Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
The Casio EX-Z850 camera living in my pocket finally developed a problem. Two buttons on the back select the Review and Camera modes; the former stopped working, which means I can’t see pictures after I take them. The Camera button may still work, but because I can’t display pix, that’s pretty much moot.
Taking the camera apart require a Philips 00 screwdriver bit and some care, but eventually you’re confronted with this:
Casio EX-Z850 camera – opened
The buttons and the mode selector dial all connect to the same flexible PCB substrate, which ends up in this connector. You should ease the black pressure bar (seen edge-on here) upward to release the flex PCB:
Casio EX-Z850 button connector
As it turns out, the two buttons have a common contact that’s the second trace from the top in the flat cable. Both buttons have good snap action, good conductivity, and seem to work fine. That puts the problem deeper inside the camera, where I don’t see much point in going; I can certainly make things much worse and likely not make them any better.
In fact, it turns out that the two buttons on the USB/charging cradle don’t work now, either, which implies that the camera buttons run in parallel with those. So there’s something blown in the camera’s guts, which is definitely Bad News.
Back in the Bad Old Days, you used to take a picture and wait a week or two to get the results back from the drug store. Perhaps it’s fashionably retro to have a digital camera without a Review mode?
A long time ago, I read this in E. E. “Doc” Smith’s The Skylark of Space:
He could study safeblowing fifteen minutes and be top man in the field
Even back then, I knew knowledge didn’t work that way. If your fingers haven’t done it, you don’t know how to do it. The more you do it, the better you get.
The Judges at the Trinity College Home Firefighting Robot contest use butane grill igniters to light the candles in the arenas, but the gadgets seem to have terrible reliability problems: very often, they simply don’t work. I brought a few deaders back to the Basement Laboratory this April and finally got around to tearing them apart.
It seems they don’t ignite because the trigger’s safety interlock mechanism shears the plastic gas hose against the fuel tank’s brass outlet tube:
Grill igniter with sheared gas tube
I tried putting a small brass tube around the (shortened and re-seated) hose, but it turns out the trigger interlock slides into that space and depends on the hose bending out of the way:
Grill igniter with brass tubing
So there’s no easy way to fix these things.
It seems to me that a device using flammable gas should not abrade its gas hose, but what do I know?
Part of the spring ritual involves cleaning the maple seeds out of the gutters, which also gives me an opportunity to inspect things up there. This year brought a revolting discovery:
Rotted vent stack gasket
It seems the rubber (?) seals around all three vent stack pipes have disintegrated. Now, the contractor installed these as part of the re-roofing project late in the last millennium, so it’s not like they came with the house. They’re an exact match for what’s currently available at Home Depot and I have no reason to believe new ones will last any longer. Sheesh.
The correct fix involves removing the shingles around the existing aluminum plates, installing new plates, and then replacing the shingles. That seems unwarranted, seeing as how the aluminum remains nicely bonded to everything, so I slipped some solid polyethylene shields around the vent stacks, tucked them under the uphill shingles, and hope that’ll suffice.
The discoloration on the roof is getting worse, except downhill from the chimney’s copper flashing. You can see one of the ugly new black plastic vent seals over on the right:
Copper effect on roof discoloration
I suspect the copper ions kill off the fungus, so, invoking Science, I tucked a foot of copper wire under the ridge vent uphill from a patch of fungus:
Anti-fungal copper wire test
We’ll see if that makes any difference. I suppose the next time I’m up there I should tuck a strip of copper flashing under the shingle on the other side of the chimney to see if a bit more surface area will have more effect.
The switch on that screwdriver failed again, this time by having the internal switch mounting bosses disintegrate:
Cordless screwdriver – broken switch mounts
Not being one to worry about outside appearances, I simply drilled out the bosses to fit a pair of 4-40 screws, put the nuts inside, and it was all good:
Cordless screwdriver – switch with screws
Except that the switch now required an unseemly amount of force to operate in the forward direction. The switch is the cheapest possible collection of bent metal strips and injection molded plastic bits you can imagine, but with some bending and re-staking and general futzing around, it works fine again.
