VOGONS


Corosion or Oxidisation

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First post, by AppleSauce

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I was inspecting the motherboard of the CM32L I just got and noticed there were some discoloured parts.
Is it from flux and the glue oxidising or are the caps leaking?

Just wanna make sure before I test power it on.

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Reply 1 of 34, by AppleSauce

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More pics

Reply 2 of 34, by chris2021

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clearly it seems like liquid is escaping.

Reply 3 of 34, by vstrakh

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Not a leakage. It should be a factory glue.
https://youtu.be/BeDKwi-GJRI?t=39

Similar glue blobs are visible on a photo of presumably working board here: http://vgmpf.com/Wiki/images/1/1d/CM-32L_-_Internal.jpg
though it didn't degrade as much.

Last edited by vstrakh on 2021-10-03, 13:10. Edited 1 time in total.

Reply 4 of 34, by AppleSauce

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Welp its not powering on , the light flashes for like a split second then goes out again

Reply 5 of 34, by AppleSauce

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The power jack looks pretty corroded so that might be the issue but I'm not sure

Reply 6 of 34, by AppleSauce

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Here's a pic

Reply 7 of 34, by AppleSauce

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Ah wait that pics kinda blurred , my bad

Reply 8 of 34, by vstrakh

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Worth checking the voltages on the PCB side to know if the PSU is up to the task.

Reply 9 of 34, by AppleSauce

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I've been using this with a stepdown , works fine for my other stuff

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Reply 10 of 34, by vstrakh

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Either way you won't go far without a multimeter. You need to probe the voltages, connectivity, etc.

Reply 11 of 34, by Tetrium

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AppleSauce wrote on 2021-10-03, 07:36:

More pics

It does seem like glue, especially this cap here which is mounted sideways to the PCB.

The corrosion on the connector does look kinda bad though.

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Reply 12 of 34, by weedeewee

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the first photo shows some white that doesn't look kosher. the brown stuff near the solder pads is, I'm guessing, Flux residue.
The other photos where there's lots of brown stuff under the capacitors, is glue.
That barrel socket definitely has seen better days, makes one wonder what the inside contacts look like.
Anyway, plug it in, turn it on, and measure the voltages.

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Reply 13 of 34, by AppleSauce

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Funnily enough my soldering iron got here today , its still pretty cheap but it has adjustable temp unlike my older ones , I'm going to try swapping the corroded jack since it seems to be the simplest thing to start with , any reccomendations on soldering temp?

Also I bought some of these jacks for fixing some other roland gear , would these be a good bet for the cm32L?

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Reply 14 of 34, by canthearu

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400 degrees C is a good starting point.

Use solder braid/wick to clear joints of solder.

Work quickly if possible. Hanging around the board with lots of heat is a good way to damage pads.
Use 60/40 leaded solder to help you rapidly install new plug. Add extra 60/40 solder to the joints if you have difficulty melting the old solder.

Reply 15 of 34, by AppleSauce

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Well I just replaced the jack , I have the exact same issue so it looks like its something else

Reply 16 of 34, by AppleSauce

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Okay after inspecting the board it turns out one of the caps has burst , I didn't notice it because one of the original factory workers drew an A on it , after cleaning the marker off its definitely got a cut.

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Reply 17 of 34, by AppleSauce

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So that's 3 recap jobs i need to do now, one for a abit bf6 mobo project , one for a Aopen psu and now one for a cm32L.

I'm sick of seeing burst caps at this point.
I suppose I'll just do one big bulk order from mouser and get it all out of the way. 🙁

Reply 18 of 34, by AppleSauce

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Okay on second thought I can't tell of its the dye of the marker or a gap.

Reply 19 of 34, by AppleSauce

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I guess I'll have to test other components, any idea on what would cause the power to cut off just after switching something on?