MikroTik CSS326 fan installation

It was time to upgrade my networking equipment in my homelab. I needed two 24p 1GB switches with 10GB uplinks to facilitate moving my homelab into my crawl space and out of my office. As things are configured right now I’d easily saturate a 1GB uplink between the switches and since I don’t have any 10GB in my homelab yet the CSS326 fits the bill. I am replacing a single first generation Ubiquiti 24p switch with two CSS-326-254G-2S+RM’s.

After receiving my CSS-326-254G-2S+RM’s I plugged them in to test them and verify my 10GB SFP+ transceivers were working properly. While I was doing that I also hooked them into PRTG using SNMP so see what kind of monitoring data I could pull from them. I had been optimistic that these new switches would run cooler than my Ubuiqiti but that does not seem to be the case. My Ubiquiti (which has a fan) runs at about 76c. The MikroTik ran at about 70c without a fan. An improvement but not a fantastic one.

Below is 1 hour of monitoring data from the MikroTik with a single 10GB SFP+ installed in it running idle but connected to my Ubiquiti via 1GBe and the other CSS-326 via fiber.

CSS-326-254G-2S+RM – 1 hour – CPU Temperature – Average 70c
CSS-326-254G-2S+RM – 1 hour – SFP+ Temperature – Average 43c

The CSS-326-254G-2S+RM has a mount for a 40mm fan and figured I’d just buy a fan and slap it in there. Unfortunately once I popped it open I saw there was no header to connect a fan to. I did some digging and came across this video which shows a significant temperature improvement once a fan is installed and the creator helpfully pointed out where you could tap into the switches board to get power. I also found this helpful forum post that also showed the J2 header and mentioned which connector was positive (+) and which was negative (-).

“YOU DON’T NEED TO DO THIS. Mine runs in a warm rack enclosure and has for 3 years now”

– Someone I know

Using my multimeter I checked the J2 connector and it outputs 24v a few seconds after the switch boots up. From what I have read, the J2 only outputs power if you connect the included power cable to your CSS-326. If you use PoE to power the CSS-326 the J2 connector does not output any power. I did not test this but since I’m using the supplied power cables this isn’t a problem for me.

Noctua is my preferred fan manufacturer but they do not make a 24v 40mm fan which means I had to use a buck converter to drop 24v down to 12v for the Noctua NF-A4x20 I wanted to use. I will put a full parts list at the bottom of this blog post.

I did not solder to the J2 connector as my first step. I just want to show where it is before continuing. Please excuse my poor soldering skills. This is only my 3rd or 4th time seriously soldering something and my first time soldering to a PCB. Using the information I gathered, I am labelling which connectors I treated as positive (+) and negative (-). I might be wrong but it all worked in the end.

J2 before I soldered my wires
J2 after I soldered my wires

Easy step first, I mounted the fan into the CSS-326 using some M3x12mm screws, nuts and a little patience.

I then 3D printed a baffle to block off the dead space to the right of the fan if you’re looking at the switch from the front. The electrical tape is just to hold the baffle in place while I’m fiddling inside the switch. Once you put the top back on the baffle is firmly pinched in place and won’t move. As designed the baffle is overkill. It could be 3mm thinner but I don’t care about saving 6g of filament so I didn’t change it for the second switch. The STL is linked at the bottom of this post in the parts list.

Using the cables and adapters that came with the Noctua fan I was able to piece things together in a way that I would never need to touch the J2 connector again if something failed. The buck converter can be detached from the main feed connected to the J2 and the fan can be disconnected from the buck converter. If either piece ever dies it should be very simple to replace them. I specifically used the extension cable and the Y-splitter. You can toss the one labelled “Low-Noise Adapter” into your spare parts bin, we won’t be needing it.

I have labelled each connector with a number so you can see how I piece things together

I removed all of the sheathing from the cables, removed any blue/green wires because I only need the yellow and black ones and then cut off some of the connectors.

Piecing them all together they will look like this:

Numbers in brackets mean a cut

(1) – Is the small connector on the extension cable that gets removed and soldered to J2

2 – Is the large connector on the extension cable that does NOT get removed. The IN on the buck connector will plug into this.

(3) – Is the large connecter on the upper leg of the Y-splitter that gets removed and soldered to the IN on the buck converter

4 – Is the large connector on the lower leg of the Y-splitter that does NOT get removed. The fan will plug into this which is attached to the OUT on the buck connector.

(5) – Is the small connector at the base of the Y-splitter. You want to cut this so that the smaller connector remains attached to the upper leg of the Y-splitter that you removed the large connector (3) from. This then gets soldered to the OUT on the buck converter

6 – Is the fans connector, leave it alone. You will plug it into 4 when everything is done

Before soldering (1) to the J2 connector feed it through the gap in baffle and under the mainboard so you can keep it all tucked out of the way. If you don’t do this first you’ll have to remove the mainboard and baffle to do it later. There should be just enough wire to make it to the J2.

