Nintendo Super System (NSS) motherboard repair

I offered to take a look at this because I am a big fan of Nintendo games and hardware and had never had a chance to play with one of these before. It was sold with the cabinet as faulty and missing the sound module, luckily the sound module is very commonly found in Super Famicoms and I just so happened to have a working loose SFC motherboard.

So that was one problem solved, the next one is that the motherboard was completely dead. It has had a rather poor previous repair attempt that did more damage than good as you can see below.

Sound module from SFC fitted.

 

 

Lifted / missing pads and shorted pins.

 

Missing pads replaced with tiny wires and the bent pads straightened and held in place with UV solder mask.

The missing pad (pin 80) is a no connect so I didn't need to replace that but I did use some UV resin on that pin to hold it in place so it cannot short to the pin next to it. 

It's possible the original cpu is working but as I know the one on the SFC board is working and it won't work without the sound module I might as well put the known working one back on the NSS motherboard.

 

With the known working CPU fitted I was still greeted with a black screen but I was expecting this, as even with a dead cpu it should boot as far as the menu using the Z80 cpu.

 

Checking the corner of the board with the BIOS and Z80 cpu under the microscope there was some corrosion next to the super capacitor. The capacitor hadn't leaked though so it must have had a drink spilled on it at some point or maybe another board stored on top of it that had a leaky battery.

 

After cleaning up the corrosion and checking all the damaged traces / vias I found one open trace.

 

 With that patched and protected I was greeted with....

 

 The board is now fully working.

Crest 275HTAG Ultrasonic Cleaner repair

Time for a something a little different, I've had a 30L no name Chinese Ultrasonic cleaner for a couple of years now and it does a good job of cleaning arcade boards. The problem is it isn't great when it comes to cleaning the odd small items here and there. As it takes a few hours to heat up the water so I was on the look out for something much smaller for these cleaning jobs.

I also wanted something better quality and I see a lot of people saying Crest is the best, the problem with the best is it's also stupidly expensive. So I was on the look out for an old and broken Crest to get it as cheap as possible, this was actually advertised as 'untested' but that's usually code for broken.
 

 

The first problem I noticed right away was that the tank was no longer properly attached to the chassis. Originally it was attached with a clear silicone sealant. I bought a tube from amazon and reattached it.

 

Leaving that a few days to dry and then filling the tank (never run these dry) it powered on and the heater works but turning the right knob to start the cleaner did nothing.

 

 

 

 

With the board out there isn't too much going on with it, it's a lot more basic than newer Crest models. I think this one is around 20 years old, but basic is good as there's less to go wrong. 

 

At first I thought the IRG4BC30 transistors were bad as neither of my testers knew what to make of them and said they were two capacitors. I ordered some new ones from ebay but those tested the same so that wasn't the issue.

 

After digging a bit deeper I found that the resistor at R1 (10K) was open, it's a wire wound 2W resistor, luckily ebay to the rescue again as one seller had a perfect replacement.

 

 

I am not actually sure if it's 1W or 2W as the original isn't marked and the replacement didn't say either but the original is the exact same size as the new one and it works now so that's good enough for me.

 

Repair complete.