Inkjet Priming and Cleaning

And now, on the Very Secret Life of Machines….

Here’s a look at a very curious mystery on a Brother MFC-J435W. On this printer the ink cartridges are loaded at the front panel and a set of small (silicone?) hoses carry the ink to the print heads.

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This is what they’re supposed to look like. The printer was brought to my desk after a new set of cartridges were loaded and it only printed black. I didn’t get a photo of it but the ink lines were totally empty…??!!

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Ink everywhere but not a drop to print

So how do you prime the lines? Well, Brother thought of that. The rubber cap that seals the printhead when not in use is connected to a vacuum pump.

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The cap and squeegee blade used to wipe the head are visible at the end.

Triggering the clean cycle over and over finally primed the lines and the color output slowly returned.

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So I’ll answer this mystery: What does an inkjet cleaning cycle do? Well, first off, the printhead periodically moves to an ink toilet off to the side and wastes some ink to keep the ink in the passages fresh. This is audible as a soft high pitched (about 5000 Hz usually) tone.

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The ink toilet.

Second, a squeegee is moved into the printhead’s path and it’s wiped clean of any dried or accumulated ink. This is typically done during print jobs as well and can be heard as one or more clicks.

Third, during manually initiated cleaning or priming cycles or after installing new cartridges or printheads, the printer uses the big suck to prime the ink feed system.

This vacuum pump isn’t present in all printers. Generally if your printer uses cartridges where the printhead’s changed along with the cartridge, it isn’t present or needed, and if your printer has permanent heads (Epson) or uses tubes like this one, a priming pump is used.

Long ago NeXT made inkjet printers that even had vacuum switches so it could confirm when the ink was primed and fix it if not. Most ain’t that fancy.

So if your printer drops a color, look for these clear tubes – they shouldn’t be!! If the vacuum pump isn’t doing its job, make the printer move its head then cut the power while it’s uncapped. Clean the cap/vacuum with a wet paper towel or cotton swabs. The ink will stain fabric and skin. You were warned. Power back up and see if it’s happier.

Only major gotcha here– repriming the color ink lines consumed a full cartridge!

Oh well– not MY printer…

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Before cleaning the Big Suck.

The oddball HP Pavilion 500

This is the weirdest mini tower PC I’ve ever seen.

It’s pure essence of cheap.

It’s almost like a Chinese fake of what you expect.

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First warning sign something is amiss : laptop power adapter.

Let’s look at that full back panel.

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There are ridges where slots should be. But why aren’t they cut out and usable?

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Oh.

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SATA drive power comes off tiny JST headers.

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This is just bizarre. It’s like a mini itx board but with 99% less flexibility.

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This is definitely a Carly Fiorina special.

When your BrightLine isn’t

Oops! Never trust a semiconductor fart.

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Looks like the IRF840 MOSFET lost its Magic Smoke and shorted (Magic Smoke is both an insulator and conductor) and unwarranted voltage got back and explosively decapsulated the controller IC.

I bet this one went Snap Crackle Pop.

This was from an older BrightLine florescent stage light. Newer versions just use a couple of little Advance ballasts instead of a big arse custom PCB. I’m upgrading it to the new hardware.

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Oh i bet the viewers smelled this one at home!!

RoHS? RoLC

I mean, Reduction of Life Cycle. Am I right or am I right?

Finally it seems that Western Digital started using better lead free solder on their hard drive logic boards.

Now, Seagate… more like Peegate, yet again it looks like someone pissed on the board.

This one has yet to exhibit the failure mode in which that piss-oxide creeps under the pogo pins leading to the spindle motor, actuator, or head stack, and causes a (sometimes repairable) failure.

Lift Station Controls or Pumping Poop With Pomp and Pizzazz

Ahhh nostalgia —-
My first introduction to control logic design was designing and building pump control panels with my grandfather. If you happen to find a relay logic panel labeled “C&K Electric”, that was us.

This isn’t one of ours, but it’s pretty similar in design and construction. We really preferred Furnas relays though, and whoever ran the line entrance to this thing needs to be dipped in…. *bwahahahaha* THE PIT!!!

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The Turd Alert.
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Schneider Electric contactors, eh, okay I guess. You heathens.
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Very nicely drawn diagram
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Pump alternator and turd alert silencer relay.

Here’s the basic operation: there are four float switches in the pit.

Switch 1: latch enable. Does nothing when switched on, but if a pump is latched on by its aux contact and it drops from low sewage level, it stops the pump(s). The alternator relay is also triggered at this point; it’s essentially a falling edge triggered gate. This changes up which pump will run next time so they take turns for wear leveling purposes.

