RF Video Distortion

[RetroMike]

Oooh... have I got one of the newer ULAs? I'd forgotten to check, but you're probably right Will attack it with a small screwdriver shortly

I really am being a bit dense today

[RetroMike]

Thanks to XorA reminding me about the adjustments needed for the later ULA chip, I've now got a functional Zed after much faffing about. Apart from forgetting the last and crucial aspect of the conversion to composite using Pokemon's excellent mini-board, I'm quite pleased with both my soldering and bravery, hacking apart the Zed to get it working again. Now it just needs a new keyboard membrane and I can plug in the ZXpand and compute!

Exhibit A:



Crowd goes wild!

[PokeMon]

Congratulation.
Yes, there maybe a recalibration necessary depending on the ULA you have.

[Moggy]

Another one back on the road great stuff.

@Mike should you ever decide to buy the AY unit for your ZXpand I will happily send you some tracks and a "juke box" player for them.

[balford]

Bear in mind you can attach the red and yellow wires to the original 5v and video in points on the PCB, avoiding the need to trail the wires around the PCB

Black can go to the inside of the modulator case.

B

[RetroMike]

Ah, didn't know that that might go on version 2 of the mod before I put the case back on. When you say that the black lead can go inside the modulator, do you mean attaching it to the shell as ground?

As an aside, does the ULA usually get hot enough that it is painful to touch? Same goes for the rectifier and it's heat sink, or have I just not noticed because it's in the case normally?

[balford]

Yep, shell as ground for both black wires is fine

And yes, ULA and regulator getting too hot to touch is 'normal'! A heatsink on the ULA should help matters.

B

[RetroMike]

Thanks - I've just ordered one off eBay. Is the voltage regulator hideously inefficient, and if so, is there a more modern and energy efficient alternative? It seems wasteful to burn all that electrickery to heat up that big Square of aluminium

[balford]

You can use one of these as a drop in replacement:
http://ie.farnell.com/tracopower/tsr-1- ... erch=true&

And if you're doing all that, you might as well replace the Z80 with a modern CMOS part
http://ie.farnell.com/zilog/z84c0010peg ... dp/1081891

B

[RetroMike]

Very interesting

Will the power regulator be more efficient & generate less heat? Doesn't seem to be anything there to attach a heat sink to, so would that be redundant? On the new Z80, what's the benefit of installing that? 10mhz? Would the board cope? All these questions and more are one of the dangers of mentioning upgrade parts to a lunatic serial upgrader