Recently, a friend of mine asked for advice on modding his N64 to allow for hdmi output as he was using one of the cheap AV to hdmi adapters and not getting very good results.
This gave me the opportunity to test out the Hispeedido N64 mod board.
This mod comes with a nice ribbon cable, making it a fairly simplistic install. Although I would say this is not for the beginner, and a digital microscope is pretty essential with this one to see what you are doing.
I lined up the ribbon and then used some kapton tape to hold in in place whilst soldering, making sure to use plenty of flux.
Once everything was installed, a small cutout to the case was needed to allow for the mini hdmi port to be accessible on the back of the machine.
After this, it was time to put everything back together and check to see how the device performed.
Overall, I was pretty impressed with the quality and I would say it was on par with my NTSC RGB modded N64 which I used to have hooked up via an OSSC. So for the £35 the device cost, I would say it is very much worth it.
It even has a built-in menu which can be accessed by pressing Start+A+B at the same time. This gives a few basic options for changing some colour settings and also the aspect ratio.
if you have the ability to do fine soldering, then I would definitely recommend this mod 😀
My latest eBay purchase was a Sinclair QL fully boxed with manual, power supply and a bunch of microdrive cartridges. This was again listed as not working so was expecting to do another repair.
When it arrived my first test was to check the voltages coming from the power supply. Nothing seemed to be being output so this was definately one of the issues I needed to sort. I didn’t want to make a start repairing this one yet as I am still working on the MSX2. But I thought I’d just open up the power supply and check for any obvious issues.
It all looked clean inside the PSU, so I plugged it back in to check some of the voltage lines only to find they now all looked fine. I checked the voltages at the connector end again and once again everything looked good.
I can only assume a loose connection at this point so I put it all back together for now. I then plugged the QL in to find it all seemed to be working perfectly. I tested both microdrives and they worked fine also.
The only issue I discovered was the keyboard membrane had a break in one of the tracks. This is a common fault with these old membrane based keyboards and luckily brand new ones are still available so I have ordered one and just need to wait a few days for that to arrive.
So, I think I got another pretty good deal with this one. Bit of a shame that it wasn’t much of a repair as I really enjoy getting stuck into that (The MSX2 repair has been great fun in that respect so will post an update about that shortly).
When I recieved this MSX2, I had concerns as it had certainly already had a reapair attempted on it. What if this person had tried everything and discovered that a custom chip had blown and it was unrepairable?
Well, I decided to carry on regardless and work through the issue myself. To start off with I checked the basics on the CPU. Clock signal, reset circuit, data and address buses. They all looked fine.
The video circuit all seemed to be operational, I could see the 15khz sync signal but the composite video output was just black.
I noticed that the CAS signal for the main RAM was missing, which suggested that the CPU wasn’t successfully executing code, even though there was a bunch of activity going on. My first assumption was bad memory. I socketed both the video RAM and the main RAM and swapped chips around but it made no difference.
I decided to add a useful tool to my inventory and purchased a mini DRAM tester off Ebay.
One by one I inserted the DRAM chips and they all tested good. Not quite as simple as a RAM fault then.
After reading through the schematics for the Sony HB-F1XD (The closest MSX2 I could find to my model) I noticed the VDP read and write signals came from a custom IC on the board labelled as a MB64H444.
I checked with my thermal camera and noticed this chip stayed completely cold when powered on. My first concern was maybe this chip was completely dead which would be game over for this computer as they are virtually impossible to purchase.
I found the pinout for this chip and probed every pin with my scope. Everything seemed to be in order.
It was at this point that I put the scope back on the composite video pin and noticed it was showing a signal!
How could this be? I’ve not changed anything!
Even though I don’t have the replacement hic board yet, I hard wired the composite video output from the vdp chip into my little monitor and there it was, a perfect working image.
Although I was happy that the computer was working and that all of the custom chips were good. I don’t like things just fixing themselves as it can always break again.
And that is exactly what happened. But I discovered that by putting some pressure on the board I could break and fix the computer at will.
My next job was to find the bad connection, so I started re-flowing the solder joints on the chips in the area where I was bending the board. I also reflowed the solder on the MB64H444 chip. At this point the computer was non working and bending the board wouldn’t bring it back to life. Back to square one 😞
Only this time, I knew all the components were working and I was looking for a bad trace or solder joint.
I went back over the MB64H444 IC as this was the last thing I touched, and that is when I noticed no activity on the A13 address line. Could it really be that simple?
As a temporary test, I soldered a bodge wire from A13 on the MB64H444 up to A13 on the ROM chip.
I crossed my fingers and powered on the machine which greeted me immediately with the MSX logo. And no amount of flexing the board would cause it to not work.
The entire computer brought to a halt because of a bad trace on one of the address lines to this MB64H444 chip.
I’m still not 100% sure what role this chip plays in this computer. The schematics list it as a speed controller. So I will be doing some more reading up now to see why this issue caused the machine to not boot.
I have alsp sourced a modern replacement for the HIC board now, so once this arrives, I will be able to put this computer fully back together and start using it.
There is something so satisfying when you finally find the issue with these old machines.
If you have anything sat in your loft broken and you fancy donating it, I will do my best to bring any computer back from the dead and give it a good home 😀
My next repair project is this Sony MSX2 computer. Purchased as not working (black screen).
Unfortunately this machine has a bit more to its history than the eBay advert let on. Upon opening it I noticed that the problematic HIC1 board (The video out multiplexer that tends to suffer from corrosion on these machines) was not only missing, but pin headers had been fitted in its place.
