I2C communication with Monome Teletype

I would be concerned about the connections there…looks like the shunt is also touching the part above too.

Yeah, I don’t think the i2c is working. I’m pulsing one of the TR 1 on script 1 with the incoming clock just to prove that’s working. I should be seeing a pulse wave on the 301, right? I’ll clean up the solder and post a new pic. Can I put a DMM across this to verify the shunt?

Which connections?

Not really because you will always get a connection, it being a piece of wire or whatever.

as @jonny says it really looks like the component above is involved too, but won’t be able to see properly without giving it a good clean.

13%20AM

Yeah, okay, I thought you might have meant the i2c connections :slight_smile:

This is how it should look, okay not precisely perfect, but clean and unambiguous:

I hope you didn’t pay for that @Joe. I can tell from here that they shorted D3 with R62 (which is OK but sloppy) and its not clear that the side of the diode away from the D3 silkscreen is properly soldered. It should look like this:

diode-shunted

I would recommend not powering up the ER-301 until you have that soldering job cleaned up so you can tell exactly what is soldered to what.

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I was just about to say it looks like there’s a trace from D3 to R62, so it actually doesn’t matter!

Could be right about the solder joint, but looking at it again it still shouldn’t matter because the end result is still that the left side of D3 is shorted to the right side of R62.

Is that right @odevices?

Urgh - don’t you just hate it when stuff like this happens :frowning:

Except I suspect they accidentally tore off the diode pad and then tried to bodge it by soldering the shunt to R62 instead. And if they damaged the diode pad enough to have to solder to somewhere else then who knows what other damage is hiding underneath that blob of solder. For example, there is a ground via right between the diode pad and the edge of the board, I wouldn’t be surprised if the resist was melted off the via causing a short to ground.

I guess I might have been just as well off doing it myself. Here’s (hopefully) a cleaner photo.

Yeah, that’s a very good point @odevices

What a mess :frowning:

So are we suggesting replacing the SOM at this point?

Would be one way to be sure - they are not that expensive.

Super annoying though!

Oh dear, I think its worse than I thought…look at the R of R62. Is the trace going through the R completely missing or is that a trick of lighting?

Here is what it should look like:

Oh my… I think you’re right, looks like they’ve torn it off :frowning:

And they would definitely know that they did.

I’m afraid I don’t have a camera that can get the close up precision that you’re getting. Here’s one more shot. It sounds like the verdict is replace the SOM and thank my lucky stars if the rest of the 301 isn’t harmed in any way from powering it up. Sound right?

Indeed, I’ve messed stuff up like that in the past (he we all got to learn and making mistakes is part of the learning process heh) and repaired similar things that other people have done and it is glaringly obvious what’s going on - there’s no way they can deny any knowledge of this happening.

It seems pretty clear at this point that they have made a complete mess of it and you should be asking them to replace the SOM they broke.

Well, unfortunately that is between Joe and the local shop that he hired but between us I’m sure we can work something out. I would prefer that Joe has a working ER-301.

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