The Adventures of a Timid Tinkerer aka LC475 upgrades

[yock1960]

The two MC88196DW80 chips that I ordered from Utsource, finally arrived yesterday afternoon. I didn't jump right on it...why rush?! This morning however, I got the board out and insulated all of the plastic parts, so as not to melt them. Then I took a break, to wait for a slight headache that I woke up with to go away.

After an hour or so, I got tired of waiting...the headache was mostly gone. I fired up the hot air rework station and successfully removed the MC88920...but wait...dang, I disturbed the two tiny zero ohm resistors that are right next to it...DOH!

No time to panic...I can fix it...I think. They sure are tiny though and if I somehow would drop one, would probably never find it!

After a bit of futzing around, I finally got them 'stuck' back on...phew!

I'll take a break now...headache is back and I need to calm my nerves for the next steps!

 

[yock1960]

OMG! I never want to do this again! I hope this works!!!!

 

[yock1960]

HOLY CRAP, IT BOOTED!!!!

Or, as Adrian Black would say, "it works, it freakin works!"!

So, as I said in my previous post, I really would rather not have to do that again! But if I had to, I would not try to drag solder the new clock generator chip!

After I cleaned off the pads, put some flux on and placed the new chip on the pads, I tacked opposite corners (legs). So far, so good. Then it went downhill. I tried to drag solder the side closest to the cpu. I got bridging. I tried putting on fresh flux, I cleaned the flux off and refluxed...nothing I did dragging helped. It's just so crowded and hard to access...especially for a newbie like me! Eventually, by doing one leg at a time, I got rid of the bridges. Then I did the opposite side one leg at a time. After that, I cleaned with IPA and checked continuity from pad to leg and from leg to leg to make sure it beeped when it should and not when it shouldn't.

I am glad that's over! Now it's time to see how far I can overclock with my 80ns VRAM. Then to decide if it's worth buying faster, since apparently I will now be limited by my 'high' esr capacitors vs. OS-CON capacitors.

 

[jajan547]

HOLY CRAP, IT BOOTED!!!!

Or, as Adrian Black would say, "it works, it freakin works!"!

So, as I said in my previous post, I really would rather not have to do that again! But if I had to, I would not try to drag solder the new clock generator chip!

After I cleaned off the pads, put some flux on and placed the new chip on the pads, I tacked opposite corners (legs). So far, so good. Then it went downhill. I tried to drag solder the side closest to the cpu. I got bridging. I tried putting on fresh flux, I cleaned the flux off and refluxed...nothing I did dragging helped. It's just so crowded and hard to access...especially for a newbie like me! Eventually, by doing one leg at a time, I got rid of the bridges. Then I did the opposite side one leg at a time. After that, I cleaned with IPA and checked continuity from pad to leg and from leg to leg to make sure it beeped when it should and not when it shouldn't.

I am glad that's over! Now it's time to see how far I can overclock with my 80ns VRAM. Then to decide if it's worth buying faster, since apparently I will now be limited by my 'high' esr capacitors vs. OS-CON capacitors.

Did you use the LC040 or the 040 with the FPU, also was this the guide you followed?

 

[yock1960]

Did you use the LC040 or the 040 with the FPU, also was this the guide you followed?

I have a full 68040 that I got off Ebay. No, I bought the Spicy O'clock overclocking gizmo. Here's the link:

Spicy O'Clock! | infinityproducts

5 Aug 2024, Special notes for New V1.3 PCB: Here is the change in the probe points and how to measure them. Please read on.Very small overclocking devices made in Japan developed for 68040, Spicy O'Clock! Is a silicon oscillator unit that can set the clock arbitrarily from 37.6MHz to 51.8MHz...

en.infinityproducts.co.jp

It only supports a handful of models, fortunately the LC475 is one.

 

[yock1960]

Hooray!

Thanks to another thread, I think I have solved my problem, using both SCSI2SD and BlueSCSI on the same computer. I swapped the BlueSCSI out and installed the SCSI2SD a few weeks ago on my LC475. Copying all of the files over worked fine. Lately though, when trying to copy files from the BlueSCSI to SCSI2SD, it always failed. After a minute or so of copying, the machine would freeze.

Of course (hindsight ), termination was the issue. Termination is a software setting on SCSI2SD, but good old fashioned terminating resistors on BlueSCSI. I was over terminated. After disabling termination on SCSI2SD, everything works! I just have to remember to re-enable termination on SCSI2SD, when I'm finished copying files...better make a sticky note for that...I forgot the very 1st time, DOH!

Now I can use my BlueSCSI as a sneaker net device, something it excels at. It'll normally be used on a Mac Plus, but unplug, swap sdcards and presto!