This tells me two things. The hic board on this machine had indeed failed. But also, someone had replaced it with the modern replacement hic board but I guess it still didn’t fix the problem so they took it back out and sold the computer.
So, I need to either build or source a hic board for starters. But even then I probably still need to get the actual machine running.
I have already gone over the board with my scope to see if I can see what is going on. For starters it seems the computer tries to start for a few seconds and then comes to a stop. I can see a horizontal sync and csync but it appears the video signal is just a black screen.
I’ve also noticed that the CAS signal for the system memory is not there. Currently I’m assuming a possible memory fault so I will try swapping that out first. If it still doesn’t appear to be running then I will probably look into the ROM chip next.
All of this is under the assumption that the MSX2 should actually run fine even without the hic board present. Unfortunately I don’t have another MSX2 to test this theory.
I’ve had this one for a few months now but forgot to add it to my list. Don’t really know too much about these yet, so will be fun having a play and seeing what I can get it to do.
Apparently they were very popular with reporters and editors as it has a good keyboard and allowed them to write articles easily.
This one is in perfect condition. Think I’ll have to get a Wi-Fi modem hooked up to it and see what it’s like browsing some BBS’s
This one came of for a bargain price on one of the Facebook groups so I coulnd’t resist adding another Amstrad to the collection. I already have a CPC M4 board for this computer to allow loading software from SD Card and over Wi-Fi. Will definately be setting this one up and experimenting a bit more with the features the M4 has to offer as I’ve not really done much with it so far.
I recently purchased a cheap Atari 800XL which was listed as not working. I’ve been trying to find some broken computers as fixing them up and learning about how they work has started to become a big part of this hobby for me.
So when I plugged in the computer and it sprang into life, I was pretty dissapointed. At this time it seemed like the only fault was a loose connection on the power LED.
However, the 800XL has a built in system test mode, and when I ran this it looked a bit odd. All the memory passed the memory test, but there wasn’t enough of it showing. This issue was confirmed when I tried to run a game on the system and it just crashed.
I looked at the system using my thermal camera and couldn’t see any obvious faults with the memory.
I had some spare RAM chips, so decided the next course of action would be to fit some sockets and start swapping the RAM chips around. I decided to fit the sockets one chip at a time and then test swapping the RAM as I go.
As luck would have it, after swapping the first chip, things started to look correct on the system test, and games now loaded without issue.
So, as repairs go, this was a pretty easy one and not the most exciting I have dealt with. But is was nice to pick up a bargain computer and return back to its working state.
My next task will be to give it a bit of a clean up and see what this system has to offer. I have a couple of other 8bit Atari’s but it isn’t really a platform I have spent too much time playing with yet. This is something I need to change.
One of the computers I have setup on my new desk is the Yamaha CX5M MSX Computer. The only issue with that is the UK version of this machine only outputs a composite video signal and that is going to look terrible on an LCD monitor.
After looking around the internet for bit, I came across the TMS RGB V2 mod from videogameperfection.com. This device works on many different systems that use the TMS9928A and TMS9929A chips, such as the MSX.
The fitment of the device is pretty simple, you just place it over the pins of the TMS chip on the underside of the PCB, and then solder the holes that have the metal ring around them.
Once that was done I routed the wires to the back of the case where I made a small cutout and fitted a mini DIN connector to output the new RGB video signal.
I then made up a quick mini DIN to scart cable and re-assembled everything. After connecting it to my Open Source Scan Convertor (OSSC), I was greated by a beautiful sharp RGB image being output to my LCD Screen.
I think I am going to be much happier now, exploring the MSX software library with a nice sharp picture. All in all, a good afternoons work 🙂
Recently a BBC Master was listed on one of the Facebook Groups I am on. It was listed as not working for £75 so I decided to grab it and try and revive it.
My assumption was that the issue was going to be the Rifa caps in the power supply.
So after waiting for Royal Mail to take a week to deliver a 24hr parcel, it finally arrived.
First of all I opened it up to see what we were dealing with. I was not surprised at all to discover the Rifa capacitors had indeed let go.
Luckily I had already ordered some replacements so a few minutes later, I had the old ones out of the board.
All of the other capacitors in the PSU looked fine so for now at least, I have only replaced the main culprits.
Upon putting everything back together, the BBC got powered back up and it sprang into life. Since the CMOS battery was also dead, I had to reset the settings and replace the batteries.
I really want to set this up somewhere where I can use it easily. So I think I’m going to look into getting an additional desk for my retro room. Hopefully I can setup some Acorn and Amstrad computers as I don’t have any out currently.
After moving house, one of my first tasks was to sort out my new retro room. I have really enjoyed getting it all sorted, but for a while now I kept having one thought which I didn’t want to know the answer to, where the hell is my FunKey S!!!!
All of my handhelds were neatly packed and bubble wrapped into a single box so nothing got misplaced during transport. However, the FunKey S is the size of a biscuit and weighs next to nothing. After searching high and low for the thing, it was finally time to come to the conclusion that it got thrown away with the box filled with the remaining bubble wrap😭
So let that be a lesson to everyone, when you move house, create a list of what you put in the boxes, and tick them off when you unpack them!
Anyway, I am not one to edit my website and simply remove an item from my collection, so instead, here it is, my new FunKey S! This time I got the transparent version so at least it’s slightly different to my previous one.
