Line 6 DT50 Amp Repair

I have a Line6 DT50 112 tube amp I love. But over Christmas, the power transformer failed. Line6 no longer makes parts, but it turns out Mercury Magnetic makes an aftermarket replacement. It’s pricey at $300, but given another used tub amp would be at least double that I figured it was worth trying to fix. Digging into the issue, I used this site as a guide to the replacement:

Fortunately all the wire colors seemed to line up. Unfortunately it seems the green/yellow strip wires for the center tap and filament are actually different voltages, and ultimately I released the “magic smoke”. Guitar Works in Evanston took about 4 months but eventually was able to find the issue and source the bad capacitors and fix it. So now I have a working amp. Mostly.

One of the cool features of the Line6 amps are that they can model different amp sounds. There’s a switch called “topology” which allows you to cycle through 4 different amp simulators. According to this site, topology I is a clean Fender, topology II is Marshall, III is a Vox, and IV is a Mesa Boogie.

Unfortunately whatever I did seems to have messed up the output from topology I and III, which are quite a bit quieter now than II and IV. I’m still debugging this via the schematics I found, but will likely need Guitar Works to take another look to find whatever other capacitor or analog component is bad and causing a lack of volume.

For those who have problems with this amp in the future, I ran across this set of schematics online. I’m not an electronics repair expert, but if you are or you have a trusted local guitar repair shop this doc might be really helpful in troubleshooting your problems. (And if someone out there is really good with schematics and can help me figure out why topology I and III are now too quiet, please write me or post a reply!)

Good luck!

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