2600 - best video out option?

[LardoBoffin]

I have just got a 6 switch woody 2600 and composite modded it using the following:-

https://www.thefuturewas8bit.com/shop/a ... o-mod.html

On LCD tellies the result varies from poor to awful with large bands going up the screen (fairly slowly - maybe 2 to 3 seconds from bottom to top). In between these bands I can sometimes see a crystal clear piece of screen.

0AA7EB1E-89D4-4095-BC02-F8E7340A85EB.jpeg

On an old glass screen telly the results are significantly better.

I don’t know if I am expecting too much - I am used to ZX81s going from being awful to pixel perfect on the same LCD tellies with similar mods.

What are the output mod options for these? Aside from the one I have used I can see this fairly sophisticated one:-

http://etim.net.au/2600rgb/

Any suggestions welcome!

Thanks

Lardo

[LardoBoffin]

I bought a game and plugged it in to test (no controllers plugged in) and no band going up the screen! I plugged in a joystick and the bands came back.
Clearly to do with the joysticks I thought. I cleaned the connectors and pins etc. and it made no difference.
I resoldered the connectors and checked for dry joints. Nothing.
I took all the switches apart and cleaned them. No difference.
I happened to knock the comp cable while it was on and the banding changed. If I moved / held the cable I could get rid of the banding completely.
Is the cable picking up interference? It is just a cheap one that came with the comp mod kit.
Would it be worth getting one that is shielded?

[LardoBoffin]

Here is the comp mod installed. After coming to the conclusion it was probably the comp cable I experimented moving it about inside the case and that also made a difference.

EA54E2A7-9F7F-4B77-BD2A-7D2B13424F57.jpeg

I notice that other comp mods show taking the video signal etc. from the PCB directly next to the comp mod board. I may try this as well - currently the wires are connected directly to the main PCB.

[DoG]

Hi!

I don't know anything about 2600, but...

Exxos is doing a 2600 video out something right now... check it out and this thread.

[LardoBoffin]

Hi!

I don't know anything about 2600, but...

Exxos is doing a 2600 video out something right now... check it out and this thread.

Thanks. I will have a read.

[LardoBoffin]

After much delay I eventually replaced the electrolytic capacitors and suddenly there was a major improvement!

I also at the same time broke the connector to the modern switching PSU I had been using and so switched to testing with a ZX81 PSU. This also made a huge difference!
No more bands or white or interference going up the screen!

I guess this one doesn't like modern PSUs.

Its not the best photo but the screen quality is now quite good!

8553C0E4-E174-4940-BCDA-38D854337EDC.jpeg

[LardoBoffin]

This ‘fix’ was still very prone to interference issues (having the joystick cable near the RF cable or just looking at it funny sometimes) so clearly there is something wrong with my 2600. I have since fitted the same mod to another 2600 and the output is perfect.
So drastic measures were required! I replaced the motherboard to composite PCB wires with shielded ones, drilled a hole in the side of the metal case to pass the wires through (to avoid them going near the motherboard), put the composite mod PCB in its own faraday cage (made from two ZX81 heat sinks!) and put a clip on clamp RFI noise killer on the video wire (I found that just holding the insulated part of the cable reduced video noise so gave it a try)! This lot combined stopped the interference finally!
So while I’m glad I finally got a usable picture out of this (after only a year or so) I think I will mostly be playing games on the 2600 Junior...
None of them like switching PSUs however.