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xrbrevin

400 32k RAM board help needed

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I am trying to revive an aftermarket 32k RAM board for my 400. It is the type that uses 16x 4116 DRAMs.

I desoldered and socketed all the chips and found 1x 4116 chip was at fault. My TL866 EPROM programmer says that all the 74LS chips are good but the board still fails to boot. As these PCBs are not the best quality, I'm wondering if I lifted a track that would need to be bridged.

 

Does anyone have a schematic diagram for a 16x 4116 chip type 32k board? I need to do continuity checks across the DRAM pins but i could do with some knowledge before I commence.

Thanks in advance!

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On 9/21/2020 at 1:11 PM, ClausB said:

Some 32K boards aren't meant to work in a 400:

https://atariage.com/forums/topic/177885-atari-800-ram-selection/?do=findComment&comment=2225206

 

I have an Axlon RAM-CRAM for my 400 and a schematic I could photograph.

thanks for the response. if you could upload the schematic that would be great.

I am aware that a number of DRAM pins are common between the whole group but some are not. Id just like to be as clued as poss before getting the multimeter out

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One with daylight instead of flash, and unyellowed. The original is an actual blueprint that has yellowed.

IMG_20200924_152439.thumb.jpg.3413b22fc66229935ddd20fb52c2f482.jpg

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11 hours ago, ClausB said:

One with daylight instead of flash, and unyellowed. The original is an actual blueprint that has yellowed.

IMG_20200924_152439.thumb.jpg.3413b22fc66229935ddd20fb52c2f482.jpg

Maybe try retr0brighting it 🤣

  • Haha 2

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