bodger: (Kim Possible)
I was going through old family slides with the old family slide projector and noticed the focus motor was running continuously. I did some quick checks and verified that the bulb worked, but the mechanism wasn't moving. This is a known issue with these older projectors. I pulled the bottom off to have a look at the mechanism.

crumbly old plastic gears

At least one problem was obvious: the plastic gears were crumbling (this being a common failure mode).

the repair process (with pictures) )

bodger: xkcd android girlfriend arc weld cherry stem (Default)
The light for the clock in my car burned out. I looked in the manual to see what kind of bulb it took, but it just said “see dealer”. That seemed ridiculous, it was probably an ordinary wedge base miniature bulb like a #194, the sort of thing I might already have lying around. There’s no obvious way to change that particular bulb without taking the dash apart (maybe that’s why it said “see dealer”), so I took the dash apart, pulled out the clock, and had a look.

It turns out it’s a weirdie plastic twist-on bulb that apparently uses a notched hole in a printed circuit board as the “socket”.

clock and bulb

I don’t have anything like that in stock. So I walked down to the brand new Advance Auto Parts here in town to buy one. They looked it up and said those don’t normally burn out in a car only a few years old, and in any case, they don’t stock them and I’d have to get one from the dealer.

This did not exactly thrill me, so it occurred to me that I could probably find the bulb elsewhere, probably cheaper. But what was it? I didn’t have a type number or anything. Some research on the web revealed that there were a lot of people looking for this bulb, and that it was a Ford part number F5VY-13B765-AA (or perhaps F5VF-13B765-A or maybe E83Z-13466-A). There were a few mentions in the pages I found to this being an 80mA bulb, and that’s a believable current for a bulb like that. The existing bulb is marked “2W”, which might mean that it’s a two-watt bulb or it might not. There’s a chance that the E83Z bulb mentioned above is a 1.2 watt version. There’s also a chance that one of those isn’t a green painted bulb like the original. I don’t know.

I decided to try out the parametric search for light bulbs available on the Don’s Bulbs site. I could make good guesses at the glass type (T-1½), voltage (12-14V) and current (.08A), but what was that base? Happily, Don’s Bulbs has pages where you can search for bases by drawings. After peering at the “automotive” category for a while, I decided it was probably a “neowedge” of some sort, but couldn’t figure out which variant. No problem, the site lets you search on broad base categories, and even a vague type of base narrows down the huge pile of results nicely. The closest match I could find was a GE type 91646, which doesn’t seem to be available much any more. It does sport a B8.4D base, but I wasn't at all sure it was the right one.

I went back to searching the web, adding “neowedge” to my search terms. I found many more pages of people trying to find this bulb, and a bunch of pointers to LED bulb vendors. However, many people had bought the LED replacements, only to have them not work.

This gave me an idea - I could convert the existing one to LED myself and have it fixed the same day! I rounded up a blue LED and calculated that an appropriate voltage dropping resistor would be about 525Ω. Some rummaging around produced some 560Ω resistors, which should run the LED at slightly lower current, for a little less brightness and longer life. I crushed the burned-out bulb so I could solder the new parts to the resulting leads.

base, LED, and resistors

I then assembled the parts into something that should fit into the space occupied by the original bulb.

LED replacement assembled

I remembered the LED bulbs I had made for my pinball machine, which runs its bulbs on AC, so the polarity doesn’t matter. But my car uses DC, so any way I assemble it is likely to be backwards. Then I realized the base was symmetrical, so if it didn’t light, I could just install it the other way. I hooked it up to a power supply to make sure it worked.

LED replacement lit

Then I went to install it in the car. Unfortunately, it didn’t light. I pulled it back out to turn around, and saw that I had broken one of the fine wires. Rats!

I took it back inside, and attempted to solder the wire directly to the terminal, but without success. I tried every flux and solder I own, slowly melting the plastic base, but it was beyond me. I considered finishing building my tack welder, but that’s a biggish project and there’s a pretty good chance I would fry the LED in the attempt anyway.

Greatly annoyed, I called the dealer to see if they had the right bulb in stock. Naturally, they didn’t — and they wanted more than fourteen dollars for the stinking bulb! I reluctantly told them to order one and call me when it got in. They said it would be in by Saturday morning.

Back to the web. I noticed a lot of the references to LED replacements were to the same place, so I figured I’d have a look. They have a facility to look up bulbs by car make and model, but didn’t list anything for my clock. So I looked at their “automobile, instrument cluster and gauge, T1.5 Base - New-Wedge, B8 Type” page. After clicking around for a while, I saw they had some nice big clear mechanical drawings of the various bases, complete with 3D renderings. From this, it seemed that I had a B8.4D based bulb. They offer LED bulbs with this base in two brightnesses, and six colors, and they don’t cost much at all ($1.59 for the regular brightness). The original bulb had a green coating, but I thought red would be nice looking, and avoid impairing my night vision. I ordered one each of the red and green, in both regular and high power.

