Upgrade 3640 to 060?

[RedDaemonFox]

Is it possible? I just got one, free, in rough shape, verifying i need the cap fix. for future reference, can I add a voltage regulator and pop an 060 in place of the 040? Or does the logic chips inhibit this or I need more parts? I need to know if I should buy the parts or not.

 

[Zetr0]

@Dreamy

the A3640 does not have enough signal lines to drive an 060 chip, infact before we even get to the hard/CPLD logic on the card.

to verify if you need the cap fix -

look at the capacitors, IF the BLACK stripe / Mark is in the "-" / negative position, then yes you do.

As you may know the silk mask is wrong on the A3640's I think all of them, even revision 3.2 which is a 3.1... long story....

 

[RedDaemonFox]

Dang it, why Commodore must you continue to F**K us up even after your demise. My card is a 3.1, and I can tell you that the caps wrong and yes, I know the mask was/is wrong. I got it for free, so i'm happy. Unfortunately, i have not the funds to fix it currently, nor a hot gun and flux, just a cheap copper soldering iron from radio shack and some silver solder . That may change with xmas around the bend, however. Right now i have a 33mhz lc where a burned out 25 rc was, will have to source a set of gold DIL sockets and an 80mhz crystal for a planned MC040RC40.

 

[MagerValp]

Unfortunately, i have not the funds to fix it currently, nor a hot gun and flux, just a cheap copper soldering iron from radio shack and some silver solder.

You don't need any special tools to replace the caps. Take a pair of pliers and gently crush the caps a few times, then you can lift them straight up leaving just the legs. The legs are easy to desolder with a regular soldering iron once they're exposed, just heat them quickly and push them aside.

 

[RedDaemonFox]

Well, digging into this subject some more, i found schematics of the 3640 on serveftp. not very good quality, but maybe one day since this board is more simple than a ppc card, I can make a (corrected) gerber file and improve upon it, such as adding firmware for the aforementioned 060 and the necessary signal and voltage lines. But getting back to topic, do i need a new crystal to run the 040 at 33 mhz? I'd guess so, a 66mhz one since it halves the clock signal. And also, where can one find the appropriate caps? Maybe radio shack has them, I'll check for next time.

 

[Kin Hell]

@ Dreamy

On your Rev 3.1 A3640 040 card, look at the Chip silk screened with U209 on the PCB. It should be top left area with the CPU connector nearest to you. There should be a label on the CHIP itself & will end with "-02".
If it ends with "-03", then whilst the card edge is Silk Screened 3.1, it is in fact a Rev 3.2!

Anthony Hoffman has spare caps & has an article here. Linky

And yes, You're right RE the Xtal speed being halved. Not all 040's will clock as far as some. It's all about binned speeds m8.

Kin

 

[rkauer]

Hardly you'll see an A3640 running at 40MHz, some of them run at 28MHz, others goes as far as 32 (but not 33), a very few accept the "insane" clock of 37MHz...

BTW: you to perform a little in the board: cut a trace and add a wire link to pass through a delay line in order to the board work over the original 25MHz.

 

[Kin Hell]

@ rkauer

*cough*

- I had a Rev 3.1 (-02) that did 33Mhz back in '92.

I sent the 66Mhz Xtal I used on that card to Arnljot a while back.

Kin

 

[rkauer]

As I said, more FEW boards pass the 33MHz barrier. You get luck.

 

[Kin Hell]

But also rkauer...no MOD as you suggest. De-soldered the 50Mhz Xtal; Solder in some flush sockets; Play with Xtals & 66Mhz was FPU Ray Tracing Stable.

Unfortunately, Anljot had no success with his A3640. :|

Kin

 

[arnljot]

@Kin

That's right. Anthony upgraded it to 3.2 and replaced all caps. But could not get it to run stable at anything else than its native 25mhz. So it turned out that I have just normal sized boing balls. (ref: Q:Commodore A3640 tinkering - Watch out I have boing balls!)

 

[RedDaemonFox]

Anthony's guide calls for solder paste, which I can't get here. Can I just suck the old solder off the SMD pads, add some flux, and just add solder back to the pad? Also, a few questions:

What type of tip should I use? I have several "pencil" style tips and several flat blade style

Are all silkscreens on all 3.1s wrong? Because the caps would've been in the correct polarity at C106 and C107, but they all have some leaking issues.

 

[arnljot]

Yes I think all silk screens are wrong. Anthony posts on this both on a.org and on his site.

 

[MagerValp]

I recommend grabbing a few VGA or audio cards with SMD caps and practice desoldering them first, if you're feeling unsure. Try the squish-with-pliers method, it's much easier than the "correct" method (like Anthony's). Whatever works...