Upgrading 520 STFM to 1 Meg

[Wally1]

Is there a solderlesss solution?

 

the Marpet maybe?

 

 

how easy/hard to do?

 

 

will anybody do this for me, i will pay handsomely!

 

thanks!

 

[Bikerbob]

The Marpett 4mb really has no soldering. You can.. solder the 2 or 4 lines you need, but you could also use the jumper cables included.. soldering is better.. but not required.

 

Depending on the model of 520.. maybe you have sockets just waiting for you to populate them..

 

James

[Wally1]

thank you

 

what is the easy way to tell if my 520 is socketed?

[scotty]

The only way would be to open it up and look.

[Wally1]

that still doesn't help me Scotty

 

beam me up

[Zogging Hell]

The Marpet memory upgrade clips (or should I say squeezes?) over the top of MMU and under the shifter. The shifter is in the silver box in the middle of the ST motherboard (its the largest chip in there). The mmu moves about depending on motherboard revision, but is a square shaped chip (there are two or three in there depending on whether a blitter is installed). If the chip is socketed it will look like just that, a chip in a socket (the shifter mostly is, the mmu not so much), if the chip is soldered directly to the motherboard it will be a pain to add a memory upgrade. Back in those days you would get some extra sockets that would plug into the Marpet that kinda acted like an upside down socket, which would fit over the offending soldered chip. They were a bit crappy though and usually worked loose at the slightest opportunity. You usually had to glue gun them in to keep them from popping off. If the shifter is not socketed, you are buggered, unless you feel comfortable desoldering the chip and fitting a socket and a new chip (or the original if by some miracle you haven't cooked it during the desoldering) or soldering the upgrade directly onto the chip itself. It tends to be the later STFMs that are soldered (cost cutting). If you have TOS 1.04 (unless the system has been upgraded) and a late release date/ motherboard revisiion, you are more at risk of this.

 

If your chips are socketed, you simply have to orientate the one bit of the upgrade correctly over the mmu then push the pins in between the chip and the socket. This is a little hair raising the first time, and also puts some extra strain on the pins in the socket, which might make the socket a bit unreliable if you ever take the memory out. From memory the other bit for the shifter, you remove the chip, add the thru socket and then reseat the shifter, making sure the orientation is right (or fried chip results). It's not hard after you have done one, but can be little daunting for the first timer. You just need to make sure you check everything a thousand times and read the manual a lot.

 

I believe Exxos also has some memory upgrades, which are probably going to be a darn sight more reliable than some ancient simms/ memory and a marpet upgrade.

[Wally1]

yeah

 

thank you for the comprehensive response.

 

well i am pretty much all thumbs when it comes to a soldering iron sad to say.

 

oh well

 

 

 

even if my ST is socketed i prolly would mess up

Edited November 8, 2017 by Wally1

[tjlazer]

I would stay away from this type of upgrade as it is very flaky it will make your computer in inoperable

[Wally1]

now i got another problem

 

it seems my floppy and/or disks are acting up

 

 

any help or ideas?

[LoTonah]

now i got another problem

 

it seems my floppy and/or disks are acting up

 

 

any help or ideas?

 

If you have another 720Kb drive to test with, do that first. If it doesn't work either, it means you have a blown FDC chip. Silver lining: if that is the case you can buy a better one that would allow for 1.44Mb drives.

[Wally1]

buy another ST?

 

is that what you mean?

 

i do have another floppy drive which would mean opening up the ST i have now.

 

hopefully the FDC chip is alright.

 

 

i can describe better what is happening: sometimes i get a white screen and it boots up in about 5 seconds. but this

is only about 1 out of every 5 tries. other times the screen stays black

and does not boot up at all. when it does boot up i can hear a whirring

sound like it used to make when i first bought the computer which was not too long ago.

 

 

thanks

[Zogging Hell]

I would stay away from this type of upgrade as it is very flaky it will make your computer in inoperable

 

That's a bit harsh, I've had them in several STs for years without any problems at all, overall I would say they are pretty solid if they are installed correctly (and don't want to run any other upgrades like a speed booster)

 

The only one I had problems with was the fit socket over the soldered MMU type. One literally popped off after some time, killing itself.

[Bikerbob]

If you turn it on with no disk in the drive at all? Do you get the exact same thing? 1 in 5 works?

 

This does not sound like the drive - if you get it to boot .. does everything then work? access etc.. ?

 

This is more sounding like a PSU issue.. old computer the PSU is the first thing that normally begins to go bad. .. Unfortunately.. this also means opening up the computer.

 

James

[Wally1]

hmm i gotta check that

 

bootup with no disk

 

i will see

[Wally1]

yeah i athink youre right

 

 

how do i replace the PSU?

[Zogging Hell]

It (the PSU) is held in by two to fours screws on motherboard, if you open the case up and remove the top metal shielding (this is held in place by a mixture of screws and metal tabs - which you need to twist straight with some pliers) you will see the psu at the back left. The screws holding it in place are on the feet of the metal 'stand' the PSU sits on. Undo these and then unplug the power cable from PSU to the motherboard (AT style plug). The PSU can then be removed by some gentle manoeuvring, although it is a bit tricky as it will not like coming out at the back where the PSU external power lead and power switch go through the case - it can be done however, just don't force anything. To make this easy you can remove the whole motherboard but that can be more faff. You then simply reverse the procedure to put the new one in.