exxos's Atari, Amiga & retro forum

After sitting on my hands for a while - I have committed to begin assembling the collected parts. I have been examining the bare board for a few hours now and comparing it to the sockets and chips and I have some questions:

I AM A COMPLETE NOOB - WITH THICK SKIN - IF I SHOULD ABORT - DON'T HESITATE TO TELL ME :lol:

1. Is there a comprehensive build guide that I am missing somewhere? I have attempted to find one but not having success.

2. MFP 68901 - I bought a 52 pin socket off the "BOM" (or lack thereof) which is SMD. Lines up with none of the markings on the board. I am ordering https://www.digikey.com/en/products/det ... =379683010 now which I think is correct?

3. RESET (IC22) (STM6315RBW13F) confirming orientation on this chip.
Under magnification I see one leg is "wider". Datasheet shows that as Pin 1 (ground). Multimeter on the H5 shows shows bottom right pad is connected to ground plane - assuming this is Pin 1 connect point?
Pin 1 VSS Ground
Pin 2 RST Active-low open drain reset output
Pin 3 MR Manual reset input
Pin 4 VCC Supply Voltage

I've soldered the DAC and MAX238 and I don't see any bridging under magnification.

Slow but steady wins the race.

That ENIG coating is a pain to solder to, so don't rush soldering as it may seem to have soldered if you do it quickly but I guarantee you'd have a few unsoldered joints on just about every chip.

Have a good look at the fixes for the B1 before you do too much and don't fit the ACSI port without doing the fix or the floppy won't work IIRC.

Other than that, make sure all donor chips have had a good clean before you try and use them. Don't be afraid to ask for advice and if you come to a bit that you think might be beyond your abilities then there's a good chance it is.

Good luck.

@PhilC thanks. To be honest, I think this is over my head. I've practiced a LOT of through hole and limited bits of surface mount soldering before attempting but - I seriously considered stopping after the difficulty I had on those two surface mount chips. I replaced a few 68000, Kickstart and Denise sockets in machines that work now - but this is a lot.

I guess what I need to know is would it be better to just find someone to take over because I doubt anyone will want to troubleshoot this if I screw it up/run into problems?

Hello, I have the same board.

officer960 wrote: 18 Oct 2021 00:40 1. Is there a comprehensive build guide that I am missing somewhere? I have attempted to find one but not having success.

I am not aware of a step-by-step-noob-proof building guide. You may look at my own thread as I am very slow at building things, and be aware that I did a contraption of pin sockets on some PLCC sockets because I initially fancied using fpgas on them, so you will be good with just soldering normal PLCC sockets directly : https://www.exxosforum.co.uk/forum/viewt ... 100&t=3903

So far, I only have overlooked one pin header, you should look at the picture by @exxos showing the extension port that is meant for flashy clock (if you intend to get one later) here : https://www.exxosforum.co.uk/forum/viewt ... 486#p67368 (the first pic entitled 'FLASHY CLOCK HEADERS'). I just brigdged the two holes that should be bridged under the DIP64 socket.

officer960 wrote: 18 Oct 2021 00:40 2. MFP 68901 - I bought a 52 pin socket off the "BOM" (or lack thereof) which is SMD. Lines up with none of the markings on the board. I am ordering https://www.digikey.com/en/products/det ... =379683010 now which I think is correct?

Seems correct to me

officer960 wrote: 18 Oct 2021 00:40 3. RESET (IC22) (STM6315RBW13F) confirming orientation on this chip.
Under magnification I see one leg is "wider". Datasheet shows that as Pin 1 (ground). Multimeter on the H5 shows shows bottom right pad is connected to ground plane - assuming this is Pin 1 connect point?
Pin 1 VSS Ground
Pin 2 RST Active-low open drain reset output
Pin 3 MR Manual reset input
Pin 4 VCC Supply Voltage

Fortunately, I did not throws my notes about this damned chip.


I also struggled to find pin #1 until I noticed the pin that was wider than the others.

PhilC wrote: 18 Oct 2021 00:54 That ENIG coating is a pain to solder to, so don't rush soldering as it may seem to have soldered if you do it quickly but I guarantee you'd have a few unsoldered joints on just about every chip.

Personally, I attribute my struggles to the lead-free solder (a SAC blend). Because when I worked with leaded solder on my lynx or my STe, I could see how solder was flowing easily.

After searching for tips, I found this document, and basically understood that I had to go more slowly.

These days, I count (approximatively the same time as "one mississipi two mississipi etc...") and my cycle is as follow :

• at "1", i put the soldering tip (with a little bit of solder for better head conduction) on the pin and the pad
• at "4", in a swift move, I put the solder lead to add enough solder, then I take away the lead
• just before "8", I remove the soldering tip from the correction, it cool downs after 1 seconds, and I go to the next pad.

This works nicelly for me, excepts for pins linked to the ground, that I still have struggle with. I attribute that to my cheap 25W soldering iron that cannot maintain heat properly at such pins, especially with a conic tip. I plan to upgrade this tool soon.

@sporniket thanks for the info and links. I had previously been following several builds, including yours. Was wondering what you were doing with those pin sockets in place of PLCC - now I know. :lol:

I installed several of the sockets, reset switch, battery holder and some odds and ends. Next is the PLCC sockets, but will probably start that tomorrow. I went extremely slow on the soldering to ensure there was a good bond between the pins and the through holes on each pin - fingers crossed - but I was meticulous.

On IC9 DS1315 (Phantom Time Chip from Maxim) found @DoG 's mention that:

EDIT2: If you don't have a DS1315 you need to jumper pin 10 and 11. It should be marked with a square on the board.

Was trying to figure out what the box around those pins was!