Initially introduced at $999 body only this was a prosumer camera back in 2006. Later years and up today photography comunity members started to report a ERR message in their cameras top display (in the shutter speed field). This error is commonly associated to the mechanical parts of the camera (shutter, diaphragm and mirror) being not properly in sync.

I have already fixed 3 cameras with these flaws. These cameras where brougth to me as for parts/teardowns so I decided to publish a small guideline on how to fix them.

Nikon D80 and the main mechanics

Seems that this specific model of Nikon had two major flawn that made the mechanics out of sync. Maybe the fault comes from the design, maybe comes from quality control. The flawns are:

Main motor pinion gets broken. This makes the pinion too loose so the motor spins without transmiting it’s force to the mecanism and rotating in void. The main electronics detects no action in it’s sensors despite givin the command to spin the motor, hence produces the ERR message. This is fixable by carefully removing the pinion, putting a smal drop of SuperGlue in the motors shaft tip then pushing back the pinion.

Nikon D80 main motor pinion broken in half

Mechanics encoder loses one brush fixing. The mechanic rotatory enconder is the electronics main sensor of the mecanics position and travel. It’s made of a gear that has a fixed brushes against a PCB board where makes it’s contact. The brushes are fixed by a plastic welding that brokes with passing time. The brushes then missaling or makes no contact at all. Electronics loses perception of the mechanics travel and position and then drops the fatal ERR message. This can be fixed with a small drop of superglue in the affected/broken plastic fixing (in this photo, the right side one).

Mechanics rotatory encoder with one broken/loose plastic fixing.

I recommend to let dry the superglue at least 1  hour before trying the fix. You can start assembling the camera inmediatly but is best for all to let it totally dry before inserting a charged battery to try it out.

Any of these flaws renders the camera unusable. Fortunally both flaws are relative easy to fix, but both requires a lot of careful dissasembly to be able to get to the afected parts. I recommend to follow the help this Nikon D80 service manual and use a welder when the disassembly requires to unsolder some wires.

Nikon D80 main mechanics, motor removed. The main encoder can be seen below, being the grey gear.

This is my last week project: a Simple Yet Powerful Handheld CO2 Meter. SYPHCOM (name in progress ..)

The use for a portable CO2 meter is to be able to measure air quality in closed spaces (i.e. the office). The higher the number (usually above 1200~1500) the worst ventilation, which means higher chances to get
the Covid-19.

CO2 Meter Front View

With this is possible to know when is time to open the windows and ventilate.

It’s main guts are:

• Arduino Pro Micro, Leonardo Atmega32u4 based.
• SenseAir S8 LP CO2 sensor.
• Vintage HP HDSP-2000 ceramic LED matrix display, manufactured week 20 year 1984. NOS.

Back view of handmade CO2 meter

The capacitor stands for when the CO2 sensor does a read cycle (every 2s): both the display and the SenseAir S8 uses so much power that you can see the display and leds in the Arduino Pro Micro sighly dim off when powered from standard USB 0.5A when a read is made in the SenseAir CO2 Sensor. Without the capacitor, the arduino can’t stand for the display refresh and does a glitch in the display.

CO2 Meter glitch

Also there’s a UDN2981A source driver to drive the columns in the HDSP-2000 display and a small momentary press button with 10K pull down resistor to launch sensor callibration if pressed on powerup (use with caution!!).

CO2 Meter first working stage

The components that makes it portable are:

• Lithium battery charger (Like this one).
• Recycled Li-Po cell (250mAh)
• Pololu s7v8a adjustable step-up DC-DC (adjusted to 5V).
• Switch.

Making CO2 Meter porable with lipo charger and battery

I use the same components to make projects portables. The good thing about the pololu s7v8a is that it is both a step-up and a step-down DC-DC converter. This is handful if a project work 3.3v as it will give 3.3v always even if the battery is reading 3.0v. Unfortunally the recicled 250mAh battery is not much for the power needs so only lasts 30m on thi battery cell.

CO2 Arduino HDSP-2000 SenseAir Schematic

Code available here.

In the video the leds seems to be dimmer than they really are because of the high light, but actually they are pretty much visible.

Overall all makes a nice looking portable and easy to use CO2 meter and Covid prevention tool in closed spaces.

I had lying around an expired RSA SecurID with the typical blank display only showing a small 3 in the right.

Looking for some info about expired tokens I found an old topic at flickr (original URL here) where Travis Goodspeed managed to revive one the tokens with a simple trick: apply 3v for a second in two of the pads behind the protective plate.

Here is the diagram:

Expired RSA SecurID Token Revival Diagram

Here the revived Token:

Expired RSA SecurID Token Revived

The token was expired since november 2011 but still got battery to keep working.

I Haven’t tested if token still is valid to autenticate against RSA daemon after revival.

This is a donation of a friend as its not working. Actually this kindle 3 stop working when booting, hence the reason that shows the booting load bar.

broken Kindle 3 Front

I tried to search for onboard blown fuses but every single fuse I found was in good condition. After that I researched over internet and found that has a debug serial port. I tried to attach my usb to serial ttl converter with a little level shifter (kindle serial port works in 1.8v) but had no luck, not even a single character was shown in my Zterm :(

broken Kindle 3 Back Opened

I wanted to install debian to see how the display could work and some few hack I’m thinking of but being the board pretty much dead (only seems to work for its battery charging) I decided to save it for parts as battery, case, metal frame, keyboard and display seems in good working conditions (although I’ve not been able to test them properly). If some generous reader has a kindle 3 with a broken display and he/she is willing to donate it to science I’ll be more than happy to pay the shipping.

One of the difficult parts when prototyping is to find reliable power sources. Today is still hard to find the battery size we want to use because country exporting frontiers stops these chemical packages. Here I’ll show how to refurbish dead batteries by combining cells and protection circuits to preserve battery life.

An (almost) dead Apple MacBook Pro (17″) battery fell in my hands so I decided to tear it down to see if there was something profitable. Inside I found that the battery pack was composed with 6 individual cells, paired in 3 groups.

Apple Mac Book Pro 17" Battery Disassembly

Seems that the third group had a small voltage difference between cells so they began discharge between them. This leaded both cells to die, condemning the entire battery pack.

Here can be seen the individual cells:

Batteries separated from the main board.

As can be seen the cells doesn’t have individual protection circuits witch are important to avoid discharge below 2.7v to preserve battery life.

I also came across with a small photo-frame that I bough just for hacking fun as is really a bad piece with almost no memory, no SD card expansion, 128×128 display and bad electronics. It cost me 1.99€ and the battery was drain dead from the first moment I opened the package.

Small and dead LiPo battery with the protection circuit.

It was inflated and reading 0.26v. Obviously battery couldn’t be rescued, but I salvaged the power cutting circuit. Here is the reverse side of the protection circuit board. Notice the polarity when soldering the LiPo cell and wires:

LiPo Battery protection circuit downside.

Once I soldered the protection circuit board to the Apple battery cell I ran some charging and discharging tests to ensure the assembly works fine and that power is cut at 2.7v:

Working Refurbished Battery