Solder it all together based on the diagram above and plug everything in except for the fan. We need to adjust the buck converter before we can plugin the fan. Odds are its default setting is too high (more than 12v) for our Noctua.

Set your multimeter for DCV at whatever setting can read higher than 20v, connect alligator clips to the OUT side of the buck converter and then connect those to your multimeter. Plug the power into the switch and check your multimeter reading. Using a flathead screw driver carefully turn the small knob on top of the blue box on the buck converter until your multimeter reads 12v.

Initial buck converter setting
Buck converter reading after a few turns

Disconnect the power from the switch, remove your multimeter and alligator clips, screw together the buck converter case and put the top back on the CSS-326. You’re done!

My final results were that the switch ended up running about 30c cooler and the SFP was 11c cooler.

CSS-326-254G-2S+RM – 1 hour – CPU Temperature – Average 40c
CSS-326-254G-2S+RM – 1 hour – SFP+ Temperature – Average 32c

I get MikroTik saving cost by not including a fan in the switch but I really wish they would have at least installed a connector on the J2 to make adding a fan an easy option.

Update – 2022-08-20

I moved my entire homelab off my old Ubiquiti switch yesterday and have some real word temperatures with actual load on the switch:

The first low section on the left was the switch idling with no load while I configured VLANs and LAGs. The gap is me unplugging it, sliding it under my Ubiquiti switch and powering it back on. The initial high temperature (45.8c) was from the Ubiquiti smothering it while I did cable swaps. I eventually removed the Ubiquiti switch and the temperatures dropped a bit.

Parts List

Buck Converter – I used a “LM2596 DC-DC Buck Converter Step Down Module Power Supply DIP Output 1.25V-30V 3A”. There are a ton of these on Amazon. Here is a non-referral link to a 10pack I bought.

Noctua NF-A4x20 – Since there is plenty of room in the case I went with the 40mm * 20mm version of this fan to get the most air movement possible.

Buck Converter Case – I printed one of these to insulate the buck converter from the chassis of the switch.

Baffle – Completely optional but I designed and printed one of these to block off the section of the case to the right of the fan mount. Seemed pointless to circulate that air since there are no electronics in there except the buck converter.

Replacing the battery in Balanzza Mini Rechargeable Scale

After my last trip to Mexico I had the desire to buy a rechargeable luggage scale so I didn’t have to remember to replace the batteries in it. When we travel we always have multiple USB chargers with us so a rechargeable luggage scale made a lot of sense. Based on the Wirecutters recommendation I looked to pickup a Balanzza Mini Rechargeable Scale (non-referral link).

I live in Canada and couldn’t find a local supplier and most online retailers in the US would have charged an arm and a leg on shipping or simply had no stock so I turned to eBay and found someone selling one, brand new condition, for a reasonable price.

I placed my order and waited the 2-3 weeks to arrive and when it finally got here it wouldn’t not power on. I figured the battery was dead and plugged it in to charge. After about 8 hours charging the charge light hadn’t switched from red to green. I was able to power on the scale and it worked until I disconnected it from the USB charging cable, then it died again. Seemed like either the charging component wasn’t working properly or the battery inside the scale was toast or had a bad connection.

The unit was brand new and in a sealed package so I didn’t feel like I’d been duped. I reached out to Balanzza support and heard nothing back after multiple attempts to contact them. Since I had nothing to lose at this point I decided to crack it open.

Sorry I didn’t take good photos of the inside initially, don’t know why:

Looks like the scale comes with a 100mAh LiPol battery (601522). These are easy enough to find on Amazon, eBay and Alibaba depending on how much money you want to trade off for time waiting for the battery to arrive.

I had some 240mAh LiPol’s lying around for a small quad copter drone so I figured I’d do a quick test with one of those to try and determine if the issue was the battery.

Very promising. This confirmed the included battery had no charge and was either toast OR the charging controller was faulty… or both. I cracked out the multi-meter and checked the 100mAh battery and it was toast, or at least toast looking enough I wasn’t going to bother trying to charge it. I also didn’t have a good way to charge it.

Space is tight inside the Balanzza and the original battery sat on the right side of the device in a very small space. Over on the left side of the scale there is a nice cavity that gave me a bit more wiggle room to put a bigger battery in but it was still too small to fit one of my 240mAh LiPols in so I was going to have to order something. Since I had to buy new batteries anyway I tried to find the biggest mAh LiPol that would fit inside the cavity on the left side of the Balanzza and came up with the 150mAh LiPol (402020) which measured 2.0cm*2.0cm*0.4 cm and would fit nicely. It seemed battery larger than that, mAh wise, was too physically large to fit.

