ST/F/M MEGA ST 4MB MEMORY UPGRADE [0035]

[WilsonB]

OK, looking really close it appears that pins are on outside.
Just verifying.

mmu2 official.jpg

[rubber_jonnie]

Yes, the pins go on the outside.

I'd also recommend removing the mainboard from the case and placing it on a piece of cardboard on a flat surface when inserting the MMU adapter. If you leave the board in the case it can flex as you insert the adapter and cause mechanical damage to the PCB such as broken vias or cracked solder joints.

It isn't something that happens a lot (I've had it happen once) but it does remove the risk since it requires quite a bit of force to insert the adapter.

I'd also suggest you tweak all the pins in the MMU socket to ensure good contact with the MMU prior to installing, plus give a squirt of contact cleaner around the sockets top edge where the pins go in as it will make insertion much easier.

[WilsonB]

Thank you..
Good advice about inserting/pressing in on a solid surface, makes sense.
Will re-do and use contact cleaner. When you say "Tweak" Pins, what do you mean?

It's great when it works..
BUT :evil:
I am constantly having issues and have to press the 3 corners to get it working again. So I know it's a connection.
Iv'e had to mess with it so much that Im almost willing to solder each wire directly to the 3 MMU sides/pins

ANYONE- Know of an alternative method for the long term?

[WilsonB]

AFter looking I found this GREAT article that looks like a good plan of action.
@rubber_jonnie Thanks!

Will take my time and bring pins out level with others, Tuner wash, and might even consider 'Tinting' each pin w/ solder for better conductivity.

viewtopic.php?f=17&t=1484&hilit=PLCC

[rubber_jonnie]

AFter looking I found this GREAT article that looks like a good plan of action.
@rubber_jonnie Thanks!

Will take my time and bring pins out level with others, Tuner wash, and might even consider 'Tinting' each pin w/ solder for better conductivity.

viewtopic.php?f=17&t=1484&hilit=PLCC

It is a great article isn't it :dualthumbup: (I would say that wouldn't I :) )

I'd suggest you don't add any solder, the tolerances on the pins of the MMU adapter are very tight in the socket and even a small amount of solder may prevent it from pushing in.

Also, the MMU adapter pins transmit heat very quickly so you risk them moving out of alignment.

Have you tried spraying contact cleaner on the socket before inserting the MMU adapter? It will help lubricate and clean on the same time and make it a little easier to insert.

[WilsonB]

:evil:
I believe I have a defective Exxos memory hat module now.
@exxos
It was working (intermittently) , would press down on Memory upgrade on MMU and would come back.
Got tired of having to do it everyday ,

Now I think something is wrong with it.

Went through everything over the weekend.
Pulled pins out of MMU socket, Contact cleaned socket pins & MMU chip pins, cleaned each pin , put MMU pack in , works.
Put Exxos Memory daughter board in.
Made sure pins are lined up.
Tested each pin from bottom of MMU socket (bottom of Atari PC board) to Top pins of the EXXos memory board, all tone out.

However, now getting this no matter what..

474608140_1329836768049175_2258272080793704139_n.jpg

474749504_1851473219005360_1709964117161647250_n.jpg

[exxos]

They are all tested before they are sent out. So the item being faulty is highly unlikely. You can return for a retest and repair if you like.

Looking though this thread quickly, looks like you have other upgrades installed which need to be removed before proper testing. I can't tell but looks like you haven't recapped your PSU or removed the old RAM. Most people have troubles with the shifter board adapter with bad connections. You never seem to consider that board or cleaning the cable itself. Repeatedly pushing down on the RAM board isn't going to help either. You can weaken the solder joints on the PCB where the pins are soldered in as the pins are small.

To me, it looks like as you have banks (blank lines) missing on the RAM test pattern, so you likely have issues relating to the ribbon cable as that is where the datalines are passed from the shifter adapter to the MMU RAM board. Its difficult to tell where the faults are unless you have the diagnostic cartridge as it tells you bad bits to look for.

[rubber_jonnie]

I'd second what @exxos said about repeatedly pushing on the MMU adapter, it's certainly feasible that the fine pitch pins now have bad joints from pushing in and out multiple times, and I have even once bent a pin on one of these. It went on to be fine but it is tricky.

What you're seeing is definitely a memory issue, but by the same token it is likely to be a connection issue.

Also, can you add a picture of the fitted adapter showing how far it is inserted into the socket and how you've disabled the original RAM.

I would add that I know these are tested before being sent out and I have fitted quite a few with no issues.

[WilsonB]

They are all tested before they are sent out. So the item being faulty is highly unlikely. You can return for a retest and repair if you like.

Looking though this thread quickly, looks like you have other upgrades installed which need to be removed before proper testing. I can't tell but looks like you haven't recapped your PSU or removed the old RAM. Most people have troubles with the shifter board adapter with bad connections. You never seem to consider that board or cleaning the cable itself. Repeatedly pushing down on the RAM board isn't going to help either. You can weaken the solder joints on the PCB where the pins are soldered in as the pins are small.

To me, it looks like as you have banks (blank lines) missing on the RAM test pattern, so you likely have issues relating to the ribbon cable as that is where the datalines are passed from the shifter adapter to the MMU RAM board. Its difficult to tell where the faults are unless you have the diagnostic cartridge as it tells you bad bits to look for.

Thank you for the reply.
I have recapped the caps in the PSU.
I removed ALL additional mods and it is back to vanilla.

The Ribbon cable is a possibility since it did look crimped.
Please suggest a ribbon replacement and will try that first. Shipping across the ocean is not my first option.

Thank you

[exxos]

Please suggest a ribbon replacement and will try that first. Shipping across the ocean is not my first option.

They are FFC / FPC cables, 1.0mm, 150mm (or 200mm) , Same Side contact, 16P.