Atom Video to HDMI Adapter

discussion of games, software, hardware & emulators relating to the Acorn Atom and Acorn System machines.
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etaoin
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Re: Atom Video to HDMI Adapter

Post by etaoin » Sun Jun 23, 2019 6:08 pm


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-B-
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Re: Atom Video to HDMI Adapter

Post by -B- » Sun Jun 23, 2019 6:13 pm

That looks very close. If anyone goes for that, please show us the end result.

Neil.
Atom | BBC Model A | BBC Model B | Electron | Olivetti PC128S.

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Re: Atom Video to HDMI Adapter

Post by hoglet » Sun Jun 23, 2019 6:48 pm

bprosman wrote:
Sun Jun 23, 2019 5:54 pm
Hi Roland,

Thanks for the offer, I have as well but the Dutch Farnell doesn't seem to have it in their catalog.
I can check the UK site.
I believe this CamdenBoss CRDCG0003 case is identical to the Evatron EVA73G:
https://nl.farnell.com/camdenboss/crdcg ... dp/1171635

But it's worth you double-checking the dimensions, particularly the PCB mounting points.

Dave

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Re: Atom Video to HDMI Adapter

Post by etaoin » Sun Jun 23, 2019 7:04 pm

-B- wrote:
Sun Jun 23, 2019 6:13 pm
That looks very close. If anyone goes for that, please show us the end result.

Neil.
It is the one I got and the pcb fits. You need to cut two bits of plastic inside but I think the original one needs that as well.

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Re: Atom Video to HDMI Adapter

Post by etaoin » Sun Jun 23, 2019 7:09 pm

etaoin wrote:
Sun Jun 23, 2019 7:04 pm
It is the one I got and the pcb fits. You need to cut two bits of plastic inside but I think the original one needs that as well.
Including the five mounting points, I might add. So it seems to be identical. And I got it from earlier in the thread, so someone already mentioned it there.
Last edited by etaoin on Sun Jun 23, 2019 7:09 pm, edited 1 time in total.

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Re: Atom Video to HDMI Adapter

Post by -B- » Mon Jun 24, 2019 8:16 am

etaoin wrote:
Sun Jun 23, 2019 7:09 pm
etaoin wrote:
Sun Jun 23, 2019 7:04 pm
It is the one I got and the pcb fits. You need to cut two bits of plastic inside but I think the original one needs that as well.
Including the five mounting points, I might add. So it seems to be identical. And I got it from earlier in the thread, so someone already mentioned it there.
Excellent! If I ever build another, I know I can get them elsewhere. And yes, you do have to remove the small ribs inside the box on the two longer sides. Also, if you make the IDC cable with a strain relief bracket, you need to remove one of the centre screw posts in the bottom too.

Sinuss.nl appear to be a Farnell reseller. You can search their site with Farnell codes. They add a little on to the price but at least you can get stuff in a couple of days (my box from eBay took two and a half weeks!).

Neil.
Last edited by -B- on Mon Jun 24, 2019 8:17 am, edited 1 time in total.
Atom | BBC Model A | BBC Model B | Electron | Olivetti PC128S.

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Re: Atom Video to HDMI Adapter

Post by bprosman » Mon Jun 24, 2019 9:06 am

Let me check , but let's build PCB first.
Hoping to have the parts arrived this week.
They add a little on to the price but at least you can get stuff in a couple of days
Well , I checked that earlier this week but a 8051 core processor was 7 Euro , versus 4 Euro directly at Farnell (VAT excluded).
But I do have a company account at Farnell.

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Re: Atom Video to HDMI Adapter

Post by bprosman » Mon Jun 24, 2019 1:28 pm

Got an e-mail from Farnell that they run out of stock for the TI version of the LM319 and then its over (220 in stock).
They recommend ON Semi.

@Dave , any experience with that brand ?

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Re: Atom Video to HDMI Adapter

Post by hoglet » Mon Jun 24, 2019 3:50 pm

bprosman wrote:
Mon Jun 24, 2019 1:28 pm
Got an e-mail from Farnell that they run out of stock for the TI version of the LM319 and then its over (220 in stock).
They recommend ON Semi.

@Dave , any experience with that brand ?
No, the only one's I've tried are TI and ST.

I have no reason to believe there will be problems with the OnSemi version, it's just I haven't personally tried them.

BTW, Phill reported issue with the Fujitsu version on his colour board. That's the only data point I have.

