exxos's Atari, Amiga & retro forum

What display are you using?

I've had issues with systems connected to my OSSC which have used the composite video for sync and the display loses sync until I adjust the OSSC sensitivity so that it ignores the chrominance and luminance signals and only sees the sync. But then again you're probably just using the composite video anyway. I'd check the signal level on the video output.

The colour killer will just be disconnecting the chrominance signal from the composite video generator.

stephen_usher wrote: 21 Mar 2023 12:24 What display are you using?

I've had issues with systems connected to my OSSC which have used the composite video for sync and the display loses sync until I adjust the OSSC sensitivity so that it ignores the chrominance and luminance signals and only sees the sync. But then again you're probably just using the composite video anyway. I'd check the signal level on the video output.

The colour killer will just be disconnecting the chrominance signal from the composite video generator.

Just using straight composite to a Dell LCD display and up to now it's been fine on it. I'll try it on something else that has composite, one of my TVs, see what happens.

The OSSC doesn't agree with the composite signal from the Apple, neither does my Retrotink, but has always been fine with the Dell. Let's see how the TVs work out, or even direct into the Dell as currently the Apple goes via a switchbox.

Ok, so I've had the ][e on the bench this afternoon and given the slots and edge connectors plus sockets a good clean. Quite a bit of dirt came out of the expansion card sockets, not to mention the memory card socket and for now at least, it's running fine.

However, I did find the 'colour killer' switch was damaged:


On the left hand side, there should also be beige plastic as on the right, however that has broken off and you can see right in. For now I don't have a suitable replacement, so I refitted it. However, given the switch is open in this position I'm not desperate to replace it, as that is PAL mode, exactly where I need it to be.

One interesting thing is that the way the colour killer works is to change the input on pin 4 of the TCA 650 chrominance demodulator. For PAL it expects between 7v and the input supply, 12v in the case of the Apple ][e. If it's between 0v & 1V, as it is when the switch is enabled, then SECAM mode is enabled and the machine runs in mono.

Since I'm using it in PAL colour, I checked pin 4 of the TCA 650 and it's about 2.8v, which is in neither the PAL or SECAM range. Of course it could be enough to work, but I'm now thinking I need to chase back the circuit that provides power for that part of the circuit, because oddly the schematics say pin 4 should be connected 5v, but it's actually connected to what I think is 12v, but it's actually reading just over 10v.

A little more digging to do perhaps...

Hmm, a bit of 'burn in' later and the RAM II/E card has disappeared again :(

I did give it all a damn good clean and it keeps coming and going, and I feel like it could well be a power issue when you also consider the video issues. I'll see about giving the PSU a service.

On another note, Adrians Digital Basement has been looking at this: V2 Analog which looks like it may be the VGA solution I'm looking for :)

Time to watch this:

This is a bit of a request for help: @stephen_usher @JezC @PhilC @Tomswork @HigashiJun

I'm not sure if you can help gents, but I am trying to find some voltage readings from an Apple ][e PAL version. If you can't help, maybe somebody else can.

Specifically I am after voltage readings from the TCA 650 (UA13) that forms part of the video circuit, and specifically I need voltage readings from:

1. Pin 14 - Power in. According to the PAL schematics I have, plus what the TCA 650 datasheet shows, this should be 12v. I'm reading 5v.
2. Pin 4 - When the colour killer switch is off, it is open and pin 4 reads 2.5v-2.7v on mine. The datasheet states for PAL to be selected it should be 7-12v, and there is a contradiction here with the schematics that show 5v to pin 4 with the switch open. I suspect that the 5v signal may be enough to make it run fine, but since mine is half that, I can't help but think there is some sort of power issue, maybe a short somewhere or the PSU is falling short.

What I'd like please if you can help, are voltage readings from both of these pins with the machine booted and the colour killer turned off. Please note this MUST be a PAL machine as the NTSC machine has a very different video circuit.

I have a suspicion that the reason that my colour display is turning off intermittently is because the voltage at pin 4 is somewhere in between the 0v-1v required for SECAM (Mono) and the 7v-12v required for PAL (Colour).

The Colour mode will either go off or flicker between that and Mono, almost like the signal is floating. I will check my own machine with the TCA 650 removed to see what the voltages are like in case it's marginal and pullng them down. I would add that when the voltage reaches the higher end of the scale, so 2.7v, it is more stable, but once it drops to the lower end, that's where the mode switching occurs.

I'd go and check electrolytics on the mainboard, but mine doesn't have any, though there are some other discrete components (Caps and a Zener) that I do need to check.

rubber_jonnie wrote: 27 Mar 2023 00:00 This is a bit of a request for help: @stephen_usher @JezC @PhilC @Tomswork @HigashiJun

I'm not sure if you can help gents, but I am trying to find some voltage readings from an Apple ][e PAL version. If you can't help, maybe somebody else can.

Specifically I am after voltage readings from the TCA 650 (UA13) that forms part of the video circuit, and specifically I need voltage readings from:

1. Pin 14 - Power in. According to the PAL schematics I have, plus what the TCA 650 datasheet shows, this should be 12v. I'm reading 5v.
2. Pin 4 - When the colour killer switch is off, it is open and pin 4 reads 2.5v-2.7v on mine. The datasheet states for PAL to be selected it should be 7-12v, and there is a contradiction here with the schematics that show 5v to pin 4 with the switch open. I suspect that the 5v signal may be enough to make it run fine, but since mine is half that, I can't help but think there is some sort of power issue, maybe a short somewhere or the PSU is falling short.

What I'd like please if you can help, are voltage readings from both of these pins with the machine booted and the colour killer turned off. Please note this MUST be a PAL machine as the NTSC machine has a very different video circuit.

I have a suspicion that the reason that my colour display is turning off intermittently is because the voltage at pin 4 is somewhere in between the 0v-1v required for SECAM (Mono) and the 7v-12v required for PAL (Colour).

The Colour mode will either go off or flicker between that and Mono, almost like the signal is floating. I will check my own machine with the TCA 650 removed to see what the voltages are like in case it's marginal and pullng them down. I would add that when the voltage reaches the higher end of the scale, so 2.7v, it is more stable, but once it drops to the lower end, that's where the mode switching occurs.

I'd go and check electrolytics on the mainboard, but mine doesn't have any, though there are some other discrete components (Caps and a Zener) that I do need to check.

I'm afraid I cannot help here rubber_jonnie, as I do not have any Apple II... And if I would have one, it would probably be a NTSC one.

:cry:

@rubber_jonnie

I'm sorry but I have ntsc apple 🍎 2 machines have you asked on tinkerdiffernt.com kia Robinson is in there

Tom

I'm afraid that I'm the same, no Apple IIs.

Sadly I can't help either...no Apple h/w of any vintage I'm afraid.

Is there an equivalent forum to this one for older apple computers (or even FB groups) as a last resort?

Good luck!

@stephen_usher @JezC @PhilC @Tomswork @HigashiJun

Thanks all for responding, I could have sworn at least one of you had a ][e, but memory can be a funny thing!!

I'll try a more general post here and will also try over at AppleFritter, see if I can get a reply over there.

Cheers