Repair on Dieter Vansteenwegen / Boxfish

Quick fix: KTE-LCD-3 electric bike controller

Sun, 06 Jul 2025 15:10:00 +0200

Introduction

Yesterday my neighbour came in asking to take a look at his electric folding bike. It had been beaten up during transport in his van and the controller on the steering wheel no longer responded to the power button.

He had taken it to two different bike mechanics, but both of them weren’t interested. The brand was unknown to them (and likely to just about everyone) and, most often, they don’t really care much for electronics in general. Figuring out which modules to replace (much less actually attempting to repair them) most often is not within the scope of what they do. It didn’t help that he had no idea where the bike was originally purchased (it was inherited from some family member long ago), or how old it was. An electrician at his job had measured voltage up to the controller and “everything was working as it should”.

Repairing a "for parts" Canon 7D Mark II.

Tue, 04 Mar 2025 17:22:00 +0100

Update (06/11/2025): I found out that “**names_are_hard**” is the lead developer behind Magic Lantern, added that information in-line. Also fixed a typo.

Introduction

I was recently looking for a replacement for my ageing (ancient?) entry level Canon 600D. I came across a cheap 7D Mark II body (7d2 from now on) that was sold as “broken, for parts only”. This repair was a fun and rewarding experience requiring no spare parts.

Boxfish

Tue, 06 Feb 2024 21:12:29 +0100

Introduction

If you need help with:

Repair of electronics
Design of electronic systems
Software

Please send me …

HP 8640B Part 2: Mains input and rectifier board replacement

Tue, 06 Feb 2024 21:12:29 +0100

Introduction

6 years ago I acquired an HP 8640B that needed work (see HP 8640B Part 1: initial state).

Over the last few years, I managed to clean up the unit cosmetically, but not dive in to it any deeper. Until now.

I recently found some time to work on it again and started looking at the power rails. I knew that (at least) the -5.2V rail had intermittent issues, and had noticed the caps on the AC input needed to be replaced as well.

HP 8640B Part 1: initial state

Sat, 10 Jun 2017 00:00:00 +0000

Introduction

I recently acquired a HP 8640B signal generator. A quick summary of the specs shows why this is an interesting piece of equipment:

500kHz to 512 MHz (option 2 adds a doubler, extending the range to 1.024 GHz)
Available power range is -145dBm to +19 dBm, within +0.5dB across the full frequency range
Extremely low phase noise (less then -130 dBc at 450 MHz, 20kHz from the carrier)
Fine tuning (when in locked mode): >+/-20ppm
Integrated counter, switchable between the internal generator and an external input
FM and AM modulation
Beautifully engineered (but that’s just an opinion)

The retail price in the mid seventies was around 12.000 USD (which in 2017 would be about 90.000 USD).

HP 8711(A): modifications, tweaks, refurbishing

Mon, 14 Nov 2016 00:00:00 +0000

Introduction

I recently acquired a fairly well preserved HP 8711A network analyser. As sold, this is an economy model, offering only scalar measurements, although vector information can be acquired through the HP-IB bus.

What makes this unit interesting, is that the hardware is the same as the never released 8712A, which has vector capabilities. Some changes in the bootrom allow the user to “convert” the unit, making it behave like a full fledged VNA.