Thread documenting my build of the F5M in a relatively compact chassis. Kicking off with shopping list of key items:
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- From the DIY Audio store, F5M essentials; "early" completion kits (also requested extra pair of thermistors); and deluxe chassis back-panel kit
- From ModuShop, Mini Dissipante 3U/300, black; base plate; and a set of black feet
- AnTek 400VA/18V transformer (the 300VA version was out of stock)
- 18AWG solid-core hookup wire, assorted colors (free shipping from DigiKey!)
- Also needed extra, X1-rated 3300pf safety capacitor for input side of transformer
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I decided to try out SendCutSend, and had my son draw up a design. Why red? Because I wanted to see what their red actually looks like, and it would have been the same price to anodize it black. STL file attached.
Also wired up power and audio-in wiring harnesses. Audio cable is Belden 1192A shielded Star Quad, leftover from Pearl 3 power supply umbilical cord. Shield is floating at audio board end, and will be connected to chassis ground.
Also wired up power and audio-in wiring harnesses. Audio cable is Belden 1192A shielded Star Quad, leftover from Pearl 3 power supply umbilical cord. Shield is floating at audio board end, and will be connected to chassis ground.
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Decided to mount transformer in the center of the chassis to balance the weight, and make it easier to move around. I found the center mounting bolt to be a convenient, well-located grounding post.
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The decision to place that huge toroid in the center of the chassis made PS board placement tricky. When I (proudly) suggested to my rising aerospace engineering junior that we place the board at an angle, he snarkily quipped, "Newsflash, electrical engineer discovers third dimension!" Sigh.
He made up for it by giving me a crash-course in CAD with AutoDesk Fusion (free personal edition). The V2 part through-holes are slightly bigger, and it's printed with PETG, high-temperature filament. Why red? Because it's high temperature, silly. Attaching STEP file.
There's room under the PS board for the rectifiers, although it's a tight fit.
He made up for it by giving me a crash-course in CAD with AutoDesk Fusion (free personal edition). The V2 part through-holes are slightly bigger, and it's printed with PETG, high-temperature filament. Why red? Because it's high temperature, silly. Attaching STEP file.
There's room under the PS board for the rectifiers, although it's a tight fit.
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Using the top of the transformer mounting bolt for a safety ground connection is not a good idea as it may possibly cause a shorted turn.
Your PS board mounting frame is non-conductive so the ground lift thermistor connection to chassis safety ground through the PCB mounting screw is no longer effective. A separate wired connection to chassis safety ground is needed. I can't tell from looking at the pictures whether one was installed.
Your PS board mounting frame is non-conductive so the ground lift thermistor connection to chassis safety ground through the PCB mounting screw is no longer effective. A separate wired connection to chassis safety ground is needed. I can't tell from looking at the pictures whether one was installed.
Good catch on the PS safety ground, thank you! But please, say more about the "shorted turn" due to using mounting bolt for safety ground?
Well that did not go well ... with four broken drill/tap bits, I can confidently say that I suck at this!
Plan B, ⅛" through-holes. Fortunately, they all line up with the gaps between fins. Next time I'm paying someone to do this.
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From post #1 it looks like current production 3U/300 Mini Dissipante chassis now use the "picture frame" style chassis mounts for the heat sinks. This is the same type used in the 4U 400 monoblocks (second picture). In the past the 3U/300 had a top and bottom rail (first picture), as was used in the ACA chassis and these were first bolted to the heat sinks. The order of assembly seems to differ for the picture frames; at least in my hands the picture frame has to first be mounted to the baseplate with countersunk flat-head screws, then later the heat sinks are bolted to the frames.
Also the Philips-style screws that hold the front plate on are tricky to access in a chassis full of trafos & PSUs. The Japanese make these wonderful right-angle screwdrivers of extremely low profile that make this job at least possible, if not easy.
Also the Philips-style screws that hold the front plate on are tricky to access in a chassis full of trafos & PSUs. The Japanese make these wonderful right-angle screwdrivers of extremely low profile that make this job at least possible, if not easy.
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Well, that's unfortunate but fixable if you'd care to persevere.
Aluminum is pretty easy material to work with and I'm sure that with a little troubleshooting and practice, you'd do just fine.
There's nothing wrong with farming out work if that's your preference but a little time with a piece of scrap aluminum, some guidance and patience is likely all you need
Aluminum is pretty easy material to work with and I'm sure that with a little troubleshooting and practice, you'd do just fine.
There's nothing wrong with farming out work if that's your preference but a little time with a piece of scrap aluminum, some guidance and patience is likely all you need
my trick, writing/showing pics all the time, using studs for front plate
easy peasy, washer-nut-wrench
I am far from an expert with the metal work but I have successfully performed the drill and tap routine with dozens of holes without breaking anything over the years (knock on wood).. So here's my basic routine and tools used.. I think the quality of the drill and tap itself is important. I got those at MSC, part #'s shown (for M3). I always center punch first so that the drill bit doesn't wander. Cutting fluid - I always use Tap Magic for any drilling and tapping operation. I run the tap by hand with the T Handle. Go slow and back out when you feel resistance. It's a slow and patient back and forth kinda thing, cutting the threads. Keep the tap clean by brushing away the excess shavings that causes the binding. I have an old Delta drill press I bought cheap at a garage sale a long time ago. That was definitely worth it looking back now. Hope something there helps..
