My first Atom....

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mark71
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My first Atom....

Post by mark71 »

Hi All

Just acquired an Atom to add to the other Acorn kit and wonder what you could tell me about it and what to check before seeing if it works.

Case looks in good nick, needs a good wash not too much yellowing, came in the orginal Poly, with the manuals and some other pamplets anyone have a Acorn GP/80 Printer?, looking at the board which seems very clean, being a Issue 4, has all the sockets populated missing IC2/3/4/5 and 24 what would have been in these?.

The LK6/7 hasn't been fitted and the power transisters on the back, look to have been busy working and a bit brown on the board. The machine looks like it was assembled by Acorn as the soldering is quite uniform and tidy. Recomendations for power supplys?, none came with it so look to fit LK6/7 and use a 5V Regulated one.

Mark
Photo 03-08-2020, 20 54 16.jpg
Photo 03-08-2020, 20 54 08.jpg
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roland
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Re: My first Atom....

Post by roland »

IC2,3 and 4 are data and address buffers. They are widely available on this forum and on well known webshops.

IC5 is a 74LS30 used for disabling those buffers when internal memory is addressed. You don't need them if there's no hardware connected that uses address and data lines on PL6/7.

IC 24 is a socket for a utility (ep)rom. Not neccessarily needed either. If you close LK 6 and 7 you can use any regulated 5V 2A power supply.

No special precautions are needed. Capacitors don't explode in the Atom. Make sure you don't swap + and - on the power input and just bring it back to life :lol:

The main board looks good so in case of failure we can fix it!

Enjoy your Atom....
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cjm
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Re: My first Atom....

Post by cjm »

mark71 wrote:
Mon Aug 03, 2020 9:37 pm
Recomendations for power supplys?, none came with it so look to fit LK6/7 and use a 5V Regulated one.
Congrats on your new Atom!

I couldn't find a power supply with the right connector for my Atom - so I replaced the connector and used one of these: https://www.ebay.co.uk/itm/5V-4A-AC-DC- ... 2749.l2649
Atom + YARRB + Noise Killer + HDMI adapter + Homebrew RPi-MMC AtoMMC V4
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anightin
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Re: My first Atom....

Post by anightin »

Welcome to the ATOM club :)

Great fun working on these machines!
mark71
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Re: My first Atom....

Post by mark71 »

cjm wrote:
Tue Aug 04, 2020 12:04 pm
mark71 wrote:
Mon Aug 03, 2020 9:37 pm
Recomendations for power supplys?, none came with it so look to fit LK6/7 and use a 5V Regulated one.
Congrats on your new Atom!

I couldn't find a power supply with the right connector for my Atom - so I replaced the connector and used one of these: https://www.ebay.co.uk/itm/5V-4A-AC-DC- ... 2749.l2649
Thanks all for the advice.

4A 5V supply ordered, one question which isn't wholly clear is polarity of the power socket +5V centre pin?.
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Multiwizard
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Re: My first Atom....

Post by Multiwizard »

mark71 wrote:
Mon Aug 03, 2020 9:37 pm
Hi All

Just acquired an Atom to add to the other Acorn kit and wonder what you could tell me about it and what to check before seeing if it works.

Case looks in good nick, needs a good wash not too much yellowing, came in the orginal Poly, with the manuals and some other pamplets anyone have a Acorn GP/80 Printer?

Mark
Hi
nice Atom... =D>

Yes I do have a Seikosha GP-80M printer... :D

But sadly I never did manage to get suitable/fitting paper for it... :(


Greetings, Wim... :-)
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roland
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Re: My first Atom....

Post by roland »

mark71 wrote:
Tue Aug 04, 2020 3:57 pm
one question which isn't wholly clear is polarity of the power socket +5V centre pin?.
AFAIK, yes the center pin is +5V. You can verify it with a multimeter: there must be almost no resistance between the center pin and pin 20 of any ram (2114) chip.
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Re: My first Atom....

Post by bprosman »

But sadly I never did manage to get suitable/fitting paper for it...
Cant you unlock the left paper guide, shift it to the left and put standard A4 paper in it ?
https://www.vikingdirect.nl/nl/Niceday- ... -p-4580757
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Multiwizard
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Re: My first Atom....

