Ahhhh, broken faders

[triff]

So I had 2 faders to replace on the circuit board for preset fader 1-10 and 31-40. I replaced 31 and now 31-40 all work fine. I replaced 8 and now faders 1-10 don't work at all.

Yelp, what have I done. I've replaced faders in the past and never had any problems. Any ideas before Monday when I need to tell my boss would be awesome.

Oh they all worked fine apart from 8 when I started the sugary and there are no bus errors

Cheers
Triff

[niclights]

Check ribbon connections.

Check solder joints for any shorts - use a craft knife to 'score' areas between tracks if you are in any doubt.

Finally you could try swapping the chips between two preset boards and see if the problem migrates.

[triff]

where are the chips?

[niclights]

I'm not near a board at the moment, but IIRC there are some small 8pin IC's on the fader side. They will be identical on the three preset boards.

You could also try swapping the boards themselves to eliminate any problems with the Analogue board (the one in the base at the front) that the Preset board ribbons connect into. (problem should migrate)

[triff]

swapped board and the problem moved.....im a little unsure about pulling out chips and swapping them.

On the boards themselves there is only one chip near where one of the ribbon connectors are. Is this the chip you're refering to and do i simply give it a tug?

Cheers
Triff

[niclights]

Yes. Just lever them out carefully with a flat screwdriver from either end (so as not to twist the legs) It's surprisingly easy. Just make sure the pins line up before pushing back in and of course the correct way round! (there should be a notch on the chip which will also be marked on the PCB)

I have successfully removed and replaced all the chips from the Analogue board and preset boards this way with no problems.

If you are unsure speak to Nick Forro.

[triff]

This week has not been a good week to say the least!

So the chip wasn't the problem. I know this now, however I also have destroyed a chip. It appears to have gone "fitz....pop" which means from 1 broken fader I got 10 broken faders, and from 10 broken faders I now have 20 broken faders.

Anyone have a part number for the chip? Is it the writing on the top of it, which is:

M75DT
LM
358N

Cheers
Triff

[niclights]

Oh dear.

Call Avo and get them to send you a new one.
There are a few spares provided with the desk. Might be worth checking to see if it is one of these.

Can you explain what the problem was and how you found out? Also, which chip blew and how? I hope not after following my suggestion above. Sincere appologies if it was, although I am concerned that a separate fault caused the chip to blow, in which case this might happen with the new one too.

Have you spoken to Nick Forro about this?

[triff]

Yea, I've emailed Nick.

I think it could have been down to my own stupidity of putting the chip the wrong way round, although I'm sure I checked!

Checked with another chip on a differerent preset fader board and it's fine, so I think the new one will fix part of the problem.

The chip that blew was the one i described above, 8pin next to the ribbon connector on the left hand side of the board as you look at. It went when i powered up the desk.

I'm now fairly convinced that if i replace the chip I'll have 10 working and if I remove the fader I orginially replaces I will have 19 faders working. I may then just close the lid on this fun little saga and stick to the topside of the desk