Tag - Cooling

Cooling my A1200 – Part 2 – Adding a Fan

5th June 2021

In Part 1 I tried some simple passive cooling techniques to increase airflow with the aim of cooling my A1200. This time around I’m going to add a hardware device to my A1200 that will monitor the internal temperatures and also add a cooling fan. Spoiler alert – this time there will be some decent results!

To be honest I probably would have stuck with the modest improvements made from the passive cooling mods had it not been for the extra heat generated by fitting my Indivision AGA Mk3 Flicker-Fixer. When I began to see artefacts on the screen caused by the Lisa chip working overtime and heating up I knew it was time to step up my game.

AmigaKit Real Time Clock and Sensors Module

I discovered this Sensors Module quite by accident whilst browsing the AmigaKit website. It’s a little battery-backed clock module that incorporates an ambient temp sensor on the board and can be expanded to include a second temperature sensor probe by means of a small 3-pin connector.

AmigaKit Real Time Clock and Sensors Module with £1 coin for scale.

In addition to monitoring temperatures and providing a clock function this module also incorporates a 5V sensor that can monitor the stability of the A1200’s 5v power rail.

Top of AmigaKit Real Time Clock and Sensors Module showing the remote sensor connector.

Handily it is also able to monitor the power level of its own battery for the clock module.

Remote sensor probe.

The temperature probe is sold separately and is available here. It simply attaches to the 3-pin socket on the sensor module and allows for monitoring a second location within the Amiga or specific chip depending on where you place the end of the probe.

AmigaKit Real Time Clock and Sensors Module with the optional probe fitted to clock port and probe placed over the Lisa chip/Indivision.

The sensor module attaches to the clock port next to the Kickstart ROMs’ and the probe can be placed anywhere inside the case. As I was interested in the temperature of the Lisa chip and the Indivision I placed the end of the probe there.

Software

Now having the hardware is all well and good, but how do you actually get the readings from it? Well AmigaKit supply a custom program for the Amiga that you install to take care of this. It actually comes as two separate programs, the first of which is called ‘AK_Sensors and is installed into the WBStartup folder. This program runs as a commodity and polls the sensors every 30 seconds and stores the values as environment variables in ENV. The polling interval is infinitely adjustable from between 1 second and 24 hours by means of a tooltype setting.

AmigaKit Real Time Clock and Sensors Module Software.

The second program, AK_Sensors_Display is what actually displays the readings on the Amiga’s workbench. This can be installed anywhere you like but if you want it to be displayed all the time then place it in WBStartup.

With the hardware and software installed it was time to get some readings. To do this I left my A1200 running for a couple of hours and then checked the readings.

Sensor readings after 2 hours.

After 2 hours the internal temperature of my A1200’s case measured 50.9C whilst the probe placed on the Indivision/Lisa chip was reading 54.2C.

Now I had accurate and easily accessible readings it was time to do something to improve them!

Active Cooling Time

After doing some research into quiet fans I settled on this one: a ‘Noctua NF-A4x10 FLX, Premium Quiet Fan, 3-Pin (40x10mm).

Just a fan, ma’am.

It got many glowing reviews online and I was especially encouraged by seeing comments like ‘whisper quiet’ and ‘near silent’.

I’ve never seen such elaborate packaging for a simple fan before!

As small cooling fans go this was probably quite expensive but my Amiga is definitely worth it so I ordered one from Amazon. I was very impressed when I received it as it’s in a really cool presentation box complete with a plethora of cables and accessory doodads.

Plenty of extras come supplied in the box.

As the fan is 12V I intended to power it from the Amiga’s 12V floppy drive supply so I also ordered a floppy drive Y-splitter power cable from AmigaKit to take care of this.

AmigaKit floppy power splitter Y cable.

This will allow me to tap into the 12V supply neatly and safely and as it replaces the original floppy cable rather than modifying it, is completely reversible too.

AmigaKit floppy power splitter closer look.

Fitting the Fan

The fan came with a whole host of different mounting options but I chose to use the silicone anti-vibration mounts. I fitted them through the 4 mounting holes in the fan and then cut the excess lengths off flush with the fan.

Silicone anti-vibration mounts fitted and trimmed to size.

