FOSS ESR/Capacitance tester for CRT and Arcade Monitor fiddlers

[hatmoose]

Bad capacitors are a constant source of excitement and fishy smells for vintage hardware enthusiasts everywhere.

Long have I cursed the lack of a top quality, modern, ESR/Capacitance tester that runs open software for working on old arcade boards and old TV's

Loads of integrated hardware options like these ones
Peak Atlas ESR
https://www.peakelec.co.uk/acatalog/esr70-capacitor-esr-meter.html
MEC-100
https://www.amazon.com/High-Precision-Capacitance-Automatic-Electrolytic-Capacitor/dp/B0797R5LS9

But this is an extremely specific use case, and the off-the-shelf products are always a compromise between price/features/performance - none of them were specifically designed for this purpose and in general the whole thing feels highly sub-optimal for this specific use case

There are bajillions of circuit diagrams for ESR/Cap testers, so surely there must be dozens of top-quality FOSS ESR/CAP tester implementations, right?
Surprisingly not, very few indeed.

This is it, this is the one - it is a very sweet thing and I like it a lot.
https://github.com/DarwinNE/EsrMeter
from this thread
https://electroyou.it/forum/viewtop...id=c6fa78dd6374447efdedb970f1562ae5&start=540

Has anyone looked into this problem too? if so I would love to hear other solutions? Especially open hardware/software?

 

[hatmoose]

In preparation for the Saroo build I decided to experiment with getting JLCPCB do some of the assembly on this one

Learnings
1) only works in chrome, fails in safari every time
2) the source files were in Eagle - in order to generate manufacturing bom/cpl files from eagle correctly follow this guide
https://support.jlcpcb.com/article/132-how-to-generate-bom-and-cpl-from-eagle-cad-automatically
3) manufacturing costs get extremely expensive extremely quickly for non-standard parts (setup for standard parts are one cent per part, setup for non standard parts is $3 per part), it is possible to walk backward through the assembly web interface to identify the non-standard parts. but...
4) unselecting the non-standard parts in the web interface causes the cart to fail, had to delete them from the .cpl and re-upload.
5) so what was left is a partially assembled board (there are over 80x0603 resistors on the thing), a big list of parts to order off Mouser.
6) there is a $US13 credit for assembly at the moment.

Will it work? Ask me in 14 working days

 

[hatmoose]

There were quite a few parts on the BOM that JLC either could not, or I would not pay to have them assemble (Basic only)

remaining parts and order codes from Digikey attached

The only part that I could not find from the BOM was the rotary decoder. the footprint on this is really weird for the strain relief - If I made more I might adjust that a bit. in the end I went with this as a temporary solution.
https://www.digikey.co.nz/en/products/detail/bourns-inc/PEC12R-2220F-S0024/4699261

 

[hatmoose]

Digikey parts ordered (above)

Aliexpress parts ordered
U$1 (4 line LCD screen) https://www.aliexpress.com/item/1005002234319914.html
U$2 (buzzer) https://www.aliexpress.com/item/1005005394197600.html
U$4 (frequency generator*) https://www.aliexpress.com/item/1005003237603900.html

*Using an aliexpress frequency generator on an instrument that I'm hand-building because all the commercial ones are inaccurate... Its a bold design choice to be sure I'll replace the AD9833+crystal with a genuine ones after I get the thing working https://www.digikey.com/en/products/detail/analog-devices-inc/AD9833BRMZ/751220

 

[hatmoose]

Progress!

JLCPCB assembly is OKish, I think most of the grottyness is that they don't clean them afterwards - I'll take some close-ups if anyone is interested.


The frequency generator/clock can sit up against the board


Soldering on all the rest of the components was a lot of fun - as you can see I messed up the BOM, will need to IC10 and IC11 (MCP6L92) when I get a chance



I replaced the expensive multi-turn trimpot RTRIM3339P with a cheap single turn one. But it its covered by the screen - which is inconvenient because this is the screen brightness control. Next time I'd probably get a right angle one like 3362W-1-503LF so I can adjust the screen brightness without having to remove the screen.



So now another pause while I wait for parts.

 

[hatmoose]

Haven't done any assembly since university about 25 million years ago - hasn't changed much. What has changed is the toolchain to compile the .asm into .hex so that I can push it to the PIC.

The sensible way to do this is with a PICKIT ICSP PIC programer
MPLABX download https://www.microchip.com/en-us/tools-resources/develop/mplab-x-ide
PICKIT2 supported devices https://www.expkits.com/?s=pickit2_device_support_list.htm (the PIC16F872 is supported)
Tested good PICkit2 clone https://www.aliexpress.com/item/1005003558613510.html

However a PICKIT2 costs $US14 - im not made of money!

So clearly the right approach is to spend dozens of hours tricking an Arduino Uno into thinking it is an ICSP PIC programer and using that to push the compiled hex instead.
https://github.com/battlecoder/zeppp/
This approach has several clear advantages. It requires a closed-source binary blob from a soulless corporation AND an unmaintained FOSS project that was abandoned five years ago, AND a fake aliexpress Arduino Uno clone.

Hold my beer...