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Atari System 2 PCB Repair - Paperboy

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    Posted: 20 Jan 2017 at 8:41pm
Following on from the thread here, I thought I would create a new thread as I go through the steps of attempting to repair a Championship Sprint PCB.

So firstly I need to see what's going on with the PCB on screen.

I received the GBS-8220 from Amazon discussed in the thread above and started looking at the wiring for it.

It looks fairly simple:


5v and ground connect at point A
Output to VGA connects to point B
EGA signal connects to point C

There are six wires that connect into point C and these match up to:

Red, Green, Blue, Grey (H Sync or Single Sync), Yellow (V Sync), Black (gnd)



Looking at the schematics of Championship Sprint (CS) it's time to work out how this hooks up to the  GBS-8220

The connector on the CS video board that outputs the display is P19.  I guess it is possible to use either H and V sync, or Comp sync.  I decided just to use Comp Sync so the pinout out would be

Pin 1 from connector P19 to Black/Gnd on GBS-8220
Pin 3 from connector P19 to Red on GBS-8220
Pin 4 from connector P19 to Green on GBS-8220
Pin 5 from connector P19 to Blue on GBS-8220
Pin 6 from connector P19 to Grey on GBS-8220

Yellow is ignored on GBS-8220

I made up a quick diagram to remember this :-)



So hopefully that's the medium resolution monitor issue taken care of hopefully



Edited by Purity - 15 Sep 2018 at 7:08pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Purity Quote  Post ReplyReply Direct Link To This Post Posted: 30 Jan 2017 at 10:33pm
Did some more work on this at the weekend.

Checked over the CPU and video board.  There were two crystals missing from the CPU PCB which won't help if there is no clock, so I replaced those.  Only had a low profile 20mhz crystal for one of them but it will do.

Also I replaced all the headers on the CPU and Video board.  They all had signs of corrosion and would mean a poor connection.  One of the 0.156" headers had been previously replaced and the soldering was fairly poor.  Big blobs of solder, so I removed all of that, cleaned it up, and fitted a new header with better soldering.

PCB's are in very decent condition though.  Hardly any signs of work on them, which is always good :-) 

I also tested out some of the chips.  Those that gained gold star status were good LOL









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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hurray Banana Quote  Post ReplyReply Direct Link To This Post Posted: 30 Jan 2017 at 10:36pm
Love the star techniqueThumbs Up
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bensonrad Quote  Post ReplyReply Direct Link To This Post Posted: 30 Jan 2017 at 10:46pm
Nice one, following this with great interest
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Purity Quote  Post ReplyReply Direct Link To This Post Posted: 30 Jan 2017 at 10:57pm
Cheers!  I'm glad I'm not boring you :-)

Once I have this up and running, I'm hoping to do the conversion to Paperboy to see how that goes
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SUPERSPRINT Quote  Post ReplyReply Direct Link To This Post Posted: 30 Jan 2017 at 11:33pm
Could you please post the part no of the CPU? trying to find one, or an equivalent.
Thank you.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Purity Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jan 2017 at 7:14am
Originally posted by SUPERSPRINT SUPERSPRINT wrote:

Could you please post the part no of the CPU? trying to find one, or an equivalent.
Thank you.


The CPU board uses a 6502 as the main processor.  Is that what you mean?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mitchell Gant Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jan 2017 at 8:16am
Originally posted by Purity Purity wrote:

Originally posted by SUPERSPRINT SUPERSPRINT wrote:

Could you please post the part no of the CPU? trying to find one, or an equivalent.
Thank you.


The CPU board uses a 6502 as the main processor.  Is that what you mean?

The 6502 is only the sound CPU. The main game CPU is a DEC T11. An interesting choice for Atari and departure from the 68000's they had been using around this time.




Boy, is this a machine!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SUPERSPRINT Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jan 2017 at 8:52am
Thanks I was wondering if there was an equivalent to the DEC chip. After looking for a while there are huge variety of DECs available and they are not cheap. So I wanted to ask if anyone has had any experience replacing this cpu?.
Thank you.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Purity Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jan 2017 at 9:58am
My bad.  I haven't looked at the schematics yet, and saw the 6502 on the PCB.  But yea CPU is a DEC chip.  Thanks for correcting Neil

Edited by Purity - 31 Jan 2017 at 9:58am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote joeks Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jan 2017 at 1:05pm
Nice work so far! Following this as I still have issues with both my Paperboy and Championship Sprint.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Purity Quote  Post ReplyReply Direct Link To This Post Posted: 31 Jan 2017 at 1:44pm
Originally posted by SUPERSPRINT SUPERSPRINT wrote:

Thanks I was wondering if there was an equivalent to the DEC chip. After looking for a while there are huge variety of DECs available and they are not cheap. So I wanted to ask if anyone has had any experience replacing this cpu?.
Thank you.


