Monday, June 5, 2023

Fixing a Hohner JT60 (updating electronics)

The other part of my JT60 that needed work was the volume control and one of the tone controls - both potentiometers needed replacing. The component list I came up with was:

  • Tone: 2x A250kΩ mini pots 15mm height The A stands for Audio.
  • Volume: B250kΩ mini pots 15mm height The B indicates linear.
  • Switch: DECO T867-0061.
  • Pickups: 3x GS1S - middle one with yellow wire (RWRP).

The electronics look like the following pictures:

Photo of Hohner JT60 wiring and potentiometers. Photo of Hohner JT60 wiring

I was unable to find a circuit diagram on-line. This is the wiring schematic for my JT60:

Hohner JT60 wiring schematic.

Fixing a Hohner Jt60 (new tremolo block)

I've had a Hohner JT60 "Hollywood" guitar for a long while. It's unusual in that it has an ATN (Advanced Tonal Network) (the link is to a discussion in German on the potential circuit in the ATN). The idea is that you can obtain a wide range of tones from combinations of the volume and tone controls.

The guitar needed some work. Opening it up I found that the tremolo block had cracked and the springs had grown weak - as shown in the picture.

Cracked tremolo block.

So the first fix was to replace the tremolo block with a Musiclily block that fitted the guitar. The dimensions of this tremolo are shown in the diagram - and it fits very well.

Photo of bridge in place, before studs and strings replaced:

New bridge in place.

Thursday, March 2, 2023

go/fast tips being published is external exposure of one of the projects I've been involved in at Google. For a long time I've felt that performance optimisation is the best job in the world, but to really move the needle we need to ensure that folks have access to information about writing efficient code - hence this blog and the books. At work, internally we've been gathering and documenting best practices for performance. Finally, we're able to publish some of these externally!