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 Post subject: The fix may be in for 8mbit problems.
PostPosted: Sat Dec 13, 2003 2:21 am 
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Joined: Tue Aug 05, 2003 9:55 am
Posts: 1035
Location: Cleveland, Ohio
I finally had more than a few minutes to sit down and really look at the 8mbit carts and XEGS that were sent in.

There appear to be 2 seperate problems with the 8mbit cartridges.

The first problem is easy enough to fix. There is a bug in the current flash code that prevents 8mbit carts from erasing/programming correctly on some systems.

This shows up as a failed erase or program, with the cart being seen as 4mbit shortly after programming. I will be uploading a new maxflash kit to fix this problem.

The second problem. For my own testing I had been using a large variety of computers but only a few power supplies. It appears that various combinations of computers and power supplies end up producing a large amount of power supply noise on the cartridge while it runs. This is not a problem for most carts, but the PLDs used in the flash carts are more sensitive to noise and use a lot more power than the proms/eproms in regular carts.

This seems to be less problem on 400/800 systems that have really good rectifier/filter systems built in. The worse combinations seem to be 130XE and XEGS systems with the black 'brick' power units or expansions that are also drawing extra power.

Fortunatly the cartridges that are already out can be fixed by adding a filter capacitor to the pcb. There is a layout on both the 1mbit and 8mbit cartridge boards for it, so adding it is not hard.

I have created a burn-in/diagnostic software package for the flash cartridge. I will be uploading it in a seperate message along with instructions on how to exchange your cart for a fixed one, or how to apply the fix yourself.

Steve


Last edited by classics on Sat Dec 13, 2003 3:09 am, edited 1 time in total.

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 Post subject: How to exchange/fix your cartridges.
PostPosted: Sat Dec 13, 2003 2:50 am 
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Joined: Tue Aug 05, 2003 9:55 am
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Location: Cleveland, Ohio
If you have problems with programming or playing your 8mbit cartridge in some or all systems you can do the following.

1) Return it for a free exchange.

E-mail classics@atarimax.com or PM me here and I will send you my address for the exchange. If you send only the cartridge it should cost $1 or so for First Class Mail.

2) Add a filter capacitor to the cartridge yourself.

If you can get your cartridge open without damaging the shell (some are hard to open, grrrr) and are handy with a soldering iron follow these instructions to apply the fix to your cartridge.

Note that the PLDs used in the flash cartridges are static sensitive devices. Do not solder on the cartridge while it is attached to the Atari or any other low resistance path to ground.

A] Open the case and remove the PCB. The black cartridge cases used are the OSS style cases with 4 pegs. These are brand new cases, so some are very hard to get open the first time.

If you have any fear you will damage the casing trying to get it open, or it seems like it just wont come open, please send it in for an exchange instead.

B] Turn the board over so the side with the PLCC chip sockets is facing up.

C] Locate the empty layout shown in picture #1. It is at the very top edge of the PCB in the center. There is a silkscreen glyph that looks like this between the pads

---[____]---

D] In this location, solder a small electrolytic capacitor, leaving enough leads sticking out so that the capacitor can lay flat. There is not enough clearance in the cartridge case to install it upright.

The (+) lead of the capacitor should to the to pad on the left, the marked (-) lead to the pad on the right.

10uf and 22uf are common values that come in small sizes, they work well. If you dont have one on hand, a few Radio Shack part numbers that should work are:

272-1025: $0.99 (10uf 35v Electrolytic Capacitor)
272-1026: $0.99 (22uf 35v Electrolytic Capacitor)

Larger farad values will work but may not fit in the cartridge casing.

After installing the capacitor, re-assemble the cartridge and re-run the diagnostic tests.


Last edited by classics on Sat Dec 13, 2003 3:20 am, edited 2 times in total.

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 Post subject:
PostPosted: Sat Dec 13, 2003 3:05 am 
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Location: Cleveland, Ohio
Before fix, location to install capacitor.


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 Post subject:
PostPosted: Sat Dec 13, 2003 3:05 am 
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Joined: Tue Aug 05, 2003 9:55 am
Posts: 1035
Location: Cleveland, Ohio
After fix.


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