A gust of wind blew Mary’s bike helmet off the seat and, by the conservation of perversity, it landed on the mirror with predictable results:
Broken helmet mirror mount
I affixed the two ends with solvent glue, then epoxied a brass tube around them to stiffen it up. While I had the epoxy and brass out, I added a splint over a previous repair near the mirror ball:
Re-repaired mirror mount
After taking that picture, I heated and bent the remaining shaft just slightly to put the ball near the middle of its range. There’s no possible way this can survive this year’s cycling, so I must get cracking on building some durable mirrors. A 3-D printer should come in handy for something in that project!
The air conditioning in our Toyota Sienna van emitted some barely cool air during the previous heat wave, which was definitely new news and not to be tolerated. The sight glass showed white foam when running and nothing when stopped, but the compressor hadn’t locked out on low pressure yet. My guess was that everything still worked and that the refrigerant had just slowly leaked away over the last 11.5 years; nothing lasts any more, eh?
I consulted with my cronies and devoted a few hours to discovering that many seemingly qualified people don’t understand the notion of vapor pressure, but that a DIY recharge wasn’t exactly rocket science. Picked up a Harbor Freight manifold gauge (on sale for 50 bucks, less one of the ubiquitous 20% coupons = $40) and two cans of R134a plus a can tapper from Autozone. Parked the car in the garage and popped the hood to let things cool off overnight.
The never-sufficiently-to-be-damned Toyota engineers put the low pressure port far back on the inside of the right-side wheel well, where I can barely reach it by standing next to the car facing forward, reaching backwards with my left arm, easing my outstretched hand through the gap between the well and the engine, then feeling around to find and unscrew and not drop the cap. No, I’m not left-handed, I just can’t contort my right hand sufficiently to do more than touch the cap.
Aligning and securing the low-pressure fitting on that port requires far more agility and strength than should reasonably be expected from one’s weak-side hand. A pox on their backsides!
Anyway.
The static pressure started out at 67 psi in the morning, which is roughly correct for R134a in the low 20 °C range: chart or table. That’s a good sign indicating that the sump still had liquid refrigerant, confirmed by the myriad bubbles in the sight glass. Eyeball the outer ring of the low-side gauge to find the R134a temperature corresponding to the pressure on the inner ring.
Harbor Freight AC Low Pressure Gauge
That gauge shows whatever pressure was left in the hose after finishing the job a few hours prior to the picture. It seems the manifold / hoses / valves hold pressure quite well, which is not a foregone conclusion given Harbor Freight’s QC.
The sticker under the hood reports the AC requires about 3 pounds of refrigerant. That’s far more than most cars because the van also has a rear-cabin AC evaporator with one honkin’ big compressor for both.
2000 Toyota Sienna Refrigerant Sticker
I made the working assumption that if the AC still had some liquid refrigerant, it also had pretty nearly all the OEM oil. Most of the year the AC stays off, so I figure we’ve got a slooowww gas leak past the (usually) non-rotating seals driven by vapor pressure, all of which left the oil down in the sump. In addition, I haven’t the slightest idea if Toyota’s ND-OIL 8 gets along with the current PAG oil and adding too much oil seemed worse than having slightly too little.
The running pressures were 7 and 75 psi: grossly low.
So I fired in both cans of R134a: one with UV leak detector and another with leak sealer. That brought the pressures up to 20 / 120 psi: still too low, but at least air from the center vent now came out at 9 °C. The sight glass showed mostly foam, although with bursts of bubbly fluorescein green liquid. No leaks in evidence anywhere I could find without a nose-to-tail under-the-car inspection back to that rear evaporator.
Another trip (this time by bike) to the Autozone fetched a third can of straight R134a, which gradually cleared up the sight glass and got the pressures up to 35 / 150 psi, roughly matching the actual evaporator and condenser temperatures. I figured a few excess ounces wouldn’t do the least bit of damage; the three cans add up to 35 ounces of refrigerant, so the system was about 3/4 empty.
Early reports from the current heat wave seem encouraging.
The Smell of Molten Projects in the Morning 