Gauck 10529c Comparator

I just received this today from the states.

It's a logic comparator much like the one made by HP for testing logic (TTL) chips in circuit, unlike the HP version this will test 18 and 20 pin TTLs or at least it will once I've built it.

I recommend picking one of these up if you do any repairs on electronics with through hole TTL as it's a real time saver. It basically compares the chip on the board with a known good one and compares the outputs, a difference is indicated by an led.

Check out this thread on the KLOV forums if you'd like to order one or need extra cards for your HP comparator as these new ones are compatible.

This is what it will look like once it's done (hopefully).

Toei GM-140TV Caplist / Map

Just a quick one, I recapped a Toei GM-140TV black and white 14" monitor chassis today from a Space Invaders cocktail cabinet. I decided to make a caplist / map since it doesn't look like anyone else has made one.

Mario Bros PCB Repair

I bought this board on ebay as untested and missing a potentiometer. Pots getting broken off of these early Nintendo boards seems to be a common problem.

First thing to do is find a suitable replacement as it's used for horizontal video placement, Bob Roberts sells nice replacements but I don't believe he ships outside the US anymore.

Finding 30K pots the right size isn't easy so I went for a 50k instead, I found some on ebay that looked more or less the right size.

After removing the unwanted bracket and bending the center pin to shape it fit nicely. 

 Now to power it up

 The title screen logo, character,enemy and pipe sprites were all missing.

Now I cheated a bit here as a quick google brings up quite a few posts and even a repair log with this exact issue. Channelmaniac's repair log was very helpful, I desoldered the Z80 DMA and ordered some off ebay.

 Soldered in a socket and fitted one of the Z80 DMAs from ebay and...

All the missing sprites returned.

Mega Drive (Radica)

Next up one of those cheap clone TV plug and play devices that uses composite video and runs off of 4x AA batteries. This is a Mega Drive (Genesis) version rather than the more common NES / Famicom / Arcade versions. The sound emulation on this thing will make your ears bleed but the controller is nice and clicky, I'd go as far as saying it's better than the original Mega Drive controller.

Usually I wouldn't bother fixing these things but it was a such a minor fault. The power button was broken but if held in it would work. Ten replacement switches were 99p from China including postage so why not.

 Power switch replaced, now fully working.