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JDT
April 24th, 2008, 03:16 PM
I could use some assistance in identifying this mobo I found earlier. I managed to get it to fire up with an AMD 40mhz cpu, I'd like to see if I can add a Cyrix FasMath 40 to it. But I'm not sure its compatible or what settings to use. Most settings are silk screened on to the mobo, thank fully. However I can not find a definite model number or manufacturer. I scoured TH99, but came up empty.. only things on the back are "ET" "E-O 9235" & "94V-O"

http://www.jdthiele.com/386mobofront.jpg

Any assistance apreciated =)

Also noted, there is an orange (tantelum?) cap that has a broken leg, left center of pic, closest to edge of board, that going to be a problem? Machine fired up fine with that CPU in it. But when I try to add the Cyrix 387, the system does not fire up, starts to, but then stutters and the PSU shuts down. Im also unsure of orientation of the FPU, as the "happy" corners make it 180deg oposite of the CPU (not sure if that matters).... and again, not sure if board supports that fpu.

Additional Note: In small print inside the 486 / 387 socket is "80387-PIN1" and an arrow pointing to another corner, once properly seated, I now have a functional Cyrix FasMath 40 =) I have 100% joy now...

modem7
April 24th, 2008, 05:34 PM
Also noted, there is an orange (tantelum?) cap that has a broken leg, left center of pic, closest to edge of board, that going to be a problem?
Depends what it's there for.
For example, tantalums near RAM chips definately need to be replaced. A good (technical) explanation as to why is on pages 51/52/53 of the document http://www.cpm.z80.de/download/dram.pdf
So if the cap's purpose can't be determined, best to replace the cap.

JDT
April 24th, 2008, 07:38 PM
Depends what it's there for.
For example, tantalums near RAM chips definately need to be replaced. A good (technical) explanation as to why is on pages 51/52/53 of the document http://www.cpm.z80.de/download/dram.pdf
So if the cap's purpose can't be determined, best to replace the cap.

Seems the 387 only works for a short time after a very cold boot. System doesnt see it after a warm reboot. If you try to actually use the 387 you get floating point errors, i can follow the traces from that cap to "close" the 387 socket... got suggestions on replacing, this something i could get at radio shack?

Amigaz
April 24th, 2008, 07:51 PM
I could use some assistance in identifying this mobo I found earlier. I managed to get it to fire up with an AMD 40mhz cpu, I'd like to see if I can add a Cyrix FasMath 40 to it. But I'm not sure its compatible or what settings to use. Most settings are silk screened on to the mobo, thank fully. However I can not find a definite model number or manufacturer. I scoured TH99, but came up empty.. only things on the back are "ET" "E-O 9235" & "94V-O"

http://www.jdthiele.com/386mobofront.jpg

Any assistance apreciated =)

Also noted, there is an orange (tantelum?) cap that has a broken leg, left center of pic, closest to edge of board, that going to be a problem? Machine fired up fine with that CPU in it. But when I try to add the Cyrix 387, the system does not fire up, starts to, but then stutters and the PSU shuts down. Im also unsure of orientation of the FPU, as the "happy" corners make it 180deg oposite of the CPU (not sure if that matters).... and again, not sure if board supports that fpu.

Additional Note: In small print inside the 486 / 387 socket is "80387-PIN1" and an arrow pointing to another corner, once properly seated, I now have a functional Cyrix FasMath 40 =) I have 100% joy now...

Checked here? http://artofhacking.com/th99/m/m386_i.htm

Druid6900
April 24th, 2008, 07:57 PM
Since it boots, get the CMOS ID string and go to WIMs site and decode it. It may, at least, give you a manufacturer which is a start.

JDT
April 25th, 2008, 05:46 AM
board is now dead =/ I noticed on one of the controller ICs that something had bent some of the tiny legs so as that they were touching, in my feeble attempt to straighten them... the leg snapped off =/ and something that small is well beyond my ability to solder. Looks like it back to searching for a 386-40 mobo =) guess I'll harvest the 80mhz crystal, tantalum caps and cache from this board...

Druid6900
April 25th, 2008, 10:42 AM
If you want to send it to me, I'll see if I can fix it for you.