New Video: Recapping the Micromac DiiMO PDS Accelerator Card

[JDW]

I made a new walkthrough video about replacing all the electrolytic capacitors on the MicroMac DiiMO 50MHz 68030 accelerator for the SE/30.  I explain my choice of Niobium Oxide capacitors over tantalum, show the replacement, then boot and run benchmarks.  The SE/30 shown has a recapped motherboard, recapped analog board, and SEASONIC PSU. The video is 4K but if you're a Mac user who loves Safari, you'll need Chrome to view it in 1440p or 4K.  Also, it was sadly during the making of this video that my Epic Blunder occurred.  My humble thanks to all of you who are so kindly trying to help me in that thread.

I make videos for the enjoyment of it and as a way to give back to the community.  I currently don't allow ADs on my videos nor do I have a Patreon account, which is why I've never earned any monetary compensation at all from my videos.  (The down side of that is Google doesn't suggest my videos as well as videos with ADs enabled.)  I make videos that I really wish someone else had made for me.  Even though what you see in my videos isn't necessarily groundbreaking or unique (some of you are far beyond me in terms of troubleshooting knowledge, repairs and mods, for example), I simply am transforming into an easy-to-digest video what otherwise has been exclusively found in "text form" in forums like this.  For the new generation of younger people who don't prefer to read, videos are becoming increasingly important.  (Even so, I still get Millennials complain my videos are too long, so we can't please everyone. I prefer to be thorough rather than worry about the clock though.)

My next video endeavor will be to show the recapping of an SE/30 analog board, and then I will have yet another video showing the recapping of the SONY PSU.

Anyway, I hope this information is useful not only for you DiiMO owners but also for those of you who need to recap 5V voltage rails, as the Niobium Oxide caps I chose work perfectly for that, assuming you need 22uF.  They come in other sizes though so give them due consideration in your recapping jobs.

 

[CC_333]

(Even so, I still get Millennials complain my videos are too long, so we can't please everyone.

<opinion>

Shame. I feel like, as a group I'm almost sorry to be a part of, they are virtually impossible to please, and their attention spans are best measured in negative numbers because they want to spend as little time as possible on things, and they expect instant everything.

The next paragraph is going to be very curmudgeon-y, so bear with me...

Many, I've noticed, are notoriously lousy at explaining themselves (Linux people, in particular, tend to be quite terse, almost to the point of being completely obtuse), and a certain subgroup which tend to congregate around San Francisco and other similar cities (this same group (I'll call them "Hipsters") always follows the latest fads, and they always drive prices up beyond insanity wherever they go) is annoyingly arrogant about technology, with the belief that an app can be written (or some sort of electronic device created) to solve ANY problem, which may be true in some cases. But what about smartphone addiction (a big problem nowadays, especially among Millennials)? It seems to me that throwing yet more apps and technology to distract people from their phones (many such apps and technologies actually *require* a phone to function 100%!) is one of the worst possible solutions!

</opinion>

Your video is a very useful contribution, even if it is little more than a reiteration of the same information found in text form. It is helpful to actually *see* someone doing the work, so the person watching has somebody to imitate (otherwise, it's all a big guessing game, and that's when mistakes happen).

Plus, it helps remove the influence of language barriers, as much information (particularly on this forum) seems to be written in English, and not everyone is fluent in that language. This can be frustrating for someone trying to get some information on something.

So, TL;DR: keep up the good work!

c

 

[JDW]

@CC_333 Thank you for your <opinion></opinion> and for your kind words of encouragement.  YouTube comments under my videos aren't always positive and upbeat like yours though.  One of the most recent on my iMac video card bake walkthrough said this (I copied and pasted it just now):

dude ,shorten up your videos , mostly your womenish talking, for God's sake

A lot of folks watch YouTube strictly for entertainment, 4 minutes a pop.  I know this by watching my 15-year-old daughter watch YouTube.  She even skims through 4 minute videos!!!  But such does not deter me in light of the fact most 15-year-old girls aren't setting out to recap vintage Mac hardware.   :beige:

More to come.  And hopefully one day I can make a video showing how, with the help of this forum, I resurrected my poor DayStar Turbo 040. 

 

[CC_333]

dude ,shorten up your videos , mostly your womenish talking, for God's sake

Hmm, well... I don't know exactly what to say in response to that.

What does "womenish talking" mean? Does that mean "descriptive" or something?

Anyway, you're quite welcome! You're sharing your knowledge, and that's good. As opposed to hoarding it. This reminds me of a local LP-FM radio station I volunteered at for a couple years. They had a web server so they could stream their broadcasts online, but it was a huge mess and almost never ran right.

Unfortunately, the guy who set it up (intentionally) neglected to document anything or provide any sort of useful information, so the end result was that only he could do anything to fix it, because he was literally the only one who had the key to the server "room" (it was a small closet) and he was the only person with knowledge of exactly what was set up where, how it was set up, and what it was for.

And of course, this guy was rarely available (he'd come in maybe once every other month) and he refused to share any of his knowledge of the setup with anyone (other than the simple fact that it existed), so if anything broke (such as the internet stream), it would stay broken for weeks, sometimes months on end, causing extreme headaches and frustration for anyone trying to get stuff done. And for those of us who knew what was wrong, we were powerless to do anything about it because everything was locked down so tightly.