Some quick soldering and shrink tube later:

and I ended up with a functioning scale. I also tested charging and after 1-2 hours the light went from red to green. Appears I fixed it and gained 50% more battery capacity!

How to use the Meater Probe in a smoker for ambient temperature only (Part 1)

Lets get this right out of the way. This is Part 1 because it failed miserably. I figured I might as well document what I did to help save someone else the trouble. Hopefully Part 2 will be how to do this properly.

Alright now that that’s out of the way…

I recently received my Meater Block Kickstarter reward and immediately realized a flaw I would have to find a solution for. The Meater probes are divided roughly in half by a safety marker. The side with pointed tip is a internal temperature probe meant to sit inside meat and never exceed 212F. The rear of the probe (black area) is an ambient temperature probe rated for up to 527F. This is all according to the FAQ on the Meater website.

This is not a problem as long as you have some meat to stick the probe into which coverts pretty much anything you’d want to smoke with one big exception. Ribs.

Ribs are to thin for temperature probes. When smoking ribs I only need to ambient temperature. This is where I realized the problem with the Meater probes. When smoking ribs you’re aiming for 225f-250f which is above the safe temperature for half of the Meater probe. This was a real bummer because I was looking forward to having a super reliable, long range, wireless thermometer to use for everything I smoke.

This got me thinking about what I could do to solve this problem since I haven’t found much online.

The solution I came up with was some kind of protective heat-sink/deflector I could insert the probe into that would prevent the lower temperature tip while still using the ambient part of the probe.

For the material I selected Smooth-Sil 940 Food Safe Silicone. I figured I could mold a simple cylinder using a empty can that I could just insert the probe into and easily remove when done.

My notes and lessons learned from this process can be found at the bottom of this article.

After the 24-hour cure time was up I cut away the can and ended up with my final creation:

I did my initial test. I threw it into my oven at 300f for roughly 1 hour, pulled it out and did a quick check. The results were not promising.

Not wanting to give up hope I proceeded with test 2. I drilled a hole in the center of the silicone so I could easily insert/remove my Meater probe.

I then threw it into the oven at 300f and waited. The results reflected my initial testing:

It only took about 1 hour for the sensitive part of the probe to hit 200f. Not good. I need this to sit under 200f for at least 5 hours for ribs. Ideally 8 hours just so I have a nice buffer.

Another thing I forgot about during this test was carry over. The probe actually got up to 224f before it started dropping. I couldn’t pull the probe out so I ended up dumping the silicone into my sink, filled it with cold water and dumped a bunch of ice in. Fortunately I did not kill my probe. It looks like the Meater folks built in a nice buffer for idiots like me.

At this point I figured this idea was a flop but I wanted to try one more thing. I let the silicone cool back down to 70f (the original temperature of Test 2) and then wrapped it in a layer of aluminum foil hoping that might deflect some heat.

The results were slightly better but no where near my goal of 5-8 hours. The aluminum foil gave me an extra ~30 minutes. I also pulled the probe right at 200f and threw it back into the ice water to avoid the red screen of death from the previous test.

To get my probe out I had to cut open the silicone.

My conclusion is that food safe silicone alone is not going to be enough to solve this problem for me. I’m going back to the drawing board and will post a Part 2 if I figure anything out.

If anyone here actually knows something about materials, heat deflection/resistance and has a solution to this problem please drop me a comment below.

Appendix 1

If anyone is curious here are my “Lessons learned” notes from trying to mix the silicone components.

Do final mix in a more ridged container
	The vacuum sealer ended up crushing the plastic container instead of sucking the air out of the silicone
	It would have worked though shockingly
	Cleaning the silicone out of the vacuumed nozzle sucked, 99% alcohol and toothpicks for like an hour

Forgot to use a vibrating platform
	Went out to the garbage and put the tin on a desk and ran the reciprocating saw for a few minutes to vibrate things as much as I could
	Won't know if this helped until cured

Using a sheet over the island was a super good idea, easy to clean and I ended up making a few splashes
	Threw everything in the garbage
	Could have kept the plastic buckets I bet but I dunno if I'm ever going to do this again

Check volume measurements before buying a kit, I barely had enough for a single application let alone the original plan of 4

Dumped the idea of the tin foil heat deflector due to above issue with material
	Will test with just silicone and then maybe test again after wrapping the silicone in tinfoil

Left the tin with the silicone on top of my server to hopefully vibrate during the entire cure and help get some air out, dunno if this will help

Keep gloves on always, this stuff feels weird on skin and is hard to wash off