Switch 2: start lead pump (as determined by alternator position). This will latch on until switch 1 opens.

Switch 3: Also start lag pump. This occurs when there’s too much flushin’ going on for one pump to handle it alone.

Switch 4: TURD ALERT!!! Condition BROWN! Sewage level is dangerously high; can occur due to pump failures, flooding, or a number of other very nasty things. While switch 4 is active, the red light comes on and an audible alarm sounds. This alarm can be silenced (will auto rearm as soon as the alarm condition clears).

On a side note– I recall the insides of those Diversified Electronics alternators being hilarious. It was like six tiny relays in a potted board and it invoked the obvious question of why not just use a spring loaded pawl mechanism like Furnas does?? Guardian Electric also made a version with a cam and ratchet; it was okay when new but the plastic cam was prone to degrading. Can’t win ’em all I guess.

No you don’t

Previously—-

No, wait. Not you again.

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Not on my watch.

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Say “Magic Smoke release” again. I dare you. Feeling lucky, punk?!

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Dip packaged op amps on this one. Curious.

I caught this one JUST STARTING to smell like hot plastic and having blown the fuse for one side of the bipolar supply…. Luckily the equipment it took audio from seems to be long gone, as is whatever it supplied.

A tale of amplifiers.

Here’s a story I’ve been meaning to tell for a while.

Once upon a time, there was a wonderful isle of dreams, and a television station built upon it. To carry the sounds to accompany its magically delivered pictures, there was a set of audio distribution amplifiers.

And oh baby what amplifiers they are….

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The guys on the right. Ignore the dark power lights, they're soldered in incandescent...

And their, uh, not the best side

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The company stuck around until 1985

And now the heart:

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Those of you who are like me will also notice, this is six individually transformer isolated outputs and one transformer isolated input.

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Fairly simple amp stages.

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The dual power supply. One regulator on each end. This is the older design; the newer one has two separate regulator cards.

These lived happily until one day, one regulator card let out a biiiiiig fart.

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For comparison, this is what the other end looked like:

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Oh how it stank that morning on the wonderful isle of dreams!

The finest nose on the isle located the stench and an engineer set to restoring the precious music of the angels to flow beyond it. Fortunately he found only two channels still in use, each feeding one output… Thus:

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Emergency passive near unity gain audio distribution system.

This engineer was haunted from that day by the knowledge that some very mission critical audio still runs through that stack and the amps aren’t getting any younger.

However, they are, at least, better than the modern equivalent.

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I'll just take my chances with the old Ramko Research shit boxes, thanks

ESP Surge Protectors

I’ve used these for years whenever I find them on the surplus market. These are really good surge protectors. They often have a label saying not to remove them — they are usually deployed on installation of fancy leased office copy/scan/print/fax machines costing kilobucks and are required as part of the service agreement.

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The green LED on this one is just a power on light. Note that some units have a safety relay inside and will not power on unless a good ground is present. They’re idiot proof. You’ll see momentarily why the ground is very important.

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All of them can be opened without damage. On this one you pry from the back and carefully release locking tabs.

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That… Uhh… That’s a static sensitive warning. I’m guessing that was some engineer’s joke as there are no static sensitive parts in this unit at all.

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Here’s the good part. Surge protection on the inlet – line and neutral first meet these MOVs and gas tubes. Now this unit is kinda interesting in that it’s wired like this:

Line in —-{two MOVs in parallel}—[gas tube]—ground—[gas tube]—neutral

Normally I see the gas tubes and MOVs in parallel.

Not gonna question it; it works.

Now those are just the castle gates. There are more defenses beyond…

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L network filters in line and neutral. Each must flow through an inductor on its way to the equipment. Once it passes the inductor which will resist the passage of both high frequency gibberish and spikes with fast rise times, a capacitor damps out the high frequency components. If you’re curious as to how this works, go deeper down the rabbit hole and research basic filter design. It starts to get quite fascinating.

One cap goes from line to neutral, two go between L/G and N/G. One resistor up before the inductors will bleed residual charge off these upon unplugging for safety.

This is a feature not present in most AC powered smoke alarms. Don’t touch their pins after disconnecting them. They bite.

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Additional MOVs are provided here and are behind 2 amp pico fuses. Not sure why the fuses are used, but for a surge to hit these, it would have had to get through the primary defenses.

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Telco protection stage; this uses poly switch fuses for current limiting (self resetting) and MOVs to limit voltage.

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The MOVs can even be replaced if they pop.
Cool, right? I’ve never had any gear get damaged plugged into one of these. They Just Work.

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