emmanuelf
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Posts posted by emmanuelf
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Ok good to know 👍
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Hello,
How did you solved the funky non compliant sync signal problem?
Most modern tv/panels/converters do not tolerate the absence of hsync during/around vsync.
Glad to see that you use a proper output buffering chip. But keep in mind that all signals should be buffered, even csync is subject to 75ohm loading.
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I've found 4.433619Mhz smd oscillators. They are on their way.
If they work well at 5v as advertised, it should be possible to do a highly integrated thing like a board to put between the maria and his socket.
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Equalizing/serration pulse omission don't disturb OSSC sync and most console/electronic devices completely omit them an use plain hsync pulses (XNOR with vsync as needed)
A complete hsync pulse omission around vsync is the most coherent explanation of the problem.
We will see with the scope capture.
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And you could count on one more. Thank you!
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Most color CRT front panel are lead free as you could see in this document and the radiation problem is on the back of the tube which is leaded and coated. But it is nitpick anyway ....
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2 hours ago, MrPix said:CRTs work by firing electrons at low level radiation energies, and using lead glass to block the radiation from reaching you.
This is inaccurate.
Lead glass would glow greenish. Starting at 15kv there is very soft low level radiation produced by the beam, but there are completely unable to pass trough the thickness of the front face (non leaded) glass and are mostly converted to visible light.
Very very old not completely coated tube could produce bad radiation, on the back. Like very old high performance scope tube. Even in this case it is irrelevant as they are generally enclosed in a mu-metal cage.
Some very specific old vacuum valves produce high level of dangerous radiation, but this is not the topic.
Anyway, I'm offtopic too 😋
Nothing will completely replace old CRT like nothing is able to really replace the ungridded vector CRT of the vectrex. But I agree, next gen OLED will help to fade the ugly rendering of old analog systems (and actual one) on modern panel, if properly scaled.
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And so you will need to do scaling and be down in the rabbit hole.... a never ending story and definitively not an "ultimate choice". "Good quality HDMI board" with these darn specific old analog sources is a complete subjective concept. The cost will be disruptive too...
If you want hdmi, look at the F18A-MK2 and DVI output, but you will not have the right pixel aspect ratio.
Or go to the full FPGA emulation route.
Good analog->hdmi conversion for these very low resolution sources involve digital conversion and scaling. It is a very complex problem which need it own complete and cost reusable/sharable solution.
In my opinion, the only good solution is/will be OSSC Pro. But it is only my opinion.
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Giving MARIA is own local color-burst oscillator is perhaps the only way to cure things.
With the buffer, what the signal look like on a scope on the maria pin ? Buffer + R on the maria side is perhaps sufficient.
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Look like clock line impedance problem.
A resistor on the line close to maria chip is worth a try.
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Yes, my mistake : not Y/C but YPbPr...
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Did you ever get this #1 module working some days ?
There is at least 3 model : PAL, NTSC and Y/C used for French consoles.
The Y/C one is pin incompatible with the standard pal/ntsc consoles.
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Mystery solved 🙂
Values are good 👍
6 hours ago, Falonn said:I had noticed once (while switching between systems) that 100mV had gone missing until I re-seated the power cord from "firmly" to "very firmly"
Yes that is where most users could experience loss.
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15ma less in the divider is great : less heat, less power loss, less tempco sensibility 👍
130ma is not anecdotal, around 15% of the 900ma 5v power rail. The external regulated power supply must be in good conditions and the case/cables connector too to minimize power loss.
The cables and the PCB of the coleco are well done, not too much additional loss to expect here, the TIP41C used in the power supply is able to deliver 6A so no problems here too, the limiting factor being the transformer.
As the regulation is done inside the power bloc, loss should be minimized at all connection points, the most problematic one being the case connector.
Did you measure the voltage at the pcb input with you bench voltmeter to see if the loss is before or after the pcb input ?
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Ok had forgotten the specified the optimal load to not disturb at the TMS output. And a second opamp stage would be overkill. 👍
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To be sure, what I've had in mind was to put the dividers before the MAX4395, with same ratio but higher values, not adding a resistor.
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Yes 150k is too much, did you try your simulation with 15k/30K/60K range ? It should cut down the current, not disturb the 4053 and not introduce noticeable error due to Ib.
But it's nitpicking.
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Before the AOP ? (MAX4395)
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Did you tried 150k range or even more before the AOP ?
It should give you the best of both world.
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Just my opinion: going further than the original analog signal and Tv resolution is falling down the rabbit hole.
RGBS is the format format which could simply bridge us to to digital world.
At minimal cost as many device are still able to get analog RGBS or with a few buck HDMI converter with reasonable result.
Going further is a never ending story and there is already a (open source/hw) solution for that : OSSC and the future OSSC Pro (with the latest and perhaps last top of the art integrated analog front end).
Even more personal opinion: I will never give Broadcom a cents for one of their ARM chip.
The ATF way of MrPix is the way to go and will not be only a proof of concept but will be better than what or had exist(ed). So one step after another 😌
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18 hours ago, MrPix said:If you want, we can combine projects. If not, that’s fine too.
I appreciate, but as all my hobby projects always suffer indefinite delays at my grand despair, I will be more a millstone than anything else.
But I will follow you with great interest and will help as I can.
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The Eprom way is a good compromise to stay on a very simple but user customisable design. And the CPLD could switch bank/palette with a simple push button.
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SECAM intelli RGB
in Intellivision / Aquarius
Posted
The current belief is that the problem is the missing hsync pulses. LMH1980/1981 will not solve it.
But you are by experiments thinking that it is more a timing problem on the hsync pulses than a problem around the vsync.
It should be confirmed by proper measurement on a scope. Perhaps timings IS the problem, perhaps trickling the vsync timing one way or another ( inverted v5 or csync slowing) minimize the missing pulse problem.
Investigating all this is on my todo list. My idea is using a little fpga to drive a standard video dac to act as "no longuer available/obsolete" ramdac and to what is need to proper reconstruct a compliant csync.
But I have no time now to put all this on the bench ....