Hughes and Kettner Grandmeister repair

Hughes and Kettner Grandmeister repair

I’ve been hoping for a Hughes and Kettner Grandmeister repair since they first came out. Luckily for me when the amp’s owner saw my tubemeister repair blog he decided to send his amp all the way from Kent to be repaired at my Newark workshop. Apparently his local amp tech said ‘I don’t do modern amps!’ 🙁

He missed out on a really interesting job – Hughes and Kettner have invented a ‘TSC’ Tube safety control auto biasing circuit that monitors the tube bias and shuts off the tubes if they get out of spec. Unfortunately a faulty tube had taken out the tube safety control – oops! I replaced the driver circuits and and the 4 FETs to finish the job – see picture below.

It’s a tightly packed amplifier with not much space so it took a bit of work to get in there and repair the TSC circuit but it wasn’t too bad a job. Here’s a video of the completed job.

The one disadvantage with Hughes and Kettner amps is that they tend to show up fingerprints, so I gave the amp a good wipe down before posting it back to Kent!

If you need a Hughes and Kettner Grandmeister repair, please feel free to bring it or post it to me.

Hughes and Kettner Grandmeister repair - resistor mounting

Hughes and Kettner Grandmeister repair - midi board

Hughes and Kettner Grandmeister repair - TSC repair

Hughes and Kettner Grandmeister repair - power off circuit

Hughes and Kettner Grandmeister repair

Hughes and Kettner Grandmeister repair - cleaning

Hughes and Kettner Grandmeister repair

Hughes and Kettner Grandmeister repair

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