Dave
Last edited by hoglet on Mon Jun 24, 2019 4:22 pm, edited 1 time in total.

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Re: Atom Video to HDMI Adapter

Post by -B- » Tue Jun 25, 2019 4:10 pm

I paid 33cents each for mine from Reichelt and it was pot luck whether I received, ST, Philips, Fairchild or Samsung.

I received Fairchilds both times and they work fine.

Neil.
Atom | BBC Model A | BBC Model B | Electron | Olivetti PC128S.

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Re: Atom Video to HDMI Adapter

Post by etaoin » Mon Jul 01, 2019 12:47 pm

Ok, back from holiday, so finished the converter.

By the way, I used an lm2950-33 instead of the LE33CZ, as I had that lying around.
IMG_7518.jpeg

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Re: Atom Video to HDMI Adapter

Post by hoglet » Wed Jul 17, 2019 11:07 am

hoglet wrote:
Mon Jun 24, 2019 3:50 pm
I have no reason to believe there will be problems with the OnSemi version, it's just I haven't personally tried them.
Well, I have now, and the OnSemi LM319N work perfecty.

They seem more widely available that the TI parts and are cheaper: 41p compared to £1.50 at Farnell:
https://uk.farnell.com/on-semiconductor ... dp/2450778

Dave
Last edited by hoglet on Wed Jul 17, 2019 11:07 am, edited 1 time in total.

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Re: Atom Video to HDMI Adapter

Post by anightin » Sat Jul 27, 2019 12:07 am

Dear All,

I seem to have inadvertently broken my previously working Atom Video to HDMI Adapter :oops:

When it Syncs I now get this on the display on both my ATOMs (reverting back to composite reveals the ATOMs are both running as normal)
IMG_3872.jpeg
Note that I did press the menu button and went to the info menu -- hence the Calibration text.

Booting the SD card to the Stardot ATOM software archive changes the white border to green but that's about it.

Was just wondering if the above would give any clues as to where to start debugging?

Many thanks

Andy
Last edited by anightin on Sat Jul 27, 2019 12:13 am, edited 4 times in total.

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Re: Atom Video to HDMI Adapter

Post by hoglet » Sat Jul 27, 2019 6:09 am

A couple of quick checks with the HDMI Adapter connected to the Atom, to make sure the Atom really is running

1. Hit BREAK

2. Blind type ^G <Return> and make sure it beeps (twice, once on the ^G, once on the Return)

3. Blind type CLEAR 4 <Return> - is there any difference to the screen (no beep should happen)

4. Blind type CLEAR 0 <Return> - is there any difference to the screen (no beep should happen)

Assuming that's all as expected, then I would start to invesigate the luminance path.

I can get the same display by adjusting RV1 fully clock wise. Note the initial position of RV1, and try adjusting it fully anti-clockwise. Does anything change? If not, this suggests the Y signal seen by the Pi is stuck high, due to a upsteam of this.

Do you have a scope?

I would start by checking the signals on pins 4, 5 and 12 of U4. That should help narrow down where the problem is.
LuminancePathPNG.PNG
The full schematic is here.

Dave
Last edited by hoglet on Sat Jul 27, 2019 6:11 am, edited 2 times in total.

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Re: Atom Video to HDMI Adapter

Post by anightin » Sat Jul 27, 2019 5:07 pm

Hi Dave,

Thanks for the quick reply. Have been out today so just had a quick look again.

BTW the other board I built up worked first time :) so at least I have two to compare now although I am waiting for a set of LM319N's so sharing between the two boards at the moment
1. Hit BREAK
2. Blind type ^G <Return> and make sure it beeps (twice, once on the ^G, once on the Return)
I get 2 beeps, and swapping to my new-build version works fine
IMG_3875.jpeg
3. Blind type CLEAR 4 <Return> - is there any difference to the screen (no beep should happen)
IMG_3874.jpeg
4. Blind type CLEAR 0 <Return> - is there any difference to the screen (no beep should happen)
IMG_3873.jpeg
With CLEAR 0 I get green blocks where character should appear at least.


Adjusting RV1 has no notiable effect -- I even desoldered RV1 and RV2 and swapped them over to check


I will see if I can borrow a scope later or tomorrow to check the signals -- note again that the IC works fine in my other build so I can rule that out at least.

Kind Regards

Andy

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Re: Atom Video to HDMI Adapter

Post by hoglet » Sat Jul 27, 2019 5:16 pm

Have you tried swapping the ribbon cable?

