March 2012

Here’s my Sega Game Gear before repair. It’s got a couple of problems: the sound is extremely quiet even with the volume turned right up, and there’s a complete lack of usable video. The machine itself is in reasonably good condition inside, so I’m hoping it’s something I can bring... Continue reading

The PC7486SLC-based Mega PC upgrade really is running at 33 MHz. Great news: the math coprocessor for the 486SLC has arrived and is recognised perfectly. It is a ULSI Advanced Math Coprocessor SX/SLC rated at 33 MHz, part US83S87. The diagnostic software also identifies it as a ULSI 84x87. I’ve... Continue reading

The replacement PC7486SLC motherboard is in. It passes POST and, unlike the original 386 board, recognises the hard drives perfectly. That strongly points to a fault somewhere in the original motherboard’s storage subsystem or related circuitry rather than the drives themselves. The old board will still make a useful spare.... Continue reading

One of my Model 1 Sega Saturns has developed a rather annoying power supply problem. It becomes more noticeable after the console has been running for a while, so I left it operating for over an hour to get everything thoroughly warmed up. The built-in music player was more than... Continue reading

Picked this up on eBay from the UK and gave it a bit of a clean. It has become my favourite Mega Drive controller. Internally it is much the same as another Mega Drive controller I cleaned yesterday, although that one sadly had some tabs snapped off the D-pad. Amstrad’s... Continue reading

A quick look inside the Amstrad Mega PC with the system pulled apart. The Sega Mega Drive hardware sits on a dedicated ISA card inside the PC. This is the same machine that arrived in not-so-good condition with NiCad battery corrosion on the motherboard. I picked this one up from... Continue reading

Or, more specifically, math coprocessors for the Amstrad Mega PC and my 486SLC upgrade. The ULSI US83S87 Advanced Math Coprocessor is intended for 33 MHz SX/SLC systems. This one has a 9401 date code and comes in a 68-pin PLCC package. 387SX-compatible math coprocessors use the sort of external interface... Continue reading

Browsing the internet, I came across an Amstrad PC7486SLC motherboard. I couldn’t help noticing how similar it looked to the Mega PC motherboard. Since my Mega PC was already giving me grief with its hard-drive controller, having another related Amstrad motherboard around for spare parts seemed like a pretty good... Continue reading

I’ve managed to get the Amstrad Mega PC mostly back together, although the top cover is still off. Here’s a quick demonstration of the 386SX PC and Mega Drive sections, both of which are finally showing some signs of life after all the work I’ve been doing on this machine.... Continue reading

Such a wonderful shade of blue. Unfortunately it has eaten the tracks on the motherboard. That’s the damage a leaking NiCad battery can do. The electrolyte is alkaline potassium hydroxide rather than acid, but it can still make an impressive mess of a motherboard. I cleaned everything up as best... Continue reading

It has arrived. My Amstrad Mega PC. A 386SX combined with a Sega Mega Drive. Amazing! Sadly after having a look inside it, I discovered the rechargeable NiCad date/time backup battery has leaked delicious NiCad goodness all over the motherboard. And the CPU in this particular machine is AMD, my... Continue reading

Ohhhoooo so very shiny! I discovered one of my Sega Mega-CDs has a blown fuse that someone replaced with a big blob of solder. It certainly passes power that way, but the fuse is there for a reason. I want the little guy to have its proper overcurrent protection back,... Continue reading