circuit board (below is a picture) which seems to have cut cables and the 6 pin chip is some sort of IR emitter. Dont know if that might be the cause.https://ibb.co/PYZQWD5

Edited November 3, 2022 by LUCASSARAGOSA

[indyld]

The SN75176BP is what deals with the DMX in. If the fixture otherwise works but just doesn't respond to a known good DMX input, this is where I would be looking next. Swap it for one from a working fixture, keeping the correct orientation of the chip. 

If there are other things that don't behave as expected, or other parts missing, these are unlikely to relate to the device ability to work under DMX control. 

[LUCASSARAGOSA]

I got this second hand, dont have any similar fixtures. Is this chip common in lots of DMX lights? And if not where could I get one of these cheap. Thanks

[themadhippy]

Quote

And if not where could I get one

All of the main component stockist (RS,cpc,arrow,digikey mouser etc) have them for £1-£2

Quote

cheap

That part is cheap,what will sting is the cost of p+p on small orders,you could risk looking on ebay,but no guarantee what your buying is what's in the chip

[Brian]

This ebay seller is OK, I've had chips from them in the past...

https://www.ebay.co.uk/itm/165397848595

[LUCASSARAGOSA]

I think the chip is ok. Just let the light run and a burning smell coming not from the bulb but from close up to the PCB. Looks like its coming near the capacitors. The photo is where the smell is around. Just realising it doesnt really work in standalone. The gobo is stuck halfway between two but the colour wheel rotates constantly (again picture below). Any ideas? The light stays constantly on when powered. Have a feeling its something to do with the power input, noticed that the PCB says AC so it could be to do with the AC/DC rectifier?

PCB part that smells: https://ibb.co/fv4pk8F

colour wheel which rotates, gobo does not seems to he stuck between two modes: https://ibb.co/wr4nGwL

Edited November 4, 2022 by LUCASSARAGOSA

[LUCASSARAGOSA]

Fixed it! Problem was one of the trimmer potentiometers. Just soldered it back properly and all works. Thanks for all the help anyways!