520 ST & GBS 8220

[yell0w_lantern]

I can't for the life of me get the picture to stop rolling and show up reliably using the GBS 8220.
Just linking H-sync and V-sync did not work. Using only H-sync did not work. There's no modulator so no C-sync over pin 2.

I've read about AND, OR, and XOR gates as possibilities.

Has anyone here gotten an earlier production 520ST working with the 8220? If so, what did you do? Did you use a logic gate of some kind?

Thank you in advance.

[vattari]

I was able to use a 74HC86 Quad 2 Input XOR IC to generate a composite signal for the GBS-8220 from my Mega ST, passing in the H and V Sync.

[yell0w_lantern]

I was able to use a 74HC86 Quad 2 Input XOR IC to generate a composite signal for the GBS-8220 from my Mega ST, passing in the H and V Sync.

Thank so much, vattari, the XOR did it!

So ends 2 weeks of frustration!

Time to get my floppy emulator warmed up.

[vattari]

Good to hear!

I’m sure you’ll find the Goteks are more straight forward

 

 

Sent from my iPad using Tapatalk