sideburn

Here’s some photos of the board and ram expansion

Ok so my full expansion showed up once in sysinfo. But my screen was going wonky so i re seated my chips. After reseating the TOS roms, the screen was all good but I lost the ram expansion. so TOS is not seeing the ram now. I will post a photo today.

Would that cause the CAS lines to stay high? Any way to figure out which ones are bad? And it’s a full 512 that’s not showing up. Both CAS low and high.

I got a new done 520 ST board and swapped all of the socked chips to the problem board and no change. So The MMU is good. Any ideas what else might be holding CAS1H and CAS1L high?

I have not but both drives fail the same and I did apply pressure to the head and moved the disk around to see if I get any kind of signs of life and no luck. Then out of the blue it will suddenly start working flawlessly and you can copy a disk or two or three and then back to fail. I think I’ve got to go through the service manual in detail and try to start probing areas with the schematic. But no idea where to start really…

I’ve swapped all the socketed chips and done a full recapping.

Yes the problem is I’ve reflowed all over and deoxit rd sockets and header and freeze sprayed and it makes no difference. It just has a kind of its own you never know when it decides to start working. But it hasn’t in awhile now. Last time I powered up the head stepper only went forward. Now that’s working properly but reading still hasn’t worked in a while now.

I just made a video clip while it is NOT having an issue initializing to track zero and still having a read fail: https://youtube.com/shorts/-B40Y8Lfpow?feature=share does this rule the track zero sensors? Same result on both drives but same logic board.

I was wondering if it might be this. But when it does start working and returning to track zero it still doesn’t read fro the disk intermittently. If it powered up and initializes properly it’s still a roll of the dice if it’s going to read the disk. I’ve also swapped drives out and have the same issue so it must be something on the board.

it’s neither. I swapped them out.

Yes I checked direct of the mmu.

Ah ok that’s what I was suspecting. That’s going to be hard to find.

I tried removing the drivers from the hard drive. But didn’t try the icd pro driver. I’m afraid to plug the US back into the STacy at this point. When I just plug the US connector in and keep the US turned off the internal drive is gone. Wgeb I power up with the US on, the internal drive starts making weird noises and spinning down and spinning up in a loop and then I unplug the US and pray that the internal drive will come back up. it continues to spin up and down like it’s dead. it takes several reboots and booting from a floppy and eventually the drive comes back to life and then it’s stable again like nothing happened. It’s very strange. it’s like the US punches the drive in the face and knocks it out and it goes unconscious. And then after 20 minutes of CPR its heart starts beating again and you dodged a bullet. it’s done this about 4 times now each time I’ve plugged the US in. Now I don’t want to push my luck.

Correct. The resistors are there. RAS1 is oscillating but CAS is stuck high. Trying to figure out why. Who’s in charge of driving the CAS lines low? Also I just noticed the video is good on the monochrome monitor but it’s out of sync on the color monitor. Not sure if that’s related.

I’m using the test boot image that has the PP driver. Here:https://lotharek.pl/productdetail.php?id=48 on the faq tab for troubleshooting. And it’s loading ok on the Atari 520 st. and I was able to use the config app for it and change the drive ID’s to 1 and 2 using the 520 ST. that made no difference on the STacy 2. yeah when I take the STacy apart I’ll try disconnecting the drive. It’s just strange to me that I cannot have multiple drives on tge STacy. I mean what’s the external hard drive port for then?!

Yeah it seems like it’s dying but once it comes back it’s rock solid again. Strange. I have to open the machine up and fix or replace the keyboard and possibly swap the lcd out. When that happens I can try disconnecting the drive. Probly best to swap drive with the US.

Hello all, i just pulled out and fired up my 520ST I had back in the early 90s and to my surprise it booted up! I cracked it open and saw that it’s got the piggy back extra 512K expansion bringing it to 1M. the problem is the upper expanded bank is not active. It was ONCE and I saw it was all there in sysinfo but it was flakey and the screen was going crazy if touched the board. so I pulled the Roms and sprayed with deoxit and reseated them and that problem went away but now the machine only sees 512K (238K available). Ram test is passing with no errors. so I put the oscilloscope on the RAS1 and CAS1L and CAS1H lines and I do see activity on RAS1 but both of the CAS1 lines are stuck high. on power up I see both CAS1 lines go low real quick and then back to high. any ideas what could be holding them high? could it be the 74LS latches? Or is all control of those pins handled by the MMU alone making it look like the MMU is bad?

Well I cannot get the Ultrasatan to work on the STacy. I created a new disk image and sd card and connected the US to my atari 520 ST and it comes up on there but intermittently. i have to reboot several times and then it will show up eventually. I then ran config and changed the id’s to 1 and 2 instead of zero and 1. I plugged the US into the stacy and then the machine boots to a blank desktop. my internal drive nor the US show up. And then my internal drive starts spinning up and shutting down in a loop and never shows back up and i disconnect everything and my internal drive doesn’t come up.. just keeps powering down and back up..I then start to panic and try booting from floppies and see if the drive mounts and no luck... eventually after 10 minutes or so my internal drive starts working again. I hope the Ultrasatan has not done permanent damage to my Stacy. -Tavis

That’s why I’m a little worried because things are behaving differently. Before I could get the US to mount using a bootable floppy and trashing then driver the hard disk so it didn’t autoboot. also hard disk started spinning up and down in a loop and making sketchy sounds while I was playing with that method. I thought I killed it a couple times but managed to get it to show back up when booting from floppy and copied the shddriver.sys file back to the root and stopped messing around. everything is back to normal now it seems.

yikes the config tool readme... VERY ACSI device must have UNIQUE ACSI ID! Two devices CAN'T have the same ACSI IDs. If you setup two devices on ACSI bus with the same IDs, they might get damaged! This may be why its behaving different now and wont even mount anymore. I hope I didn't damage my internal hard drive. The problem now is the config tool is an ST program ( US_CONF.PRG)... I cant config the drive without it being mounted. check / egg syndrome.

SO the DMA port on the STacy is sharing the same bus as the internal ACSI/SCSI hard drive? Im scouring the internet trying to confirm this.

I think it is conflicting with my internal hard drive and i just got lucky the one time it did mount. I think the Ultrasatan is using ID:0 and ID:1 on the SCSI chain and my internal is probably on ID:0 I don't know enough yet but thats my hunch... That would explain why my internal drive is disappearing when I turn the US on.

Now nothing works.. Cant get the disk to mount with a floppy or not. I bought THAT SD card because its supposed to be ready to go.. Oh well guess I will have to buy some drivers and try to build an sd card from scratch. Is it possible to have both the internal drive and the ultrasatan drive mounted at the same time? Its starting to look Like I can have one or the other, and maybe the fact that I have an internal drive is causing the problem?

I saw this but the sd card is supposed to have the drivers installed as it says here-- " Driver : PERA PUTNIK drivers DEMO VERSION /6 partitions, some games and demos/ (since September 25th 2019) "

I just dragged my 520st i had in the 80s out of the closet to test, repair, restore and the rocker switch is also frozen. Must be a common occurrence?