Resurrecting Sparrow board #50

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derkom
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Resurrecting Sparrow board #50

Postby derkom » Sat Jul 21, 2018 1:02 pm

Hi guys! Occasional lurker here, finally made an account. :)

I have just come into possession of one of the Sparrow boards that have been on offer (#50, specifically--the highest serial known?), and I am hoping to bring it back to life. The board is visually in very good condition, so I feel good about possibilities here. I have poked around in this forum and elsewhere and have picked up a lot of information, but I still have a couple of questions/concerns I'd like to address before considering applying power to this little piece of history...

CPU - If I'm not mistaken the right CPU for this is MC68030RC16. I already have a MC68030RC25, which is 25 MHz version of the same chip. Same packaging, same socket. According to the Motorola MC68030 electrical specifications manual, page 5, the 25 MHz version of this chip should accept a clock signal as low as 12,5 MHz. So, would this chip work as a drop-in replacement, or do I need to scrounge up an actual MC68030RC16?

Power supply - The connector on the board seems to be the same as ST/STE PSU. Is this indeed the right PSU to use for this board? I found some discussion on this forum of it appearing to be suited for an ST power supply, but no confirmation that that actually is the right PSU. I obviously don't want to power this board up with the wrong PSU!

DSP - The DSP56001 on this board appears to have a dab of solder shorting two of the legs on the left hand side. See here:

dsp.jpg


Looking at the chipmunk database, I see that boards #37 and #40 have the same legs soldered together, but other Sparrow boards appear not to be this way. I think I'm not worried about this since my board isn't the only one, but I wonder if anyone has any comments on that?

I still need to scrounge up some parts to get this into possibly working shape, and I'm sure some more confusion will arise as I do. :)

Thanks for any input. And yes, I will add this to SN database. :)
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Gaiyan
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Re: Resurrecting Sparrow board #50

Postby Gaiyan » Sat Jul 21, 2018 5:41 pm

Those pins are both VCCQ which are internal logic power inputs.
Image

derkom
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Re: Resurrecting Sparrow board #50

Postby derkom » Sat Jul 21, 2018 5:46 pm

Gaiyan wrote:Those pins are both VCCQ which are internal logic power inputs.


Okay, so nothing to worry about with the short then. Thanks. Still wondering why the short on some boards and not others. :shrug:


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