A useful measurement with a volt meter would be to measure the voltage between Pin 5 of IC4 and ground. Measure this with RV1 at each extreme. It should read ~0.8V at one extreme and ~2.5V at the other extreme.

Then measure the voltage across R7 - it should be ~1.0V

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Re: Atom Video to HDMI Adapter

Post by anightin » Sat Jul 27, 2019 6:05 pm

Have you tried swapping the ribbon cable?
Yes both cables work the same on the working and non working boards:
A useful measurement with a volt meter would be to measure the voltage between Pin 5 of IC4 and ground. Measure this with RV1 at each extreme. It should read ~0.8V at one extreme and ~2.5V at the other extreme.
Working board:
Pin 5 : 0.8v and 2.48v :D

Non-working board:
Pin 5 : 179mv and 0.6V :?

Maybe a clue?

I notice on the working board, I start to loose the picture at around 1.2v so explains why RV1 is making no noticeable difference on the non-working board.
Then measure the voltage across R7 - it should be ~1.0V
~1.0v on both boards

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Re: Atom Video to HDMI Adapter

Post by anightin » Sat Jul 27, 2019 6:26 pm

Eureka! Found the culprit! :D
IMG_3876.jpeg

It was C7 that decided to go from a 100nf to a 0.6nf Capacitor!
Screenshot 2019-07-27 at 19.30.09.png
IMG_3877.jpeg
Thanks for steering me in the right direction again Dave. I enjoyed the learning experience 8)



Much apprecaited as always.

=D>


Right, once my comparators arrive, I can now run each ATOM side by side with it's own HDMI interface. :D
Last edited by anightin on Sat Jul 27, 2019 6:32 pm, edited 2 times in total.

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Re: Atom Video to HDMI Adapter

Post by hoglet » Sat Jul 27, 2019 6:30 pm

anightin wrote:
Sat Jul 27, 2019 6:05 pm
Non-working board:
Pin 5 : 179mv and 0.6V :?
If you look at the schematic, R7/RV1/R8 are just a simple voltage divider.

So this suggests either the 3.3VA supply is dodgy, or there is a problem with R8.
anightin wrote:
Sat Jul 27, 2019 6:05 pm
Then measure the voltage across R7 - it should be ~1.0V
~1.0v on both boards
This suggests the 3.3VA supply is OK.

I'd investigate around R8. Look for dry joints.

Dave
Last edited by hoglet on Sat Jul 27, 2019 6:31 pm, edited 1 time in total.

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Re: Atom Video to HDMI Adapter

Post by anightin » Sat Jul 27, 2019 6:37 pm

hoglet wrote:
Sat Jul 27, 2019 6:30 pm
anightin wrote:
Sat Jul 27, 2019 6:05 pm
Non-working board:
Pin 5 : 179mv and 0.6V :?
If you look at the schematic, R7/RV1/R8 are just a simple voltage divider.

So this suggests either the 3.3VA supply is dodgy, or there is a problem with R8.
anightin wrote:
Sat Jul 27, 2019 6:05 pm
Then measure the voltage across R7 - it should be ~1.0V
~1.0v on both boards
This suggests the 3.3VA supply is OK.

I'd investigate around R8. Look for dry joints.

Dave

As per above it was C7, I guess the next question is why did it fail? :?
Last edited by anightin on Sat Jul 27, 2019 6:38 pm, edited 1 time in total.

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Re: Atom Video to HDMI Adapter

Post by hoglet » Sat Jul 27, 2019 6:45 pm

anightin wrote:
Sat Jul 27, 2019 6:37 pm
As per above it was C7, I guess the next question is why did it fail? :?
Glad you found that.

This is quite unusual....

Did it fail short circuit? Can you measure it's DC resistance with a meter?

Where did you buy them from?

Dave
Last edited by hoglet on Sat Jul 27, 2019 6:46 pm, edited 1 time in total.

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Re: Atom Video to HDMI Adapter

Post by anightin » Sat Jul 27, 2019 7:14 pm

Did it fail short circuit? Can you measure it's DC resistance with a meter?
Unfortunately it's now in the gloop at the bottom of the dustbin but I'm pretty sure it had failed near short-circuit.

All voltages are back where they should be with a now different brand of cap.

I got the dodgy one from eBay (where else for dodgy components I guess #-o )...

https://www.ebay.co.uk/itm/102-822-50V- ... 3864382196

Regards

Andy
Last edited by anightin on Sat Jul 27, 2019 7:21 pm, edited 1 time in total.

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