1MB upgrade for original 520ST...

[tjlazer]

So, I have gotten a Frontier Xtra-RAM 512K.

 

I installed it in my 520STM and I just got various yellow screens with it in place. I removed the socket inserts and saw that he socket contacts no longer work for simple PLCC DMA chip (could be pulled back into place maybe, it now occurs to me) -- so I bought another STM...

 

I tried the install this time and the system works fine with the Shifter and DMA chip inserts in place, and with the two ribbon cables attached to the Xtra-RAM board ... or with them not attached to the RAM board. However, SYSINFO shows no memory over the standard 512K on the ST. I had soldered in the ground wire to an edge tab and recently soldered in a second ground wire that the instructions suggested may be required. Still no recognizing the 512K on the board.

 

How likely is it that the RAM chips are dead? Any other ideas on this? It's upsetting that my ST is in pieces and I feel strange about zipping it back up with ribbon cables tied to nothing.

 

Some pics:

 

https://twitter.com/blakespot/status/533680289495908352

 

Any thoughts? Thanks.

 

 

 

bp

 

Sounds like it's not making contact. You will probably have to use a very small screw driver and pry the legs so they make better contact. That's the problem with these types of upgrades that wedge into the PLCC chips. They make the chip lose connection when you remove the upgrade. You can fix this like I said here, use a screw driver to push all the legs back one by one.

[blakespot]

 

Sounds like it's not making contact. You will probably have to use a very small screw driver and pry the legs so they make better contact. That's the problem with these types of upgrades that wedge into the PLCC chips. They make the chip lose connection when you remove the upgrade. You can fix this like I said here, use a screw driver to push all the legs back one by one.

 

On another board, after removing the PLCC insert, yes - I had to use a small hook to pull the contacts back and that worked. But, contact isn't the problem here.

 

On this board, I've never removed the PLCC insert -- it's still there, with the ribbon cable coming off of it. If I remove the ribbon cable from the RAM board, leaving the PLCC shim in place, the ST works fine. The ST works fine with the RAM board connected also - but just not with any more RAM than the std 512K.

 

The fact that it works fine with the PLCC shim in place and the ribbon cable not connected to the RAM board shows that it's not a contact issue.

 

For the system to be functional, signal must be passing from socket contact to shim pin to PLCC chip contact for each contact. So contact is being made.

 

That said, what are the odds that the RAM chips are bad? Is it worth buying more RAM chips before I try to replace the RAM board itself (order another kit)?

 

This is a pain in the a**, I must say. I hate seeing my ST lying there in pieces. I need to get this sorted.

 

 

bp

[blakespot]

So, what should I do here? This 520ST has been lying in pieces for nearly 3/4 of a year after attempting two different Xtra-RAM upgrade boards. After killing the PLCC socket on first ST, I replaced its motherboard and tried with a second RAM board. Neither are recognized. Contacts seem good as the ST functions, but without recognizing RAM.

 

I am reluctant to leave the PLCC shim and cable in place, removing the RAM board, and closing up shop and giving up on the upgrade, as it seems wrong to have that just hanging off the PLCC unused. I've got the RAM board soldered to ground, fwiw.

 

Do I wait for another to come along, spend another $100 and try again, maybe needing to replace the motherboard again if failure? are there other types of RAM upgrades for the 520ST that are more likely to work?

 

Note that I prefer the formfactor of the orig 520ST(M) and I've mounted a SD card drive emu inside an ext SF54 that I want to use as the A: drive -- so I am not looking to move to a 1040ST or an ST with internal boot floppy.

 

Any advice here? Frustrating having this ST in pieces on the floor.

 

https://www.flickr.com/photos/blakespot/2376515667/in/album-72157604329654261/

 

Thanks.

 

 

 

 

bp

[exxosuk]

Have you seen my site ?

 

http://www.exxoshost.co.uk/atari/last/ram/index.htm 1MB DRAM (classic upgrade STFM)

 

http://www.exxoshost.co.uk/atari/last/4mb/index.htm 1MB / 4MB SIMM Upgrade (STFM)

 

http://www.exxoshost.co.uk/atari/last/4MBMMU/index.htm 1MB/4MB PLCC (ST/F/M)

Edited June 30, 2015 by exxosuk

[Tillek]

Have you seen my site ?

 

http://www.exxoshost.co.uk/atari/last/ram/index.htm 1MB DRAM (classic upgrade STFM)

 

http://www.exxoshost.co.uk/atari/last/4mb/index.htm 1MB / 4MB SIMM Upgrade (STFM)

 

http://www.exxoshost.co.uk/atari/last/4MBMMU/index.htm 1MB/4MB PLCC (ST/F/M)

Yeah, but aren't all of those for the STFM? I think this is about the original 520ST... I know that's what I'm currently looking to upgrade.

[exxosuk]

The last link will will ST/F/M machines.

 

In fact the kit should fit any ST with a socketed MMU.

Edited July 2, 2015 by exxosuk

[tjlazer]

What did you end up doing Blakespot? Why don't you just look into buying a 1MB upgraded 520ST and keep yours as 512k and a spare machine? I have like 5 myself. One has 1MB in it (not for sale) LOL

[Bikerbob]

I have one of those aweful revision D boards.. my blitter is right at the front of the board.. so if I am going to return it all to the case etc.. after the 4mb upgrade.. I have to cut the pins and the shield.. not really looking forward to that.. mostly the pins on the board.

 

James