TL;DR again: What good is knowledge if no one shares it?

c

 

[JDW]

What good is knowledge if no one shares it?

Exactly.  I hope my videos can inspire others among us (those who have a decent video camera, of course) to share their own experiences on YouTube.  It's a lot of trouble compared to just recapping or repair something without being filmed, but I think it's worth it because the video will benefit a lot of people and last as long as YouTube does, which hopefully will be a very long time to come.  Just imagine what we all would be doing (or NOT be doing) with our vintage Mac hobby if Gamba and this excellent forum didn't exist.  So I think of videos as being equally important moving forward.

 

[LaPorta]

Don't stress over the fools that post comments like that. I'm 35 and technically am at the extreme end of "Millennials", though I don't identify with them at all. What a bunch of whiners. For those who "respect and want total equality," it shows that it is not the case with comments like that. Keep making your videos. I wish that I could do something even half as good as that.

 

[Unknown_K]

Videos are great for complicated descriptions and actions, text is great for simple things.

 

[Trash80toHP_Mini]

How can you possibly be offended or discouraged by a semi-literate numbskull using "womenish" as if it were a word.

edit: looks like it may be an intentionally misspelled instagram thing  .  .  .  but that pretty much proves my point.

 

[Trash80toHP_Mini]

Videos are great for complicated descriptions and actions, text is great for simple things.

A well crafted HowTo web page from the dawn of time did both and much better. Video can better that in some ways, but not for step by step instruction IMO. Now you have to comb through dozens of youboobtube vids to find the two or three where somebody appears to know his or her stuff and be able to present it well within the medium..

 

[CC_333]

Apparently I can no longer typel ;-/

It's been a long day.

c

 

[just.in.time]

@JDW your camera has great focus and sharpness.

 

[JDW]

My camera is a Panasonic GH5 (great for stills and video).  Lens is an Olympus 12-100mm F4, which is a very sharp and rather price "Pro" lens.  I shot in the GH5's HLG profile (to get the maximum dynamic range) and used the Leeming HLG LUT v5.02 to convert Rec.2020 footage to Rec.709 and edited in FCPX.  I added a bit of sharpening in FCPX using a free Unsharp Mask plugin.  Mic used in my SEASONIC video was a SONY PCM-D100 stereo recorder using its built-in mics.  My DiiMO recap video used a cheap wired LAV mic called the Purple Panda (sold on Amazon).  The LAV pics up a buzz from the fluorescent room lighting, so I need to use my iZotope dialog denoiser plugin in FCPX to eradicate it.

 

[Crutch]

Thanks so much for making this. I have been contemplating recapping my DiiMO and your visuals will be extremely helpful. I look forward to trying it out. (I also thought your recent power supply replacement video was terrific, as someone who just did very similar surgery putting a Seasonic PSU into an SE/30.)

 

[JDW]

@Crutch Thank you for your kind words.   

I highly recommend these Niobium Oxide capacitors for a DiiMO recap.  

I spent a considerable amount of time researching the best caps, and for reasons stated in my video I decided to restrict my consideration to only caps with solid electrolytes which won't leak or dry out over time.  Some may argue that you can get an ESR of much less than the rated max of 0.7-ohm@100kHz (I measured 0.22-ohm@100Khz) if you use ceramic caps, but sadly there's capacitance drop with applied voltage on all ceramic caps other than NP0(C0G), and NP0 don't come in large sizes like 22uF.  The best non-NP0 ceramic caps are X7R's, but even they have a voltage derating because as voltage applied across the capacitor increases, the capacitance drops sharply.  And it's not a simply matter of just choosing a very high voltage rating for the ceramic cap because case size increases according to voltage rating.  Consider the following Taiyo Yuden X7R capacitor rated at a substantial 25V and note that even it's capacitance drops by about 25% once the voltage applied across the capacitor reaches a mere 5V:



So if you want an X7R ceramic cap that assures you of a full 22uF capacitance at the nominal 5V voltage level of the DiiMO, you'll need a 50V rated X7R ceramic, but such are physically too large to fit the PCB pads on the DiiMO!  Even if they could fit, the cheapest of those 50V 22uF ceramics costs $3.62 each in quantities of less than 10pcs from Mouser!  Yet another disadvantage to X7R and lower grade ceramic caps is that their physical size changes as voltage rises and falls causing them to shake the PCB such that you can actually hear a whine from them, especially when they are used with switching power supplies.  Such is probably not an issue on the DiiMO but it is something you have to consider in any design where you consider using ceramics and switching power.  And while the ceramics with little metal feet attached are built specifically to attenuate that piezoelectric audible effect, such caps come with a high monetary cost and with increased physical capacitor size as well.

Ceramic capacitors would have the small (and perhaps even imperceivable) "benefit" of an ESR possibly as low as 0.005 ohms; but again, for reasons already stated, ceramic capacitors are not always a feasible solution, and excellent NP0 (C0G) type capacitors rated at 6.3V or higher only come in small capacitance sizes of pF and nF.  At the end of the day, Niobium Oxide on the DiiMO are better than tantalum, better than ceramics, fit the PCB perfectly, have much lower ESR than the stock electrolytic capacitors even when they were brand new, are fairly low cost, and are easily purchasable from vendors like Mouser.  

In summary, you won't go wrong using the exact caps shown in my video.