7800 chip indentification - help needed

[birdie3]

I am attempting to trouble shoot a problem with my socketed 7800 motherboard and I am not sure which chip is which. Can anyone assist me with identifying all of the chips on the motherboard? Thanks in advance.

Edited November 1, 2007 by birdie3

[birdie3]

Anybody?

[birdie3]

Thread topic changed. Thanks again!!

[ninermaniac]

I guess were all not to mechanically inclined. I had a similar conendrum awhile back. Couldn't get help either.

[DanBoris]

I guess were all not to mechanically inclined. I had a similar conendrum awhile back. Couldn't get help either.

 

I could do this, but I don't have easy access to a 7800 right now. If someone could provide a high resolution image of the PCB I could identify the chips.

 

Dan

[birdie3]

Here we go.. Kinda low res but hopefully should be OK. Thanks.

[krupkaj]

sorry, but it is not possible to read texts on chips. Unfortunately my 7800 is totataly different. I gues the biggest chip is MARIA.

[mimo]

This may help

http://www.atari7800.org/schematic.htm

[+Mitch]

This is a little crude but looking at that picture the large IC's are laid out like this:

 

		 RAM
	 RAM
	 BIOS
Maria	TIA
6502	 6532

 

Mitch

[DanBoris]

Yeah, the numbers on the chips aren't readable in that pic, but I dug out one of my 7800's:

 

The major chips are

 

Left side

 

CO25349-30 (MARIA) - Handles graphics in 7800 mode, and clock generation and address decoding in both modes.

CO14806C-29 (CPU) - Atari's version of the 6502 CPU

 

 

Middle column

 

6116L-5 (RAM) - 2K x 8bit static RAM, only used in 7800 mode

6116L-5 (RAM) - 2K x 8bit static RAM, only used in 7800 mode

 

BIOS ROM - Used for boot up

 

CO10444D-01 (TIA) - Graphics in 2600 mode, Sound and fire buttons in both modes

 

6532 (RIOT) - RAM and Timer in 2600 mode, Joystick direction, difficulty switches, pause, select, and reset switched in both modes.

 

Dan

[birdie3]

OK. I have made some progress with my issue. If anyone is interested you can also read about it in the Hardware section in this thread:

 

http://www.atariage.com/forums/index.php?s...p;#entry1400978

 

At this point, there are two issues. One being that the console upon start up will quite often bypass the Atari intro/logo screen and boot up a game with garbled and wavy/rolling graphics. The other issue is that there are some games (like 7800 Commando and 7800 Xevious) that have no fire button response with stock Atari 7800 joypads while all 2600 games and games like 7800 Joust have full response with the joypads.

 

Any help with figuring this out and how to fix it is greatly appreciated. Thanks again!!

[Shawn]

OK. I have made some progress with my issue. If anyone is interested you can also read about it in the Hardware section in this thread:

 

http://www.atariage.com/forums/index.php?s...p;#entry1400978

 

At this point, there are two issues. One being that the console upon start up will quite often bypass the Atari intro/logo screen and boot up a game with garbled and wavy/rolling graphics. The other issue is that there are some games (like 7800 Commando and 7800 Xevious) that have no fire button response with stock Atari 7800 joypads while all 2600 games and games like 7800 Joust have full response with the joypads.

 

Any help with figuring this out and how to fix it is greatly appreciated. Thanks again!!

 

 

Sounds like you need to fix the controller ports as there is a dead conection there somewhere. Also you best clean your contacts on the cart connector as it sounds alot like the 4 end pins on the left and right might not be clean.

[birdie3]

Sounds like you need to fix the controller ports as there is a dead conection there somewhere. Also you best clean your contacts on the cart connector as it sounds alot like the 4 end pins on the left and right might not be clean.

 

The strange part is that the controller ports have always worked fine up until last night. This controller button issue is a totally new problem. I did notice that I scraped a couple of the circuit leads on the PCB from the under RIOT chip socket when I was removing it with a flat head from it's socket. Perhaps I buggered up the lead that connects the controller buttons.

 

What do the four end pins on the connector do? I have tried removing the plastic housing around the connector but it seems to be attached pretty good to the board. I assume that the connector is attached directly to this housing and I would have to de-solder the connector to get it off.