New paint; a stark contrast, illuminated.

Decided to rub down and repaint the fenders on the bike. I had never been very fond of the gray/white color scheme and with the addition of the gloss black fuel tank it started to look out of place. Plus, the white paint was beginning to look in poor condition from being stored out in the elements for years.

DA sander

Started with some 120-grit paper on the DA sander to take the old paint down to a good surface and provide a key.

rubbed back

Once rubbed back it was wiped clean. The paint is really very thick and has protected the metal well.

gloss

Gave the fenders each a couple coats of rust-protect gloss black paint and left them hanging to dry.

polish

Between times I decided to see how the exhaust pipe would react to a bit of polish. As it turns out, really very well.

reassembled

Moved the rear light to the back of the rear fender and reassembled everything. Just needs the handlebars rubbing back now and painting up (again, black).

as-was

It’s quite a difference from how the bike started out. This is a picture of it a few years back.

mag

Next, I turned my attention to the lights. The magneto stator was meant to come with two windings, but only arrived with one. I ordered a replacement but that arrived with one winding and two wires soldered to the output. Utter nonsense.

generator stator

Bought an extension piece to the stator that turned it from a horse-shoe shape into a full hoop with a second winding to generate power for lights.

illumination

At a fast idle it creates enough energy to light the 4.5W bulb in the headlight. I might end up doing what I did not want to and fitting an LED lamp to it instead, as it is significantly more efficient and should power from the generator acceptably from idle on up.

Computer stuff and a motor assisted bicycle

I got fed up of having a mismatched set of drives and a hole in the front of my TRS-80.

neat and tidy

This prompted me to go find some software and find a way to transfer files to and from the TRS-80. Turns out running an emulator, using it to convert binary files to hex, transmitting them across serial and converting them back works well.
Also, on a plus note, have managed to get a word processor software working and printing properly. Real proportional print on the old daisy wheel printer!

snow

It snowed. This prompted good “out in the garage” type work, as it was pleasantly cool.

pile of parts

I decided to try a bit of a fun project. Bolted an engine to my bicycle. A few things needed a bit of ingenuity- the sprocket at the back is clamped to the spokes between two discs of rubber. That pushed it too far out and didn’t let the brake work (hub brake on the rear wheel).

rag joint

An afternoon of adjusting and tinkering and setting up and I got it to run.

motorized

50cc, 1.5hp.. geared to do about 20-25 tops. Decided it needed a speedometer. Ordered an old-fashioned mechanical one. Decided I did not like the face that was on it so redesigned it, in the style of 60’s BMC Smiths gauges.

gauge design

Printed out rough draft and compared to the one it came with.

faces

The gears also had no lubrication, instead relying upon the nylon being inherently slippery- that only works for a short while, so added some silicone grease to try extend the lifespan of them a little.

face

Mounted the face, decided it looked well enough. Painted up the center of the needle with silver paint.

spray paint

Finish is acceptable. Not mirror but certainly shiny.

shiny

All finished up, looking better than it did.

speedometer

Took a while to calibrate, and it’s far from accurate but it’s good enough for the job it’s doing. Also, pulled the trip reset dial off and blanked it, turning it into an odometer.

black chain guard

Painted the chain guard up, made a few adjustments to the way the chains route.

lens

Bought a light set for it, the front lens was all hazy. Polished it up so it was a lot clearer.

clear

All back together it looks a fair bit better.

lamp

All attached to the bike, adding to the look and usefulness.

lights

Next up is an engine driven generator, switchable to the wheel generator. Might add a battery in there someplace but for now it’s all AC lights.

Processor and a monitoring panel (plus holiday oddments)

After the previous discovery that the -12V rail was collapsing under load, I read up on the datasheet for the 8080A processor. It states that the voltage rails must be brought up in a particular order (-5, +5, +12) and if the -5 is missing then there’s a very high chance of damaging the processor. The 8085 negated this and required a single, positive power source- the 8080 has strict requirements.
The 4116 RAM states that it should be brought up with the -5 first then the +5 and then the +12 but any of the rails missing should not cause damage to the chips. Bonus there.
So, I decided just to fling a processor at it. For $4 a pop, I decided that it was worth a shot, having fixed the power supply.

