Just a short one this time. I picked up a cheap Gameboy Advance but instantly realised how awful the screens were, something that I wasn’t aware of as I had always had PSP’s. But a quick search on AliExpress surfaced this upgrade kit which was exactly what I was after. This instructions were non-existent, even though the seller said they would send them afterwards I never got anything.
As part of my want to recreate some of my earliest machines growing up I thought I would go back to the very first one, a 486. It was a hand me down desktop style with Windows 95 on it. I don’t think I had it long before I upgraded to a Pentium 100/120.
It wasn’t really going to be a reality until I saw a pair of machines at the retro tech sale in Onehunga just before the very first covid lockdown. Sadly I couldn’t open them up properly to look inside other than seeing they had 486 chips inside. Once I got them home as well as some ram I could open them up and see the horror that awaited me. Both boards had bad battery damage and were completely non functional, at least the cases, power supplies, floppy drives and expansion cards were all in working order. Lucky for me, one of my fellow retro gamers had found some 486 boards at the same sale that he gifted me to get me up and running with a 486, as well as a VLB video card.
As a bit of a fluke purchase I spotted a listing for 3kg’s of CPU’s. Everything from Pentiums, 486’s, Pentium Overdrives and more. A lot of the chips had bent pins as they had clearly been sitting in a box/bin for years. It wasn’t overly cheap but I managed to remove some of the double ups and get all my money back, essentially making my ones free. These chips will give me a good base to test from.
The first round of testing went so so. A lot of the boards that I had were battery damaged. One of the the hardest parts of diagnosing these boards was actually finding the manuals to get the jumper settings for each board. Some of them I just couldn’t find anything on them so I had to resort to putting a less ideal chip in them to see if I got any post codes come up, if only to get a model number or something to be able to look up. I did managed to get 4 boards going on this round.
I did manage to track down a fairly unusual issue. Upon closer inspection of one of the boards I was given from my mate, the main chip was actually not connected to the board at all, and on even closer inspection, it looked like it had been hit but something and bent a few pins/ripped some traces. I did attempt to reconnect these pins but had no success getting the board to work.
Once I had two boards working for the two cases I picked up I loaded up my DOS image and got everything working.
About 8 months after a few other projects I decided to revisit the boards and see if I had learnt anything and if I could get any more going, or at a minimum get rid of the ones that I couldn’t get working. Turns out I did learn something. Out of this batch I managed to get 5 boards going. Some of the issues I had were:
So it was a good second round of repairs. Sadly I still had 3 boards that showed no signs of life. They all showed power, and the bios read good but the reset line just stayed high and the post code reader showed 00. Something that I found out this time around was that the 4 digit post code readers actually are just two 2 digit readers, with the ones on the left being the current code and the ones on the right being the previous code. This made diagnosing it much easier as I could actually look up the code and know what the issue was ( like things in the 80’s being keyboard related and low error code being ram issues ).
One likely obvious thing I discovered this time around which was likely a big part of the success was that there is actually two types of 72pin SIMMS. EDO and FPM and that ‘most’ 486 boards only support FPM modules. Even externally they are not easy to tell apart but I saw something on a forum that if the part number of the chips ends a 0 (zero) it will likely be FPM and if it ends in a letter it will likely be EDO, something that checked out for all the modules that I had. I had no luck with the 30pin modules, which was likely a jumper issue and a lack of manuals available.
So out of the full set of 10 boards I ended up with 7 that work in some way or another, my base level is, if it posts to a bios screen I consider it a success for now. The 7 boards are:
The two full machines are both loaded with my DOS Image:
As for the non working boards, I actually got one of them working in the photo, so I am left with two PCI boards and another MB-4DUVC-P-AB with the bent pins/traces. These showed no signs of life and with 7 others I figured i’d move past them and onto other projects.
After visiting my friend for a few times and seeing this old XYZ Da Vinci sitting on the ground I said to him that I would take it off his hands and try and get it going. He said he had it for a few years and never got it to work, but since I had recent good success with my Makerbot I figured I would give it a crack for him. Turns out it was in worse shape than I expected, although it turned on it would not connect to the standard XYZ software ( which sucks btw and you need to create an account to even use it ).
Luckily, it get it to print something there was a sample print stored on the internal SD card which was enough to test it out. Leveling it was nightmare and I ended up doing it manually by turning off the machine just as it goes to print and then using a 0.08mm feeler gauge on the glass bed as the auto leveling kept failing.
After this I downloaded Repetier Host and managed to connect to the printer! I also found a bunch of profiles online that i will link at the bottom. For the record, I also got Simplify 3D to work with this machine if that is what you are using, which has profiles built into it.
This project isn’t specifically a build project, but it is something that I have wanted to put together for a long time. When I was in Nepal I picked up a small “legit” Northface mini pack as I thought it would be good for first aid kit, something that I have never had other than the crappy ones you get from the pharmacy. Its a pretty basic kit that I will keep in my car. The concept was to have everything I would need if I came off my mountain bike in the forest.
After an awesome find on Facebook marketplace I came home with a Pentium 2 and Pentium Pro machine. Both had their issues. This one had a bad bios battery and a dead VRM board, something that wasn’t apparent right away. The machine actually booted up at first until it released the white smoke.
Turns out one of the capacitors on the VRM board decided to explode and take the PCB with it. I suspect that the cap leaked and shorted both layers and burnt a hole through it. Once I cleaned it out and found new copper to put the new caps.
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