Stephen's A8 Blog - IO Board and (not so)Simple Stereo install - WIP

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The time has finally arrived, I am building my dream Atari. It started as a very yellowed PAL 130XE[picture needed]. I while back, I purchased one of the EPG Jr. machines. That was kind enough to donate its case & keyboard[picture needed]. It is 100% unyellowed and almost completely dust free. I haven't even brushed it off yet. It does have some scuff marks from the straps that held it in the rack. Also, one of the alignment tabs is busted off the back of the case. This will not be an issue, because I have an ECI+CART to PBI adapter that will be used to hook up a Speed Drive . I will Retrobrite the nasty case & keyboard one of these days. I'll be adding the stiffer key cups to it (although later this post I'll explain why that won't really be necessary).

 

Here I will detail my installation of candle's wonderful IOBoard, SimpleStereo, and VBXE2. Future upgrades will be 1MB SIMM and Internal SDX + 4-in-1 OS.

 

Step 1 - Here is the mainboard before I touched anything. I do not know what the "mod or fix" is. It was there when I got the machine along with a 2-in-1 OS which I removed in preparation for the internal SDX mod.

 

 

Step 2 - Always flux top and bottom before desoldering. I place the board in a vise, heat from the top (angle a fine tip iron against the IC pins touching close to the PCB but being careful not to overheat the board. This will be evident if the PCB turns white or if you gouge the tip in the board. Worse yet, you can lift a trace or rip out a barrel. Patience is the key here. (LOL at misspelled picture name)

 

 

Step 3 - The following pictures will show how clean these boards must be before attempting to remove the ICs. What is not shown here is that even after seeing all that light through the pins, I still used a few inches of thin solder braid and carefully freed all 40 pins one at a time before putting an ounce of pressure on the chip. When done correctly, you can turn the board over and tap it, and the chip will fall out. Anything more than that on the majority of XE series PCBs and you will be running wire jumpers to fix the damage. We'll not go into details of why I know this. For these mods, I had to desolder the ANTIC and PoKey chips.

 

PoKey:

I removed PoKey first.

Top of mainboard :

 

Bottom of mainboard :

 

Before inserting the machine pin socket, the board was cleaned off, and refluxed.

 

Note how straight and clean all the pins are. This is very important as the Simple Stereo board uses precision machine pin sockets.

 

With the nice socket in place, clean all traces of flux then replace PoKey and test the machine. I loaded Ice-T XE and logged into Darkforce BBS which was a good indication that all was well.

 

 

ANTIC:

Here the top 20 pins have been sucked. As clean as they look, I still refluxed and went over with solder braid.

 

Same as above, showing the lower 20 pins.

 

Bottom view - note that all pins are still touching the barrels. With a dry but CLEAN tip (absolutely no solder or scale), quickly and gently heat then push the pins to the center. This will free them completely without stressing either the pins or the barrels.

 

No damage to the PCB or traces - always a nice feeling on these (relatively) fragile boards.

Top of mainboard :

 

Bottom of mainboard :

 

 

Here lies the ANTIC. Carefully straighten the pins, remove all flux and when the socket is in, replace the IC and test the machine. Do not proceed until the machine works. You don't want to have to find and fix more than one problem at a time.

 

I had a nasty scare after replacing ANTIC and testing the machine. It initially booted up fine but part way into the self test the screen corrupted. Then it wouldn't reboot. I somehow got the diagnostic cart to spit out a memory error and after that, it was dead. After coming here and begging for help, I had to get out the schematics and pin to pin test all 40 connections from ANTIC to their respective destinations (thanks to all who responded BTW). Well, every connection was good as tested from the top of ANTIC. Turns out I had not adequately removed the flux from the top and bottom of the mainboard. After a thorough scrubbing and good drying with compressed air it came back up, bit crashed when hitting reset. The Start key was not responding well either. Turns out the keyboard was acting up. No bother, it was the aforementioned nasty yellow one. After plugging in the minty white keyboard, all was well. I could finally proceed.

 

Step 4 - Now it's time to mount the IO Board. This will require drilling out the rivets holding the SIO connector to the mainboard. I used a 5/32 drill bit and went SLOWLY! I ran the drill at a very low 200-300 RPMs and used a very nice sharp cobalt drill bit. It went through the soft aluminum rivets like butter. Take care to secure the PCB and don't let the drill "rip" through the board. Slow and steady means no damaged board.

 

 

Once the rivets are out, screw the stand offs in place to secure the SIO connector and also provide the mounting posts for the IO board. [picture needed]

 

Step 5 - Now it's time to drill the 2 round holes and cut a square hole above the SIO opening (back of the case, lower panel). I made the square hole by drilling a 3/8" hole and then using a square file. Patience is key if you want a decent fit. To get a good fit, you will want to make sure the PCB is properly placed in the lower half of the case WITH the lower shielding in place. Make sure all screw holes are lined up and the two tabs in front fit up through the mainboard. Now place the IO board over the standoffs. I used a very fine tip mechanical pencil to mark out the locations of the audio jack (1/4 inch hole) and the USB port (3/8" hole then several minutes with a square file. Once these two were done the board can go in place. I then marked the opening for the PS2 port. I currently have a 3/8" hole but I am fairly certain I will have to open that to 1/2" to allow the PS2 plugs to fully insert.

Board is not lined up in this shot. It does fit properly - I promise.

 

Nice and compact, this is mounted using the 15mm standoffs.

 

I was pleased with the final results. Connectors are as follows (top row L-R is the new stuff): stereo audio, PS2 keyboard since this contains the Dark AKI (keyboard interface), USB (onboard SIO2PC interface). Bottom row is of course, the original fully intact SIO port. Grunge is the last bits of hot melt glue left from when the machine was bolted into the EPG Jr. enclosure. Alcohol usually makes that stuff peel right off.

 

 

That's it so far! A note on getting everything to fit. I have the IO Board screwed in place and the lower shield attached to the mainboard. It will then angle down and everything just fits in place. The upper shield will not clear without modifications. It may not go back in since it appears the 1MB SIMM upgrades take a bit of space. Here is the motherboard with the ANTIC socketed, Simple Stereo board in place populated with 2 PoKeys, and IO board firmly mounted.

 

 

Excuse any spelling / grammar mistakes. It's late and I really wanted to get this posted.

 

Stephen Anderson

 

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