8080A

Same behavior upon power-up. At least I have a couple spares now.

repeating trash

Pulling the video RAM does show a different pattern on the screen so that at least is moderately positive- it initializes the memory in the same fashion each time it it switched on. Pulling the CPU and I/O cards and powering up the video card only liberates a solid beep, no crackling warbles.

voltmeter

Bought some little voltmeters from China- self-powered with internal self-regulated reference. They work from about 2.5 Volts all the way up to 30 which is impressive.

contrast

Also, bought some red transparent acrylic to serve as a mounting plate and to act as a contrast-improving device for the displays.

cut out

Marked up, cut with a hacksaw to size and sanded down smooth. Gently heated it up with my butane torch and bent it into a shape that stands up by itself.

measured

Measured up for the meter locations, drawing the positions on the front in Sharpie.

pva

Spread a thin layer of PVA glue on to each meter. It’s nice because it dries clear and doesn’t attack the plastics.

row of meters

Five meters stuck on and waiting for the glue to dry.

heat shrink

Trimmed the wires down to length and soldered on a length of multi-core wire, and using a spoon as a heat shield, added some heat shrink tubing to each join.

clips

Soldered some test leads onto the other end of the cable and marked them up as to which is which.

plugged in

Got everything hooked up onto the appropriate locations on the PSU.

meter on

With a few labels to show what’s what (and a couple others because I got carried away) the output of the PSU is monitored fully. Everything is in spec, all loaded down with all boards fitted. Now that I have this set up, I’m happier in the knowledge that everything is doing what it’s meant to in terms of power.

Next up, pulling it all out of the chassis to get the analyzer clipped on properly.

new light

Back to the house, I bought a new 4′ Lithonia light fixture to replace the junky Lights of America one that refused to light one tube and barely lit the other. Wired it up, fitted the old 25W tubes and flicked the switch. Nice bright light with instant start, too.

recapped tv

Recapped a TV for someone at work. The ventilation grilles at the back had become lodged with dust due to the location it was kept in (TV stand with no access to the sides) and as such, had cooked itself. Uprated the heat ratings of the replacements (all the originals were 85C, the new ones went in all 105C with a few in really warm locations at 135C) and ran it for an evening. Worked well.

Jeep

Traded the Challenger in against a new vehicle- Jeep Grand Cherokee. A bit more practical than ferrying the family around in a 2-door muscle car.

drip drip

Changed the ignition amplifier in the Renault and also a new distributor cap and arm, along with the crank position sensor. The CPS was at fault causing the non-running but the ignition amp appears to have been a bit marginal because it has a lot more torque now. Also, the power steering has stopped leaking and is holding fluid. The gearbox is leaking though, along with a weep of coolant onto the exhaust manifold that I need to find the source of because it smells when I start the car up. Other than that it is actually working moderately well.

Eighty-Eighty

I decided that I had wanted to give myself a little bit of mental exercise so I started work on the Lanier again.

Lanier on table

This began by dumping the thing on the table, pulling the CPU card out and trying to begin modeling its schematics in KiCAD. This is slow, problem-riddled (the board traces go back-front-back-front and are difficult to follow).

Made a decision to power it up after far too long sat up doing nothing. Pulled the PSU out and brought it up slowly on the Variac.

slowly, slowly

Same old nonsense, the thing didn’t do a whole lot of anything to begin with, a bit of a beep, floppy drive lights on. Hooked it up to my new logic analyzer on what looks to most likely be the bus on the backplane.

logic analyzer

There’s a bit of life, and the behavior begins to change. The floppy drives begin to clatter and rattle. I solder a bypass onto the video card to make the screen always show what’s on-screen (blanking bypass) and it’s got some nonsense changing here and there, occasionally filling the screen with alternating patterns.

logic traces

The logic traces look “dirty”, there’s a lot of glitches and the machine in general seems rather unhappy.

omooikkiakka

Some of the random content on the screen can be moderately amusing though.

Right around this point I was contacted by a guy in Ireland who used to service these things, still has one, schematics, discs and spares- everything I thought I’d never got for it. He says it’s a real early model with the screws holding the case on at the sides (probably circa 1975).
His suggestion was check the power supply, because random freaking-out type behavior is normally bad power.

power

I pulled the PSU and checked the voltages present. Everything was where it was supposed to be. Plugged the boards back in and same problem. Started to probe voltages on-load and found that the -12V rail had dropped down to +0.4V which is rather odd. Put a light bulb across the rail- it flashed then went out. Pulled the video card out and the rail stayed stable.

