SE30 Micromac Dimmo 030 board Question

[AndyMc1280]

Hi there

Just wondered if anyone has one of the above boards with 40Mhz Marked parts (40A) and replaced with 50Mhz (50C) revisions. Still running at 50 Mhz Im aware there'll be minimal performance difference, but with the 50C revision I'm sure there's a downsize to 0.8 micron technology..... which might make things cooler/less power draw.

No I'm not planning to overclock, but was wondering if anyone has used later revison chips ?

 

[zigzagjoe]

Hi there

Just wondered if anyone has one of the above boards with 40Mhz Marked parts (40A) and replaced with 50Mhz (50C) revisions. Still running at 50 Mhz Im aware there'll be minimal performance difference, but with the 50C revision I'm sure there's a downsize to 0.8 micron technology..... which might make things cooler/less power draw.

No I'm not planning to overclock, but was wondering if anyone has used later revison chips ?

Unless you're experiencing instability, I wouldn't bother. The PGA 68030s already run cool enough they don't require a heatsink, and fractionally reduced heat/power wouldn't be worthwhile.

 

[AndyMc1280]

Unless you're experiencing instability, I wouldn't bother. The PGA 68030s already run cool enough they don't require a heatsink, and fractionally reduced heat/power wouldn't be worthwhile.

mm. Currrently the Dimmo accelerator is awaiting a recap. Analog and logic board have been done and some nice sausage on here has very kindly sold me a new wiring loom and neck-board... so any flakiness should be ironed out after that's all done.
Oddly its fine with everything connected except the floppy drive, doesn't want to boot when thats on. Voltages are fine.

Its a bit wonky at the moment but I suspect that's 32 year old caps on the accelerator and a skanky wiring loom that's even older (its been flooded). Swapping the chips would be a "because can" excersise.

 

[zigzagjoe]

Haha I might know who that was

If you've got any instability, it couldn't hurt to swap them out anyways - I've heard of some stock diimos that were unstable since they're pushing those early revision 68030s hard. Check out eric woo's rare chips - he sells good authentic stuff. Any 68030 marked F91C or G40W will work at 50mhz regardless of rated speed.

Does that floppy work if the other stuff isn't in? A floppy preventing the system from booting is a new one for me....

 

[AndyMc1280]

Haha I might know who that was

If you've got any instability, it couldn't hurt to swap them out anyways - I've heard of some stock diimos that were unstable since they're pushing those early revision 68030s hard. Check out eric woo's rare chips - he sells good authentic stuff. Any 68030 marked F91C or G40W will work at 50mhz regardless of rated speed.

Does that floppy work if the other stuff isn't in? A floppy preventing the system from booting is a new one for me....

Like these ?

 

[zigzagjoe]

Your FPU is fake unfortunately, but that CPU is legit and will work nicely. I'd just leave your original FPU in there; the diimo SE/30 only runs FPU at 25mhz for some reason so any 68882 will work fine.

 

[AndyMc1280]

Your FPU is fake unfortunately, but that CPU is legit and will work nicely. I'd just leave your original FPU in there; the diimo SE/30 only runs FPU at 25mhz for some reason so any 68882 will work fine.

poo. Oh well ebay refund on it then I guess. Less work replacing only one chip hahaha.

I've worked out what the issue is with the floppy.

SE/30 Power Supply: Recap or ATX?

Use the SONY CR-44 PSU as a frame of reference for the voltages and minimum Current output you will need: +5V: 6.0A +12V Sweep: 1.25A +12V Disk: 2.1A -12V: 0.5A Sweep and Disk are not isolated, so you could drive both with a single +12V power line rated at 3.35A or higher. And no, a -12V...

68kmla.org

Discussions on PSU replacement. Not necessary to read. The important bit is @JDW s post on original SONY PSU which is what I have:

Use the SONY CR-44 PSU as a frame of reference for the voltages and minimum Current output you will need:

+5V: 6.0A

+12V Sweep: 1.25A

+12V Disk: 2.1A

-12V: 0.5A
Sweep and Disk are not isolated, so you could drive both with a single +12V power line rated at 3.35A or higher. And no, a -12V line rated at 0.3A is not acceptable, in my opinion, since the -12V line of the SONY is 0.5A.

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With the above in mind, I have replaced the sony with the pico adapter from dekunukem and a 150w pico. SO. Floppy failure would suggest that the floor box/power converter from an XBox 360, although having 135 watts, is a bit puny on the -5v rail at 1A (As far as I can find out) and probably doesnt have enough go for the 5 and 12 either. But thats what my recapping person has and is using to test, But I'll send him over a proper 12v 12A rated Power supply which is correct for the pico.

Basically not enough oomph (its not the PSU or the adapter) it is the rail supply, or box on the floor. Problem should then hopefully be solved. But a recap for the card, wiring loom etc will of course help. I'll bundle it all off to him.

If I'm wrong I'll be back here to moo about it, but that "explains" it. Will wail at ebay about the fake 68882.