Please help me get my Atom working!

discussion of games, software, hardware & emulators relating to the Acorn Atom
ghostrider
Posts: 6
Joined: Tue Nov 28, 2017 8:51 am

Please help me get my Atom working!

Postby ghostrider » Wed Nov 29, 2017 10:04 am

Just dug out my old Atom from my mum's house......

12k model with no extra ROMS I think - not used since about 1986!

Anyway from memory (!) this was working fine till I tried to fit an aftermarket (non-official) colour card. This involved soldering some wires to PL4 and cutting away capacitor C2, and connecting on the colour board wires to it (bit still left as you can see from photos). Basically it didn't work, so I desoldered the wires from PL4 and then Atom was put away.

I tried booting it up recently but to no avail.........

- Power supply is 1.8A, 8V official Atom one and gives steady ~12.7V without load.
- No signal on TV out of UHF (I guess because capacitor C2 is missing?)
- No sound on Ctrl-G (worrying?)
- I did notice heatsink got really hot to touch within 1-2 mins of attaching power supply

I'm not a great engineer so don't remember trying to convert to 5V and it looks like the LK6 & 7 links are not there so its still the 8V requirement?

Any suggestions about where to start apart from replacing the C2 capacitor (22uF?) - I did see an alternative was to connect a cable to pins 9 & 10 of PL4?

Thanks for any advice

Cheers

Gary
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hoglet
Posts: 6620
Joined: Sat Oct 13, 2012 6:21 pm
Location: Bristol

Re: Please help me get my Atom working!

Postby hoglet » Wed Nov 29, 2017 11:25 am

Hello and Welcome to StarDot!

Without C2 there will definitely be no output from the UHF modulator.

If you have a suitable TV with a composite video input, then it's worth making up a cable that connects to PL4 pins 9 (video) and 10 (ground). This should work even without C2 being present.

It's quite possible the Atom will have developed a RAM fault (the 2114L chips are very unreliable after 25 years). But until you get the video sorted, then it's going to be very hard to debug this.

The heatsink getting very hot is expected with a fully loaded Atom running off the original 8V supply. Once you yet it working again, it's definitely worth converting it to run off 5V. But one thing at a time!

Do you have a multimeter? Another basic check is to test for 5V (usually 4.7-4.8 in practice) across several of the ICs.

Dave

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NilByMouth
Posts: 18
Joined: Mon Nov 06, 2017 11:42 pm

Re: Please help me get my Atom working!

Postby NilByMouth » Wed Nov 29, 2017 11:46 am

User avatarhoglet
Posts: 6502
Joined: Sat Oct 13, 2012 7:21 pm
Location: Bristol


I just noticed the number of posts you've made is very apt for this forum.

ghostrider
Posts: 6
Joined: Tue Nov 28, 2017 8:51 am

Re: Please help me get my Atom working!

Postby ghostrider » Wed Nov 29, 2017 8:27 pm

Thanks Dave

Will investigate and report back

Cheers

Gary

ghostrider
Posts: 6
Joined: Tue Nov 28, 2017 8:51 am

Re: Please help me get my Atom working!

Postby ghostrider » Fri Dec 01, 2017 5:57 pm

An update.....

Found a composite cable and with the XBOX SCART adapter managed to connect to SCART on LCD TV.

Then connected ground to pin 10 and signal to pin 9 of PL4 and voila...... boots up fine, screen as expected and even better than I remember with the old UHF signal.

So no need to do anything with capacitor C2 - ctrl G even gives a beep and I managed to run a few of the routines in Atom Theory and Practice.

I have a few more questions but will post them under separate topics

Thanks for the all the help & advice.

Cheers

Gary

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danielj
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Joined: Thu Oct 02, 2008 4:51 pm
Location: Manchester

Re: Please help me get my Atom working!

Postby danielj » Fri Dec 01, 2017 6:03 pm

Great news :)

d.


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