mer. 12 juillet 2023

Numworks N0110 calculator full repair

My daughter's Numworks N0110 graphing calculator got fried when plugged in a cheap USB PSU. Black screen, heating up killing the battery in a matter of a few tens of minutes.

The design being originally Open Source (hardware and firmware), it makes sense to try to fix it instead of …

sam. 09 octobre 2021

HP 34970A Data Acquisition Unit - part 6

Quick follow up; I recently got back on this project to try to complete it and fix remaining problems.

The source code for the firmware is available here:

The Kicad project is available here:

Making the USBDevice work …

sam. 07 novembre 2020

HP 34970A Data Acquisition Unit - part 5

After a loooong pause on this project, I have recently been able to work on it again. In the previous post in this series, I've started to implement a replacement board prototype based on a an NUCLEO board and an SSD1322-based OLED display.

Meanwhile, I have also almost completely described …

ven. 06 décembre 2019


A month ago, a friend of mine called me to ask for help with a technical device that seemed not to work properly.

He was testing with a friend some video recording setup. They use vMix to mix (live) video streams from 4 (or more) vide cameras (Panasonic GH5 if …

sam. 19 octobre 2019

Dell 2407WFP Monitor

A had a non-working Dell 2407WFP LCD Monitor in my stash for quite a long time. I recently decided to see if I can fix it. It is a quite old but pretty nice 24" LCD monitor, with a 1920x1200 resolution.

The symptom was the nice kind: dead. No light …

jeu. 17 octobre 2019

EIP 545B RF Frequency Counter - Firmware

This part will focus on the analyze of the firmware I made so far, in order to fix a few issues I have encountered in my unit, as related in previous previous part.

It will be updated as I make progress on disassembling and understanding the firmware.

Original Firmware

The …

mar. 28 août 2018

EIP 545B RF Frequency Counter - Part 6

Band 3 Sensitivity

I have been trying to figure out a bit more about the sensitivity problem described in part 3.

The main problem remains the first YIG sphere that has fall off the holding rod. I have tried to manipulate it with thin wood stick, under my cheap USB …

ven. 20 avril 2018

HP8662A Synthetized Signal Generator - Part 3

This is the part 3 on my series about my HP 8662A Signal Generator, and is about the third main problems I found with this unit, as evocated in part 2: Error 04 is lit and there are some very unpleasant spectrums at some frequencies.

Low Fequency Section

If the …

jeu. 12 avril 2018

HP8662A Synthetized Signal Generator - Part 2

This is the part 2 on my series about my HP 8662A Signal Generator. After fixing the PSU, several more problems needed to be addressed:

  • a few sloppy keys on the keypad,
  • the know did not work at all,
  • and more importantly, some very unpleasant spectrums at some frequencies (covered …

sam. 24 mars 2018

HP8662A Synthetized Signal Generator - Part 1

I recently pulled an HP 8662A I bought a while ago from my cellar. I don't remember exactly in what condition it was advertized when I purchased it, but it was most probably advertized as non working (otherwise it would have been cheap enough, more, what the fun in buying …