These mounts appeared to be sized perfectly to mount the fan above the Indivision board and by positioning them around it would also keep the fan anchored in place.

Fan fitted neatly over the Indivision. The back 2 legs are splayed slightly which actually helps to keep it held in place.

With the method of fitting the fan sorted I then turned my attention to wiring it up. I snipped off the power connector on one side of the Y splitter cable so I was left with 4 wire strands. Then I snipped off one of the black (ground) wires and the red (5V) wire from the same side. This left me with the Yellow (12V) and remaining black (ground) to power the fan. I then replaced the floppy power cable with the modified Y splitter version.

Tapped into the 12V and Ground wires using skotchlock connectors.

Next I used the ‘OmniJoin’ cable (supplied) together with a couple of Skotchlock connectors (also supplied) to attach the fan to the two wires from the floppy drive Y connector.

Wiring tucked away neatly.

The black wire of the floppy cable connected to the corresponding black wire of the OmniJoin cable. However the yellow wire from the floppy cable needed connecting to the red wire of the OmniJoin cable. The fan does actually have a yellow cable of its own but this for sensing the fan speed and not required for our Amiga project.

Everything fitted ready to put it all back together.

I also made sure that the red/black wires of the OmniJoin cable correctly lined up with that of the fan when it was plugged in. You can just make out the colours of the fan wires going into the fan plug in the image below.

Making sure that the red and black wires match up on the two connectors.

With everything in place I gave it a quick power-on to ensure the fan was working. It whirred into life immediately so I re-fitted the keyboard to check the clearance and was happy to find there was just enough to not cause any issues. If there had been I could have just trimmed a little off the mounts to shorten them.

Just enough clearance between the keyboard and the top of the fan.

Finally I replaced the lid and carefully inserted the screws from underneath. If I flipped it over like I normally would then the fan would become dislodged as it’s not actually fastened down.

Will you Start the Fans Please

With everything back together and the cooling fan installed in my Amiga I powered it back on to assess the fan noise. I was pleasantly surprised to discover that it was very quiet indeed, just as advertised. It’s not silent and I can hear it but it’s just a soft whirring sound and not at all distracting even in a quiet room.

Of course being quiet is one thing but was it actually going to cool my Amiga down? I left my A1200 powered on for a few hours just like I’d done previously without a fan installed to find out. Two hours later I checked the readings and you can see them in the image below.

Sensor readings after 2 hours with fan installed.

As a reminder, without the fan, after two hours the internal Case temperature was reading 50.9C and the Indivision was at 54.2C.

With the fan installed and after running for the same length of time the internal case temperature was now 6C cooler at 44.9C whilst the Indivision had dropped an impressive 11.3C to 42.9C. The case also felt noticeably cooler with no prominent ‘hotspots’ like before.

Needless to say I am delighted with this modification. The whole thing was non-destructive and completely reversible and it only cost around £20 all-in. As the 12V floppy power feed is for the drive motor it’s an ideal power source as most of the time it’s idle anyway. Even so I’ve used floppies pretty extensively since fitting the fan and have had no issues at all even then. Of course your mileage may vary and if you have a borderline PSU then this might just tip the balance.

Just one more thing…

Throughout this whole project one thing had been bugging me – the Compact Flash IDE adaptor and its ‘flappy’ ribbon cable. When it wasn’t getting in the way of the fan it was stopping the top of the case from fitting back on properly. It had to go!

90 Degree CF-IDE Adapter.

I had a look around and discovered a nifty looking right-angled 90 degree CF-IDE adapter on eBay so I bought one immediately.

90 Degree CF-IDE Adapter.

Fitting it was a breeze and the card now sits neatly just above the PCMCIA socket and everything looks neat and tidy once more, just how I like it.

Neat and tidy again.

Cooling my A1200 – Part 1 – Passive Cooling

1st May 2021

Steven

Amiga

1 Comment

I’ve been using my A1200 a lot recently and noticed that it was getting pretty warm after a few hours of use. This was especially noticeable at weekends when I’ve had it running for 12-16 hours straight. The area above the trapdoor (around the cursor keys) was getting vary warm indeed and I could actually feel the heat through the underside of the desk too. I’ve been running it with the trapdoor removed to help keep the Blizzard cool but this has had a limited effect due to the small gap under the A1200.

