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600XL Video Upgrade


Larry

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There are pictures of the PCB, I have already started taking out components so that I can add sockets as I trouble shoot the problem.  the only socketed chip was that weird one that fits in a 14 pin socket but only has I pins.  I had taken out the OS ROM and BASIC.  I added a socket for the OS ROM.  I will get some more work done tomorrow.  

 

Update: I may have found the problem, the 14806 is bad.  I need to solder in sockets for the ICs I removed and retest.  If the computer works I don't know if I will continue to add sockets or not.

 

1595122411_Unsocketed600XLa.thumb.jpg.81450d6ec7e865d39c35d3dd922190e9.jpg1713665555_Unsocketed600XLd.thumb.jpg.54e748fd7734bcb8aa6ef1741ca78cb0.jpg1504635649_Unsocketed600XLc.thumb.jpg.fd68b164d816627ad7585a2af1e6b207.jpg1098403175_Unsocketed600XLb.thumb.jpg.d660679006eba84bad1552512ac57468.jpg

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My 600XL had a bad Sally, a bad Pokey, and two bad RAM chips.  I think they were fried by a long gone power supply.  

 

It's weird seeing the board without sockets as everything on my 600XL was socketed.  It made it really easy to swap chips around.  You might want to consider socketing the RAMs and the three ICs that need to have pins lifted to perform the RAM upgrade. 

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35 minutes ago, hueyjones70 said:

I had taken out the OS ROM and BASIC.

When you put in a BASIC socket you will probably want to use a 28-pin socket, since you have the 600XL PCB version that can use a mask ROM or an EPROM for BASIC, this would allow you to install an 2764 compatible chip with Rev.C BASIC on it if desired.

 

The soldered jumpers to select are just to the left of the capacitor behind the BASIC socket, indicated by arcs in the silkscreen similar to below.

 

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1 hour ago, BillC said:

When you put in a BASIC socket you will probably want to use a 28-pin socket, since you have the 600XL PCB version that can use a mask ROM or an EPROM for BASIC, this would allow you to install an 2764 compatible chip with Rev.C BASIC on it if desired.

 

The soldered jumpers to select are just to the left of the capacitor behind the BASIC socket, indicated by arcs in the silkscreen similar to below.

 

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I would like to know more about this.

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Thanks for all the info.  I installed sockets for the ICs I had removed and with a working SALLY the computer is partially working.  I cannot get chroma.  I ran the wires to the monitor jack according to the instructions for the SuperVideo 2.1 modification.  I cut the trace that grounded chroma.  The Luma is very sharp.  Is there another point besides the junction of resistors 123 and 124 that would give me a good chroma hook-up.  Is the problem possibly because of using a PAL computer on a CRT monitor.

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I have almost done a successful SV2.1 on a 600XL.  I say almost because I have luma and chroma but no composite.  My composite appears to be about the same as chroma only. It appears that there is a trace for composite to the monitor jack.  I am wondering if this is not actually the case and If I need to run a wire from somewhere to the composite connector post on the monitor jack and eliminate the aforementioned trace.

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I don't know why this worked but there were 3 empty spots for resistors, capacitors, etc so I installed jumper headers in those spots and when I added the jumper to L12 I got composite video.  There is no part listed for L12 in the manual and L12 is not mentioned in the instructions for the Super Video 2.1 upgrade.

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On 2/18/2020 at 5:28 PM, hueyjones70 said:

I don't know why this worked but there were 3 empty spots for resistors, capacitors, etc so I installed jumper headers in those spots and when I added the jumper to L12 I got composite video.  There is no part listed for L12 in the manual and L12 is not mentioned in the instructions for the Super Video 2.1 upgrade.

The schematics in the 600XL Field Service Manual do show L12, but many of the video components were left out of the NTSC model. Most of the video circuit is shown on page 66 of the linked PDF.

http://www.atarimania.com/documents/Atari_600XL_Computer_Field_Service_Manual_Rev_1.pdf

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Just now, hueyjones70 said:

I know there is a spot for L12 but the parts list for the NTSC does not specify what part goes there. On my PAL machine it appears to be a ferrite bead.

In electronics nomenclature, "L" usually refers to an inductor, which is exactly what a ferrite bead is. It's also not strictly necessary - it will (theoretically) help isolate some degree of RF noise from the signal. You can either install one or not, as you choose.

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  • 8 months later...

I just finished upgrading a 600XL with Supervideo 2.1. The S-Video is great but I can't get composite. I have a ferrite bead in L12, everything appears to ne installed correctly. The composite cut off switch is supposed to be connected to the holes of L13I didn't want to add the switch so I put a ferrite bead in the holes. No composite with the bead, no composite without the bead. Does anyone know where composite originates so I could pick off the signal and run a wire directly to the monitor jack.

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