Atarisrule

It's been a while but I recall using a very small screwdriver to pry up each side a little at a time until it could be wiggled out.

I ordered one from Best Electronics this morning. If that falls through I'll take you up on the offer. I had some other stuff to order anyway so this took me over the minimum shipping threshold.

Solved! One by one okay except the last. The WD2793PL-02 chip is bad. It killed the good drive and the replacement woke up the bad drive. Now to source one. Any ideas? The chip sources I have links to do not show this chip, or at least not by this number. Is there an Atari number for this? It is the 40 pin chip all the way to the left. Edit: I see this is the Atari FC100542 and Best has it for $15.95. Does anyone have a spare from a dead drive?

What jumpers? I will swap chips and see what happens.

Correct. With no SIO connection to anything, just powering on the drive it does nothing but turn on the power LED. It should cycle the head and drive but there is no activity at all. Whatever circuit is supposed to tell the drive to do that is not functioning or is blocked.

Thanks for the idea. Unfortunately no change though.

A little more info. Random checks throughout the main board show correct voltages. Also I have 12V in both red wires of J15 going to the drive body. Still no activity light. No feedback to the computer.

The drive powers on but does nothing. When switched on the lower red switch light comes on but the upper "activity" light never comes on and the drive never moves. I have another 1050 that does work great so I know what it should be doing. Also the computer never recognizes the drive is there if it's hooked up - I just get the Memo Pad. Not so with the good drive - it talks perfectly with the computer. I've read through all the posts I could find and did some work on the drive, but nothing seems to have worked. I've replaced the two rectifier diodes and the three large caps and the two small ones below them. The regulators are putting out 5V and 12V like they should from the right hand pin so I didn't replace them. Nothing gets really hot or anything, but I did notice the heat sink/shield that the regs are attached to did warm up when I had the power supply attached. So, short of throwing this to the parts bin, what else can I try? It's starting to cost more than it's worth just in repair parts.

Okay, so it can do more. However in my otherwise unmodified 800 is there at benefit? Processng speed or 64K (vs. 48K currently)? I do have an open memory slot (one board is 32k) but to my knowledge the system will not recognize anything over 48K. If it's an easy mod I might consider it.

I saw that ad earlier. I assume it has a Synertek 6502B on it. What is the 65C802 and why would I use it instead? I'm sure this has been widely discussed so maybe you could point me to a thread summarize here? Note that my good CPU board has a 6502A and the bad has a MOS C01437705.

I swapped the CPU board and it seems to have fixed it. Lots of programs that would not load or glitched are now functioning normally. I'm not sure which of the three is bad but a replacement assembled board should not be hard to find.

Thanks for the replies. The problem did NOT follow the ROM board. I used the same ROM boad when I tried it on the other computer that did not exhibit the fault. I thought it might be the POKEY also since it controls I/O, but on the Atari there are no on-board drive controllers so I have my doubts. I'll have to swap the CPU board today and see what happens. If that doesn't do it I'll try the Pokey chip.

I'm working on some 800's and thought I had one all buttoned up, but on the final check I found it was not loading disks all the way to DOS. It will load to Basic then load DOS but stops (locked up) every time at "Disk Operating Sys" on the top line. This is consistent on every regular DOS disk and on three drives, an 810, 1050 and IndusGT. I loaded OS/A+ to see what happens and it loads to D1: no problem but when entering DIR sometimes it completes the task and other times maybe one or half of the files list before lockup. These same disks and drives work just fine on another 800 using the same OS board. I can swap parts to see what's wrong but I hope someone has an idea which component could be causing this. It seems to forget to ask for all the info from the drive or locks up before finishing. The "boop" sounds just stop. Note I did try each of the RAM modules independently and there was no change in the random directory behavior or consistent DOS behavior. Also with no Basic cartridge and loading straight to DOS it also stops at "Disk Operating Sys". This must be one sector of data and it fails to ask for more. CPU? ANTIC? GTIA? POKEY? Other?