Oh crap, show system all down, I need your help please

[Tim Fischer]

Christmas_time_karl_UK wrote:

Although your theory is possible, surely with another 15 similar connections 1 of them or more could of over heated and with 31 days of use with same system last year.

I am not bad, but I havent a clue where I can get new components in the UK and the boards been burnt back to like the mesh under the green/blue coating surface. I was hoping LOR would come through for me

Are you comfortable with removing the board from the box, and removing the heatsink from that half of the board?

Not sure what LOR can do for you short of shipping another board, and I'm guessing that won't be quick...

[Christmas_time_karl_UK]

Yeah I can do this happily, I did build our 1st LOR board in kit form albeit it didnt work and I had to send it to John to sort out....

[Christmas_time_karl_UK]

bump

[Tim Fischer]

Christmas_time_karl_UK wrote:

bump

Just got back after leaving shortly after my last reply, but not sure why you bumped this-- thought we were waiting on your pics of the reverse side of the board

[LightORamaDan]

Not sure what happened there although a loose connection or some contamination may have started it and once there is some oxidation on the board the oxidation becomes the problem and makes things worse. I am leaning towards some type of contamination (could have been there for a long time). It is difficult to see but if it were a loose connection the female connector should have been very hot an the plastic and wire on that connection more affected.

We will be sending a replacement board asap.

Dan

[Christmas_time_karl_UK]

Thankyou very much Dan, Thankyou.
Here is the underside of the board,





any chance it could be repaired just to get some functionality until the new board comes?


Ive sourced the nearest chip I can to the Optoisolater which was MOC3023, I can get MOC3020- http://www.maplin.co.uk/Module.aspx?ModuleNo=2239

according to the MOC3023 datasheet there interchangable?: http://pdf1.alldatasheet.com/datasheet-pdf/view/27238/TI/MOC3023.html

The resistors are resistors easily have them,

The triacs BTA16-600BW I can get BTA16-600B:
http://www.maplin.co.uk/Module.aspx?ModuleNo=19095

The tracks look fine, I can get continuity through the resistors when probed, the charrard board looks like it will clean up the mesh material underneath is visable but isnt conductive according to my continuity meter....

Could I do this a temporary fix till a replacement board can reach me here in the UK? I have a new soldering iron and I think I can pull it off...just need some advice for a go/no go!

Thanks Dan btw your great!

[Christmas_time_karl_UK]

or can I remove the dodgy components which are shorting the board and then continue using the remaining 14 channels?

And ensure channels I remove the components - triac and optoisolator are removed from the seuquence grid to ensure not activated?

[Christmas_time_karl_UK]

anyone - please my show should go live at 16:30 GMT and if theres a chance I could get somelights just on id be grateful!

Many thanks

[Max-Paul]

Looking at those pictures that are a little blurred. It appears that something caused a short between the Triac and the lead coming in from the load / lights. Note that there was a lot of heat around the lead and resistor area on that board.

I have to ask were was this board at? was it in a metal or plastic box? Was it out in the yard or I think you might have alluded to a shed? You guys get a lot of fog so I wonder was the inside of the box wet or dry?

Here is a suggestion for next year. This summer take the board out of the box, off of the heat sink and tape over all electrical connections. Tape over the ICs that are mounted in sockets. Tape over the heat sinks for the two regulators. Now get some clear acrylic spray paint and give the board two good coats. I am wondering if some bug or moisture caused an arc on your board. The only way you might be able to use this board is you have to give that area a good cleaning. You cant leave any black soot or any melted metal on the board, NONE. It will need to be a top notch job. This includes between the triac leads and the resistor, and the opto chip leaks. So you might have to desolder the chip and resistor and maybe the triac. In order to do a very good job of cleaning off the board. Might as well leave those componets off of the board any way. Now as long as the AC voltage has not gotten to the rest of the board it might limp along without those two channels..

Good luck, and sorry to hear about the rotten luck.

[Christmas_time_karl_UK]

Plastic box, closed up with a lid.
Inside a shed which is weather proof more like a summer house etc
Box was dry, all shed is dry.

What techniques/tools can I use to clean the soot, I scracth away at it and its just working through the board material stuff it does become the normal colour but its like I am digging through the board.

[Jeff Sand]

The difference between MOC3023 and 3020 (and 3021 and 3022 for that matter) is the amount of current (I_F) required to trigger the internal LED. That range is listed (going off a Fairchild data sheet here) of 5-60mA for the 3023 and 30-60mA for the 3020. So, if you drop in a 3020 as a direct replacement for a 3023, it may trigger...it may not trigger...depends how LOR designed the PIC output circuitry.

Now that said, from the picture of the underside of the board, it looks like some of the soldermask has completely burned off leaving some bare copper visible. I'm not sure I'd want to try operating the board like that.

Here is the data sheet I'm looking at: http://digchip.com/datasheets/parts/datasheet/161/MOC3020-pdf.php

[-klb-]

As long as you are comfortable with the degree of cleaning you can accomplish, and any exposed traces, there should be no reason not to remove impacted components, carbon soot, and anything else that it takes to not have unwanted conduction in the area. Then I think you should be able to run with not more than three channels missing. As hot as it looks like things got, I would not be surprised if some of the fiberglass cleans away in cleaning off the soot. I would try to get as much of the soot cleaned away as possible, so it doesn't contribute to a repeat performance.

[Christmas_time_karl_UK]

I just removed both triacs, both opto isolaters and connections to it and I have the show working in limp mode will a new lor arrives here in the UK for us.

Thanks for all your help! It is very odd....

The LOR computer was plugged into the same ring mains as 1 of the LOR boards which has a single supply. As soon as you plug in an ethernet cable into the dodgy board it trips the power...

Moved the pc to the same power ring mains as the 2 dual feeds for the dody board and no tripping, the other LOR board is fed on the different power mains...

So moving the pc's power ring main supply to same as 1 of the other boards made all the difference....

[-klb-]

That is an odd new symptom.

As for the meltdown, it looks like somehow line voltage wound up across the resistor between the opto and the triac trigger. I'm not sure exactly how that would happen at the moment. Maybe the triac failed open, with the gate shorted to the output side?

[Christmas_time_karl_UK]

I know....

I am wondering if we should get some dedicated power supplies to the shed fitted by an electrician (freind of my fathers) and have all of these with RCD breakers on each line. what do you think?

[Max-Paul]

Karl,

Please take this as a ribbing between friends. But you bloody brits and your interesting terms. RCD is this what us yanks call a Ground Fault Interrupter? There is no way that a 15 amp fuse is going to protect you from things like this. It is there to protect you from the whole board becoming a flaming inferno. Now one can get anal and put a fuse between the triac output connector and the load. And if you know the actual amp draw per channel, you could taylor the actual fuse rating for that channel. But this is a lot of work and cost. I am starting to wonder if I think it was Tim suggested that there was a problem with the actual connection. I did not see the back of the board pictures before I commented. But I am still seeing a little soot over on the one triac leads. But that bulls eye ring around the stake on says that there was something going on there too. So, I am not real sure what the cause was. BTW was there any soot on the heat sink? And was the heat sink grounded?

Glad to hear that cleaning it up is at least in LIMP mode.. Good show old chap..
BTW Daughter was in Lancashire at Landcaster U. for semester, just got home to Missouri yesterday.