Three Sparrow Mainboards on EBay

[mikro]

Hmm... as I was replacing the CPU I have noticed that I actually didn't push it that far in the socket (you know how it is -- Falcon motherboard is synonymous for fragile, for Sparrow motherboard is like a castle made of matches). So I'm like OK, let's play hard... I could hear the click, yes... replaced all the stuff again, switch on...

... I could see the same screen for a second and then ...

BOOOM, IT FREAKING WORKS !!!

IMG_20180826_181623.jpg

IMG_20180826_181753.jpg

I can't believe I have two working Sparrows. Actually I don't because I have only one pair of TOS ROMs. :D

I haven't done further tests but interestingly, VGA output is also not working on this one (hint for you perhaps). I'm more and more confident this must be an NVRAM issue but first I have to code my own NVRAM tool because none of the ones I have works on Sparrow. ;-)

EDIT: to at least somehow decrease the amount of operations needed I have installed one of the 4 MB RAM cards lying around -- works all right.

[derkom]

Wow, awesome mikro. Glad my comment got you swapping those CPUs around.

Thanks for the tip on the VGA output. I'll see about getting a proper RGB hookup going.

Quick question for you: Can you tell me what your jumper settings are for these jumpers both next to the TOS ROMs and in between the TOS ROMs and the RAM? I've tried to duplicate the settings I've seen in photos of others' boards (not reflected in this picture), but it would be good to know what the configuration is on a known working board. Do we even know what these jumpers are? I never found any discussion of them, nor did I observe any different behaviour when changing them.

IMG_20180826_195714_1.jpg

[mikro]

Quick question for you: Can you tell me what your jumper settings are for these jumpers both next to the TOS ROMs and in between the TOS ROMs and the RAM?

I'm pretty confident those are ROM wait states settings, similar to what you have on Falcon on the far left of the PCB (actually pretty much anything on Sparrow can be found in Falcon in one form or another).

Mine look like this:

IMG_5846.jpg

I haven't tried to change them.

EDIT: better picture:

IMG_20180531_222520.jpg

[derkom]

I'm pretty confident those are ROM wait states settings, similar to what you have on Falcon on the far left of the PCB

Ah, yes, good call.

Thanks for the pic. That matches what I saw in some other photos, so yes, I've tried that configuration, to no avail. But now I have hope for RGB working better than VGA. Need to get my hands on something that can handle 15 kHz.

[mikro]

But now I have hope for RGB working better than VGA.

Good luck - from what I have seen your #50 looks very, very close to what I have working (#35 & #40) so if there isn't some mechanical damage, you stand a chance.

[derkom]

Yep, it looks pretty much identical, including the rework. The only difference is I've got no fan.

...and at least to a visual inspection, it looks perfect. No evidence of any board damage anywhere. One of the MIDI ports has a corner cracked off, but other than that, everything looks visually perfect. And nothing explodes when it's turned on.

[calimero]

Hi Mikro,
you receive only Sparrow motherboards, without case?

I was wonder what kind of badged (label) does Sparrow had...?
Is FX-1 from Sparrow?


https://www.maedicke.de/atari/hardware/sparrow.htm

[derkom]

you receive only Sparrow motherboards, without case?

I was wonder what kind of badged (label) does Sparrow had...?
Is FX-1 from Sparrow?

FX-1 and Sparrow are indeed the same thing. I have a FX-1 case I picked up years ago (seems they made more of these than actual boards), and never expected I would ever have a board to put into it. Hopefully I'll get the two put together, after some further work on the board to get it in running order.

[calimero]

Great news derkom!
and thanks for clarification about FX-1!

So yours and Mikros Sparrow are essentially the same?

btw
Mikro, please put yours photos and serial numbers of Sparrow in database: http://milan.kovac.cc/atari/chipmunk/

[derkom]

So yours and Mikros Sparrow are essentially the same?

They look to be. All of the Sparrows are either the rev.1 or rev.2 board. Most of the boards are rev.2, including the ones that mikro has and the one I have. The only difference between the various rev.2's seems be the amount of rework on them, and from what I can see in mikro's photos, it looks like both his rev.2 boards and my rev.2 board have the same rework. So I have to suspect they are effectively identical.