Just been looking at the DEC chip.  It seems that there is a Russian clone called the KR1807VM1.  I wonder if that works on a System 2 board without issues.  Has anyone tried one?

They seem to be a lot cheaper compared to the DEC T-11 !
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Purity Quote  Post ReplyReply Direct Link To This Post Posted: 01 Feb 2017 at 12:47pm
I was scratching my head about power requirements to get this PCB up and running, as I don't have an Atari power brick or an AR3 suitable.

I knew that the game needed +15v DC and -15v DC, and I was thinking that I might get away with using +12 and -12v DC from a PC power supply.  All the other power requirements seemed ok.  +5, gnd etc.

So I started looking at the wiring diagrams last night and noticed that it mentions using an alternate 5v supply to P20 or J20.  I assume this is instead of the standard power supply/AR3?  Here is what it says:



So this looks like this is a good option for me, and I've made a connector up to power the board and the video converter from a PC ATX power supply.  It will be interesting to see what it does.

Can anyone see anything wrong with this?


Edited by Purity - 01 Feb 2017 at 12:54pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote karlcdoe Quote  Post ReplyReply Direct Link To This Post Posted: 01 Feb 2017 at 1:09pm
Well, it's been a while since I put one on a test bench so this is purely from memory but Paperboy has two power supplies, one for each board but later games like APB and 720 have one. I powered the paperboy off a single bench power supply.

 In terms of the additional power requirements I think I used +12volts, probaly got away with not bothering with -15 (12v).  I recall the additional voltage is used to drive the reset circuit amongst other things so if you don't connect it you get a nice black screen. Looking at P5B of the 720 degrees schematics (which I happen to have in front of me) reset and watchdog clear use the +15v line but double check the paperboy schematics as well as I know the boards are slightly different.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Purity Quote  Post ReplyReply Direct Link To This Post Posted: 01 Feb 2017 at 1:57pm
Thanks.  I had a very quick look at the schematics and I can see it is required for elements of the video circuit etc, so definitely required.  I'll factor that in


Edited by Purity - 01 Feb 2017 at 1:58pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Purity Quote  Post ReplyReply Direct Link To This Post Posted: 27 Feb 2017 at 11:14pm
I can see quite a serious problem Cry





The T11 CPU is pretty much unobtainable :-(

It looks like almost every leg is affected.  Best I can do is try and transplant some legs onto the chip and see if I can get it into a socket to solder in place.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote strykr Quote  Post ReplyReply Direct Link To This Post Posted: 27 Feb 2017 at 11:29pm
ooof.....

fingers crossed and some fiddly soldering ahead!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SUPERSPRINT Quote  Post ReplyReply Direct Link To This Post Posted: 27 Feb 2017 at 11:33pm
The Dec cpu on my system 2 super sprint looked the same as that. I did just what you suggest, cleaned up the rust with a very fine sanding pad and soldered it into a new socket, making new legs with solder where needed. Works a treat, luckily.
The game was behaving very strangely until I noticed this problem and it's fine now.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tb2000 Quote  Post ReplyReply Direct Link To This Post Posted: 27 Feb 2017 at 11:34pm
Easiest way to fix that is to insert it into a socket so it has a carrier (and also the original legs don't take any more pounding if you need to remove it again), then you can insert little component leg offcuts or whatever and connect them to the leg stumps.

Edit: as you say above!

Edited by tb2000 - 27 Feb 2017 at 11:35pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Purity Quote  Post ReplyReply Direct Link To This Post Posted: 27 Feb 2017 at 11:36pm
It's going to be extremely tough.  I just need to slightly touch the leg and they are dropping off, so I think most are going to be goners even trying to just clean the legs.  I'm going to have to try though - I will really struggle to get another one of these


Edited by Purity - 27 Feb 2017 at 11:37pm
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