Zener

The RAM in the machine was all 4116, which requires +12, +5 and -5V supplies to work. I had replaced the CPU board with 4164, which needs only +5 so that cuts down on heat and current requirements significantly. The video board still uses 4116 so would definitely not be working without -5, which is derived from the -12 rail. The circuit is rather simple, a diode to the -12V rail, through a 330 Ohm resistor and the other side of that held to a stable voltage by a 5.1V Zener diode. I pulled one leg of the Zener off, removed all the RAM chips and put the video card back in and powered the machine up. The screen filled with [] symbols, which was expected as the RAM is not present and all lines would remain at zero. The -12V rail stayed stable also so the Zener was suspect. I’ve had them fail in the past and turn into almost a dead short. Found a temporary replacement in my box of stuff (half the Wattage rating but OK for a temp try).
Back into the chassis and still the -12V rail collapses. Start tweaking the crowbar adjustment and manage to get it to an unhappy -11.5V before it would just trip out over and over. Turn the PSU over.. and the -15 rail, which the -12 comes from.. is the only line I’d not replaced the main filter capacitor on.

capacitor

It’s all leaky up top, the vent is showing signs of having vented out. Not good. That’s most likely going short, drawing too much current and when the boards are added to that draw, the over-current crowbar is kicking in and shutting the rail down.
I had a dig and find a 15000uF, 50V capacitor with clip lugs. Soldered that in on short flying leads and powered the PSU up. -12 rail is at 12.04V, -15 at 13.3 unloaded so I adjusted them and then hooked up the computer boards. Made a slight tweak to all the voltages and got them within 0.01V stable.

There’s still something that’s not happy because switched on cold it beeps (with a somewhat crackling warble modulating the beep) and the drives click. Once it’s been on for a while it begins to not beep any more and it still goes a bit haywire but at least now I know that the main supply is good. I need to order the correct screw-in capacitor and a higher Wattage Zener for the -5 rail supply on the video card, but this is positive progress.

Mac back on track

Despite the little set of ceramic capacitors I put in having a combined value in an acceptable range for C1, it would appear they were either breaking down or otherwise incapable of sustaining the horizontal frequency of the screen scan.

caps being meaured

So, a different set of capacitors was used and that brought the screen back to life.

working again

That appears to overall conclude the work on this machine.

Broken Macintosh

Very short-lived, this one. I took everything apart and adjusted up the screen so it was central.

Nice and even

Set it on the side to do a bit of a burn-in test, and the decoupling capacitor for the horizontal yoke let out all its magic smoke, the screen went a bit funny and I switched it all off quickly.

c1

Decided to build the little capacitor network suggested in the manual, of several ceramic capacitors in parallel to build up the capacitance but reduce the ESR.

c1c1c1c1

Put it back together and again we have screen but.. the horizontal isn’t aligned any more. The two interlaced pieces of the screen, all stretched out – do not line up.

interlaced

I’m going through the schematic, I’ll check all values and make sure that the capacitor failing did not draw too much current through the flyback and fry one of the windings.

Rejuvenated Macintosh

I decided that the wobbly-screen Macintosh needed to have a bit of work done to make it a bit more trustworthy and reliable. The electrolytic capacitors had been installed in it since 1985 (8113th device produced in the 24th week of 1985 in Fremont, per the serial, so a real early 512k).

mac on table

Took it to pieces after ordering a bunch of spares (total about $15, so not bad), with the replacement caps rated at least one voltage rating over what was fitted and 105C rather than 85C as fitted originally to try and keep them a little more stable.

logic board

Not many capacitors on the logic board, though it is a 4-layer PCB so extra care had to be taken. I’ll give them this, it’s a well made PCB.

logic board closeup

Tried to keep the solder-work neat. Don’t think I did too bad a job, to be honest.

work in progress

Got stuck in doing the power and sweep board, which has the majority of the capacitors.

powered up

First test, and things were promising until the brightness control decided to stop working.

broken brightness pot

Turns out the center carbon track had completely fallen apart. Checked the schematic, fairly standard 16mm 1MOhm linear pot, so went on the hunt for something similar in the electronics catalogs online.

new pot

Closest modern variant I could find. The board is the right size and the connecting pins the correct length, important in this application because of the way the computer is assembled.

take apart

Carefully undid the new piece, as the thing was essentially backwards from how it needed to be.

sweep

This side is where the old one had the handle coming out. I removed the crimped section and split it all down, had to file the ears of the board a little to make it fit but managed to put it back together again, and have it test good and smooth operation across its range of travel.

reassembled pot

Put that back in the circuit and the brightness is now adjustable again. Checked the voltages and the 5V rail (the master) was a bit low at 4.72V so that was tweaked up to 5.00V. The 12V rail, slaved from it sat happily at 12.2V so that’s all well within limits.