I went by the dealership on the way to Balticon on Saturday, but they had closed early for Memorial Day weekend. Fie on them.

The LED lights showed up in today’s mail.

LED from Super Bright LEDs

I popped the regular brightness red one in, it fit perfectly, and lit on the first try. I’m looking forward to seeing it at night. As for the dealer, I still haven’t heard back from them, and at this point, I no longer care about their overpriced bulb.

bodger: (What terrible problems you have)
As I'm susceptible to kidney stones (I've had a few), I live in the "kidney stone belt", and the water here in P'ville is laden with minerals, I distill my drinking water. I use ordinary countertop stills that can process a gallon at a time. I wear them out. I think I'm on my third or fourth one at this point. However, I don't tend to give up the first time they break down. The current one started making unhappy fan noises a while back. For a bit, we could get it to shut up by whacking it just right while it was running. Then it was time to take it apart and have a look. This was delayed by the need to find a long, thin T-10 driver to get at the deeply recessed screws holding the thing together. The fan motor is the usual common shaded-pole synchronous fan motor. However, for use in this unit, a fairly specific type would be required (constrained by width, height, lamination thickness, shaft length and diameter, and connector type and orientation). And the lam thickness isn't a common one, this is a pretty thin motor. However, the fan is just a (tough) press fit on the shaft and the bearing assemblies (cheap sleeve bearings) can be removed by simply removing their mounting screws. So I took the thing apart, cleaned the grime off the shafts, lubricated everything, and put it back together. Worked a treat.

That was maybe a year or two ago. Recently, it developed a new quirk, where it would leak water all over the counter. It wouldn't do this every time, and some of the water ended up in the pitcher where it belongs, but it was enough of a leak to make a thorough mess of things. When I had enough time to watch it closely in operation (the cycle time is a few hours, and it didn't always leak), I was able to tell it wasn't any of the external seals, it seemed to be leaking from within the mechanism. So I finally took it apart and carefully studied the steam/water path. I figured it was sealed all the way down and a seal had failed. Nope, it's not sealed. There's a riser tube, an L-shaped plastic connector tube, the spiral heat exchanger, which drains into a plastic assembly integrated with the pitcher-detector plunger/switch. At first, I suspected the connector tube, which felt as if it may have cracked along a seam. I snipped off the tie-wraps and had a close look, and realized two things. One was that it wasn't cracked. The other was that there's a neat hole drilled in the top of the heat exchanger. It isn't pressurized, and is designed not to be. A good idea – see the Mythbusters "exploding water heater" episode for a graphic depiction of why (the high speed footage of the water heater pretty much destroying a whole house really drives the point home). I opened up the plastic assembly and saw that the lower end of the heat exchanger is simply positioned above the top of the output assembly; it's open to the air and drains into it by gravity.

Hmm, not obvious what's going wrong. The design isn't what I expected, but everything seems to be in place. So reassembled it, except for the top cover, plugged it in, and watched it carefully while it was running. Eventually, I could see steam in the L-tube, and then water coming out of the heat exchanger, but there was a longish delay before it actually came out into the pitcher. Curious. But no obvious leaks. I carefully jiggled and poked things (mindful of both the hot steam and exposed mains voltage), to no avail. So I kept watching, and sure enough, I saw some water start to dribble out of the ring vents around the output assembly. That isn't supposed to happen. So I opened it back up (which deactivated the pitcher-detect switch), hot-wired the switch, and waited for it to heat back up.

The water started to dribble into the output cup, as expected, but started to pool up. Odd. Why would the water pool up? It should just go to the lowest point and run out.

Then I finally realized what was actually going on. There's a little gasket at the bottom of the output cup that the pitcher detect plunger engages to shut off the water if you remove the pitcher while the unit is running. What I had missed was that the gasket was supposed to stay with the plunger, not sit on the output opening! In that position, it blocked the output, and the pip on the plunger (that's supposed to hold the gasket) merely plugged the hole in the gasket (the plunger doesn't rise very far). To put it back to the original configuration, I'd attach the gasket back to the plunger. But it's made of one of those "low surface energy" plastics that's difficult to adhere to, which likely led to the problem in the first place. What if I just removed the gasket? The water would have a clear path to drain, the pitcher detection switch would still work, it would just leak water if I removed the pitcher while it was running. No problem, neither Andrea nor I do that anyway. So I left the gasket out, reassembled the thing, and fired it back up.

It shut down after maybe a third of a gallon. NOW what was wrong? Oh right, we had shut it down partway through because it was leaking, and emptied the pitcher. The boiler only had part of a gallon to start with. So I refilled it, set it running, and observed it until it started dispensing water into the pitcher like it's supposed to. Seems to be working again, yay!

May 2017

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