Post by Multiwizard »

bprosman wrote:
Wed Aug 05, 2020 2:43 pm
But sadly I never did manage to get suitable/fitting paper for it...
Cant you unlock the left paper guide, shift it to the left and put standard A4 paper in it ?
https://www.vikingdirect.nl/nl/Niceday- ... -p-4580757
Tried that years ago when I received it, still no A4... :(
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Re: My first Atom....

Post by Kazzie »

Multiwizard wrote:
Tue Aug 04, 2020 6:03 pm
Hi
nice Atom... =D>

Yes I do have a Seikosha GP-80M printer... :D

But sadly I never did manage to get suitable/fitting paper for it... :(


Greetings, Wim... :-)
I've got one of those that I received as part of a job lot. It uses eight-inch fan-fold paper, as opposed to the more common ten-inch variety (which I have a bit of in the attic).

Mark, if you're interested, my Seikosha is yours for the cost of postage. It responds sensibly to printer commands from a Beeb (with a hell of a loud racket! :)), but I expect that the ribbon will need re-inking.
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Re: My first Atom....

Post by mark71 »

Kazzie wrote:
Fri Aug 07, 2020 7:14 pm
Multiwizard wrote:
Tue Aug 04, 2020 6:03 pm
Hi
nice Atom... =D>

Yes I do have a Seikosha GP-80M printer... :D

But sadly I never did manage to get suitable/fitting paper for it... :(


Greetings, Wim... :-)
I've got one of those that I received as part of a job lot. It uses eight-inch fan-fold paper, as opposed to the more common ten-inch variety (which I have a bit of in the attic).

Mark, if you're interested, my Seikosha is yours for the cost of postage. It responds sensibly to printer commands from a Beeb (with a hell of a loud racket! :)), but I expect that the ribbon will need re-inking.
Hi Kazzie

So tempting, just dont have the room at the moment, in the process of making a new Mancave/Office to work in the future and want to get all my acorn kit in use so can play whilst listening to boring zoom meetings whilst working........

Mark
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Re: My first Atom....

Post by Kazzie »

mark71 wrote:
Sun Aug 09, 2020 9:34 pm
Hi Kazzie

So tempting, just dont have the room at the moment, in the process of making a new Mancave/Office to work in the future and want to get all my acorn kit in use so can play whilst listening to boring zoom meetings whilst working........

Mark
It's unlikely to find any other takers in the meantime, so feel free to give me a shout when your reorganising's done, if you like.
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Re: My first Atom....

Post by mark71 »

Well, fitted the two links and put a new power socket in, powered the old girl up and no beep, but got a randon assortment of characters on the screen, see below, any ideas to look for?. Seems to be the exact randomness everytime it re-boots...

Next steps pop out the IC's and de-ox the sockets and try again. Has many chips populated, whats the minimum spec to boot?.

Mark
IMG_6211.jpg
IMG_6214.jpg
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Re: My first Atom....

Post by marcusjambler »

Press the Break key
mark71
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Re: My first Atom....

Post by mark71 »

marcusjambler wrote:
Sun Aug 09, 2020 10:23 pm
Press the Break key
I did, nothing happened, other than some noise sometimes, CTRL G tried that nothing, will investigate keyboard contacts.
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Re: My first Atom....

Post by mark71 »

Hi All

Looking for some advice on bringing my Atom back to life, i had another go last night, took the Atom back to minimum spec, from looking at the forums here. Still now joy same pattern on screen, one thing i did notice if i touched the 8255 IC i would get some noise as if there was a bad connecton somewhere. Any ideas?, am thinking of redoing the solder joints on the sockets on the backside.

Also the whte sockets are showing some browning on them, i think this is from age and maybe from the residual flux that has been left on the board?.

Thanks

Mark

Minimum Specification
IMG_6240.jpg
New Screen if touching the 8255
IMG_6237.jpg
Interesting colouration of the white sockets.
IMG_6241.jpg
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roland
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Re: My first Atom....

Post by roland »

Maybe you can get some inspiration from another topic with similar problems: viewtopic.php?f=44&t=18020&start=150

Especially focus on the power supply (do all the IC's get their 5V (+/- 5%) and the behaviour of the CPU.

What equipment do you have for measuring signals?
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Re: My first Atom....

Post by oss003 »

The best start is indeed minimum configuration.
Then take out the IC's one by one and clean the IC legs and socket before putting it back.
Next step is to check if the +5V is available on the IC's and eg pin 1 and 31 op PL6/7.

Also switching the 2114's will help if one is broken.

Is your Atom still original on the other side of the mainboard, aren't there any extra wires?