[mikro]

Mikro, please put yours photos and serial numbers of Sparrow in database: http://milan.kovac.cc/atari/chipmunk/

I keep my "private" database here: viewtopic.php?f=27&t=31148#p312095

I have pictures to most of them but basically there's not much to see. All of the boards are same, some have more wires than others (even if they are the same revision).

[calimero]

^
Ah, I see. Maybe you should put info on yours website (github), somewhere more permanent then forum...

And what is the difference between rev 1 and rev 2?

[derkom]

I've been poking at this Sparrow board a bit more today, now with a proper Atari RGB adapter and a monitor known to accept 15 kHz hsync. Unfortunately, things do not bode well for my board, as I noticed while looking back through this thread that mikro's working board has a bunch of components mine doesn't.

Here's mikro's working board, relevant areas circled:

IMG_20180826_181753.jpg

And here are the same two areas on my board:

P1020947.JPG

P1020948.JPG

I'd noticed the missing components around the RF converter area before and thought/hoped they were just RF output related, and therefore unnecessary. But it was only today that I noticed mikro's board has a bunch of stuff around the expansion connector that my board lacks. Too bad.

It sure does look nice in the FX-1 case though...

cased1.jpg

cased2.jpg

cased3.jpg

[troed]

But it was only today that I noticed mikro's board has a bunch of stuff around the expansion connector that my board lacks. Too bad.

Too low res picture to see clearly, but that looks like stuff that should be possible to source.

[derkom]

Too low res picture to see clearly, but that looks like stuff that should be possible to source.

I was thinking that, depending on what the missing IC is near the expansion connector, although with such a small package, it's unlikely to be anything custom.

mikro, we need better photos!

[czietz]

I don't think we need better photos:

Judging from the components missing (two crystals, two diodes, some transistors), I suspect this is the "famous" PLL to lock the system clock to the PAL color frequency. It is present in all Ataris with a PAL modulator -- starting with the 520STM. See it here in the Falcon schematic: https://www.dev-docs.org/docs/htm/searc ... 28Rev+G%29, page 2, the block annotated "stuffed in PAL systems only". derkom's Sparrow is a "non-PAL" model and hence has the crystal oscillator that is missing in mikro's machine.

As for the things in the output circuitry: mikro's has a modulator, derkom's hasn't. Hence only the transistor and diodes to generate composite sync, much like in the ST.

[mikro]

True, true. All of my Sparrows are PAL. See the first working one here: viewtopic.php?f=15&t=33758&start=25#p346463

[derkom]

Judging from the components missing (two crystals, two diodes, some transistors), I suspect this is the "famous" PLL to lock the system clock to the PAL color frequency. It is present in all Ataris with a PAL modulator -- starting with the 520STM. See it here in the Falcon schematic: https://www.dev-docs.org/docs/htm/searc ... 28Rev+G%29, page 2, the block annotated "stuffed in PAL systems only". derkom's Sparrow is a "non-PAL" model and hence has the crystal oscillator that is missing in mikro's machine.

You appear to be correct. Looking at the crystal that I've got and mikro doesn't, it's a 32.084988 MHz, which is exactly what the Falcon schematics show as "stuffed in non-PAL systems". So the IC on mikro's board is going to be the 74LS74 found in PAL systems. Good catch.

As for the things in the output circuitry: mikro's has a modulator, derkom's hasn't. Hence only the transistor and diodes to generate composite sync, much like in the ST.

Right. I was never concerned by the lack of the modulator, and just a little by the components "missing" from nearby. Now that I've looked at an STF motherboard, I see that the missing components are indeed supposed to be missing.

So I'm back to this being a mystery for now. I do not know for a fact that I have a good 68030 (it just came from some random parts I've amassed over the years and I've never tested it), and I have yet to try with a genuine Atari RAM board. I've used Exxos' SIMM board with a 16MB SIMM (which got me the green specs I mentioned a couple of months ago) and I've used a Falcon Wings board with 4MB in it (got sync, but nothing on the screen).