The feet, well some of them anyway – forgot to take the photo before I started…

Putting my best foot forward

To try and improve the situation I tracked down some new silicone rubber feet that would raise my A1200 up and improve the air circulation under it. I found these on Amazon which looked ideal and I liked the fact that they were transparent so would blend in well.

Placing the new foot alongside the old one.

The pack came with 18 feet so there were plenty of spares. I’ve already used another 4 on my printer to help stop it sliding around. They’d probably also be great for a 3D printer to dampen any vibrations as they are quite pliable.

That trapdoor slot is packed with heat generating chips.

Anyway I stuck one foot in each corner next to the originals which I left in situ in case I ever want to go back to a stock machine.

The new foot dwarfs the old one.

The existing feet are actually recessed so the new ones are significantly taller . This can be clearly seen in the photographs above and below.

Another side-on view of the foot showing the difference in height.

In the following photo you can see there’s now a significant amount of space under the case. Probably 4 times as much as before looking at the height differential of the old and new feet. Combined with running without a trapdoor fitted hoped there would be more opportunity for air to flow under the machine to help carry the heat away.

Plenty of air clearance under the A1200 case now.

I made sure not to forget the PCMCIA adapter I have on the side of the A1200. For this I took one of the feet and sliced it in half vertically as the adapter is quite narrow. Additionally I also lopped a few millimetres off the bottom of each to ensure it sat at the correct height.

One foot sliced in half and trimmed to the correct height for the PCMCIA adapter.

The increased clearance also allowed me to fit a heatsink to the CPU. There still wasn’t a massive amount of clearance so I couldn’t go mad here but I found a nice 35mm x 35mm x 5mm anodised aluminium heatsink on Amazon that looked like it would do nicely. It was a perfect match for the dimensions of the ‘030 chip and came with a strong self-adhesive thermal pad which would be essential given it would be fitted upside down.

68030 CPU with heatsink fitted.

Now I’m fully aware that heat rises and given this was to be fitted upside down there wouldn’t be much scope for heat to convect away from the CPU. However heat also travels by conduction and radiation and I hoped that combined with the increased surface area of the heatsink and the potential increased airflow under the Amiga that it would help cool the processor down.

The heatsink protrudes beyond the bottom of the case but there’s still plenty of clearance.

Once finished I could barely tell the difference visually. My A1200 certainly doesn’t look like it’s on stilts or anything like that. In fact unless I get get my eyes level with the desk surface I can’t even tell it’s raised up.

Did it actually help to cool my A1200?

Before making any changes at all and with the trapdoor fitted I left the computer on for an hour and then recorded the CPU temperature. The highest temp I recorded off the surface of the CPU was 59 degrees Celsius. I believe the maximum operating temperature of the ‘030 is 70C so this is well within acceptable levels.

After raising the case and fitting the heatsink I did the same test again and recorded a maximum of temperature reading of… 57C. So not the massive drop I was hoping for. I shouldn’t really have expected much given that it’s quite a small heatsink fitted upside down with no active airflow…

There was one positive outcome though… the top of the case directly above the CPU was noticeably cooler now. So although the changes weren’t sufficient to cool the CPU by a significant amount it did seem to be helping reduce the build-up of heat inside the case. Unfortunately I never thought to measure the surface temperature before I made the changes so I have no readings to back this up other than my own senses.

The Takeaway

So not the resounding success I’d hoped for, but not a complete waste of time either. The parts cost less than £15 all-in and I have a bunch of spare feet and heatsinks left over for several other projects now too.

It’s pretty clear that the only way to significantly cool the processor down is to add a fan. The heatsink needs a decent flow of air over it to permit it to do its job. Whether it would need to be directly attached to the heatsink or just blowing air under the case across the heatsink I’m not sure.

Maybe one day I might do this but I’d want one that’s practically silent. One of the joys of using the Amiga is just how quiet it is so the last thing I’d want to do is ruin that by having a noisy fan inside whirring away!

To be continued…

[Update] There is now a Part 2!