Studer B67 recap: Part IV

I pulled out the transport board to recap it, and someone’s been there before me. First, all but one tantalum are green. The original tantalum on this machine were blue. More importantly, someone did this:

The traces were cut and the two pins connected together.

The traces were cut and the two pins connected together.

Then they're connected to some point under one of the switches.

Then they’re connected to some point under one of the switches.

Doesn’t seem to be factory job because the soldering joint are a little amateurish (for instance, they left flux residue). I’m not sure what this mod is all about, so I’m taking the time to figure it out and see if I should reverse it or keep it this way.

Meanwhile I replaced most tantalums. Like I said, they’ve been replaced before but I don’t know when, so I figured it’s worth it to replace them again.

For a while I thought about replacing the tants with electrolytics. These tantalum capacitors are connected to ground (I assume to provide a low impedance path to ground for high frequency signals), and since they fail short, when they fail next they’ll pull the whole signal that’s passing through them to ground. I ended up not replacing them with electrolytics because I wasn’t sure they’ll work here, but I also don’t have any at hand and didn’t feel like ordering them and waiting, etc. I’m sure this isn’t the last time I’ll be poking inside this machine, so I’ll have other chances to replace these with electrolytics.

One last thing about the transport board – it’s thicker and has smaller solder points, so I had to change my tip and removing the old capacitors was a bit of a pain.

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