5 volts

The screen became a bit intermittent- traced that eventually down to a couple broken solder joints on the connector to the end cap of the tube.

broken joints

Removed the old solder and re-added new.

working now

All up and working again. Need to adjust the centering of the screen a little, I think I must have knocked the centering rings when I put the wiring back in. Overall, a lot better than it was.

Centrifugal.

The Renault had been making some unhappy noises from the engine bay recently, bad bearing kind of noises. I drove it to work and back and on the way home it decided to buck and jolt badly, feeling like a bearing jamming up (more on that later).

old pump

After having to purchase an 11mm wrench (not a real size, why it’s used is beyond me) I removed the water pump. Due to the design, it was impossible to remove by hand, as the bolts undo and the pump came off with a gentle tap, but the impeller got stuck in the aperture with the pulley wedged against the frame rail. A bit of wiggling and there was 1/8″ holding it back so a thump from the bottom of the mallet handle saw it liberated onto the floor.

coolant

I’m quite impressed by the coolant. It’s very clean, all things considered. This is a good thing.

water pump removed

Water pump aperture, including original gasket, which probably could have stayed, in hindsight. Note the really large space to work in (by general Renault standards, at least. I can get my hand in there and even see what I’m doing. Luxury).

gasket scraper

Spent an hour swearing at the old gasket, which was particularly awkward to remove.

no more gasket

Eventually it did come up clean. I’m just glad the block is cast iron because the angle I was forced to work at with the blade would have scratched and taken chunks out of any softer metal. Surprisingly also, the pump housing is remarkably rust free where the impeller spins, so I’m guessing this coolant does have some anti corrosion properties.

new pump

The new pump came with a new gasket (which didn’t fit very well, the holes didn’t line up properly) and has a different impeller design. Previous one was a pressed steel affair which was effective enough, had 4 vanes. This one is cast metal and has many more (and upon actually having run it now, pumps a much higher volume of coolant, particularly at idle).

sealant

Gave the gasket a coating of sealant and installed the bolts, which were held in place by the gasket (useful side effect of the holes not lining up well).

pump in place

There was a moderate period of jigsaw/Jenga type thought and experimentation that occurred before the pump went in. In the end, the bolts had to be in place, the pulley had to be on the shaft but not attached so the pulley could wobble about enough to allow access to put the pump in place. Thankfully there’s enough room to see one bolt past the frame rail and also space to stick a locking rod so the pulley bolts can be tightened.

alternator bracket

Then it was time to put things back on! Alternator and aircon compressor bracket assembly first.

alternator

Alternator with top adjustment bracket.

compressor

Finally, aircon compressor and belt, which took a while to remember which way round all the pulleys it goes.

battery

Finally, the battery tray and battery went back in. Filled up the coolant and let it burp as best it can with the engine off.

grubby

Been a while since I’ve had grubby hands, made a change from moving boxes and furniture.

running

Finally, all buttoned up, topped up and running. Aircon even works still, which is nice. There howling bearing noise is gone, but initially it was still bang thump, kangarooing and running intermittent badly on the test run. This was traced back to a rubber bungy that had split and fallen off one of the big spigots on the brake booster. Replaced that with a short length of pipe with a wire nut stuffed in the end because that shouldn’t split now. Normal, smooth running resumed. This fuel injection system really doesn’t do well with vacuum leaks at all.

It’s nice to have it back on the road, even if the front brakes are now sticking because they’ve not been used. Next job, that.

New Arduino Project – matrix LED display

I salvaged a couple of displays from some old equipment that was being thrown away. Pulled up the datasheet and started trying to make my Arduino Uno display things.

gibberish

After bit-bashing in some dots, I managed to get it to correctly display a letter, this case a lowercase “a”.

a

Now it actually works- I’ve made it scroll text input from the Serial port, full ASCII table. 3.8kb of code, not bad compiled from C.

nmmm

The above was from a leafed/paged test of the full ASCII table I made it loop.