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Re: My first Atom....

Post by daveejhitchins »

If you've the patience (?) perhaps replace all the white sockets! They seem to be of very poor quality!

Dave H.
mark71
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Re: My first Atom....

Post by mark71 »

daveejhitchins wrote:
Tue Aug 18, 2020 7:17 am
If you've the patience (?) perhaps replace all the white sockets! They seem to be of very poor quality!

Dave H.
Hi Dave

The machine looks in a very clean original situation, no wires on the other side, i have a feeling that the CPU was from another machine but dated from 1980 i think, need to check, as looks like solder on the legs.

Seems to be a expanded machine with FPU rom and all the ram sockets filled with 6522, soldering looks like it was done by Acorn as very good looking on inspection and consistent.

Its something i am thinking of to replace the sockets and re-cap it, from rolands link, indicates could be CPU, can a CPU from a Electron work in the Atom?.

The 8255 when touching was showing intermittent contact, which could indicate issues with the sockets.

Mark
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Re: My first Atom....

Post by mark71 »

roland wrote:
Mon Aug 17, 2020 9:46 pm
Maybe you can get some inspiration from another topic with similar problems: viewtopic.php?f=44&t=18020&start=150

Especially focus on the power supply (do all the IC's get their 5V (+/- 5%) and the behaviour of the CPU.

What equipment do you have for measuring signals?
Hi Roland

Thanks for the link, interesting reading, Looking at the topic does show a lot of similarity's with it, the power supply is new, by passing LK6/7. I have a multimeter at the moment so can check the voltages, logic probe/analyzer/scope not yet. Looking at the topic indicates potential issues with the CPU, also old age with the sockets too. Will measure the voltages and see what show.

Mark
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Re: My first Atom....

Post by mark71 »

oss003 wrote:
Tue Aug 18, 2020 6:52 am
The best start is indeed minimum configuration.
Then take out the IC's one by one and clean the IC legs and socket before putting it back.
Next step is to check if the +5V is available on the IC's and eg pin 1 and 31 op PL6/7.

Also switching the 2114's will help if one is broken.

Is your Atom still original on the other side of the mainboard, aren't there any extra wires?

Greetings
Kees
Hi Kees

Looks in a very original condition, no modifications, full compliment of Ram, looks to have been used alot as heat damage to the board from the power transisiters.

Mark
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cjm
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Re: My first Atom....

Post by cjm »

++ to Kees suggestion regarding switching the 2114's around - it worked for me.

Another possibility is that the system clock is not working - if you have an oscilloscope measure pin 37 of the CPU, it should have a 1 MHz signal on it.
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Re: My first Atom....

Post by oss003 »

IC's 51/52 are the zeropage rams and the other ones for the display. If zeropage rams are broken, the Atom won't boot and if the other ones are broken then the Atom will boot but you just get wrong characters on the screen.

Greetings
Kees
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Re: My first Atom....

Post by Prime »

From the scrambled video image, I'd say part of the problem is the connection between 8255 and 6847,as the 8255 sets the video mode and other lines on the video chip. Could also be that it's not being initialized correctly.

Yeah and those white Acorn fitted sockets are pretty crappy, I've ended up replacing them for a lot of the major chips in some of my Atoms.

Cheers.

Phill.
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Re: My first Atom....

Post by hoglet »

Prime wrote:
Wed Aug 19, 2020 7:46 am
From the scrambled video image, I'd say part of the problem is the connection between 8255 and 6847,as the 8255 sets the video mode and other lines on the video chip. Could also be that it's not being initialized correctly.
Exactly. I found that if the Atom reset code doesn't execute, then the 8255 isn't initialized. This leaves the video mude "outputs" incorrectly set as inputs, and just putting your hand near then is sufficient to induce a mode change.

Even with dodgy RAM, the Atom should get to this part of the reset code, as it doesn't invole any JSR subroutine calls.

So this suggests that something is stopping the processor from executing the reset code, e.g.
- a reset issue
- a system clock issue
- a ROM issue
- something loading the data bus (which could be a bad RAM chip)

Dave
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Re: My first Atom....

Post by John Ferguson »

I have managed to get 4 Atoms working.

Using the minimum configuration I would replace gradually the support chips and 2114 memory chips if broken starting with the IC that controls the reset of the cpu and the 8255. That is IC 9.

Then review what happens on the screen. Further action could be replacing the crystals for the cpu and the 8255 IC’s.

John
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