New project: Repro Camputers Lynx

[rubber_jonnie]

I just realised that the Xgecu T48 could test the 74LS166...


74LS166-test.jpg


It's dead Jim! :-)

It certainly is.

[stephen_usher]

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

[HigashiJun]

Nice video !

A pleasure to watch.

[peters]

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

[stephen_usher]

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.

[stephen_usher]

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.

[rubber_jonnie]

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