exxos's Atari, Amiga & retro forum

stephen_usher wrote: 17 Apr 2026 13:36 I just realised that the Xgecu T48 could test the 74LS166...


74LS166-test.jpg


It's dead Jim! :-)

It certainly is.

Here's a shortish video of my exploits...

Nice video !

A pleasure to watch.

I might have to dig out my Lynx tape collection and see what state it is in.

Given that there are very few working tape images of any games just making a recording as a wav file of any tapes would be a bonus. Practically all the TAP files are broken and too short.

Seeing as the preparations for Retrofest have been going so well and a replacement TEA1002 had arrived I thought I'd have another quick look at the colour composite video output.

The new chip definitely halps. There's no-longer a flickering green background to the display, but the colours are still messed up and I can't get them to display properly. Blue is flickery magenta, red is flickery green and green is flickery brown.

I then touched pin 11 of the TEA. This is the chroma filter pin which requires a tuned filter. On the Lynx this is implemented using a 10uH inductor and a couple of resistors pulling up to the 12V rail. When I touched the pin sometimes I got, for a short while, reasonable colours.

Now, the only thing which could cause the filter not to be tuned is the inductor. Given that this is a cheap thing from a kit bought from Amazon this is the first thing to be questioned. So, I desoldered it and tried one of the lower value, 6.8uH, inductor... and I got the proper colours... ish. The inductor also got pretty warm. So, culprit found methinks.

I couldn't get any through hole inductors from either RS or Farnell so I've had to use Mouser, bulking the order out with capacitors. Thinking about it I should have added some 5V zener diodes as well. Never mind.

We'll have to see if this works once it all arrives, probably next week.

That all sounds rather promising, fingers crossed the new inductor will fix it properly :)